PhD Thesis
Browse
83 results
Search Results
Item A Comprehensive Analysis of Residual Antibiotics, Organochlorine Pesticides and Heavy Metals in Beef and Chicken(© University of Dhaka, 2026-04-19) Parvin, NargisBangladesh is renowned for its agriculture-based economy. The farming of poultry and livestock is extremely popular in the country. Consumers in Bangladesh have a strong preference for beef and chicken meat, and these products are widely available. Toxic substances from various sources can permeate food animals through their feed and the environment, eventually making their way through the entire food chain via bioaccumulation and biomagnification. Additionally, these chemicals can enter the human body through the consumption of these foods, leading to significant public health concerns. This doctoral research focuses on identifying and measuring chemical pollutants such as leftover antibiotics, organochlorine pesticides, and heavy metals in beef and broiler chicken meat as well as liver samples, while assessing the health risks associated with each contaminant. Additionally, it aims to explore potential methods for reducing these contaminants. In this research, the presence of antibiotic residues (including tetracycline, oxytetracycline, chlortetracycline, amoxicillin, and patulin) in samples of beef meat, liver, and chicken meat, liver was examined utilizing reversed-phase High Performance Liquid Chromatography with a photodiode array detector (HPLC-PDA). Organochlorine pesticides and heavy metals were assessed using Gas Chromatography with an electron capture detector (GC-ECD) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), respectively. The beef and chicken meat and liver samples were extracted employing a modified version of the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method designed for antibiotics and organochlorine pesticides. A total of 180 biological samples, including beef meat, beef liver, and broiler chicken meat and liver, were collected for this study from local markets of Dhaka North and South City, Bangladesh. A total of one hundred and twenty samples (with 30 each of beef meat, beef liver, chicken meat, and chicken liver) were examined for each antibiotic. The correlation coefficients (r²) demonstrated a linear relationship, measuring 0.9978, 0.9980, and 0.9988 for oxytetracycline, tetracycline, and chlortetracycline, respectively, across six concentration levels. Matrix-matched calibration was performed for each matrix, resulting in linear correlation coefficients (r²) of 0.9980, 0.9990, and 0.9981 for beef meat; 0.9985, 0.9984, and 0.9973 for beef liver; 0.9988, 0.9982, and 0.9993 for chicken meat; and 0.9980, 0.9985, and 0.9991 for chicken liver concerning oxytetracycline, tetracycline, and chlortetracycline, respectively. The intra-day and inter-day recovery tests for each of the tetracyclines (TCs) were conducted, with relative standard deviation (RSD%) remaining below 10%. The Limit of Detection (LOD) for oxytetracycline, tetracycline, and chlortetracycline were recorded at 1.11, 1.15, and 1.19 μg/kg, respectively, with the associated Limit of Quantification (LOQ) being 3.17, 3.84, and 3.96 μg/kg. Residual oxytetracycline was V found and measured in eight beef liver samples, with levels varying from 86.76 to 368.97 μg/kg, all below the Maximum Residue Limit (MRL) set by Codex. However, one beef liver sample surpassed the MRL established by the European Union (EU), registering at 368.97 μg/kg. Oxytetracycline was detected in three chicken meat samples (220.94, 153.45, and 101.32 μg/kg), tetracycline was present in two samples (715.00 and 698.88 μg/kg), and chlortetracycline was found in one sample (677.35 μg/kg). Four of the positive samples exceeded the Codex recommended MRL, while six positive chicken meat samples were above the MRL limit set by the EU. The linear correlation coefficient (r²) for standard amoxicillin across six different concentrations was determined to be 0.9982. For amoxicillin in various samples, the respective linear correlation coefficients (r²) were 0.9979 for beef meat, 0.9980 for beef liver, 0.9995 for chicken meat, and 