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Electrochemical Study Of Catechol In Presence Of Sulfanilic Acid And Diethytamine At Different Ph
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2015-12) Uddin, Md. AIim; Motin, Prof. Dr. Md. Abdul.
The electrochemical behavior of catechol in presence of diethylamide and sulfanilic acid & catechol in presence of sulfanilic acid + diethylamide have been studied by cyclic voltammetry, controlled potential coulometry, differential pulse voltammetry and chronoamperometry techniques using Glassy carbon (GC), Gold (Au) and Platinum (Pt) electrodes. The voltammetry studies have been carried out in variation of catechol, diethylamine and sulfanilic acid concentration, buffer solution of different pH, different electrodes and scan rate. Upon addition of diethyl amine and sulfanilic acid in catechol solution at the second scan of potential a new anodic peak appeared at the negative potential and the reduction peak shifted with respect of pure catechol. Also the anodic and cathodic peak current decreases significantly compared with the pure catechol that indicates the participation of reaction of o-benzoquinone with diethylamine, sulfanilic acid and their mixtures. The products generated from the reaction of catechol with diethylamine and sulfanilic acid are assumed to be 4-(diethylamino)-benzene- I ,2-diol, and 4-(bis(3,4-dihydroxyphenyl)amino) benzenesulfonic acid, respectively that undergo electron transfer at more negative potentials than the catechol. The electro-synthesized products originated from catechol with diethylamine and sulfanilic acid were isolated. The formation of new products was also confirmed by FTIR spectra. The effect of pH of catechol in presence of diethylamine and sulfanilic acid were studied by varying pH from 3 to II except sulfanilic acid 2-9. For diethylamine, it is seen that at pH 3-5, no new anodic peak appeared after repetitive cycling. In the pH 7-1 1, the o- benzoquinone undergoes nucleophilic attack by the amines that voltammetric new anodic peak A0 appeared after repetitive cycling. In contrast, for sulfanilic acid at pH 9 no new anodic peak appeared after repetitive cycling. Whereas in pH 7, the voltammogram shows a small peak. For diethylamine, the maximum peak current is obtained at pH 7 but the maximum peak current of sulfanilic acid is obtained at pH 3. The slopes of the peak potential, E vs pH plot was determined graphically as the anodic peaks of catecholdiethylamine (69 mV/pH for first anodic peak A1mV/pH for appeared peak Ao) and catechol-sulfanilic acid (36 mV/pH for first anodic peak A1 or 38 mV/pH for appeared peak Ao) at 0.1 V/s. This indicates that the oxidation reaction of catechol-diethylamine adduct proceeded via the 1e71H process whereas catechol-sulfanilic acid adduct proceeded via the 2ei2H processes. This also suggests that during the reaction not only electron but also proton are released from the catechol-amine adduct. The reaction was strongly influenced by the pH as well as concentration of diethylamine and sulfanilic acid. The reaction was mostly favorable in 250 mM of diethylamine with fixed 2 mM of catechol at pH 7. The reaction of catechol in presence of sulfanilic acid was favorable in 2 mM sulfanilic acid, 2 mM catechol at pH 3. The electro-oxidation of catechol-diethylamine adduct are facilitated in neutral media whereas catechol-sulfanilic acid in acid media. The scan rate effect on cyclic voltammogram of catechol in presence of diethylamine and sulfanilic acid were also studied. The peak current of both the anodic and the corresponding cathodic peaks increases with the increase of scan rate. The nearly proportionality of the anodic and corresponding cathodic peak suggests that the peak current of the reactant at each redox reaction is controlled by diffusion process. The current function for anodic peak A0, (I/v) of catechol-diethylamine derivative was found to be decreased exponentially with increasing scan rate. Catechol-diethylamine derivatives have been found to undergo electrochemical reaction with ECE (electron transferchemical reaction- electron transfer) type mechanism. But, the current function for the anodic peak A0, (I1,/v) of catechol-sulfanilic acid derivative was found to be decreased with increasing scan rate and such a behavior is adopted as indicative of an ECECE type mechanism.
Studies on Heavy Metals in Fruits of Samta Village of Jessore in Bangladesh
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2015-12) Rahim, Md. Abdur; Morshed, Prof. Dr. Mohammad Hasan
Various fruits such as Mango (Mangifera indica L.), Jackfruit (Artocarpus heterophyllus L.), Guava (Psidiun guajava L.), Hog plum (Spondias dulcis L.), Carambola (Averrhoa carambola L.), Pomelo (Citrus grandis L.), Lemon (Citrus limon), Wax apple (Syzygium samarangense), Papaya (Carica papaya L.), Coconut (Cocos nucifera L.) and Sapodilla (Manilkara zapota) were collected from Samta village of Jessore district of Bangladesh, and screened for arsenic, manganese, lead, cadmium and chromium by Atomic Absorption Spectrophotometer (AAS). The average moisture contents in soil and fruits were found 11.90±0.19% and 80.10±12.92% respectively. The mean concentration of arsenic in irrigation water, soil and fruits were 0.51±0.17mg/L, 8.40±1.73mg/Kg and 0.206±0.14mg/Kg respectively. Maximum concentration of arsenic in irrigation water, soil and fruits were monitored 0.78mg/L, 11.31mg/Kg and 0.53mg/Kg respectively. Minimum concentration of arsenic in fruits was 0.10mg/Kg. In case of irrigation water, arsenic concentration was higher than that of standard (0.100mg/L) value of Bangladesh. The concentrations of arsenic in soil and fruits were observed somewhat less than that of standard value recommended by WHO. The average concentrations of manganese in irrigation water, soil and fruits were found 0.10±0.03mg/L, 269.14±20.71mg/Kg and 4.96±4.28mg/Kg respectively. The maximum concentration of manganese in soil and fruits were 296.82mg/Kg and 12.83mg/Kg respectively which were lower than that of standard value recommended by WHO, EU and BADC. The presence of lead, cadmium and chromium was not found in water, soil and fruits in this study area. In our research, 120 people were monitored for calculating the consuming of arsenic and manganese through daily intake of fruits and their health risk factor was analyzed. The average age, body weight and daily intake of fruits per person per day were 35.04±14.55 year, 60.77±8.62Kg and 263.20±166.73g respectively. Average 0.0018mg of arsenic and 0.055mg of manganese was consumed in each person (61Kg body weight) per day which was lower than WHO standard for arsenic (0.002mg/Kg body weight) and manganese (0.033mg/Kg body weight) intake for human body.
