Synthesis and Adsorption Properties for Cationic Dyes of Acrylic Acid/Vermiculite Hydrogel Initiated by Glow-Discharge-Electrolysis Plasma

In this work, an acrylic acid/vermiculite (AA/VMT) hydrogel was prepared by glow-discharge-electrolysis plasma initiated graft copolymerization, in which N,N-methylenebisacrylamide was used as a cross-linker. The structure, thermal stability, morphology and surface area of AA/VMT hydrogel were characterized by FT-IR, TG, SEM, and automated porosimeter. Cationic dyes such as Crystal violet (CV) and Methylene blue (MB) were used for testing the adsorption property. Factors influencing adsorption such as pH, contact time, concentration were investigated by batch experiments. Adsorption kinetics and adsorption isotherms were employed to illustrate the hydrogel-dye interaction. The results showed that the best parameters for the adsorption of dyes were pH = 6 and contact time 2 h. The adsorption kinetic followed the pseudo-second-order model with multi-step diffusion process. Both Langmuir and Redlich-Peterson isotherms were well agreed with the experimental data. The maximum adsorption capacities of CV and MB on AA/VMT hydrogel were 2575.2 and 2674.0 mg g(-1), respectively.