0.9981 for chicken liver. The intra-day and inter-day recovery experiments were conducted for amoxicillin, yielding a relative standard deviation (RSD%) within 10%. The limit of detection (LOD) and limit of quantification (LOQ) for the validated method were found to be 0.55 and 1.84 μg/kg for standard amoxicillin, respectively. The Codex Alimentarius Commission and the EU have established a maximum residue level (MRL) of 50 μg/kg for amoxicillin in beef and chicken meat and liver. Residual levels of amoxicillin were identified in seven beef meat samples, with concentrations ranging from 4.89 to 9.36 μg/kg, and in fifteen beef liver samples, which varied from 10.39 to 89.47 μg/kg. Among the beef liver samples, two exceeded the MRL, with values of 53.46 μg/kg (BL10) and 89.47 μg/kg (BL14). The linear correlation coefficient (r²) was determined to be linear at 0.9991 for standard patulin across six different concentrations. For patulin, the correlation coefficients (r²) were found to be linear at 0.9984, 0.9983, 0.9980, and 0.9990 in beef meat, beef liver, chicken meat, and chicken liver, respectively. An intra-day and inter-day recovery study was conducted for patulin, and the RSD% remained within 10%. The limit of detection (LOD) for the proposed method was established at 0.18 and 0.60 μg/kg for standard patulin. Residual levels of patulin antibiotic (as well as mycotoxin) were identified in twenty-five beef samples, with concentrations ranging from 47.72 to 193.91 μg/kg, and in eighteen chicken meat samples, with levels from 16.94 to 310.53 μg/kg. Patulin was detected in six beef liver samples, with concentrations between 43.31 and 166.91 μg/kg, and in eleven chicken liver samples, with levels ranging from 14.75 to 52.88 μg/kg. The health risk for each antibiotic was assessed for adults, and the hazard index (HI) was found to be less than 1. A total of one hundred and twenty samples (30 each of beef meat, beef liver, chicken meat, and chicken liver) were subjected to analysis for organochlorine pesticides (OCPs). To establish a standard calibration curve, six varying concentrations of a standard solution (comprising 20 OCPs) were injected into the gas chromatograph-electron capture detector VI (GC-ECD). The correlation coefficients (r²) showed a linear relationship, with values of 0.9999, 0.9994, 0.9990, 0.9988, 0.9980, 0.9997, 0.9991, 0.9994, 0.9993, 0.9996, 0.9983, 0.9978, 0.9995, 0.9985, 0.9990, 0.9997, 0.9981, 0.9991, 0.9994, and 0.9998 for alpha- BHC, gamma-BHC, beta-BHC, delta-BHC, heptachlor, aldrin, heptachlor epoxide, transchlordane, cis-chlordane, endosulfan I, 4, 4’-DDE, dieldrin, endrin, 4, 4’-DDD, endosulfan II, endrin aldehyde, 4, 4’-DDT, endosulfan sulfate, methoxychlor, and endrin ketone, respectively. Recovery experiments for intra-day and inter-day were conducted for 20 OCPs, and the relative standard deviation percentage (RSD%) remained within the acceptable limit of 20%. Out of thirty beef meat samples tested, alpha-BHC was detected in 11 samples (ranging from 1.01 to 62.49 μg/kg), gamma-BHC in 9 samples (with levels from 1.22 to 103.01 μg/kg), beta-BHC in 9 samples (from 1.13 to 8.94 μg/kg), and delta- BHC in 28 samples (with concentrations between 84.45 and 329.08 μg/kg). Heptachlor was found in 13 samples (ranging from 0.97 to 29.64 μg/kg), while aldrin was present in 20 samples (from 0.96 to 61.71 μg/kg). Heptachlor epoxide appeared in 28 samples (with levels from 57.87 to 304.25 μg/kg), trans-chlordane was found in 14 samples (from 0.86 to 7.90 μg/kg), and cis-chlordane in 18 samples (ranging from 0.61 to 6.22 μg/kg). Endosulfan I was detected in 26 samples (with concentrations between 1.23 and 22.86 μg/kg), and 4, 4´-DDE was found in 20 samples (ranging from 0.17 to 21.41 μg/kg). Dieldrin was present in 22 samples (from 0.47 to 36.50 μg/kg), endrin in 17 samples (ranging from 0.63 to 16.98 μg/kg), and 4, 4´-DDD was detected in 23 samples (with levels from 0.48 to 38.94 μg/kg). Endosulfan II was found in 27 samples (ranging from 1.61 to 187.29 μg/kg), and endrin aldehyde was present in 19 samples (from 0.98 to 24.70 μg/kg). Additionally, 4, 4´-DDT was detected