Voltammetric Studies of Paracetamol with Some Functional Amines at Different pH Media
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-02) Rahman, Md. Hafizur; Motin, Prof. Dr. Md. Abdul
Electroactive paracetamol adducts such as paracetamol-diethylamine and paracetamol-diisopropylamine were synthesized electrochemically. The products has been studied by Cyclic voltammetry (CV), Controlled potential coulometry (CPC), Differential pulse voltammetry (DPV) and Chronoamperometry (CA) techniques using Glassy carbon (GC), Gold (Au) and Platinum (Pt) electrodes. The studies have been carried out in variation of paracetamol, diethylamine and diisopropylamine concentration, buffer solution of different pH, different electrodes and scan rate. After the insertion of diethylamine and diisopropylamine in paracetamol solution at the second scan of CV potential, new anodic and cathodic peaks appeared at the negative potential. In the presence of nucleophiles with paracetamol as Michael acceptors the oxidation and reduction peak shifted with respect of pure paracetamol. Also the anodic and cathodic peak current changes significantly compared with the pure paracetamol that indicates the participation of reaction of p-quinoneimine with diethylamine and diisopropylamine. The products generated from the reaction of paracetamol with diethylamine and diisopropylamine are assumed to be N-(3-(diethylamino)4- hydroxyphenyl)acetamide and N-(3-(diisopropylamino)-4-hydroxyphenyl)acetamide respectively that undergo electron transfer at more negative potentials than the paracetamol. The influence of pH of paracetamol in presence of diethylamine and diisopropylamine was studied by varying pH from 3 to 9. For diethylamine and diisopropylamine, it is observed that at pH 3-5, no new anodic peak appeared after monotonous cycling. In the pH 7, the pdienone endures nucleophilic attack by the amines that voltammetric new anodic peaks A1 and A2 appeared after monotonous cycling. Whereas in pH 9, the voltammogram display a new peak at the first scan of potential. In lieu of diethylamine and diisopropylamine, the maximum peak current is observed at pH 7. The slopes of the peak potential, E vs pH plot was determined graphically as the anodic peaks of paracetamol-diethylamine (37 mV/pH for first anodic peak A3) and paracetamol-diisopropylamine (23 mV/pH for first anodic peak A3) at 0.1V/s in the cycle. This ascribed that the oxidation reaction of paracetamol-diethylamine and paracetamol-diisopropylamine adducts proceeded via the 2ei2H process. This also indicates that during the reaction not only electron but also proton are released from the paracetamol-amine adduct. The reaction was strongly influenced by the pH as well as concentration of diethylamine and diisopropylamine. The reaction was mostly favorable in 150mM of diethylamine and 150mM of diisopropylamine with fixed 2mM of paracetamol at pH 7. The electrochemical reaction of paracetamol-diethylamine and paracetamol-diisopropylamine adduct are facilitated in neutral media. The effect of scan rate on cyclic voltammogram of paracetamol in presence of diethylamine and diisopropylamine were also investigated. The peak currents of both the anodic and the corresponding cathodic peaks increase with the increase of scan rate. The nearly proportionality of the anodic and corresponding cathodic peak ascribes that the peak current of the reactant at each redox reaction is controlled by diffusion process. The current function, I1,/v"2 of paracetamol-amine derivatives were found to be decreased exponentially with increasing scan rate. In all the studies of paracetamol-amine derivatives have been found to undergo electrochemical reaction with ECE (electron transfer-chemical reaction- electron transfer) type mechanism. Controlled-potential coulometry was studied of catechol in presence of diethylamine and diisopropylamine. During the course of coulometry, the appeared peaks height increase proportionally to the advancement of coulometry, parallel to the decrease in the height of paracetamol peak. These observations also indicate the participation of reaction of paracetamol with the studied nucleophiles. The electro-synthesized products originated from the bulk electrolysis of paracetamol with diethylamine and diisopropylamine were isolated. The formations of new products were also ascertained by FTIR spectra.
Studies on Redox Interaction among the Dihydroxybenzene Isomers
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-05) Afrin, Afsana; Motin, Prof. Dr. Md. Abdul
Redox interaction of catechol, hydroquinone and resorcinol has been investigated in different pH (3-9) media using acetate buffer, phosphate buffer and in only supporting electrolyte containing KCl media at platinum (Pt), glassy carbon (GC) and gold (Au) electrode. The study has been carried out using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques at various scan rates and various concentrations. The results suggest that the all three electrodes exhibited an excellent electrocatalytic effect on the redox behaviors of the dihydroxybenzene isomers. Catechol and hydroquinone show one pair of redox peaks in buffer solution of pH 7 at GC and Pt electrode. But catechol and hydroquinone show two pairs of redox peaks at Au electrode at different pH. In KCl media, catechol and hydroquinone also shows two pairs of peaks at GC and Pt electrode. Resorcinol shows irreversible anodic peak at GC electrode but it shows quasi-reversible voltammogram in Pt and Au electrodes in all electrolytic media. The electrochemical process in all the isomers was controlled by diffusion process. The electrochemical behavior of catechol, resorcinol and hydroquinone in presence of sulfanilic acid has been studied by cyclic voltammetry and differential pulse voltammetry using glassy carbon (GC), gold (Au) and platinum (Pt) electrodes. Voltammetric appearance reflected that sulfanilic acid has been formed adduct with catechol and hydroquinone. But no reaction has been occurred between sulfanilic acid and resorcinol. The peak position of the redox couple is also found to be dependent upon pH. Electron transfer is most favorable in neutral media. The slopes of the peak potential, Ep vs pH plot was determined graphically as the anodic peak of dihydroxybenzene isomers or adducts at 0.1V/s at different electrode. The value of slope is close to the theoretical value (60mV/pH) for one-electron, one-proton transfer process. This indicates that the oxidation reaction of dihydroxybenzene isomers proceeded via the 1e−/1H+ process. This also suggests that during the reaction not only electron but also proton are released from the oxidation of dihydroxybenzene isomers. Among the dihydroxybenzene isomers, the electron transfer of hydroquinone is easier than the catechol and catechol is easier than the resorcinol. As -OH sites in resorcinol are connected via meta linkage, so the electron transfer at meta position is unfavorable (electron deficiency) to that at a para (hydroquinone) or ortho (catechol) –position. The interaction energy of catechol and hydroquinone in KCl media are 37.63J and 38.60J respectively. So the extent of delocalization of charge through phenyl ring of hydroquinone is higher than the catechol. Resorcinol shows only one anodic peak, -OH sites in resorcinol are connected via meta linkage, so the electron transfer at meta position is unfavorable due to the deficiency of electron. The redox interactions of the dihydroxybenzene isomers are media dependent.
