Cross-linking of poly(dimethylaminoethyl methacrylate) by phytic acid: pH-responsive adsorbent for high-efficiency removal of cationic and anionic dyes

Abstract

A new high-efficiency adsorbent for cationic and anionic dyes named PAGD was synthesized via polymerization of dimethylaminoethyl methacrylate by employing glycidyl-methacrylate-modified phytic acid as a cross-linker. The experiment demonstrated that PAGD is pH-sensitive, and the maximum adsorption capacities of anionic dye Reactive Red 24 (RR24) and cationic dye Fuchsin Basic (FB) were 1871.23 and 482.54 mg g⁻¹, respectively. To the best of our knowledge, there has been no previous report on a dye adsorbent possessing an adsorption capacity of over 465 mg g⁻¹ for RR24. The excellent adsorption abilities toward RR24 are due to the introduced phytic acid groups, which could promote protonation of tertiary amine groups under acid pH conditions. Moreover, PAGD is able to selectively remove RR24 in a mixed solution of cationic dye and RR24. The adsorption isotherms and kinetics of PAGD fit well with the Langmuir isotherm and pseudo-second-order kinetic model, respectively. These results imply that PAGD is a promising adsorbent for removal of both cationic and anionic dyes.