PhD Thesis
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Item Synthesis and Characterization of Solid Catalysts(University of Rajshahi, 2004-12) Azad, Md. Abul Kalam; Rahman, M. AnisurAmorphous silica-alumina catalysts having different silicon aluminum ratios were prepared. The Brönsted surface acidity of these catalyst samples was measured by the base exchange method using aqueous CHCOONH solution and the results were compared with those measured by the base exchange method using NH4OH and KOH as adsorbates from aqueous solution. The amount of NH4' in CH3COONH4 and NH4OH and K in KOH adsorbed was determined by spectrophotometrically and titrimetrically respectively by measuring the concentration of NH4 and K in the solution before and after adsorption. Variation of surface acidity of catalyst samples-A (synthesized without pore regulating agent), sample-B (synthesized with tetramethylammonium bromide as a pore regulating agent) and sample-C (synthesized with pore regulating agent and base exchanged with NILCI solution to obtain H' form by calculation) have been studied using different concentrations of ammonium acetate, ammonium hydroxide and potassium hydroxide solutions. It has been observed that the surface acidity of a given size catalyst increases with the increasing of concentration of CH3COONH, NH4OH and KOH but dilute solutions of CHCOONH, NH4OH and KOH are sufficient to saturate the catalyst surface. It has been observed that the surface acidity of the catalyst samples found by using CHCOONI, is greater than that of NH4OH and KOH: Of the two bases NH4OH gives slightly greater surface acidity than that of given by KOH. At a given concentration of CH3COONH, NH4OH and KOH solutions the surface acidity was more pronounced when ammonium acetate solution was used as an adsorbate. A plausible explanation for this discrepancy is that with the use of NH4OH and KOII as bases considerable dealumination takes place with a consequent decrease of surface acidity of the catalyst samples. In all cases, the surface acidity was found to increase with the decrease of sample size. Surface acidity was also found to increase as the Al content of the catalyst was increased. The surface acidity of the catalyst samples-13 and C are greater than that of sample-A. But this increase of surface acidity is more noticeable in case of sample-C. Iron(III) dispersed on silica was prepared by the incipient wetness method and its surface acidity measured by CH3COONH, solutions was found negligibly small and was comparable to that of chromatographic silica and alumina. Finally, the Brönsted surface acidity of the catalyst sample-A measured by the base exchanged method using ammonium acetate has been found to be well correlated with the equilibrium pH of CH3COONH4 solution. This may therefore, be concluded that surface acidity of silica-alumina catalyst depends on its mode of preparation, sample size, ratio of Si:Al and concentration of titrants although very dilute solutions of titrants are sufficient to saturate the catalyst surface. A weak base like CH3COONH4 gives comparatively high values of surface acidity of all the silica-alumina catalyst samples where dealumination from the silica-alumina catalyst samples are supposed to be negligible. The total surface acidity of the silica-alumina catalyst sample was also determined by the Tamele method (Amine titration method). Considering the carcinogenic effect of benzene and toxicity of n-butylamine substitutes of benzene as a solvent and n- butylamine as a titrant have been sought. With this end in view attempts have been made to modify the Amine titration method by replacing benzene with cyclohexane or n-hexane or n-heptane and replacing n-butylamine by di-n-butylamine or di-iso- butylamine or sec-butylamine. For this parameters varied were concentration of di-n- butylamine, di-iso-butylamine, n-butylamine and sec-butylamine solutions, sample size of catalyst and types of catalyst samples. The results in the present investigation show that surface acidity of catalyst samples tends to increase with the decrease of catalyst sample size. Unlike Brönsted acidity for a given size of sample the total surface acidity tends to increase with the silicon content of the catalyst sample. For bases, the total surface acidity of various catalyst samples increase in the order of di-iso- butylamineItem Some Physico-Chemical Properties of Cyanex 272 and Extraction of Some Metal Ions(University of Rajshahi, 2006-05) Singha, Hari Prosad; Biswas, R. K.Using