Investigation of the Electrochemical Behavior of Catechol in Presence of Glycine, Aspartic acid and Glutamic acid
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-07) Uddin, Md. Nazim; Motin, Prof. Dr. Md. Abdul
To monitor the electrochemical behavior of Catechol in presence of Glycine, L-Aspartic acid and L-Glutamic acid; cyclic voltammetry (CV), differential pulse voltammetry (DPV), controlled potential coulometry (CPC) and chronoamperometry (CA) techniques have been employed. A wide range of concentration (10mM to 150mM) of nucleophiles (Glycine, L-Aspartic acid and L-Glutamic acid), various pH media (5 to11), different electrodes ((Glassy carbon (GC), Gold (Au) and Platinum (P)) and successive scan rate (0.05 V/s to 0.5 V/s) have been used to find out the favorable condition. Catechol is an electroactive substance which shows a pair of redox peak whereas Glycine, L-Aspartic acid and L-Glutamic acid are electroinactive, hence it shows no anodic and cathodic peak in the potential range (-0.6 to 0.9 V) of investigation. By the addition of above nucleophiles in Catechol solution arises a new peak at lower potential, the corresponding redox peak shifts and peak current intensity of Catechol decreases with respect to the pure Catechol that indicates the participation of 1,4-Michael addition reaction of o-benzoquinone with mentioned nucleophiles. The formation of adducts from the reaction of Catechol with Glycine, L-Aspartic acid and L-Glutamic acid are assumed to be 2-((3,4-dihydroxyphenyl)amino)acetic acid, 2-((3,4-dihydroxy phenyl)amino)succinic acid and 2-((3,4-dihydroxyphenyl)amino)pentanedioic acid severally that go through electron transfer at more negative potentials than the Catechol. The influence of pH of Catechol in presence of Glycine, L-Aspartic acid and L-Glutamic acid has been studied by varying pH from 5 to 11. It is seen that at pH 3, 5, 9 and 11 no new anodic peak appears after repetitive cycling. In the neutral media (pH 7), the o-benzoquinone undergoes nucleophilic attack by the above nucleophiles that voltammetric new anodic peak A0 appears after repetitive cycling. The slopes of the peak potential was determined graphically from Ep vs pH plot as the anodic peaks of Catecholglycine adducts (27 mV/pH) proceeded via one step 2e−/2H+ process, Catechol-aspartic acid adducts (50 mV/pH) and Catechol-glutamic acid adducts (69 mV/pH) via two step 1e−/1H+ process. The reaction is strongly influenced by the different pH media as well as various compositions of nucleophiles. These reactions have been carried out wide range of concentration of nucleophiles. The optimum conditions for the formation of adducts such as Catechol-glycine (pH-7, Concentration 70 mM, GC electrode and Scan rate 0.1 V/s), Catechol-aspartic acid (pH-7, Concentration 70 mM, GC electrode and Scan rate 0.1 V/s) and Catechol-glutamic acid (pH-7, Concentration 30 mM, GC electrode and Scan rate 0.1 V/s) system are observed. The effect of scan rates has been investigated on cyclic voltammogram of Catechol in presence of above nucleophile. The anodic and cathodic peak current increases proportionally with increasing square root of scan rates. This linear relationship indicates the reaction is controlled by diffusion process. The current function, Ip/v1/2 decreases exponentially with increases scan rate which determine the reaction is controlled by ECE mechanism. The electro-synthesized adducts generated from the controlled potential coulometry of Catechol with Glycine, L-Aspartic acid and L-Glutamic acid was isolated and the generated adducts supported by FTIR spectra.
A Novel Sensor for Simultaneous Detection of Dihydroxybenzene Isomers
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-08) Tonu, Nusrat Tazeen; Yousuf, Prof. Dr. Mohammad Abu
A novel, facile and low-cost electrochemical technique for the detection of dihydroxybenzene isomers (DHBIs), catechol (CC), hydroquinone (HQ) and resorcinol (RS), in aqueous system was developed. An attempt was made for the analyses of HQ, CC and RS in the same aqueous system by UV-Vis spectroscopy. UV-Vis spectrum of CC, HQ and RS exhibited absorbance maxima in PBS supported aqueous solution at 275.4, 288.6 and 273.2 nm respectively. But in the possible binary and ternary mixture of CC, HQ and RS, UV-Vis spectra showed single absorption peak instead of two and three separate peaks respectively. So, simultaneous detection of DHBIs was impossible by UV-Vis spectroscopy. Three electrodes electrochemical system was employed which was controlled by computer supported auto potentiostat. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were adopted as detection techniques. 2B pencil collected from the local stationary shop was used for fabricating working electrode termed as pencil graphite electrode (PGE) in the experiment. PGE electrode was characterized by Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDX). From the SEM it was seen that surface morphology of PGE was not smooth as conventional glassy carbon electrode (GCE) instead contained huge grooves as well. It indicates that the graphite rod of the pencil was not pure crystalline. From EDX it was seen that PGE surface are impure as propped up by SEM. Results showed that it is composed of 79.39% carbon, 10.03% Si, 3.06% O2, 3.49% Al, 2.68% Fe and trace amount of Mg and Ca. So a lot of defects and few foreign materials were present in the surface of PGE confirmed by both SEM and EDX. PGE was first modified electrochemically by ionic liquid (IL), [1-Hexylpyridinium hexafluorophosphate (HIL) or 1-Butyl-3-Methylimidazolium hexafluorophosphate (BIL)] and then used in detection analyte by CV and DPV. Modified electrodes were termed as HIL-PGE and BIL-PGE in total working process. Modified electrodes showed excellent electroanalytical activity effect on the redox reaction of DHBIs. Total analyses and detection processes were performed in phosphate buffer solution (PBS) at pH 7.0 which was used as supporting electrolyte. The influences of scan rate and concentration on the redox behavior of HQ, CC and RS in both HIL-PGE and BIL-PGE were discussed. The anodic peak current versus the concentration of HQ, CC and RS showed a linear relationship. The variation of peak current was also plotted with Square root of scan rate. The electrochemical processes were diffusion controlled. Variation of peak potential separation was plotted with scan rate. The anodic peak potential shift was positive, which was due to IR drop. HIL-PGE showed splendid selectivity and strong anti-interference for detection of HQ, CC and RS simultaneously in aqueous media with excellent results. The limit of detection (LOD) was calculated by signal-to-noise ratio (S/N = 3). In simultaneous detection, the LOD for HQ, CC and RS at HIL-PGE were 6.38 μML-1, 4.56 μML-1 and 19.6 μML-1 respectively and those were 9.09 μML-1, 8.15 μML-1 and 26.78 μML-1 respectively at BIL-PGE. The sensitivity for HQ, CC and RS is 448.49 μA/mM/cm2, 627.35 μA/mM/cm2 and 146.10 μA/mM/cm2 respectively at HIL-PGE and 525.21 μA/mM/cm2, 585.68 μA/mM/cm2 and 178.0 μA/mM/cm2 respectively at BILPGE in simultaneous detection.
Development of Sensor for Free Available Chlorine Estimation in Surface Water
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-08) Islam, Md. Juel; Jamal, Dr. A.B.M. Mamun
The development of portable sensors that can be used outside the lab is an active area of research in the electro analytical field. A major focus of such research is the development of low-cost electrodes for use in these sensors. Current electrodes, such as glassy carbon, platinum or gold electrodes, are costly and require time-consuming preparation. In this work an alternatives have been proposed, where pencil graphite electrodes (PGEs) has been used as sensing platform. Surface of pencil has been used to make it suitable for estimating free chlorine in water sample. Chlorine is a common disinfectant in the water industry, and the residual free chlorine concentration in water distributed to the consumers must be lower than the value set by the regulatory bodies. The pencil graphite-electrode shows high selectivity, low detection limit and linear response to free chlorine in the relevant concentration range at the applied potential of 1.5V and no response to commonly interfering ions such as NO3 -, SO4 2-, CO3 2-, Cl-, HCO3 - has been observed. Further investigation has been conducted on the storage stability and response time on FAC sensing. The sensitivity of free chlorine has been found to be 50μAmM-1cm-2. The pencil graphite electrodes were also used for detection of chlorine with a relatively wide concentrations ranging up to 8 mM, with a limit of detection of 46 μM. It exposes that the stability of PGEs 97.93% after 14 days of its initial activity. This sensor is being proposed as a low cost device for determining free chlorine in water samples with short response time of t90 less than 5 sec.
