Bacterial Cellulose Structure Control And Its Application Research

Bacterial cellulose(BC)is a kind of cellulose materials fermenting by Acetabacter xylinus and shows properties such as high water holding,good biocompatibility,chemical modification and biodegradability.Recently,due to its excellent properties,BC shows good applications in textile,medicine,food,conductive material areas.At present,there are problems with BC production of high cost and low yield.Meanwhile,its application also faces the problem of a single performance.Therefore,how to find cheap and available fermentation raw materials or production factor,how to control the three-dimensional networks structure of BC and develop the BC matrix composites,is an urgent problem in the BC industrial application.In terms of the BC fermentation production.This paper explores the feasibility of making soybean meal as raw material to produce BC.The results show that when the condition of pretreatment of soybean meal including that the concentration of sulfuric acid is 1.5 wt%,acid mass ratio of 1:4,hydrolysis time for 20 h,hydrolysis temperature is 80 ℃,the BC yield can reach 5.2 g/L,and the BC cost showing a competitive cost advantage.In terms of the BC structure control.First,this paper investigated the effect of adding of rare earth chloride(RECs)to Acetabacter xylinus growth metabolism and the BC yield,morphology and structure.The results indicate that there are eight kinds of RECs(Sccl3、Prcl3、Gdcl3、Dycl3、Ecl3r、Ybcl3、Ycl3、Tbcl3)shows an obvious role in promoting BC production;There are five kinds of RECs(Smcl3、Cecl3、Eucl3、Hocl3、Tmcl3)shows obvious inhibitory effect to BC production;There are three kinds of RECs(Lacl3、Ndcl3、Lucl3)shows no obvious effect to BC production and among them,when the concentration of Lacl3 is 0 mg/L,20 mg/L and 500 mg/L,the crystallinity of the BC is 75.58%,68.11%and 48.11%,showing a remarkable decrease.At the same time,the porosity is 97.3%,96.1%and 97.1%,respectively,Secondly,the effect of different direct-current electric field to Acetabacter xylinus growth metabolism and the BC yield,morphology and structure was studied in static fermentation within 24 h.The results show that in the central of the electric field under 10 mA electricity,the BC fibers are directional alignment,and fiber diameter decreases from 119.4 nm to 74.7 nm.In addition,the crystallinity of the BC in anode and cathode decreased from 75.58%to 48.76%and 58.59%,and the porosity decreased from 97.3%to 90.0%and 92.8%,respectively.In terms of the preparation and application in BC composite material.On the one hand,the BC/epsilon-polylysine(BC/ε-PL)nanofibers composites were fabricated by solution impregnation method and cross-linking technique.The results indicate that theε-PL content in BC/ε-PL can be adjusted through the concentration of ε-PL solution,and the antimicrobial properties of escherichia coli and staphylococcus aureus are enhanced with the increase of the concentration of ε-PL solution.Among them,the inhibition rate of escherichia coli and staphylococcus aureus is 99.04%and 97.89%within 24 h when the concentration of the s-PL solution is 0.75 wt%.On the other hand,a sulfur,nitrogen and phosphorus co-doping of bacterial cellulose based carbon nanofiber electrode material(N/P/S-PBC)applied to symmetrical type supercapacitor was prepared through solution impregnation method,freeze drying and high temperature pyrolysis technology.The results demonstrate that in the current density of 1.0 A/g,the specific capacitance of N/P/S-PBC is 255 F/g,and when its power density is 489.45 W/kg,the energy density can reach to 8.48 Wh/kg.