in 15 samples (ranging from 0.24 to 76.81 μg/kg), endosulfan sulfate in 12 samples (with levels from 0.83 to 11.10 μg/kg), methoxychlor was found in 18 samples (ranging from 0.77 to 14.04 μg/kg), and endrin ketone was present in 4 samples (from 0.83 to 10.55 μg/kg), all measured in μg/kg. Among the thirty beef liver samples analyzed, alpha-BHC was detected in 28 samples (ranging from 17.40 to 340.42 μg/kg), gamma-BHC in 16 samples (from 1.75 to 15.79 μg/kg), beta- BHC in 16 samples (from 2.87 to 42.82 μg/kg), delta-BHC in 24 samples (from 2.24 to 26.41 μg/kg), heptachlor in 22 samples (ranging from 4.67 to 16.67 μg/kg), aldrin in 21 samples (from 0.66 to 20.93 μg/kg), heptachlor epoxide in 28 samples (ranging from 65.92 to 197.61 μg/kg), trans-chlordane in 16 samples (from 0.43 to 29.68 μg/kg), cis-chlordane in 10 samples (from 1.19 to 6.22 μg/kg), endosulfan I in 24 samples (ranging from 1.15 to 5.02 μg/kg), 4, 4´-DDE in 11 samples (from 0.10 to 3.38 μg/kg), dieldrin in 21 samples (ranging from 1.03 to 6.43 μg/kg), endrin in 20 samples (from 1.03 to 6.43 μg/kg), 4, 4´- DDD in 7 samples (ranging from 0.59 to 1.84 μg/kg), endosulfan II in 20 samples (from 0.22 to 25.55 μg/kg), endrin aldehyde in 26 samples (from 0.21 to 31.55 μg/kg), 4, 4´-DDT VII in 9 samples (ranging from 3.08 to 17.75 μg/kg), endosulfan sulfate in 2 samples (from 0.04 to 0.05 μg/kg), and methoxychlor in 8 samples (ranging from 0.26 to 11.67 μg/kg). In the thirty chicken meat samples, alpha-BHC was detected in 2 samples (at 1.00 and 2.87 μg/kg), gamma-BHC in 1 sample (at 4.94 μg/kg), delta-BHC in 27 samples (ranging from 5.91 to 201.65 μg/kg), heptachlor in 4 samples (ranging from 6.81 to 8.93 μg/kg), aldrin in 10 samples (from 1.60 to 33.93 μg/kg), heptachlor epoxide in 25 samples (ranging from 137.76 to 270.60 μg/kg), trans-chlordane in 13 samples (from 3.64 to 27.96 μg/kg), cischlordane in 7 samples (ranging from 0.44 to 2.24 μg/kg), endosulfan I in 25 samples (from 1.72 to 5.91 μg/kg), 4, 4´-DDE in 2 samples (at 0.41 and 1.69 μg/kg), dieldrin in 12 samples (ranging from 0.72 to 13.53 μg/kg), endrin in 10 samples (from 0.44 to 12.73 μg/kg), 4, 4´-DDD in 17 samples (ranging from 1.48 to 5.75 μg/kg), endosulfan II in 9 samples (from 0.97 to 56.96 μg/kg), endrin aldehyde in 16 samples (ranging from 0.93 to 5.03 μg/kg), 4, 4´-DDT in 7 samples (from 1.39 to 71.84 μg/kg), endosulfan sulfate in 6 samples (ranging from 0.21 to 3.14 μg/kg), and methoxychlor in 13 samples (from 1.59 to 5.95 μg/kg). In a study of thirty chicken liver samples, alpha-BHC was detected in 23 samples, with concentrations ranging from 2.12 to 159.13 μg/kg. Gamma-BHC was present in 3 samples, showing levels between 2.17 and 5.85 μg/kg, while beta-BHC was found in 10 samples, with values between 13.87 and 69.96 μg/kg. Delta-BHC was identified in 25 samples, displaying concentrations from 1.67 to 224.65 μg/kg. Heptachlor was detected in 3 samples, at levels ranging from 3.01 to 7.78 μg/kg. Aldrin appeared in 10 samples, with concentrations varying from 0.91 to 259.93 μg/kg. Heptachlor epoxide was found in 28 samples, with a range of 58.71 to 196.47 μg/kg. Trans-chlordane was present in 3 samples, with levels from 5.26 to 336.49 μg/kg, and cis-chlordane was identified in 4 samples, showing concentrations between 0.12 and 280.64 μg/kg. Endosulfan I was found in 26 samples, with values ranging from 1.23 to 22.86 μg/kg. The compound 4, 4'-DDE was detected in 9 samples (0.54 to 12.79 μg/kg), while dieldrin was present in another 9 samples, ranging from 0.84 to 9.09 μg/kg. Endrin was found in 9 samples, with concentrations between 1.24 and 40.29 μg/kg, and 4, 4'-DDD was detected in 10 samples, showing levels from 0.35 to 28.90 μg/kg. Endrin aldehyde appeared in 18 samples, with concentrations ranging from 1.12 to 307.65 μg/kg. 4, 4'-DDT was identified in 12 samples, at levels between 1.37 and 29.80 μg/kg, while endosulfan sulfate was found in 5 samples (0.97 to 204.26 μg/kg) and methoxychlor in another 5 samples, ranging from 0.72 to 5.68 μg/kg. Endrin ketone was present in 4 samples, with concentrations from 1.95 to 4.47 μg/kg. The health risks associated with