a reported technique for purifying organophosphorous extractants, the as-received Cyanex 272 extractant containing 85% bis-2,4,4-trimethylpentyl- phosphinic acid [BTMPPA] has been purified to a purity of about 99% BTMPPA. The purified reagent has been characterized and compared to the literature values. A technique for the colorimetric estimation of purified Cyanex 272 has been developed. It consists of the digestion of pure sample or its aqueous solution (after evaporating out most of water) with concentrated HNO3 (70%) - HCIO (70%) mixture at 2:1 ratio for 1 h. The oxidizing mixed acid quantitatively converts Cyanex 272 to a clear solution of orthophosphate which can be easily estimated by the molybdenum blue colorimetric method at 830 nm. The method is sensitive with a molar extinction coefficient of 2.6 x 10 and reproducible within ± 2%. Applying this technique of analysis, the dimerization constant (K2), distribution or partition coefficient (K) and the ionization constant (K) of the purified Cyanex 272 ie. BTMPPA have been estimated to be 190, 53 and 5.52 x 10, respectively. Interactions of BTMPPA+ diluent (n-hexane cyclohexane / benzene / toluene / chloroform / carbon tetrachloride / 1,2-dichloroethane (DCE) / 1-heptanol) binary mixtures have been studied in terms of density and viscosity measurements and also in terms of derived properties such as excess molar volumes (V), excess viscosities (n) and excess Gibbs free energy changes of activation of flow (AGE). Variations of these values together with the variations of the Grunberg-Nissan interaction parameter (d) for BTMPPA diluent binary systems show that BTMPPA interacts with the diluents in varying degrees. However, no correlation between d, AGE, nor V and the Cu2+/ Fe3+ - extraction characteristics with BTMPPA could be noticed. - The interfacial adsorption property of Cyanex 272 (purified) at the 0.50 mol/dm3 H2SO4 (pH = 0.8) / BTMPPA - diluent (carbon tetrachloride / cyclohexane/ DCE/ n-hexane / toluene / kerosene / benzene / chloroform / 1-heptanol/ 1-hexanol) interface have been investigated. Applying the Gibbs adsorption isotherm to the y vs. log [BTMPPA] plots for each of the diluent used (y being the interfacial tension, mN/m), the apparent cross-sectional areas (A in A2) of BTMPPA molecules adsorbed at the interfaces have been estimated. A (A3) is found to vary in the order: CCl4 (157 A2)Item Solvent Extraction of Mn(II), Ni(II) and Zn(II) by Cyanex 272: Equilibrium and Kinetic Studies(University of Rajshahi, 2010-06) Rahman, Md. Saidur; Biswas, Ramjit KumarThe solvent extraction systems: Mn(II)-SO, -Ac Cyanex 272-kerosene, Ni(II)- SO4-Ac Cyanex 272-kerosene and Zn(II)-SO4 Cyanex 272-kerosene have been thoroughly investigated from equilibrium and kinetic point of views. From the dependence of extraction ratio (at constant equilibrium values of other parameters) on various parametric concentrations, the equations for extraction ratios have been derived at 303 K as: log Dmn=-6.17+2 pHm) + log [H2Azam)-log (1 + 1.9 [SO"]) log Di-11.16+2 pH)+ log [H2A2)-log (1+ 6.92 [SO."])-log [Ac"]; at [H2A2]) <0.05 kmol/m log DN-11.56+2 pH)+3 log [H2A2km)-log (1+6.92 [SO, D)-log [Ac]; at [H2A2 >0.10 kmol/m log Dzn --3.11+2 pH)+ log [H2A2])-log (1+2 [SO,"]); at [H2A2] (en) <0.05 kmol/m3 log "Dzn -2.08 +2 pH() +2 log [H2A2](o)-log (1+2 [SO"]); at [H2A2]()>0.10 kmol/m where, the first terms on the right hand sides represent the logarithmic values of extraction equilibrium constants (Kex). The equilibrium extraction reactions in low concentration regions of extractant are suggested as M(II) + H2A2(0) [MA2](0) + 2 H; but disolvated and monosolvated species are extracted in the cases of Ni(II) and Zn(II), respectively, at high concentration regions of Cyanex 272 (H2A2). The extraction processes are found to be endothermic. The maximum loading capacities of the extractant are found to be 9.52 g Mn(II), 21.28 g Ni(II) and 11.5 g Zn(II) per 100 g extractant. The extracted species are strippable by dilute H2SO4, HNO3 and HCl solutions. In kinetics of forward extractions of the selected divalent metal ions by Cyanex 272, the rates have been measured the single falling drop technique at various extraction parametric concentrations in order to determine the orders of reaction with respect to various concentration terms and also to evaluate the log kr values. Rates have measured at various temperatures to determine E., AH* and AS* values at various parametric conditions for all systems under consideration. The