The Research On Adsorption Of Aromatic Ring Containing Acidic Organic Wasterwater Using Layer Double Hydroxides Compounds

To adsorb the Acid Fuchsine (AF) and2,4,6-Triehlorophenol (TCP), layer double hydroxides (LDH) and calcined layer double hydroxides (CLDH) were synthetized. The effects of contact time, pH value, initial concentration of adsorbates and dosage of adsorbents on capacity of adsorption were investigated. Batch kinetic data from experimental investigation have been described by pseudo-first-order kinetic model, pseudo-second-order kinetic model and Elovich equation. The data were also used to fit Langmuir isotherm and Freundlich isotherm. The adsorbents were characterized by FT-IR、XRD、SEM to discuss the mechanism of adsorption.The1results of removal of AF using LDHs and CLDHs showed that MgAl-CLDH revealed higher adsorption capacity than MgAl-LDH, which were227.7and94.7mg/g, respectively. The optimized conditions for adsorption were contact time of longer than16h, pH of less than11, and the adsorbents’dosage of0.14-0.15g. The adsorption kinetic study showed that it fit Elovich equation better at the low temperature while the data fit pseudo-second-order kinetic model better at a temperature over313K. The activity energy of adsorption indicated that the process of AF removal was controlled by diffusion. The isotherm study showd that the adsorption fit Langmuir isotherm better, which indicated that monolayer adsorption was occered. The other thermodynamic parameters suggested that the adsorption process was spontaneous and endothermic. The translational freedom of adsoption system increased. The adsorption of AF on LDHs was signify physisoption. The molecules of AF did not be intercalated into layers. Similarly, the process of adsorbing AF on CLDHs was signify physisoption. However, the structure of CLDH reverted to layered structure after adsorption. The adsorption could be happened on the basis of Van der Waals forces, hydrogen bond and ligands bond.The removal of TCP using MgAl-CLDH showed that the optimized conditions for adsorption were contact time of longer than12h, pH of less than7, and the adsorbents’dosage of0.14-0.15g. The kinetic study showed that the adsorption fit pseudo-second-order kinetic model better. The activity energy of adsorption indicated that the process of TCP removal was controlled by diffusion. The isotherm study showd that the adsorption fit Freundlich isotherm better, which suggested that there were substrate-substrate interactions on the surface of adsorbents. The other thermodynamic parameters suggested that the adsorption process was spontaneous and endothermic. The translational freedom of adsoption system increased. The adsorption of TCP on CLDHs was signify physisoption. The structure of CLDH reverted to the layered structure after adsorption. Based on wan der waals forces, hydrogen bond and ligands bond, the adsorption could be happened.