Development of Glutamate Sensor Based on Nickel Oxide Nano Particle
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-08) Chakrabarty, Sumon; Jamal, Dr. A.B.M. Mamun
L-glutamic acid is one of the 20 standard amino acids used by all organisms. It plays an important role in clinical applications and in food processing and well known as a flavor enhancer commonly found in various foods. The excessive intake of this flavor enhancer can cause toxic effect to the human health. Therefore, development of sensors or biosensors for the determination of glutamate has been of great interest over the past two decades owing to its importance in food and biomedical industries. In this study nickel oxide nanocrystal and nickel oxide hollowsphere have synthesized by using sol-gel and hydrothermal methods. Morphological characterization of nickel oxide particle was carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The crystallite size of nickel oxide prepared by sol-gel method has been found 60 nm. Nickel oxide nanocrystal shows higher selectivity towards glutamate detection compare to nickel oxide hollowsphere. The enzyme-free sensor has been fabricated through modification of glassy carbon using the mixture of nickel oxide nanocrystals and citosan (NiO/GCE). Cyclic voltammetry (CV) and amperometry were used to investigate the electrochemical behavior and catalytic properties of the assembled sensor for glutamate electro-oxidation in alkaline media. It has been found that NiO/GCE showed remarkably enhanced electrocatalytic activity towards glutamate and the electrochemical reaction is diffusion controlled. The sensitivity of NiO/ GCE has been found to be 11 μA/mM/cm2. Under optimal detection conditions, the sensor exhibited linear behavior for glutamate detection in the concentration up to 8 mM with a limit of detection of 272 μM. The interference study of NiO/GCE has been found a significant current response for glutamate compared to the uric acid and ascorbic acid. The stability of NiO/GCE has been studied over a period of one week and found to retain 65% of its original activity towards glutamate detection. Experimental results show that NiO/GCE has significant promise for fabricating cost effective, enzyme-less, sensitive, stable and selective sensor platform.
Electro-oxidation of 1,2-dihydroxybenzene in Presence of Alanine, Phenylalanine and Leucine at Different pH Media
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-08) Dhar, Palash Kumar; Motin, Prof. Dr. Md. Abdul
The electro-oxidation of 1,2-dihydroxybenzene generates o-benzoquinone (Michael acceptor) and its reaction in presence of different concentration of L-Alanine, LPhenylalanine and L-Leucine (nucleophiles) has been investigated. The overall study has been carried out in buffer solution of different pH (5, 7, 9 and 11) by using Cyclic Voltammetry (CV), Controlled Potential Coulometry (CPC) and Differential Pulse Voltammetry (DPV) techniques at different electrodes (GC, Pt and Au) and scan rates (0.05-0.5 V/s). Cyclic voltammogram of electro-active 1,2-dihydroxybenzene in pure buffer solution (5-11) shows one anodic and corresponding cathodic peak within a quasireversible process. Pure L-Alanine, L-Phenylalanine and L-Leucine are electro-inactive having no peak in the potential range of investigation (-0.6 to 0.9V). Addition of different composition of L-Alanine (10-150 mM), L-Phenylalanine (2-100 mM) and L-Leucine (30-200 mM) in fixed 2 mM of 1,2-dihydroxybenzene solution, in the second scan of potential a new anodic peak (A0) arises at the more negative potential with respect to the pure 1,2-dihydroxybenzene. The anodic (A1) and cathodic peak (C1) current intensity of 1,2-dihydroxybenzene also decreases significantly. This indicates the participation of 1,4-Michael addition reaction of o-benzoquinone with L-Alanine, LPhenylalanine and L-Leucine to produce 2-((3,4-dihy droxyphenyl)amino)propanoic acid, 2-((3,4-dihydroxyphenyl)amino)-3-phenylpropanoic acid and 2-((3,4-dihydroxyphenyl) amino)-4-methyl-pentanoic acid adducts. The 1,4-Michael addition reaction of 1,2-dihydroxybenzene is strongly influenced by the concentration of nucleophiles. The electrooxidation of 2 mM 1,2-dihydroxybenzene is mostly favorable in 50 mM of L-Alaline, 20 mM of L-Phenylalanine and 100 mM of L-Leucine respectively. The effect of pH on 1,2-dihydroxybenzene in presence of different nucleophiles has been studied by varying pH ranging from 5 to 11. In acidic pH media (pH <7), no new anodic peak arises after repetitive cycling due to protonation of amine group. But in the neutral (pH=7) and basic media (pH >7), o-benzoquinone undergoes nucleophilic attack by the amine part of amino acids and the maximum peak current is observed at pH 7. The slope value of 1,2-dihydroxybenzene-Alanine, 1,2-dihydroxybenzene-Phenylalanine and 1,2-dihydroxybenzene-Leucine adducts have been calculated (70.5 mV/pH for first anodic peak A1), (59 mV/pH for first anodic peak A1) and (68.5 mV/pH for first anodic peak A1) at 0.1 V/s respectively. These values indicate that the nucleophilic substitution reactions are preceded via 1e−/1H+ process. It is also suggested that during the course of reaction, electron and proton are released simultaneously from the 1,2-dihydroxybenzene-Amino acid adducts. The nature of voltammogram, peak position and current intensity for the studied systems are different for different electrodes and the voltammetric response of GC electrode is better than Au and Pt electrodes. The effect scan rates on cyclic voltammogram of 1,2-dihydroxybenzene in presence of LAlanine, L-Phenylalanine and L-Leucine have also been studied. The peak current of both the anodic and the corresponding cathodic peaks increases with the increase of scan rate. The nearly proportionality of the anodic and corresponding cathodic peak suggests that the peak current of the reactant at each redox reaction is controlled by diffusion process with some chemical complications. The current function, Ip/v1/2 vs scan rates (v) of 1,2-dihydroxybenzene-Amino acid adducts are found to be decreased exponentially with increasing scan rate which suggests that the behavior of reaction mechanism is Electron transfer-Chemical reaction-Electron transfer (ECE) type for all the studied system. The products obtained by bulk electrolysis have also been analyzed by FTIR spectra.
