Synthesis of a novel isatin and ethylenediamine modified resin and effective adsorption behavior towards Orange G

Abstract

In this study, a novel crosslinked resin 135-I-EDA modified by isatin and ethylenediamine was synthesized through two continuous functionalization steps using chloromethylated styrene-divinylbenzene copolymer as the substrate. In the first step, the cross-linking reaction and isatin incorporation were realized in a creative one-pot reaction using Friedel–crafts reaction in the presence of isatin to give resin 135-I; in the second step, ethylenediamine was successfully introduced on the carbonyl of the modified isatin to further increase the chemically interacting sites. The double-modified resin 135-I-EDA displayed the best adsorption performance (113.38 mg g⁻¹) towards Orange G, which is 1.99 times and 3.49 times as much as that of 135-I (56.94 mg g⁻¹) and commercial resin H-103 (32.51 mg g⁻¹) respectively. This is attributed to its superior porous structure formed in the Friedel–crafts reaction and multiple modified groups in isatin and ethylenediamine. π–π conjugation and hydrogen bonding are the main driving forces for the adsorption. The pseudo-second-order rate equation characterizes the adsorption kinetic curves well and 135-I-EDA displayed the fastest adsorption rate. The study also proved that the 135-I-EDA has a better adsorption capacity for OG in more acidic solution, at higher temperature and higher salinity, which provides a basis for the treatment of industrial dye wastewater.