Preparation And Adsorption Property Of Carboxymethyl-chitosan Modified Montmorillonite

In recent years,montmorillonite has been widely used in wastewater treatment as an adsorbent.In particular,the modified montmorillonite has good adsorption properties for all kinds of pollutants in water due to higher specific surface area and stronger cation exchange capacity.Therefore,it has broader application prospects in the field of environmental protection.In this study,ca-montmorillonite(Ca-Mt)was chosen as the raw material.Sodium carbonate and carboxymethyl-chitosan(CMC)were applied to modify montmoiillonite,and we got the sodium-montmorillonite(Na-Mt)and carboxymethyl-chitosan modified montmorillonite(CMC-Mt).The characteristics of modified montmoiillonite were determined with XRD,FT-IR,TGA and so on.Sodium modification to Ca-Mt has been studied by sodium carbonate.The results showed that the various characters of Na-Mt were better than that of Ca-Mt,such as expanded volume and cation exchange capacity.On the base of the preparation of Na-Mt,carboxymethyl-chitosan was chosen to prepare CMC-Mt.Through analysis on CMC-Mt using XRD and FT-IR,it showed that CMC successfully inserted into the layers of Na-Mt.The measurement results of TGA showed that the heat absorption peak was offset,and the thermal stability of CMC-Mt was better than that of Na-Mt.CMC-Mt was used in the adsorption of antibiotics,removal of Pb2+ and decoloration of dye solutions,which resulted in good effects.The removal rate of tetacycline hydrochloride and chlortetracycline hydrochloride were 95.2%and 96.9%,respectively.The adsorption kinetics data of the two kinds of antibiotics fitted the pseudo-second-order equation and Freundlish model.The removal rate of Pb2+ in the solution was over 92%,and the adsorption was well described by pseudo-second-order kinetic model(R2>0.999).According to the data calculated from Langmuir model,Pb2+ could be adsorbed by CMC-Mt with adsorption capacities of 100.40mg g-1.The adsorption of Congo red on CMC-Mt well followed the pseudo-second-order kinetic model and the Langmuir isotherm,and the decoloration rate was over 98%.What’s more,the adsorption process of Congo red was a spontaneous endothermic reaction.