Physico-Chemical Properties of Some Alcohols in SDS-Acetonitrile Containing Ternary Systems
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-11) Das, Biswajit Kumar; Motin, Prof. Dr. Md. Abdul
The critical micelle concentration (CMC) of sodium dodecyl sulfate (SDS) in 80% acetonitrile + 20% water was determined from the conductance and viscosity measurement. They shows a sharp break in their values where micelle starts to form. The estimated CMC of SDS was found to be 0.02 mol. L-1. Densities and viscosities of ternary mixtures of Ethanol + (80% acetonitrile + 20% water + 0.02M SDS), n-Propanol + (80% acetonitrile + 20% water + 0.02M SDS), iso-Propanol +(80% acetonitrile + 20% water + 0.02M SDS),n-Butanol + (80% acetonitrile + 20% water + 0.02M SDS), iso-Butanol + (80% acetonitrile + 20% water + 0.02M SDS), n-Pentanol + (80% acetonitrile + 20% water + 0.02M SDS) and iso-Pentanol + (80% acetonitrile + 20% water + 0.02M SDS) have been studied over the entire range of composition (0 ˂ X2 ˂ 1) at 98.15-323.15K with an interval of 5K. In pure state the density of alcohol has been found to be in the order of: n-Pentanol > Ethanol > n-Butanol > n-Propanol and iso-Pentanol > iso-Butanol > iso-Propanol The values of densities of Alkanols + (80% acetonitrile + 20% water + 0.02M SDS) at equimole fraction solvent systems has been found to be n-Pentanol + (80% acetonitrile + 20% water + 0.02M SDS) > Ethanol + (80% acetonitrile + 20% water + 0.02M SDS) > n-Butanol + (80% acetonitrile + 20% water + 0.02M SDS) > n-Propanol + (80% acetonitrile + 20% water + 0.02M SDS) and iso-Pentanol + (80% acetonitrile + 20% water + 0.02M SDS) > iso-Butanol + (80% acetonitrile + 20% water + 0.02M SDS) > iso-Propanol + (80% acetonitrile + 20% water + 0.02M SDS) The value of the density of alcohols in 80% acetonitrile + 20% water + 0.02M SDS increases with increasing of composition of the alcohols. The densities of all alcohols increase with carbon number which may be depend on the molecular weight of alcohols and structural formula. The densities decrease regularly with increasing of temperature. This is due to the thermal agitation and hence the dipole-dipole interaction or the dissociation of H-bonding are occurred. The excess molar volumes, VE were calculated from the densities of the mixtures at different temperatures. The values of VE for all the systems are negative over the entire range of composition, showing minima at ~ 0.5 mole fraction of Ethanol, ~ 0.8 mole fraction of n-Propanol, ~ 0.8 mole fraction of iso-Propanol, ~ 0.7-0.8 mole fraction of n- Butanol, ~ 0.8 mole fraction of iso-Butanol, ~ 0.7 mole fraction of n-Pentanol, ~ 0.7 mole fraction of iso-Pentanol. The increasing of VE with carbon chain length of alcohols may be related to increase of the size of alcohols. The values of VE for the studied alcohols increase with increase of temperature. The observed values of VE for the mixtures have been explained in terms of physical, chemical and geometrical contributions. The viscosity coefficients, ɳ of all the above mixtures at all the different temperatures have also been determined. The viscosities increase initially slowly up to ~ 0.8 mole fraction of Ethanol, n-Propanol, iso-Propanol, n-Butanol, iso-Butanol, n-Pentanol and iso-Pentanol in 80% acetonitrile + 20% Water + 0.02M SDS systems and later on, the viscosities increases sharply until the pure alcohol is reached specially at lower temperature. In the pure state the viscosity of the alcohols has been found to be in the order of n-Pentanol > n-Butanol > n-Propanol > Ethanol and iso-Pentanol > iso-Butanol > iso-Propanol and iso-Pentanol > n-Pentanol and iso-Butanol > n-Butanol and iso-Propanol > n-Propanol These are a marked decrease in the viscosity with the increase of temperature for all the studied alcohols. This ascribed that the alcohol solutions are less stable at higher temperature. The increasing of viscosity with carbon number of alcohols ascribed that the solution resistance increase with the increase of carbon chain length. The linear dependence of lnɳ against 1/T shows for the all studied alcohols. The branched chain isomers are less stable than linear chain isomers at higher temperature. The excess viscosities, ηE values are found to be negative, indicating that the (80% acetonitrile + 20% water + 0.02M SDS) solutions of alcohols are non-ideal. Excess viscosities are negative at all the temperature over the entire range of composition for all the systems with minima occurring between 0.7-0.8 mole fraction of Ethanol, n-Propanol, iso-Propanol, n-Butanol, iso-Butanol, n-Pentanol and iso-Pentanol. The negative excess viscosities, ηE of the systems indicate that the dissociation of component through dispersion force or steric hindrance. The position of minima virtually does not change remarkably with the variation of temperature. The negative VE, negative ηE and negative  for the systems indicate the segmental inclusion of Acetonitrile in the interstices of polymolecular alkanols aggregate; these will be fewer surfaces available for friction that may results in a reduction of viscosity. For long chain or branched chain alkanols, maximum geometrical for the steric hindrance are occurred. The thermodynamic parameters such as free energy (ΔG#), enthalpy (ΔH#) and entropy (ΔS#) change of activation for the viscous flow for these systems were examined for the entire range of composition. The free energy (ΔG#) were found to be positive in magnitude indicating that the kinetic species involved in forming cavities or holes in the liquid medium is giving by the work required in forming the hole against surface tension of the solution. The excess properties (VE, ηE, ΔG#E) data have been fitted by the least square method to the four parameter Redlich-kister equation and the values of the parameter ai and standard deviation have been reported.
Volumetric and Viscometric Studies of Paracetamol in Aqueous Solution of Alcohols at Different Temperatures
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-11) Dey, Shishir Kumar; Morshed, Prof. Dr. Mohammad Hasan
Paracetamol in presence of Water, 80% Water + 20% n-Propanol, 20% Water + 80% n- Propanol, 80% Water + 20% n-Butanol and 20% Water + 80% n-Butanol were studied through the measurement of viscosity and density at different temperatures (298.15K to 323.15K) with an interval of 5K. The results were discussed on the basis of structure making and breaking mechanism of paracetamol in aqueous and aqueous alcohols solution under experimental conditions. The apparent molar volumes increase with the rise of concentration of paracetamol for all the studied systems indicating the structure making interaction for all the studied systems. The limiting apparent molar volume (φv 0) or partial molar volume at infinite dilution of paracetamol are positive and increase when paracetamol content in the solvents increase. The positive values of transfer apparent molar volume (Δφv)tra suggest the structure making ability through hydrophilic-hydrophilic interactions between polar groups of paracetamol and polar groups of alcohols-water. The values of limiting apparent molar volume expansibilities (Eφ0) are positive and the values of (δEφ0/δT)p are small which suggest the structure making property in these systems. Viscosities increase with increasing of paracetamol concentration. The B-coefficients for paracetamol in the studied systems are positive and thus suggest the presence of solutesolvent interactions or structure making properties. The values of D-coefficient are mainly negative showing weak solute-solute interactions. The changes of free energies (ΔG#) are increased with the increase of concentration of paracetamol and the values are positive for all the studied systems. It is also seen that the changes of free energies (ΔG#) of paracetamol in aqueous solutions of n-Propanol and n-Butanol increase very slowly with increasing solute concentration and decrease with increasing temperature. The values of enthalpy of activation (ΔH≠) indicate the interaction presence in solute-solvent through H-bonding. The entropy (ΔS≠) values are positive for all the systems and decrease with increase of paracetamol concentration. The positive values of change of chemical potential (Δμ1 ≠ - Δμo≠) for all studied show greater contribution per mole of solute to free energy of activation for viscous flow of the solution and are good agreement with the values of B-coefficient showing structure making properties between solute and solvent.
