Comprehensive Utilization Of Corn Cob Waste From Xylose Production Industry

With the increasing shortage of fossil resources, the use of renewable biomassresources tomanufacture fuels and chemicals has become an inevitable trend ofhuman sustainable development. It has been proved that it is a successful precedent ofbiomass resource utilization to prepare xylose from Corncob hemicellulose. Thismethod includes a series of processes of dilute acid catalyzed hydrolysis, bleaching,concentration, ion exchange, cooling and crystallization.However, the hydrolysisresidue is usually disposed by combustion as general waste materials, which lead tothe waste of lignin and cellulose resources. Moreover, it increases the cost ofproduction of xylose, making the xylose industry in a low profit or maintain state. Inthis thesis, two schemes are used to address the xylose residue with the aim of thecomprehensive utilization of corn cob waste from xylose production industry. Thefirst scheme is to extract lignin to produce alkali lignin and phenolic resin adhesive,and separate cellulose to prepare modified cellulose and carboxymethyl celluloseorother biomass chemicals, as alternative of fossil products, respectively. The secondscheme is to use the corn cob waste, lignin and crude cellulose as carbon source forthe production of activated carbon, and make comparative analysis of the variousfactors that influence of raw materials on the properties of activated carbon.Through systematic research, the main research results are as follows:1) The cellulose and lignin in the waste residue were effectively separated by theoptimization of alkali treatment conditions. The yield of alkali lignin was48.6%，when the ratio of2wt%sodium hydroxide solution and xylose residue is10:1refluxing5h. Lignin based phenol formaldehyde resin adhesive was synthetized fromphenol and hydroxymethyl modified alkali lignin, which was involved in thepolymerization reaction as raw materials. Experimental results show that the phenolic modification is the most effective way for the synthesis of lignin based phenolic resinadhesive, and the bonding strength was as high as1.24MPa whentheligninreplacement was40wt%.2) Cellulose powder, whose white degree is above95, was prepared bypurification and bleaching fromcrude fiber. By alkalization and etherification, sodiumcarboxymethyl cellulose, with a substitution degree of1.67that satisfied the nationalstandard for production of sodium carboxymethyl cellulose standards, was obtainedfrom cellulose powder prepared in the previous step. These results proved that thatcellulose powder product is a good substitute for short staple cotton material.3) The activated carbon with good electrochemical and adsorption propertieswere prepared by chemical activation from xylose residue and its components as thecarbon source, respectively. Their specific capacitances all are higher than210F/g, ina scan rate of10mV/s. Besides, the iodine adsorption values all are higher than2255mg/g.Wherein the lignin-based activated carbon possess a high specific capacitance(219F/g), smaller impedance, better rate performance and higher magnificationiodine adsorption value (2687mg/g).