rates of forward extractions of Mn(II), Ni(II) and Zn(II) at 303 K can be expressed respectively as: log F-3.6+ log [Mn(II)] +0.5 log [H2A2]()-log (1+ 105 [H])-log (1+1.58[SO"]) log Fr=-3.7+ log [Ni(11)] +0.5 log [H2A2](o)-log (1+ 10635 [H])-log (1+6.3[SO, ])-log (1 +0.55 [Ac"] log Fr=-8.4 + log [Zn(II)-log [H])+0.5 log [H2A2])+ log (1+ 1.07 [H2A]()) where, Fr represents flux of metal transfer from one phase to another and defined as rate per unit interfacial area. From the rate equations, the mechanisms of extractions are given. Invariably in all cases under investigation, the attachment of the first monomeric anion of the extractant (A') to the metal ion is the rate controlling (M2++ A slow [MA]'); which has been supported by high activation energy (>48 kJ/mol). However, in certain parametric conditions diffusions rather the chemical reaction stated become rate controlling, which is supported by low activation energy. In case of Ni(II) extraction, at high concentration region of extractant, the reaction: Ni2++ HA2 (int) → [NIHA2] becomes rate controlling. The highly negative AS* values in all cases suggest the chemical rate determining step occurs via SNo2 mechanism. The kinetics of stripping of metal ions from highly metal ion loaded organic phases by sulphuric acid solutions have been investigated by the single falling drop technique to derive respective stripping rate equations at 303 K. The stripping rate equations derived for stripping of Mn(II), Ni(II) and Zn(II), respectively, are: log F1 = -4.88 + log [MnA2])- 0.5 log (1+0.002 [H]') + log (1 +5.129 [SO,")) log F-4.35+ log [Ni-H2A2 complex])-log (1 + 1042 [H])-log ([H2A2])+2.5 [H2A2])+ log (1+6 [SO, ])+ log (1 + 3.2 [Ac']) log F-5.24+ log [Zn-HA, complex]) + log [H]-0.5 log [H2A2]) + log (1 +1.5 log [SO."]) The rate equations have been analyzed to give stripping mechanisms. It is found that the dissociation of second anion ligand from [MA2](o) is rate determining which occurs in the bulk aqueous phase (MA slow M2++ A), which is, supported by high Eq. values. This mechanism is valid for Mn(II) and Zn(II) covering all concentration region of free extractant in the organic phase; and also for Ni(II) in low concentration region of extractant, but at its high concentration region, the dissociation of dimeric anion (HA2) from [Ni(HA2)2. H2A2] (0) appears as rate determining. However, low E, value suggests this step occurs via SN2 mechanism. The extraction equilibrium constants (Ke) for Mn(II) and Zn(II) derived from equilibrium studies are matchable to those from respective kinetic studies (Kex = kr/k). But in the case of Ni(II), a deviation by a factor of 10 is obtained, which may be attributed to the loss buffer action resulting the change of interfacial pH. The possibilities of separations of the metal ions under consideration from their mixtures by Cyanex 272 have been theoretically evaluated and it has been shown that the mutual almost complete separation of this metal ion by single or by at least two stage extractions by Cyanex 272 solution in kerosene is possible.Item Modification of cotton fabric with Natural antimicrobial agents for Ecofriendly protective textiles(University of Rajshahi, Rajshahi, 221) Saha, Joykrisna; Mondal, Md. Ibrahim H.; Sheikh, Md. Rezaul KarimIn recent time‘s health and hygiene issues have achieved the greatest attention among the awareness people of all over the world. Health and hygiene are the primary obligations for human beings to live comfortably and work with maximum safety. The aim of the present work is to develop environment friendly protective textiles using Aloe vera, chitosan and sericin on bleached cotton woven fabrics for medical and health care apparel against gram-positive Staphylococcus aureus and gram-negative Escherichia coli bacteria. Aloe vera, chitosan and silk sericin are natural biopolymer which exhibited different significant biological property. Aloe vera extract was prepared from Aloe vera leaves through methanol solvent using a rotary evaporator. Chitosan was made from shrimp shell through several steps of alkali and acid treatments and silk sericin powder was obtained from a boiled water solution of silk cocoons through ethanol precipitation. Extracted Aloe vera, chitosan and sericin powder were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Energy dispersive spectroscopy (EDS), UV-visible spectrophotometer, X-ray diffraction (XRD). Solubility, degree of deacetylation, antibacterial activity, antioxidant property and UV protection factor were also analyzed. Both quantitative and qualitative methods were used to assay the antimicrobial activity. The antioxidant activity was evaluated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radicals. Chitosan was found to have a 90% degree of deacetylation.