Volumetric and Viscometric Study of N-acetylcysteine in binary and ternary system
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-12) Gosh, Utpal Kumar; Yousuf, Prof. Dr. Mohammad Abu
Volumetric and viscometric studies of binary mixtures of ethanol-NAC (N-Acetylcysteine), water-NAC and ternary mixtures of ethanol-water-NAC were done. NAC have been investigated in binary and ternary systems over a concentration range of (1-18) % (w/v) at 298.15 to 323.15 K at 5 K intervals. Densities of the binary systems, water-NAC and ethanol-NAC have been found to be increased with increasing concentration of NAC and decreased with increasing temperature. Densities of water-NAC have been found higher than that of ethanol-NAC system. On the other hand, in ternary system densities increased with the increasing ratio of water in ethanol-water mixtures. The densities of ternary system are higher than binary system. The apparent molar volumes, 𝝋𝒗 of both binary and ternary mixtures were determined from the densities of the mixtures. The 𝝋𝒗 values have been found to be positive throughout the whole concentration range for NAC in ethanol, water and aqueous ethanol systems. The apparent molar volumes, 𝝋𝒗 of NAC in ethanol, water and aqueous ethanol were found to be increased with concentration at all temperatures. These results may be due to the solute-solvent, and solute-solute interaction through H-bond, dipole-dipole and S˖˖˖S linkage in the solutions. 𝝋𝒗 values were found to be increased with increasing temperature at any concentration of the solution may be due to increased thermal agitation at higher temperatures. It may also be assumed as the concentration increases because solute-solute interactions by S˖˖˖S linkage start to gain importance in addition to solute-solvent interactions. This shows that 𝝋𝒗 values are dependent upon concentration as well as the temperature. The apparent molar volumes at infinite dilution (𝝋𝒗 𝒐) were computed by extrapolating 𝝋𝒗 values to zero concentration. The 𝝋𝒗 𝒐 values provide information on solute-solvent interactions, as solute-solute interactions can be assumed to be eliminated at infinite dilution. The variations of both 𝝋𝒗 𝒐 values with temperature were examined. 𝝋𝒗 𝒐 Values were found to be increased with increasing temperature for all systems. Investigated systems showed small positive values for Sv which indicate that the solvation process involve strong interaction but not pure ionic. The apparent molar expansivities at vii infinite dilution (𝜑𝐸 0 ) were found to be positive. Positive values indicate that, on heating some NAC molecules may be released from the solvation layer of ion. Viscosity values, η of NAC in ethanol, water and aqueous ethanol were found to be increased with concentration at all five temperatures but decreased with the increase of temperature. The increase of η values of NAC with concentration can be attributed to the increase in both solute-solvent and solute-solute interactions with concentration as mentioned. At the same time, at a constant temperature and concentration, values of η are found to be increased with the ratio of the water in ethanol-water of ternary system but in binary system ethanol-NAC is higher than water-NAC viscosity because of larger molecule of ethanol. The change of free energy values for viscous flow, ∆G* were found to be positive indicate that work has to be done to overcome the energy barrier for the flow process. The positive ΔH values indicate that work has to be done for all the investigated systems. That is, the viscous flow is not thermodynamically favored for the systems studied. The ∆S* values are positive for all the systems studied except ethanol–NAC system. This means that except ethanol–NAC system other binary and ternary systems are random that those of the pure one.
Studies on the Physico-chemical Properties and Pharmacology of Heated Edible Oils
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2016-12) Ahmad, Md. Raju; Morshed, Prof. Dr. Mohammad Hasan
The present study was carried out to evaluate the physico-cheniical properties like iodine value, acid value and compare FT-IR spectra of unheated and heated edible oils, the effects of consumption of heated edible oils diet oil blood lipid profile, biochemical parameters and hematological profile of rabbits. On the other hand, the present study aimed to observe the histological change in rabbit liver, kidney, heart, lung, brain and spleen tissues after feeding heated edible oils. The experimental data showed that the lowest iodine value and the highest acid value were observed in 20 hours heated palm oil (18.02±0.05), (7.01±0.03) and soybean oil (83.06±0.08),(5.68±0.05) respectively. The spectra of unheated and 2, 10, 20 hours heated palm and soybean oils showed very similar FT-JR spectra in this study. The body weight of experimental rabbit 20 hours heated palm oil diet group P3 (821.57±3.29 gm) and similar soybean oil diet group S3 (730.50±2.20 gm) were higher than that of control group. Total white blood cell (WBC) of 2 hours heated palm oil diet group P1 (9.5x10 3±0.16x103 blood cell/121), red blood cell (RBC) of P3 group (6.58±0.03 in! .tl), platelet count (PC) of 10 hours heated palm oil diet group P2 (593±2.44 thousand/jt!) were higher than that of fresh normal rabbits. Creatinine of S3 group (1.1±0.08 mg/dl), serum glutamic pyruvic transminase (SOPT) of P3 group (8 1±2.16 UIL), serum glutamic oxaloacetic transminase (SGOT) of P3 group (147±0.82 LJ/L) and uric acid of P2 group (1.9±0.08 mg/d!) were higher than that of control group. The total cholesterol (TC) of P3 group (158±2.16 mg!dl), high density lipoprotein (1-IDL) of P3 group (57±1.63 mg!dl), low density lipoprotein (LDL) of P3 group (8 1±1.41 mg/dl) and triglyceride (TG) of P3 group (176±0.82 mg/dl) were found higher than that of untreated rabbits. Histopathological study of liver, kidney, heart, lung, brain and spleen of the heated edible oil treated rabbits showed abnormalities as compared to control group organs. Consumption of heated edibles oil may occur infection, stress, allergy, hepatic damage, anemia, vascular disease, renal system damage, liver cirrhosis, pulmonary infarction, coronary artery disease of the consumers. Liver, heart, kidney, lung, brain, spleen and muscles may be damaged by chronic consumption of heated edible oils.
Volumetric and Viscometric Study of Dimedone in Ethanol-Water Mixtures
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017) Hossain, Md. Jahangir; Yousuf, Prof. Dr. Mohammad Abu
Density and viscosity of binary (Dimedone-Ethanol) and ternary (Dimedone-Ethanol – Water) mixtures of Dimedone, Water and Ethanol were determined at various temperatures (298.15 to 318.15 K at 5 K intervals) in between a concentration range of 0.05 to 0.25 mol L-1 of Dimedone with a view to determining the molecular interactions among Dimedone, Water and Ethanol. Dimedone is an organic substance which has the applications in colorimetry, crystallography, luminescence and spectrophotometric analysis. And it can also be used for chemistry involving organic compounds of low electrical resistance. Ethanol is a colourless organic polar solvent has led to its largescale production in recent years with negligible toxicity. Ethanol is completely miscible with universal solvent water. So Ethanol– Water mixture can be a vital binary solution in investigating Dimedone that was taken as topic of research in this study. The apparent molar volumes, (φ ) were obtained from the experimental density data. In the Dimedone–Ethanol and Dimedone–Water–Ethanol system, the apparent molar volume of Dimedone increases. In addition, apparent molar volume at infinite dilution (φ ), apparent molar Expansivity and Sv (values of experimental slopes) were also calculated according to the experimental density data. The apparent molar volume at infinite dilution gives an idea about the presence of solutesolvent interactions whereas Sv is the experimental slopes which give an idea about the prevailing solutesolute interactions in the mixtures. The calculated data indicate that there may be solute-solute and solute-solvent interactions present in the binary and ternary solutions. It is seen that Dimedone has good structure making property in ternary solutions than the binary systems. Both binary and ternary systems shows rapid increase of viscosity values with the increased Dimedone concentration but the values of viscosity decreased with the increase of temperature. The viscosity data were employed to determine the viscosity coefficients (A&B), change of free energy, G*, change of enthalpy, H* as well as change of entropy, S*. From these thermodynamic parameters state of the spontaneity of the investigated systems were known. Moreover, positive A co-efficients and negative B co-efficients suggesting that strong solute-solute but weak solute-solvent interaction present in the binary and ternary solution. On the basis of this data, the predominant molecular interactions occurring between Dimedone-Ethanol and Dimedone–Water–Ethanol were found to be solute-solute interaction. The results suggest that there is a significant effect of Dimedone on Water and Ethanol.
