Experimental Investigation Of Purification And Spinning Of Rice Straw Cellulose

With the development of society and human civilization, problems of energy and environment have increasingly drawn people’s attention. Among them, a significant product of petrochemical industry (synthetic fiber) has brought serious challenges to the textile industry in our country due to lack of raw materials, rising price and contamination to the environment. Biomass cellulose, the primary material of the textile industry is one of the oldest natural polymers that boast the richest reserves in the world. It largely exists in the crops and natural plants, such as cotton, linen, timber, bamboo, phragmites, straw, bagasse and the like. The total output of the cellulose around the world can reach up to26billion tons per year. In our country, straws are the principle source of the cellulose, which annual yield of about1.145billion tons more than anywhere else in the world. Owing to the advantages of excellent biodegradability, biocompatibility and a wealth of sources, straw cellulose enjoys great attention from the public. This graduation thesis studied some key points such as purification and spinning technology of the straw cellulose. This thesis includes such work as:purification of the cellulose is optimized, the straw cellulose that meets the requirements of the textile industry is acquired and the application of straw cellulose to spin. The detailed works are listed as follows:1. Purification of the straw cellulose by delignification, whitening and de-ashing. The purification technology was optimized by taking average degree of polymerization, a-cellulose content, acid-insoluble lignin content and pentosan content as evaluation criterion. Through a continuously optimization, an ideal cellulose purification technology was finally obtained. Meanwhile, in consideration of water resource conservation and environment protection, recycling recovery of the water used in the purification by vacuum evaporation and its recycling were studied.2. The cellulose isolated from rice straw contains large content of inorganic components, commonly referred to as ash constituent. The ash content of straw cellulose is too high to be used in the spinning applications. With respect to utilizing two kinds of mixed solution, NaF-hydrochloric acid mixture and hydrofluoric acid-hydrochloric acid mixture, the de-ashing process was conducted on the mentioned rice straw cellulose through orthogonal experiments; the de-ashing conditions were optimized. In addition, the processed straw cellulose was characterized by FT-IR, XRD, SEM, ICP, degree of polymerization(DP), content of a-cellulose, content of pentosan, etc. Results showed that there was no significant change in chemical structure of the cellulose undergoing the above-mentioned two methods, but the crystallinity was relatively imcreased. Results of ICP analysis showed that in the de-ashing process, hydrochloric acid, NaF and hydrofluoric acid respectively act on different impurity elements to achieve the de-ashing purpose. From the recycled waste liquid left after the treatment of rice straw cellulose with hydrofluoric acid, it has been found the waste liquid can be used for producing H2SiF6, realizing utilization of the waste materials.3. We have also studied spinning technology of the straw cellulose through a spinning machine made by the research group. Optimize spinning technology of the straw cellulose by referring to the shape of cellosilk from the spinneret orifice of the spinning equipment and the crystallization index analysis by XRD and FT-IR. Analysis the problems of the straw cellulose spinning technology by comparing it with the cotton pulp cellulose spinning technology.