these pesticides were assessed, revealing that the hazard indices for delta-BHC, heptachlor, aldrin, heptachlor epoxide, endrin, endrin aldehyde, and endrin ketone exceeded 1 for both adults and children. VIII A total of 120 biological samples were examined, comprising 30 each of beef meat, beef liver, chicken meat, and chicken liver for ten heavy metals. The samples underwent digestion with concentrated HNO3 and H2O2. In the ICP-MS, four varying concentrations of a standard solution (a mix of the ten metals) were injected to establish calibration curves. A linear correlation coefficient (r²) was determined for chromium (Cr), nickel (Ni), lead (Pb), cadmium (Cd), arsenic (As), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), and selenium (Se), with values of 0.9988, 0.9989, 0.9990, 0.9991, 0.9991, 0.9994, 0.9991, 0.9994, 0.9998, and 0.9993, respectively. The Limits of Detection (LOD) and Limits of Quantification (LOQ) were calculated for each of the ten metals. Copper (Cu), manganese (Mn), cobalt (Co), zinc (Zn), and selenium (Se) were detected and quantified across all beef and chicken meat and liver samples. The concentration of Cu ranged from 2.82 x 10⁻⁵ to 1.24 x 10⁻⁴, 0.09 to 0.23, 0.93 to 4.68, and 3.94 to 12.52; Mn levels ranged from 1.77 x 10⁻³ to 6.69 x 10⁻², 7.62 to 57.28, 0.005 to 0.05, and 0.04 to 0.10; Co concentrations were between 2.89 x 10⁻³ to 2.95 x 10⁻², 5.33 to 11.82, 0.03 to 6.28, and 2.95 to 9.18; Zn levels varied from 0.11 to 0.55, 81.03 to 203.27, 23.70 to 41.20, and 41.26 to 152.73, while Se was found in a range of 5.02 x 10⁻⁵ to 4.40 x 10⁻⁴, 0.38 to 1.54, 0.48 to 0.81, and 1.12 to 2.54 in all beef meat, beef liver, chicken meat, and chicken liver samples, respectively. Cr concentrations were found to be between 2.63 x 10⁻⁵ to 3.20 x 10⁻⁴, 0.06 to 0.20, 0.58 to 1.68, and 0.32 to 1.42 in 30 beef meat, 9 beef liver, 30 chicken meat, and 30 chicken liver samples. Ni levels varied from 2.43 x 10⁻⁵ to 9.86 x 10⁻⁵, 0.04 to 0.92, 0.10 to 1.45, and 0.06 to 42.63 in 30 beef meat, 29 beef liver, 29 chicken meat, and 30 chicken liver respectively. Pb was found at concentrations ranging from 1.12 x 10⁻⁶ to 7.46 x 10⁻⁴, 0.05 to 24.36, 0.05 to 1.71, and 0.03 to 5.28 in 30 beef meat, 29 beef liver, 26 chicken meat, and 22 chicken liver. Cd levels were detected between 4.82 x 10⁻⁶ to 5.61 x 10⁻⁴, 0.04 to 1.17, 0.14 to 0.18, and 0.04 to 0.24 in 30 beef meat, 12 beef liver, 2 chicken meat, and 3 chicken liver respectively. As concentration ranged from 1.34 x 10⁻⁶ to 4.41 x 10⁻⁴, 0.01 to 0.69, 0.005 to 0.52, and 0.005 to 10.79 mg/kg in 30 beef meat, 28 beef liver, 19 chicken meat, and 24 chicken liver samples respectively. The health risk assessment (EDI, THQ, HI, TCR) for heavy metals was conducted for both adults and children. Chemical pollutants can build up in the fatty tissues of beef and poultry, potentially changing the fatty acid profile and causing genetic mutations. Therefore, the fatty acid composition and overall fat content were examined using gas chromatography with a flame ionization detector (GCFID). The average fat content (%) calculated was 1.57, 6.19, 0.78, and 2.95% for beef meat, beef liver, broiler chicken meat, and liver, respectively. This research underscores comprehensive evidence of the occurrence of antibiotic, pesticide, and heavy metal residues in raw beef and broiler chicken meat and liver in Bangladesh. Although most samples were within internationally accepted limits, several exceeded Codex and EU MRLs, posing potential public health concerns.Item Synthesis and X-Ray Crystallographic Analysis of Nickel(ii), Copper(ii), Palladium(ii) Complexes Having N, O and N, S Donor Ligands and Study of Their Antimicrobial and Antioxidant Activities(University of Rajshahi, 2024) Khan, Sultana Shakila; Howlader, Md. Belayet Hossain; Ansary, Md. Rezaul HaqueTransition metal complexes featuring with N, O, and N, S donor Schiff base ligands have garnered considerable attention owing to their promising potential across various biomedical and chemical applications, including anticancer, antibacterial, antifungal, nonlinear optical, and insecticidal activities. The