-----Item Synthesis and Chracterization of Eco-Friendly Hydrogels from Cellulosic Materials(University of Rajshahi, Rajshahi, 2019) Haque, Md. Obaidul; Mondal, Md. Ibrahim H.; Sayeed, Md. Abu; Yeasmin, Mst. SarminaHydrogels are insoluble, three-dimensional, crosslinked polymeric networks which swell in the presence of water and other fluids. They can imbibe plenty of water without dissolution compared to their own mass. Most of the present superabsorbent hydrogels are petrochemical-based and non-degradable in nature. Cellulose is the most abundant natural biopolymer which possess an intrinsic nature of degradability, biocompatibility and non-toxicity. Some cellulose derivatives show smart behavior. Cellulose-based biodegradable Super Absorbent Hydrogels (SAH) have been synthesized from three cellulosic materials (cotton, sugarcane bagasse and CMC) by simple and energy-efficient graft co-polymerization. Among the materials, cotton is pure cellulosic material. Sugarcane bagasse is a cellulose-enriched agro-waste product. Carboxymethyl cellulose (CMC) is the most-consumed cellulose derivative all over the world. Every year, in Bangladesh, a large amount of agro-waste is produced and becomes a source of environmental pollution. This is one reason that three cellulosic sources (cotton, sugarcane bagasse and carboxymethyl cellulose) have been chosen for this research to synthesize biodegradable hydrogels. Besides synthesis, another objective was to characterize the product, physically and instrumentally, and find the applications which could be beneficial to human welfare. Biocompatible hydrogels were synthesized from base material cellulosic sources (cotton, sugarcane bagasse and carboxymethyl cellulose) and, by varying combinations of monomers [acrylic acid (AA), acrylamide (Am) and methyl methacrylate (MMA) and one polymer-poly vinyl pyrollidone(PVP)], a number of hydrogel samples were synthesized. The prepared hydrogels in this research work are, i) Cot-g-poly(AA-co-Am) hydrogel; ii) Cot-g-poly(Am-co-PVP) hydrogel; iii) Cot-g-poly(Am-co-MMA) hydrogel; iv) Sugarcane bagasse-g- poly(AA-co-Am) hydrogel; v) Sugarcane bagasse-g-poly(Am-co-PVP) hydrogel; vi) Sugarcane bagasse-g- poly(Am-co-MMA) hydrogel; vii) CMC-g- poly(AA-co-Am) hydrogel; viii) CMC-g-poly(Am-co-PVP) hydrogel; ix) CMC-g- poly(Am-co-MMA) hydrogel and x) anti-microbial hydrogel.Item Processing of Ilmenite by Various Roasting, Leaching and Solvent Extraction Processes(University of Rajshahi, 1992) Habib, Md. Ahsan; Islam, M.F.; Biswas, R.K.The processing of ilmenite (TiFe03) to produce pigment grade while Ti02 and black Fe2 03 by various thermal, leaching and liquid-liquid extraction with subsequent precipilation treatments has been investigated. Thermal pre-treatment of ilmente with LPG-pyrolysed product at 7oo·c for 75 min- at LPG-flow rat.e 230 cm3 min-1 peoduces a roasted mass which gives ~83.5% titanium and 80% iron dissolutions in 6 g eq dm-3 hydrochloric acid at its boiling point, solid to liquid phase ratio (S/L) of 0.02 kg dm-3 and at pulp agitaLion speed of 350 rpm for 5h. Under similar condition sulphuric acid diss0lves only 66% titanium o.nd 73% iron. X-ray powder diffraction patterns (XRD) of ilmenite and roasted muss suggest the chemicaJ/physical change occurring during roasting. A different method of thermal treatment of ilmenite is to react with the reformed products of the LPG-H20 vapour mixture in presence of nickel catalyst. The optimum conditions for roasting are 700 ° C temperature, 110 cm3 min-1 LPG-flow rate, 0.041 atm. water vapour pressure and 40 min time. XRD shows the changes but the composition of roasted mass can not be identified. Hydrochloric acid gives better leaching results than sulphuric acid of identical concentration. About 93% titanium and 95% iron are dissolv,•d in (i g eq dm-3 hydrochloric acid at its boiling point, S/JJ ratio of 0.02 kg dm-3 and at 350 rpm for 4h. Under simHar condition, only ~46% titanium and ~64% iron are dissolved in sulphuric acid. --------------Item Preparation, Characterization and Application of Activated Carbon for Arsenic Separation from Water(University of Rajshahi, 2013) Jahan, Israt; Rahman, Md. Sahedur; Asadullah, Md.; Hassan, A.T.M. KamrulArsenic removal from water in