Studies on Arsenic and Lead contamination in Crops and Vegetables of Harischandrapur Village of Jessore District in Bangladesh
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-02) Sultana, Nusrat; Morshed, Prof. Dr. Mohammad Hasan
Various fruits and vegetables such as Mango (Mangifera indica L.), Jackfruit (Artocarpus heterophyllus L.), Guava (Psidiun guajava L.), Pummelo (Citrus grandis L.), Lime (Citrus aurantifollia), Papaya (Carica papaya L.), Coconut (Cocos nucifera L.), Sapodilla (Manilkara zapota),Yard long bean (Vigna sesquipedalis), Okra(Abelmoschus esculentus), Ribbed gourd (Luffa acutangula), Plantain (Musa paradisiacal), Cucumber (Cucumis sativus), Green hot chili (Capsicum frutescens), Stem Amaranth leaf (Amaranthus lividus), Red Amaranth (Amaranthus gangeticus), Indian Spinach (Basella rubra), Brinjal (Solanum melongena), Pumpkin (Cucurbita moschata), Pea seed (Pisum sativum), Rice (Oryza sativa L), Leaf of Taro (Colocasia esculenta) and Corm of elephant yam (Amorphophallus paeoniifolius) were collected from Harischandrapur village of Jessore district of Bangladesh and screened for arsenic, lead, iron, manganese, copper and zinc by Atomic Absorption Spectrophotometer (AAS). The average moisture contents in soil, fruits, fruity vegetables, root-stem vegetables, leafy vegetables and seed vegetables were found 19.91%, 82.25%, 87.67%, 88.65%, 83.36% and 45.00% respectively. The mean concentrations of arsenic, iron and manganese in irrigation water were 0.11 mg/L, 4.28 mg/L and 0.48 mg/L respectively which are higher than Bangladesh drinking water standard. The average concentration of arsenic in irrigation water is higher than FAO standard (<0.100 mg/L for irrigation water). The average concentrations of arsenic, iron, manganese, copper and zinc were found 8.63 mg/Kg, 12162.78 mg/Kg, 256.07 mg/Kg, 21.91 mg/Kg and 57.40 mg/Kg respectively in soils which are lower than FAO, USEPA & EU standard for agricultural soil. The average concentrations of arsenic in fruits, fruity vegetables, root-stem vegetables, leafy vegetables and seed vegetables were detected 0.17 mg/Kg, 0.14 mg/Kg, 0.23 mg/Kg, 0.51 mg/Kg and 0.15 mg/Kg respectively which are lower than that of standard value recommended by WHO and FAO (<1.00 mg/Kg) for food. The average concentrations of iron in fruits, fruity vegetables, leafy vegetables and seed vegetables were monitored 31.13 mg/Kg, 60.38 mg/Kg, 338.68 mg/Kg and 42.83 mg/Kg respectively that are lower than WHO/FAO standard (<1.00mg/Kg) for food. The mean concentrations of manganese in fruits, fruity vegetables, leafy vegetables and seed vegetables were detected 2.86 mg/Kg, 12.90 mg/Kg, 24.26 mg/Kg and 8.48 mg/Kg respectively which are lower than EU standard (<500mg/Kg). The mean concentrations of copper were found 3.40 mg/Kg, 9.36 mg/Kg, 4.76 mg/Kg, 9.70 mg/Kg respectively in fruits, fruity vegetables, leafy vegetables and seed vegetables which are lower than EU standard (<20.00 mg/Kg) for food. The average concentrations of zinc in fruits, fruity vegetables, leafy vegetables and seed vegetables were detected 14.72 mg/Kg, 28.48 mg/Kg, 23.37 mg/Kg and 27.15 mg/Kg respectively which are lower than EU standard (<50.00 mg/Kg). The concentration of lead in all selected soil, water, fruits and vegetables were lower than detection level. Maximum average concentration of arsenic, iron and manganese was found in leafy vegetables. On the other hand maximum mean concentration of copper and zinc were measured in fruity and seed vegetables. In our research, 40 peoples were monitored for calculating the consuming of arsenic, iron, manganese, copper and zinc through daily intake of food (fruits and vegetables), water and their health risk factors were also analyzed. In this study area, the people’s average age, body weight and daily intake of water, rice, vegetables and fruits were 28.48 years, 46.60Kg, 2.80L, 0.39Kg, 0.12Kg and 0.14Kg respectively. The order of daily intake and health risk index of metals from food and water was Iron>Manganese>Arsenic>Zinc>Copper. The fruits and vegetables of the study area are safe for human health according to WHO oral dose reference data (Rfd) for metals and health risk index.
Drinking Water Quality Assessment in Khulna City Corporation Slum Area
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-03) Kundu, Abanti; Yousuf, Prof. Dr. Mohammad Abu
Drinking water is characterized as free from microorganisms, terribly toxic compounds and that have no adverse effects on health. Waterbome disease is a major concern of public health and it is important to know the microbial as well as the physico-chemical qualities of drinking water. This study was conducted to assess the quality and suitability of groundwater for drinking purposes in different slum area of Khulna City Corporation (KCC) and explored the variation of bacteriological status of water between sources (deep Tube-wells) and household stored water. The study was conducted from July 22, to August 28, 2016. A total of 100 samples; 50 from sources and other 50 samples from household storage vessels were collected for exploring physico-chemical and bacteriological status. The parameters that were investigated found to have variation in the range of pH 7.4 to 8.55 was slightly basic, electrical conductivity 544 tS/cm to 2.21 mS/cm; Hardness 50 to 650 as CaCO3 considered, hardness classification shows that maximum sample are hard type and very hard type. Total Dissolved Solid (TDS) 281 to 1176 mg/L, However, TDS classification of GW shows that maximum samples lie within good (300-600 mg/L), Chloride 31.68 to 721 mg/L, As
Cost Effective Graphite Based Sensor for Simultaneous Detection of Phenolic Isomers
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-03) Khan, Md. Muzahedul Islam; Yousuf, Prof. Dr. Mohammad Abu
A facile and low-cost electrochemical technique for the detection of phenolic isomers (PIs), hydroquinone (HQ), catechol (CC), and resorcinol (RS), in aqueous system was developed. In this research, graphite based electrode (GBE) fabricated from a regular HB pencil (Brand: Faber Castell). HB pencil collected from the local stationary shop was used for fabricating working electrode termed as HB pencil electrode (HBPE) in the experiment. Then HBPE was also modified electrochemically by amino acid (AA), namely Glycine (GLY) and Aspartic Acid (ASA). Modified electrodes were termed as GLY-HB and ASA-HB in total working process. HBPE, GLY-HB and ASA-HB electrodes were used in detection of PIs by CV and DPV. The bare HBPE showed good electroanalytical activity effect on the redox reaction towards PIs. Both GLY-HB and ASA-HB electrodes showed catalytic activity on the redox reaction to PIs over HBPE. A series of pH dependent reactions were performed in phosphate buffer solution (PBS) and total analyses and detection processes were continued at pH 6.8 which was used as the supporting electrolyte. The influences of scan rate and concentration on the redox behavior of HQ, CC and RS in both GLY-HB and ASA-HB were discussed. The anodic peak current versus the concentration of HQ, CC and RS showed a linear relationship. The variation of peak current was also plotted with Square root of scan rate. The electrochemical processes were diffusion controlled in all cases. The constructed electrodes produced reproducible and stable results in all cases. The limit of detection (LOD) was calculated by signal-to-noise ratio (S/N) = 3. In simultaneous detection, the LOD for HQ, CC and RS at bare HBPE were 12.473 μML-1, 16.132 μML-1 and 25.25 μML-1, respectively. The sensitivity for HQ, CC and RS is 470.481 μA/mM/cm2, 363.781 μA/mM/cm2 and 232.416 μA/mM/cm2, respectively at bare HBPE. LOD for HQ, CC and RS at GLY-HB were 5.498 μML-1, 7.119 μML-1 and 14.794 μML-1, respectively and those were 22.459 μML-1, 25.478 μML-1 and 38.303 μML-1, respectively at ASA-HB in simultaneous detection. The sensitivity for HQ, CC and RS is 364.785 μA/mM/cm2, 282.712 μA/mM/cm2 and 135.560 μA/mM/cm2, respectively at GLY-HB and 374.483 μA/mM/cm2, 330.108 μA/mM/cm2 and 219.574 μA/mM/cm2, respectively at ASA-HB in simultaneous detection. Cost of one HBPE is about 5.00 BDT, one GLY-HB or ASA-HB electrode is about 7.00 BDT while one glassy carbon (GC) electrode is 14,000.00 BDT. So HBPE is at least 2800 times and that for GLY-HB or ASA-HB electrode is 2000 times cheaper than conventional commercial GC electrodes.