exploration in this field is continually expanding. Hence, recognizing the pivotal role played by dithiocarbazate and hydrazone groups across diverse fields of chemistry, it appears both attractive and worthwhile to synthesize novel complex compounds of nickel(II), palladium(II), and copper(II) featuring these ligands. Therefore the present research conducted three distinct series, each focusing on different aspects or applications. The synthesized compounds are characterized by NMR(1H and 13C), Mass spectrometry, IR, UV-Vis spectroscopy, magnetic moment and conductance measurement techniques. Additionally, X-ray crystallography studies, photoluminescence, antibacterial and antioxidant properties were explored. The first series synthesized some novel Schiff bases and their complexes of nickel(II), palladium(II) and copper(II) having N, S donor atoms containing long chain pendent arms. The Schiff base [R(R1/H)C=NNHC(=S)SC8H17], 1, 5, 9, 13, 17 were synthesized by the reaction of S-octyldithiocarbazate with thiophene-2-carboxaldehyde, furfuraldehyde, cinnamaldehyde, isobutyraldehyde, and acetophenone respectively. The Schiff base complexes are [M(R(R1/H)C=N-N=C(S)SC8H17)2], where M = Ni complex 2, 6, 10, 14, 18; Pd, complex 3, 7, 11, 15, 19 and Cu, complex 4, 8, 12, 16, 20. Along with spectroscopic data of the compounds some selected Schiff bases 5, 9, 17 and complexes 2, 6, 10, 12, 14 and 18 were characterized by X-ray crystallographic analysis and the complexes revealed the square planar geometry. X-ray crystallography study suggest that this maximum complexes are primitive monoclinic and primitive triclinic system. Fluorescence intensity of the complexes 6, 7, 10, 11, 12, 14, 15, 18, 19 and 20 quenched compared to their ligands. Additionally, the fluorescence intensity of the complexes 2, 3, 4, 8, and 16 enhanced compare to their ligands. Antimicrobial screening activity via disc diffusion method indicated that neither the ligands nor any of the complexes exhibited activity against the tested organisms. Schiff base ligands 1, 5, 9, 13 and 17 were assessed for their antioxidant activity. Among these, Schiff base 13 demonstrated significant antioxidant activity, while ligands 1, 5, 9, and 17 exhibited moderate antioxidant activity in comparison to the standard ascorbic acid, as indicated by their IC50 values.Item Particle Phase Organic Compounds in the Atmospheric Particulate Matter at Urban and Rural Areas in Bangladesh(© University of Dhaka, 2026-03-02) Islam, Md. NazrulParticle Phase Organic Compounds (PPOCs) are significant organic fraction of atmospheric suspended particulate matter. They comprise of harmful chemicals which have adverse effects on human health. There is very limited research regarding the source, seasonal variation and health impact of PPOCs in Bangladesh. The objectives of this study are to measure the 16 PPOCs at four different locations with seasonal variation, correlation coefficient, source identification with positive matrix factorization (PMF), influence of wind direction with backward air mass trajectory analysis by HYSPLIT and potential health risk assessment. In this study, suspended particulate matter samples have collected on quartz filters with a low volume sampler (Model: 700) at four locations in Bangladesh (Dhaka, Rajshahi, Narayangonj and Bhola) for one year at each location between January, 2016 and February, 2020. Concentration of 16 organic compounds (Naphthalene, Anthracene, Diazinon, Deltamethrin, Pyrabenzoxime, Pyrazosulfuran, Prophenophos, Butachlor, Propiconazole, Cymoxanil, Cypermethrin, Lamdacyhalothrin, Dimethoate, Chlorpyriphos, Carbofuran, and Metalaxyl) were determined with a Gas Chromatography-Mass Spectrometry (GC-MS). The total average PPOCs concentration was 11.60 ± 0.1 μgm-³ in Dhaka, 8.69± 0.3 μgm-³ in Rajshahi, 11.84±0.4 μgm-³ in Narayangonj and 7.22± 0.2 μgm-³ in Bhola. These concentrations were 2 to 18 times higher during winter season than that of monsoon season. The PPOCs concentration was similar between Dhaka and Narayangonj and it was 32% higher than Rajshahi and Bhola. Source apportionment by Positive Matrix Factorization (PMF) revealed five sources of PPOCs - diesel exhaust, biomass burning, industrial emission, gasoline exhaust, and other sources. Industrial emission was predominant in urban areas whereas biomass burning was the major pollution vi source in rural areas. Backward air mass trajectory analysis by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) indicated that during winter more than half of the period wind (60%) comes entirely from the Indo- Gangetic Plain (IGP) region originating from Africa. In monsoon, half of the wind (50%) comes entirely from the Indian Ocean through the Bay of Bengal. According to the health risk assessment study, 16 PPOCs had a Hazard Index (HI) value of 30.19, indicating a serious non-carcinogenic effect. The largest contributor to the hazard index (32%) was dimethoate. One in 340 people had a chance of getting cancer in their lifetime. The average lifetime cancer risk value (2.9410-3) was higher than the US Environmental Protection Agency's (USEPA) recommended threshold (110- 4). Naphthalene was found to pose the highest carcinogenic risk. As particulate phase organic compounds are mostly emitted from anthropogenic sources and pose severe health threat, so public awareness should be raised and more detailed research should be conducted in local and regional level.Item TREATMENT OF WATER-SOLUBLE DYES USING DIFFERENT PHYSICOCHEMICAL METHODS(Shahjalal University of Science and Technology(SUST), 2023-06) HASSAN, MOHAMMAD JOBAERWater quality is crucial for human welfare, yet industrial activities continue to contaminate freshwater sources with toxic dyes, adversely affecting soil, crops, aquatic life, and human health.This thesis investigates the treatment of dye-contaminated wastewater through various methods, focusing on adsorption, photocatalysis, and electrochemical degradation.Initially, gypsum is explored as an adsorbent for the removal of Chlorazol Yellow, an anionic dye, demonstrating high efficiency due to its positive charge and affinity for anionic molecules.The second phase utilizes amine-modified tannin gel to target cationic dyes such as Brilliant Green, highlighting the importance of developing cost-effective, natural adsorbents.The third section addresses photocatalytic degradation using tri-metal doped TiO2 to enhance visible light absorption, thereby maximizing sunlight utilization for dye degradation.Finally, an electrochemical approach employing a Pb-modified stainless steel electrode is proposed for rapid dye degradation, emphasizing the need for efficient, time-sensitive treatment methods.Collectively, this research presents a comprehensive exploration of innovative strategies for managing dye effluents, contributing to environmental sustainability and public health.Item Development and Fabrication of Conductive Metallic Thin Films on Polyether Ether Ketone Monofilament in Wet Chemical Method(© University of Dhaka, 2025-07-07) Foisal, A.B. M.The aim of this work is to develop and fabricate conductive metallic silver thin films on polyether ether ketone (PEEK) monofilament surface. It was coated with silver particles using wet chemical method after being treated with low-pressure glow discharge plasma of gases like air, nitrogen, oxygen, etc. at a definite condition of plasma parameters. The wet chemical method was based on the use of metallic salt silver nitrate (AgNO3) and ammonium hydroxide (NH4OH), which are well-suited to form a silver diamine complex and tetra ethylene pentamine (TEPA) used as an adhesion promoter. Catalytic silver was used to coat the modified monofilaments and after chemical reduction, the cationic silver transforms into metallic silver particles on the filament surface. The concentration of AgNO3 and reducing agent are varied at different stages of wet chemical method. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) analysis were used to observe the morphology of the silver particles and characterize the elemental analysis of the silver coated filaments respectively. The silver particle size was determined by ImageJ software. The atomic force microscopy (AFM) was used to monitor the surface roughness of the plasma treated and silver coated filament. The oxygen/carbon (O/C) ratio on the plasma treated surface was determined by x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) pattern was used to find out the crystallite size of the PEEK and silver particles. The thermogravimatric analysis (TGA) is performed to find out the thermal stability and silver percentages present on silver coated monofilaments. Electrochemical impedance spectroscopy (EIS) analyzer was used to determine the electrical resistance on dependency of frequency through the silver coated PEEK monofilaments and alternating current (AC) conductivity is measured. To find out how the modification affects the mechanical properties of plasma-modified and silver-coated PEEK monofilaments, universal strength tester was used. The coated monofilaments were also integrated into textile to investigate the capability of resisting the friction during sewing of silver coated monofilaments into the cotton woven plain fabric. PEEK monofilament surfaces have been rough due to low-pressure glow discharge air, N2, and O2 plasma treatment. The roughness of plasma treated monofilaments is higher than the unmodified surface as well as the O/C ratio is increased on the plasma treated surfaces of the monofilaments. Both exhibit synergistic effect on plasma modified surface for adhesion of metallic silver particles. The particles are distributed on plasma modified surface homogeneously and covered the surface as thin films. The roughness of the plasma modified surface has been reduced after deposition and dispersion of silver particles on the modified surface. The characteristic diffraction peaks of PEEK are not remarkably altered by covering the surface with silver nanoparticles. The breaking force and elongation of plasma treated and silver coated monofilament are not significantly changed in comparison with the normal monofilament. The thermal decomposition of normal PEEK and plasma modified-silver coated PEEK both exhibit above 500 °C which indicates thermal behavior has not been remarkably changed. In terms of electrical properties, AC conductivity was increased with the increment of silver percentages on plasma modified-silver coated surface. The increment of silver wt. (%) on the surface of the plasma modified PEEK monofilament has remarkably changed and turned it from insulating to conductive behavior. The electrical conductivity of silver thin film coated monofilament increases with the increase of concentration of AgNO3 and the silver contents (wt.%) on the surface of plasma modified PEEK monofilament. A pronounced non-linear dependence of electrical conductivity is observed on the silver coated PEEK monofilament. The surface morphology, roughness, particles distribution, elemental composition and apparent silver content (wt.%) of O2 plasma modified-silver thin film coated PEEK monofilament intensely influences the electrical conductivity over air and N2 plasma modified-silver coated PEEK monofilaments. Finally, silver thin film coated PEEK monofilament has been integrated into woven fabric to observe resistance of friction between coated filament and fabric during sewing manually. The electrical resistance was measured after integration into textile. The electrical resistance remains stable within range, which indicates that the silver coated monofilament can be integrated into textile and used as conductive threads for smart textiles.Item Innovation of building materials from Indigenous sources of Bangladesh and studies of their Physio-Chemical properties(© University of Dhaka, 2025-03-19) Ahmed, Akhtar UddinItem Studies on vulcanized rubber and rubber products(© University of Dhaka, 2025-03-19) sen, Ashis ratanItem Modification of jute fibres and fabrics by etherication(© University of Dhaka, 2025-03-19) RAHMAN, Md. AzizurItem Modification of jut e fibre by chemical Means and blending of the modified jute Fibre with cotton, rayon, polyester and Silk.(© University of Dhaka, 2025-03-19) islam, Md. NuralItem Studies on the chemical modification Of jute fibre/fabric/yarn by crosslinking reaction(© University of Dhaka, 2025-03-19) rahman, S.m. badier