Preparation Of Lignin-based Adsorption Composites And Study On Its Properties

Biomass materials have attracted public attention because of their rich resources,environment friendly and recycling characteristics.In this paper,sodium lignosulfonate/polyaniline composites(SL/PANI),lignin-based-carbon/zinc oxide/zinc sulfide composites(SL-BC/ZnO/ZnS)and lignin-based-carbon materials(SL-BC)were prepared by using lignin as a by-product of pulping-papermaking.The prepared materials were applied to wastewater treatment to study their adsorption performances of organic pollutants in water.Specific research contents are as follows:(1)Sodium lignosulfonate/polyaniline composites(SL/PANI)were prepared by using sodium lignosulfonate(SL)and aniline(An).The morphology and structure of SL/PANI composites were analyzed by characterizations of XRD,FT-IR and SEM.Using methylene blue(MB),acid red(AR),acid orange(AO)and methyl orange(MO)as organic pollutants,the adsorption properties of different SL/PANI composites were investigated.The results showed that SL/PANI-0.2 composite had the best adsorption performance for four organic pollutants(MB,AR,AO,MO).And their removal rates were 92%(MB)and 100%(AR,AO,MO)respectively.The thermodynamic and kinetic fitting results showed that the adsorption processes of organic pollutants by SL/PANI composites were more consistent with the pseudo-second-order kinetic model and Langmuir isothermal adsorption model.The saturated adsorption capacities of four organic pollutants were 52.8 mg·g-1,140.2 mg·g-1,186.2 mg·g-1 and 200.0 mg·g-1,respectively.(2)Lignin-based-carbon/zinc oxide/zinc sulfide composites(SL-BC/ZnO/ZnS)were prepared by using sodium lignosulfonate and zinc acetate(Zn(Ac)2·2H2O).The presences of BC,ZnO and ZnS in the composites were confirmed by XRD,XPS and FT-IR analysis.SEM and EDS showed that SL-BC/ZnO/ZnS composites had a porous structure,and they were equally distributed.By changing the ratio of SL to Zn(Ac)2·2H2O,the morphology,structure and adsorption performances of SL-BC/ZnO/ZnS composites for organic pollutants were investigated.According to the analysis of MB adsorption tests,SL-BC/ZnO/ZnS-1:2 had the best adsorption performances,,and the adsorption reached 94%.The thermodynamic and kinetic fitting results showed that the adsorption processes of MB by SL-BC/ZnO/ZnS-1:2 were more consistent with the pseudo-second-order kinetic model and Freundlich isothermal adsorption model.(3)Lignin-based-carbon materials(SL-BC)were prepared by acid etching method.The influence of the ratio of SL and Zn(Ac)2·2H2O was explored on the morphology,structure and adsorption performances of SL-BC composites to organic pollutants.And the adsorption performances of organic pollutants by SL-BC materials were explored under different preparation conditions.The results showed that the SL-BC prepared by acid etching had a high adsorption performance for MB.When the mass ratio of SL to Zn(Ac)2·2H2O was 1:3,the removal rate of MB by SL-BC-1:3(50 mg·L-1,200 mL)reached 90%in 5 min and 100%in 120 min.By exploring the adsorption performances of SL-BC-1:3 on MB under different pH values,the result showed that the equilibrium adsorption capacity of SL-BC-1:3 was 312.4 Mg·g-1 with pH=12.The thermodynamic and kinetic fitting results showed that the adsorption processes of MB by SL-BC-1:3 were more consistent with the pseudo-second-order kinetic model and Langmuir isothermal adsorption model.