Efficient and sustainable treatment of anionic dye wastewaters using porous cationic diatomite

Abstract

How to develop an effective and cheap adsorbent for removing dyes completely from wastewaters and avoid disable adsorbent secondary pollution have great challenges for green dye and dyeing industrial production. In order to realize this aim, in this work, the porous cationic diatomite was prepared for the first time by covalently immobilizing poly-epichlorohydrin-dimethylamine onto natural diatomite, and its adsorption characteristics and sustainable utilization were investigated. The results indicated that the immobilizing reaction was found to happen both on the surface of diatomite and the inner wall of its pores. Cationic diatomite possessed a high removal efficiency to anionic dyes. The batch dye adsorption processes were endothermic and spontaneous, and better consistent with pseudo-second-order kinetic model and Freundlich isotherm model. The completely colorless effluent solution could be obtained when cationic diatomite was used as fixed-bed adsorbent, and its maximum dye adsorption capacities were more than 200 and 3 times larger than that of natural diatomite and commercial activated carbon, respectively. Most importantly, the disabled cationic diatomite could be used in colored coatings as pigment and filler simultaneously, thereby avoiding secondary pollution. In conclusion, this study can provide a green viable solution for controlling pollution in dye and dyeing industrial production.