2. Chemical Functionalization of Cellulose Derived from Nonconventional Sources

Chemical functionalization of cellulose aims to adjust the properties of macromolecule for different purposes, particularly, as a chemical feedstock for production of cellulose derivatives for a variety of applications. The conventional sources of cellulose include cotton linters and wood pulp which now-a-days are discouraged on account of the cost of the former and environment conservative regulations associated with the latter. Further, renewable raw materials are gaining considerable importance because of the limited existing quantities of fossil supplies. In this regard, cellulose-rich biomass derived from the nonconventional sources such as weeds, fibers, bamboos, and wastes from agriculture and forests, etc. acquires enormous significance, as alternative chemical feedstock, since it consists of cellulose, hemicellulose, and lignin, which contain many functional groups suitable to chemical functionalization. Etherification of cellulose through methylation, carboxymethylation, cynaoethylation, hydroxypropylation, single or mixed, is one of the most important routes of cellulose functionalization. Chemical composition and rheological characteristics make possible the selection of the modified cellulose to serve special applications. Prompted by above facts, possibility for chemical functionalization of cellulose rich biomass derived from bamboo, Dendrocalamus strictus (DCS), and noxious weeds – Lantana camara (LC) and Parthenium hysterophorus (PH) for their utilization was examined and results are reported. Proximate analysis of these materials was conducted and processes were standardized for production of α-cellulose on 1 kg batch scale. The percent yield, Av. DP, and the percentage of α-cellulose content of the obtained celluloses were found in the range of 35–40, 400–825, >90 (Brightness 80% ISO), respectively. Processes were optimized for production of water-soluble carboxymethyl cellulose (DCS, LC, and PH), cyanoethyl cellulose (DCS) and water-soluble hydroxypropyl cellulose (DCS and PH). The optimized products were characterized by IR spectra. Rheological studies of 1% and 2% aqueous solutions of the optimized carboxymethyl celluloses and hydroxypropyl celluloses showed their non-Newtonian pseudoplastic behavior. Thus, abundantly available biomass from Dendrocalamus strictus bamboo and the weeds – Lantana camara and Parthenium hysterophorus seem to be a potential feedstock for production of α-cellulose and its subsequent functionalization into cellulose derivatives for variety of applications. This was also demonstrated that these noxious weeds could also be managed by their utilization into products of commercial importance.