Microwave induced green synthesis of biopolymer immobilized nanocomposites Thesis

Abstract

xv newlineAbstract newlineNanocomposites have gained importance in medicine, environment and other fields. In this study, chitosan-g-poly(acrylamide)/ZnS (CPA/ZS), chitosan-g-poly(acrylamide)/CuS (CPA/CS), chitosan-g-poly(acrylamide)/Zn (CPA/Zn) and chitosan-g-poly(acrylamide)/Cu (CPA/Cu) nanocomposites have been synthesized using microwave radiations. The synthesized nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA). newlineFTIR results established the grafting of acrylamide onto chitosan backbone. TEM analysis revealed the size of the CPA/ZS nanocomposite particles in the range of 19-26 nm. XRD technique predicated the semi-crystalline behavior of the CPA/ZS nanocomposite. XRD, TEM and FTIR analysis confirmed the formation of CPA/ZS nanocomposites. Zeta potential for CPA/ZS nanocomposite was found to be +28.2 mV which indicated its stability. The CPA/ZS nanocomposites were investigated for drug release behavior and found maximum of 79% drug release at pH 2.2. Moreover, CPA/ZS nanocomposite also possess antimicrobial activity against E. coli bacteria. About 78% killing of E. coli was observed after 24 h. The photocatalytic activity of CPA/ZS nanocomposite was evaluated for methyl orange (MO) and congo red (CR) dye degradation in aqueous solution under simulated solar irradiation. After 60 min of simulated solar irradiation 75% and 69% of congo red and methyl orange dyes were degraded. Langmuir model (R2 = 0.991) was found to be best fitted with maximum adsorption capacity of 0.004 mg/g. The kinetic study was described by pseudo-second-order kinetics (R2 = 0.98). The thermodynamic parameters such as enthalpy change (and#916;H°) and entropy change (and#916;S°) were found to be -19.716 kJ/mol and -0.049 J/mol/K, respectively. The negative value of and#916;G° and and#916;H° confirmed the spontaneous and exothermic nature of the reaction. newlineThe drug release studies for chitosan-g-poly(acrylamide)/CuS (CPA/CS) nanocomposites were investigated at different pH (2.2, 7.4 and 9.4) and time intervals (2, 4, 6, 8, 10, 12, 14, 16 h). The maximum drug loading efficiency of 85% was recorded for CPA/CS nanocomposite. The maximum drug release of 76% was observed at 2.2 pH after 18 h onto newlinexvi newlineCPA/CS. Nanocomposites were also tested for antibacterial activity against E. coli bacteria. After 24 h 97% killing of E. coli was observed. In aqueous solution under simulated solar irradiation the photocatalytic activity of CPA/CS was evaluated for methyl orange (MO) and congo red (CR) dye degradation. 97% of congo red dye and 96% of methyl orange was degraded after 60 min of solar irradiation. Langmuir model (R2 = 0.996) was found to be best fitted with maximum adsorption capacity of 0.0139 mg/g. The pseudo-second-order kinetics was observed from the kinetic study of CPA/CS nanocomposite onto Pb(II) (R2 = 0.89). The enthalpy change (and#916;H°) and entropy change (and#916;S°) were found to be -2.841 kJ/mol and -0.141 J/mol/K, respectively. The spontaneous and exothermic nature of the reaction was confirmed by the negative value of and#916;G° and and#916;H°. newlineChitosan-g-poly(acrylamide)/Zn (CPA/Zn) nanocomposite was synthesized and confirmed by different spectral techniques. The nanocomposite was used for controlled drug delivery of ofloxacin. The maximum drug release was 75% which was observed in acidic medium. CPA-Zn nanocomposites were also studied for their antibacterial activity against E. coli bacteria. About 85% killing of E. coli was observed after 24 h. The photocatalytic activity of CPA/Zn was evaluated for methyl orange (MO) and congo red (CR) dye degradation in aqueous solution under simulated solar irradiation. 61% of congo red and 78% of methyl orange was degraded after 60 min of solar irradiation. Langmuir model (R2 = 0.998) was found to be best fitted with maximum adsorption capacity of 0.0139 mg/g. The kinetic study was described by pseudo-second-order kinetics (R2 = 0.99). The thermodynamic parameters such as enthalpy change (and#916;H°) and entropy change (and#916;S°) were found to be -2.841 kJ/mol and -0.141 J/mol/K, respectively. The negative value of and#916;G° and and#916;H° confirmed the spontaneous and exothermic nature of the reaction. newlineChitosan-g-poly(acrylamide)/Cu (CPA/Cu) nanocomposite was investigated for different applications. The maximum drug release was 68% was observed in acidic medium. CPA/Cu nanocomposites were also studied for their antibacterial activity against E. coli bacteria. About 87% killing of E. coli was observed after 24 h. The photocatalytic activity of CPA/Cu was evaluated for methyl orange (MO) and congo red (CR) dye degradation in aqueous solution under simulated solar irradiation. After 60 min of solar irradiation, 85% newlinexvii newlineof congo red dye and 83% of methyl orange was degraded. Freundlich model (R2 = 0.996) was found to be best fitted with maximum adsorption capacity of 38.93 mg/g. The pseudo-second-order kinetics was observed by kinetic study of chitosan-g-poly(acrylamide)/Cu nanocomposite (R2 = 0.98). The thermodynamic parameters such as energy change (and#916;G°), enthalpy change (and#916;H°) and entropy change (and#916;S°) were found to be -3.881 kJ/mol, -51.58 kJ/mol and -168.12 J/mol/K, respectively. The negative value of and#916;G° and and#916;H° confirmed the spontaneous and exothermic nature of the reaction. newline