Disposable and Low-cost Free Chlorine Sensor Based on Pencil Drawn Paper Electrode
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-04) Dutta, Apu Kumar; Jamal, Dr. A. B. M. Mamun
This is the first alternative analysis of pencil drawn paper electrode for free available chlorine (FAC) detection. It is one of the new technologies for fabricating simple, low lost, portable and disposable analytical device for many application areas including clinical diagnosis, food quality control and environmental monitoring. In this work a complete analysis of physical and electrochemical properties of pencil graphite electrode (POE) and pencil drawn paper electrode (PDPE) has been performed to detect FAC in surface water. Cyclic voltammetry (CV) and amperometry were used to study the electro-catalytic properties. Excellent catalytic activity has been obtained for free chlorine detection using both POE and PDPE with a sensitivity of 121 ± 5.38 .iAmMcm 2 and 36 ± 3.65 pAmM4cm 2 respectively and a linearity range up to 12 mM and 7 mM for both platforms respectively. Also limit of detection POE and PDPE has been found to be 59.5 and 88.9 p.M respectively. There is no response obtained for common interfering ions in surface water such as NO3 , SO 2 , C0 32 , Cl'and HCO3 . Both the sensors were evaluated for their storage stability and response time and thereby can be applied as a low-cost electrochemical sensor for determining FAC in surface water. The unique properties of this sensor allow the passive liquid transport and compatibility with chemical/biochemical are the main advantage of using this sensing platform. In addition, this sensor could better meet the current objectives of a viable low cost and portable device in addition to offering high sensitivity, selectivity and multiple analyte discrimination.
Development of Novel pH Sensor Based on Nanoparticle Modified Electrochemical Sensing Platform
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-04) Akhter, Irani; Jamal, Dr. A.B.M. Mamun
In biological and environmental applications, pH is an important parameter that needs to monitor in regular basis. Conventionally, the measurement processes take a considerable amount of time involving several calibration steps and handling of fragile electrodes. In this work, we propose a new, robust and reliable way of sensing pH. The sensor has been fabricated based on tungsten oxide nanoparticle modified glassy carbon electrode (WO3/GCE). WO3 is a promising material for pH sensor because of its availability, stability, good morphological and structural control of the synthesized nanostructures. In this work, hydrothermal synthesis method was used for the fabrication of WO3 nanoparticles. For the fabrication of the pH sensor, the nanoparticles were mixed with Nafion and chitosan before drop coating onto the GCE surface. Scanning electron microscopy (SEM), x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX) and Raman spectroscopy were used to characterize the nanoparticle. Cyclic voltammetry (CV), zero current potentiommetry (OCP) and square wave voltammetry (SWV) were used to monitor the potential shift based on different pH in the buffer solutions. This electrochemical pH sensor showed a sensitivity of 60 mVpH-1 and a potential drift of 2.4 – 5.0 % after three hours of continuous use. The sensor showed linearity range of pH 3 -11 and could retain 95% of its initial activity after 1 week of use. The electrode was found to respond both in the presence and absence of oxygen, further expanding the potential applications to include de-oxygenated environments. The WO3 based sensor showed good sensitivity and long term stability, which would be a potential platform to develop a low cost pH sensor for a wider range of applications.
Synthesis and Antimicrobial Activities of Chromene Derivatives
(Khulna University of Engineering & Technology (KUET), Khulna, Bangladesh, 2017-05) Islam, Md. Tarikul; Badal, Prof. Dr. Md. Mizanur Rahman
The design and synthesis of chalcone and chromene derivatives and their antibacterial activities were studied in this research. Conveniently, all products were synthesized from commercially available acetophenone, 4-hydroxybenzaldehyde and dimedone. Different synthetic strategies were used to obtain an easily accessible chromene scaffold with appropriate handles. At first, this research work was involved in an efficient procedure for the attachment of 4-hydroxybenzaldehyde and acetophenone in the presence of 10% NaOH to produce 3-(4-Hydroxy-phenyl)-1-phenyl-propenone. 4-{3-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-propenyl}-phenol phenylamine has been synthesized by the reaction of 2,4 dinitro phenyl hydrazine with chalcone. Reaction of dimedone with chalcone under refluxing condensation using dry benzene and zinc chloride as a catalyst to give the corresponding chromene derivative 4-(4-Hydroxy-phenyl)-7,7-dimethyl-2-phenyl-4,6,7,8-tetrahydro-chromen-5-one. This reaction also carried out by Microwave Irradiation and use ethanol as a solvent, without any catalyst. It was found that the preparation time for the compounds was reduced from 72 hours to 5-10 minutes during microwave irradiation. The structures of the all synthesized compounds were characterized by their IR, 1H NMR spectral data. The antibacterial and antifungal activity of the compounds was also investigated. The antimicrobial activity of the compounds at concentration 300 μg/disc was performed against three gram-positive bacteria (Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes) and three gram-negative bacteria (Escherichia coli, Salmonella typhimurium, and citobacteria frundi) by Kirby-Bauer disc diffusion method using Ciprofloxacin as standard. Antifungal screening was carried out against one fungi (Tricodarma harzianum) using Michonazole as standard. Compound, I, 3-(4-Hydroxy-phenyl)-1-phenyl-propenone exhibits no activity against the tested bacterial strains Bacillus cereus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Citrobacter freundii, but showed moderate activity against the tested bacteria Staphylococcus aureus having inhibition zone 8 mm and also show antifungal activity aganist Trichoderma harzianum inhibition zone 10mm. Compound, II, 4-{3-[(2,4-Dinitro-phenyl)-hydrazono]-3-phenyl-propenyl}-phenol exhibits no activity against gram negative, gram positive strains but showed antifungal activity against Trichoderma harzianum inhibition zone 6 mm. Compound, III, 4-(4-Hydroxy-phenyl)-7,7-dimethyl-2-phenyl-4,6,7,8-tetrahydro-chromen-5-one showed activity against Gram positive, Gram negative except Listeria monocytogenes, Escherichia coli, Salmonella typhimurium. This compound, III also showed antifungal activity against Trichoderma harzianum inhibition zone 8 mm.