Environmental Science And Technology - Mphil Thesis
Permanent URI for this collectionhttps://kr.cup.edu.in/handle/32116/86
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Item Studies in the hydrolysis of cellulose using cellulase in imidazolium based ionic liquid(Central University of Punjab, 2012) Kumar, Rabindra; Babu, J.N.Ionic liquids are the modern day revelations as a green solvent. These solvents have found many applications in biofuel strategy. The cellulose pretreatment using ionic liquid is currently being studied for future biofuels from lignocellulosic biomass. The strategy involves the dissolution of cellulose in these solvents, followed by precipitation by an anti-solvent like water or acetone, leading to the formation of amorphous cellulose which is easy to hydrolyze by biocatalytic methods. Further studies had been conducted in the inhibitory effect of ionic liquid traces present in pretreated cellulose, on the biocatalytic hydrolysis by cellulase. Apart from this, biocatalytic hydrolysis had been studied in binary aqueous-ionic liquid solution for a one-pot process for simultaneous pretreatment & hydrolysis. These process involved the study of biocatalytic hydrolysis in imidazolium based ionic liquids namely, [EMIM]OAc & [BMIM]Cl, as hydrophilic solvents. These solvents have anions with predominantly strong hydrogen bond acceptor capacity. The study reveals the deactivation of the enzyme in presence of these ionic liquids. Thus in an effort to increase the hydrolysis efficiency of the enzyme without loosing the hydrogen bond acceptor capacity of the IL, was essentially required. Thus in the present study, we have investigated one-pot biocatalytic hydrolysis of cellulose in IL with variable alkyl chain length of the cation leading to hydrophobic environment around the biocatalyst. The ILs used in the present study are [BMIM]Cl, [HMIM]Cl & [OMIM]Cl. The biocatalysis was studied in both homogenous as well as heterogeneous conditions. In homogenous conditions dissolution of cellulose was maintained throughout the reaction period. The homogenous biocatalysis was studied with or without the presence of surfactants. The results indicate that [HMIM]Cl is a promising solvent for cellulase catalyzed hydrolysis of cellulose in both homogenous & heterogeneous condition, resulting in more than 70% hydrolysis in presence of non-ionic surfactant PEG-1500 and in the binary mixture of 40% w/w [HMIM]Cl in citrate buffer, respectively.Item Studies in the synthesis and chromium adsorption behaviour of microcrystalline cellulose immobilized zero valent iron nanoparticles (MCC-nZVI)(Central University of Punjab, 2014) Sharma, Archana Kumari; Babu, J.N.In this study iron nanoparticles (nZVI) are used for the chromium removal from water. nZVI are synthesized in ionic liquid [BMIM]Cl and water, binary solution by borohydride reduction method. For stability of the nZVI, it is immobilized in microcrystalline cellulose (MCC). Varying concentration of iron was used for both the MCC-nZVI synthesized in ionic liquid and water. 6%, 12% and 24% w/w loading of Fe were studied in MCC-nZVI (5-7) synthesized in ionic liquid-water binary mixture, whereas MCC-nZVI (8) and MCC-nZVI (9) were synthesized in water. The synthesized MCC-nZVI materials were characterized by SEM, TEM and FTIR analysis. The MCC-nZVI material was fully dispersed in water with a particle size distribution of 30-100 nm estimated from TEM. The MCC-nZVI contained spherical nZVI; with few of them immobilized in MCC and attached to the surface. FTIR analysis of MCC and MCC-nZVI (5-7) upon comparison showed the strong binding of nZVI to the hydroxyl moieties of MCC. The MCC-nZVI materials were studied for the adsorption of Cr(VI). Batch experiments were performed for chromium adsorption with optimization for contact time, pH, concentration, adsorbent dose etc. on the extent of adsorption by MCC-nZVI. Langmuir and Freundlich adsorption isotherm were best applied to analyze the adsorption data of chromium. MCC-nZVI(6) shows optimum adsorption efficiency. The adsorption efficiency of MCC-nZVI was dependent on their surface area. Maximum adsorption of chromium was found to be 57 mg of Cr(VI)/g of MCC-nZVI (6) at pH 3 and 24 h equilibrium time. The adsorption kinetics could be described by pseudo second order kinetic model