the form of As(III) and As(V) using activated carbon and iron loaded activated carbon has been studied. Activated carbon has been prepared from jute stick using both chemical activation and physical activation methods. In chemical activation, H3P04 was used as an activating agent while in physical activation steam was used. The activated carbons produced were characterized by determining BET surface area, iodine value, methylene blue dye number, reactivity, pore volume and pore size. In addition, the studies on structural feature, surface functionality and morphology were also carried out using Raman spectroscopy, FT-IR spectroscopy and Scanning Electron Microscopy (SEM). The maximum BET surface area, iodine value and methylene blue number were found to be 1664 m2/g, 1440 mg/g and 475 mg/g, respectively. Activated carbon produced at optimum conditions was used for As(III) and As(V) separation from water in different method, such as batch process, continuous column filtration method and commercial filter method. Around 48% of As(l11) separation while complete removal of As(V) was achieved using chemically activated carbon (ACC) in column filtration method. However, the main objective of this work is to remove As(III) to an acceptable range (below 0.01 ppm), which is the predominant species in the most underground water, especially in Bangladesh. To enhance the arsenic adsorption capacity, iron species was loaded onto the ACC as well as physically activated carbon (ACS). The iron loaded activated carbon F ACC exhibited superior performance in As(III) separation in column filtration method. Almost complete removal of As(III) was achieved when 9 cm of bed thickness using 1.5 g of F ACC was used in a glass column. However, in order F ACC to utilize in practical filtration of arsenic contaminated water an investigation in the scale of 24 L/day of water, a minimum requirement of commercial filtration, was perfonned. In this study a commercial house hold filter body was used after removing the ceramic candleand layers of filter cartridge. The F ACC was filled in the blank filter cartridge and used for filtration. To compare the separation capacity ofFACC, ACC and FACS were also used in the commercial filtration method. The F ACC showed the dominant performance and almost 99% arsenic was removed from the water. Based on the characterization data, F ACC poses much higher BET surface area, micropore surface area and micropore volume which mainly contributed in liquid phase adsorption. In addition, surface polarity due to the presence of functional groups on ACC contributed to widely distribute of iron species on the surface which in turn contributed to efficiently adsorb As(III) from water. Finally, this study embarked an efficient way of As(III) and As(V) separation from water which can be recommended to commercially use for drinking water purification, especially in the countries where arsenic contamination in drinking water created a public health problems.Item Solvent Extraction of Ti(IV) and V(IV) by Cyanex 301 and Cyanex 302 and Application of Yates Experimental Design(University of Rajshahi, 2012) Karmaka, Aneek Krishna; Biswas, Ranjit KumarThe solvent extractions in (i) Ti(IV)-Cyanex 301 {HA), (ii) Ti{IY)-Cyanex 302 (H2A2), (iii) V(IV)-HA and (iv) V(IV) - H2A2 have been investigated from equilibrium and kinetic points of view. Yates Experimental Design has been made to the equilibrium and kinetic data for all systems. In system (i) and (ii), heptanol and hexanol (respectively) have been used as de-emulsifier. The equilibration times are 40, 30, 15 and 20 min, respectively. The extraction equilibria at 303 K can be expressed (respectively) as: Kcx = 101.1 17 = co (1+316.2 [Ti(IV)]) {I+ 0.794 [SO/] ([H+] + 229 [W]2) / [HA)to) K.x = 10°.339 = cD (I+ 141.3 [Ti(JV)]) (I+ 1.86 [SO/°]) ([H+)+58.88 [H+J2) I [H2A2Jtii1 K.x = 10·t.42 = cD [H+J2 / [HA)fo) (1+1.58 [SO/]) Kcx = cD [H+r (I +2.24 [SO/·]) / [H2 A2 lfo) [Kcx depends on 'x' and 'x' varies between 2 - OJ The processes are endothermic with H values of -27, -50, -16 and -25 kJ/mol (at l.t.r and - 90 kJ/mol at h.t.r), respevtively. The loading capacities are 7.11, 5.08, 7.87 and 4.05 g/L respective metal ions/ 100 g respective extractant. Suitable diluents are chlorobenzene, n-heptane, kerosene and toluene (benzene) respectively, for systems (i), (ii), (iii) and (iv). The cited equilibrium expressions have been used to suggest equilibrium reactions. The extracted species are [TiOA2], [TiOA2.HA], [VOA2] and [VO(HA2)2] in