Removal of cationic and anionic dyes from waste water in five seconds by a facile synthesis of a covalent organic polymer

Abstract

Discharge of organic dyes from various industries into water bodies have polluted the resources appallingly which made them unsafe to use. Various materials developed for the removal of these dyes often lacks from cost effectiveness, good removal capacity and fast kinetics. On account of the imperative need for a cost-effective and efficient system for this purpose, we have developed a facile approach for the synthesis of Covalent Organic Polymer (COP) in a two-step strategy by incorporating a versatile functional group dithiocarbamate. This dithiocarbamate-based covalent organic polymer (D-COP) could remove multiple dyes (both cationic and anionic) simultaneously within a flash time with high uptake capacity. Out of five dyes, Eriochrome black T was removed with exceptional uptake capacity of > 4000 mg/g triumphing the existing reports followed by Congo red (1013 mg/g). On top of that, the removal was ultrafast, within 5 s with pseudo-second-order rate constant value 156.25 g/mg.min which is the highest ever reported. The selective adsorption of these dyes over methylene blue and Rhodamine B make D-COP applicable for the separation and purification of these dyes from the mixture. The material was also completely recycled and reused up to several cycles without hampering the performance under different pH, and ionic strength conditions too. The ultrafast and high removal efficiency even in real water samples makes the material more competent. This material, being efficient in terms of low-cost synthesis, removal efficiency, kinetics, and regeneration capability, can be further employed for higher scale water treatment applications.