Kinetics, process design and implementation of zwitterionic adsorbent coating for dipolar dyes removal in wastewater treatment industry

Abstract

Kinetic, thermodynamics and process design of the adsorption of dipolar dye molecules, namely Brilliant green (BG) and Naphthalene Blue 12B (NB12B), from aqueous solution using a zwitterionic adsorbent coating (ZwitAd) were investigated. This zwitterionic adsorbent coating was synthesized by a facile technique, which implied only 3 main chemicals: acrylic polymer emulsion (binder), bentonite (fillers) and EPIDMA (cationic polyelectrolyte). The scale-up of this formulation was proved showing that this coating adsorbent is viable to be adopted in a large-scale production. This novel adsorbent was synthesized in a coating form to obtain a feasible and practical application for the adsorption of both cationic and anionic dyes from wastewaters. Besides, this new adsorbent could be easily separated from the system without applying extra processing methods such as filtration or centrifugation. Adsorption studies showed that Freundlich model described satisfactorily the BG adsorption, whereas the NB12B adsorption was fitted with Langmuir isotherm. A single stage process was designed and the corresponding mathematical formulations was developed using the best adsorption models. Process design was performed to optimize the adsorbent amount for achieving a specific target of given initial effluent concentration and volume of treated wastewater. This optimization contributed to minimize the capital investment cost in order to satisfy a standard defined for the dye removal. Different alternatives for the application of this novel adsorbent in an industrial facility have been described and discussed. This study contributes with new findings to improve the implementation of novel adsorbents for water treatment and purification at industrial scale.