respective systems; but the reacting metallic species depends on the aqueous pH and sulphate ion concentration ranges. The kinetics of forward extraction of the systems (i), (ii), (iii) and (iv) have been investigated by measuring initial flux of metal ion transfer in a Lewis cell operated at 3 Hz………………………………………Item The Effect of Starch Interactions with Soap or Surfactants Studied by the Ternary Phase Diagram(University of Rajshahi, 2014) Hossain, Md. Mohsin; Mondal, Md. Ibrahim H.Starch interactions with various surfactants have been studied for the investigation of ability and cleansing activity of starch-surfactant-water system. The surfactants investigated were sodium dodecyl sulphate (SDS), cetyltrimethyl ammonium bromide (CTAB), Triton-X-100, Brij-30 and tween-20. The Degree of substitution of starch is 0.8 and the concentration of starch was varied from 0.01 to 1% w/v. The effect of mixing on the micellisation of the ternary surfactant solutions can be described to a good approximation by taking into account only the effects of the volume difference between the hydrocarbon chains length. Mixed micelle formation with starch depends on the chain-length difference in the same way as for starch-surfactant micelle…………………………………………….Item Biodegradable Polymers: Drug Release Characteristics(University of Rajshahi, 2014) Mahmud, Abu; Bakr, Md. AbuFour polymers namely: i) maleic acid-butane-1,4-diol polyester (MBP), ii) maleic acid-adipic acid-propane-1,2-diol co-polyester (MAPC), iii) malic acid-adipic acid-butane-1,4-diol co-polyester (MABP) and iv) maleic acid-citric acid-propane-1,2-diol co-polyester (MCPC) from different composition and ratios of their corresponding monomers were synthesized and characterized. Their biodegradation and in-vitro drug release behavior in simulated physiological environments were also investigated. All of these four polymers were synthesized using xylene as the reaction medium in Dean-Stark apparatus. The polycondensation temperature was varied from 130 to 1450C for different polymers. The reaction time was about 5 hours followed by 1 hour post curing and anhydrous FeCl3 (approximately 0.4% of the total weight) was used as catalyst. The synthesized co-polyesters were collected from the reaction vessel by dissolving them in acetone and re-precipitated using water as non-solvent. The purified co-polyesters were characterized by their solubility tests in common organic solvents, molecular weights, IR-spectra, elemental analyses, hydrolytic and soil degradation tests. Probable structures of the co-polyesters were also assigned. Molecular weight determination was carried out by end group analysis and viscosity method. Soil burial tests revealed that, all of these polyesters degraded biologically and normally mixed with soil imparting no natural imbalance. At room temperature, hydrolytic degradation study in solutions of different pH values showed that co-polyesters i), ii) and iii) remained almost intact in solutions of pH 0-3.0, slight degradation was observed in pH range 3.0-6.0 but they gradually degraded in solutions of pH >6.0. Such pH responsive degradation nature of these polyesters led us to investigate their possible application as enteric coating material. Diclofenac sodium and naproxen core (uncoated) tablets were used as model drugs for this purpose. Simulated physiological environments and procedures according to British pharmacopoeia (BP) were followed to monitor the drug release pattern of polymer coated tablets and satisfactory results were obtained. However, hydrolytic degradation study of the co-polyester (iv) reveals that in acid medium the polymer sample swells insignificantly. But in alkaline medium it swells well and the ester linkage is hydrolyzed with respect to time. Because of such time dependent pH responsive nature, this polyester was tried as a drug carrier for extended release drug-polymer matrix tablets and pure dichlofenac sodium was used as the model drug. The drug was incorporated in the polymer matrix by melt granulation process keeping the drug polymer ratio as 1:2. The prepared granules were compressed in a single punch tablet machine to get them in tablet forms. In-vitro drug release from these matrix tablets were studied spectrophotometrically under physiological condition (phosphate buffer of pH 7.4 at 370C). The release pattern has shown a bit higher release in the first hour, then a nearly zero order release for 10-11 hours followed by declining release for the subsequent few hours.