Preparation And Adsorption Properties Of Lignosulfonate-Based Composite Material

Water pollution is one of the most attention to the environmental problems of the world.adsorption method has become one of the widely used methods because of its advantages of high adsorption efficiency,simple operation and low cost.It is of great significance to seek a kind of environmentally friendlyadsorbent with high adsorption performancein the process of using the adsorption method.In this paper,sodium lignosulfonate(SL)was used as raw material,chitosan(CS)and citric acid/?-cyclodextrin(CACD)were used to compound with SL,chitosan lignosulfonate based composite adsorption material(CS-SL)and cyclodextrin/chitosan lignosulfonate based composite adsorption material(CS-SL/CACD)were prepared.The effects of reaction time,reaction temperature and reactant mass ratio on the yield and adsorption performance of composite adsorbent were investigated.The synthesis mechanism was investigated,and the structures of the two composite adsorption materials were characterized.The adsorption properties of the two composite adsorption materials for Congo red,Rhodamine B and Cr(VI)were investigated,respectively.The main results are as follows:(1)The preparation process parameters of CS-SL were as follows: reaction temperature was 25 ?,reaction time was 1 h,mass ratio of SL to CS was 10:3;FTIR analysis showed that the surface of CS-SL contained amino and sulfonate groups;SEM analysis showed that the CS-SL molecular chain had good directivity;The synthesis mechanism of CS-SL is as follows: the composite adsorptive material is cross-linked by hydrogen bond between CS and SL and electrostatic attraction between cation and cation groups.(2)The absorption performance of Cr(VI),Congo red and Rhodamine B by SL is greatly influenced by the solution p H,adsorption time and pollutant concentration.The adsorption process is consistent with the quasi-second-order kinetics and Langmuir model,indicating that the adsorption process of CS-SL for the three pollutants is mainly chemisorption.The adsorption of the three pollutants by CS-SL is mainly hydrogen bond and electrostatic force.(3)The preparation process parameters of CS-SL/CACD were as follows: reaction temperature was 25 ?,reaction time was 1 h,mass ratio of SL,CS and CACD was 10:3:3;FTIR analysis showed that the surface of CS-SL/CACD contained ester bonds,amino groups and sulfonates;SEM analysis showed that the surface of CS-SL/CACD was rough and loose,and the specific surface area increased;The synthesis mechanism of CS-SL/CACD is as follows: the carboxyl group of citric acid and the hydroxyl group of ?-cyclodextrin are esterified first,and then the-NH3+ of CS-SL is cross-linked with the-COO-of CACD through electrostatic interaction.(4)The adsorption properties of CS-SL/CACD for Cr(VI),Congo red and Rhodamine B were greatly affected by solution p H,adsorption time and pollutant concentration.The adsorption process of CS-SL/CACD was consistent with the quasi-second-order kinetics and Langmuir model,which indicated that the adsorption process of CS-SL/CACD for the three pollutants was mainly chemical adsorption.The adsorption of the three pollutants by CS-SL/CACD mainly includes the cooperation of electrostatic attraction and the host-guest cooperation of ?-cyclodextrin.