Preparation Of Functionalized Cellulose-Based Aerogels And Selective Adsorption Performance Study

Modern textile industries produce large amounts of printing and dyeing wastewater,which is a serious ecological and human health hazard if discharged directly.Therefore,before printing and dyeing wastewater is discharged,appropriate methods should be used to treat it and mitigate its harm to the ecosystem.The adsorption method is used to treat printing and dyeing wastewater with complex compositions.One option for treating wastewater with complex compositions is the non-selective simultaneous removal of all dye components,but this method requires nonselective adsorbents with high adsorption capacity,and large quantities of adsorbent are required.Most importantly,after non-selective adsorption,the dyes cannot be used further and require secondary processing,which can lead to secondary contamination.Selective adsorption allows the dyestuff to be reused in the relevant industry and avoids secondary contamination.In addition,selective adsorption usually requires an adsorbent that has a highly selective and high adsorption performance.Cellulose-derived aerogels,which are made from a rich source of easily modified cellulose,have attracted a lot of attention as a selective adsorbent in the field of water treatment.Hence,two different types of cellulose-derived aerogels are investigated for their structural design,modification strategies,and selective adsorption performance as follows:Amino-functionalized cellulose composite foams(CCFs)with ultra-light porous structures were prepared by freeze-drying using cellulose as the raw material,polyethyleneimine as the modifier,and epichlorohydrin as the cross-linking agent.The morphological characteristics and physicochemical properties of the above materials were characterised by SEM,XPS,and FTIR.Six dyes were used as target pollutants to investigate the sorption performance of CCFs.CCF3 displays outstanding adsorption capacity for anionic dyes due to its stable positive charge in both single dyes as well as in binary dye mixtures.The removal efficiency of CCF3 for eosin(EY)was up to 99.5%.Secondly,CCF3 had a maximum adsorption capacity of 855.79 mg/g for the anionic dye EY,which was attributed to the three-dimensional porous structure of the aerogel and a large number of amino groups.In addition,the cycling experiments show no significant reduction in the removal of eosin(EY)by CCF3 after six desorption-adsorption cycles.CE/CN aerogels were successfully prepared by calcination of KOH-etched carbon nitride(CN),which was doped into cellulose-based aerogels.Surface morphology,chemical structure,charge distribution,and chemical thermal stability of CE2/CN aerogels were characterized by SEM,FT-IR,XPS,Zeta potential,and TG.Doping with CN gives CE2/CN good thermochemical stability and excellent selective adsorption of cationic dyes.The adsorption properties of the material were investigated using the cationic dye methylene blue(MB)as the target dye and the effects of temperature,pH,and coexisting salt ion concentration on the adsorption capacity of CE2/CN were explored.The removal of the cationic dye MB by CE2/CN is 98.5%and its maximum adsorption capacity is 212.105 mg/g.Moreover,CE2/CN retains a high adsorption capacity at pH>7.Compared to other adsorbents,CE2/CN aerogels are unique in their regenerative properties in strongly alkaline conditions and consistently excellent adsorption performance over six cycles.