Haile et al. Bioresour. Bioprocess.
(2021) 8:35
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Fig. 12 Extracting CNC from trees
in washing and value additions in wet and chemical processing industries such as detergents, softeners, and binders can be produced using dissolving pulp as a pre- cursor. These chemicals are cellulose ether-based and can be extracted from the dissolving pulp. Dissolving pulp besides its utilization as raw material for the paper mill and surfactant synthesis it can be used for the manufacturing of textile fibers (Ma et al. 2011). The dissolving pulp can be prepared from cellulosic wastes using the same pulping route described in the cur- rent review and can be utilized for the making of viscose rayon and cellulose acetate fibers (Woodings 2001). Once the required grade of dissolving pulp is availed viscose rayon can be manufactured using wet spinning technol- ogy and cellulose acetate is manufactured using dry spin- ning technology. The manufactured viscose rayon and acetate fibers have diversified applications (Fig. 13). The use of dissolving pulp as a precursor for the man- ufacture of commodity textile fibers has an economic impact on developing countries that entirely depend on using a single fiber such as cotton for the production of textile materials. In the region of concern, where the supporting data for availability study is conducted it has been described that the paper mill entirely depends on the imported pulp and it is not possible to produce and market the important textile fibers. It is vital to con- sider the economic advantage of producing potential fibers from indigenous pulp and paper wastes. Modern manufacturing techniques such as dry jet wet spinning and electrospinning techniques can be utilized for the
Method of synthesis of CNC generally adopts break- down of cellulose chains to the desired nanoconfigura- tion via different techniques. The chemical and biological techniques utilize different chemicals and enzymes, while the physical technique involves the mechanical break- down of the cellulose chains. The chemical process mainly involves hydrolysis using acids and alkalis or a series of reagents by the partial breaking of glucosidic bonds for obtaining the CNC. The four steps in the syn- thesis of CNC via mechanical method are high-pressure homogenization, fluidization to micro-level, grinding to fine particles, and finally smashing under freezing condi- tions. Conventionally combined methods are utilized for optimized processes and characteristics of the cellulose nanocrystal (Song et al. 2019). The biological and com- bined methods of the CNC synthesis method employed for hydrolysis minimize concerns with regards to envi- ronmental pollution. The production technique of CNC is well-practiced; ensuring high-grade purity of the cel- lulose with well-advanced extraction technology could eliminate the associated challenges in terms of high value-added products especially those used for medical items. Synthesis of textile fibers from dissolving pulp Dissolving pulp has versatile applications. Dissolving pulp can be used as a source of pulp for the paper mill (Kihlman 2012). This is particularly important as eco- nomic support for developing countries that are entirely based on imported pulp. Besides many chemicals used
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