Bagasse Cellulose Pretreatment And Preparation Of Modified Cellulose Based Hydrogel And Dye Adsorption

Bagasse cellulose is the main solid waste in sugar industry and papermaking industry.The recycling of bagasse is mainly through the combustion and recovery of its heat energy.Bagasse is mainly composed of cellulose,lignin and hemicellulose,and the content of cellulose is 40%～50%.In this study,the bleaching pulp of bagasse was pretreated mainly through a hydrothermal reactor.The conventional physical pretreatment methods and chemical pretreatment methods were combined to extract cellulose and activate it.The specific method was to dissolve the raw bagasse cellulose in a certain mass fraction of sodium hydroxide solution and then performed steam explosion in a hydrothermal reactor at a certain temperature.Under the effect of high temperature,high pressure and alkali,the lignin and hemicellulose were largely removed.A large number of hydrogen bonds inside the cellulose are destroyed,and the closed hydroxyl groups are also more exposed,and the length and width of cellulose are reduced.The effects of sodium hydroxide concentration,reaction temperature and reaction time on bagasse cellulose were investigated in the experiment.The structures and properties of cellulose under different conditions were characterized by SEM,FTIR,XRD and cellulose analyzer.The results showed that the cellulose pretreated with sodium hydroxide with mass fraction of 10%,reaction temperature of 150℃ and reaction time of 70 min was more favorable for the subsequent chemical modification of the cellulose and the preparation of the hydrogel.So far,various treatment technologies have been developed for dye removal,including nanofiltration,ion exchange,chemical oxidation,electroflotation,reverse osmosis and adsorption.Among them the adsorption technology has the advantages of low capital cost and convenience for operation,which has been widely used in industry.In order to improve the bagasse cellulose adsorption capacity,epoxy chloropropane and thiourea were used to modify bagasse cellulose in this study,respectively.The modified bagasse cellulose and carboxymethyl cellulose were dissolved in the solven system of 7wt%NaoH,12wt%urea and 81wt%water,respectively and epoxy chloropropane was used as cross-linking agent to crosslink the functional cellulose hydrogel and then was used in the dyes methylene blue(MB)and crystal violet.The effects of pH,adsorbent dosage,adsorption temperature,adsorption time and initial concentration of dyes(MB and CV)were discussed.The structures and properties of functional cellulose and hydrogels were characterized by SEM,EDS,FTIR,TGA and XRD.The kinetics and adsorption isotherms of adsorption process were also discussed.The results show that the adsorption process fitted well to pseudo-second-order kinetic model and Langmuir adsorption isotherm in the single-component adsorption system,and the adsorption capacity of MB and CV are 632.9 and 574.7mg/g,respectively.In the binary system,the adsorption process fitted well to the Langmuir competitive adsorption model,and the adsorption capacity of MB and CV are 555.6 and 427.4 mg/g respectively.The adsorbent has good adsorption and regeneration ability.The adsorption mechanism of adsorption is mainly electrostatic adsorption and ion exchange.