UV-radiation manufacturing of natural macromolecular products salecan and tannic acid-based functional gel material as superadsorbent for toluidine blue remediation

Abstract

Adsorbent materials constructed from natural macromolecular products are favored because of their wide range of sources, biodegradability, and environmental friendliness. Salecan is a novel extracellular polysaccharide with ideal physicochemical and biological activities. Here, we have designed a polymer gel through UV-initiated polymerization of [2-(Methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) in the mixture of salecan and tannic acid. Photopatterned polymerization process allowed in situ formation of gel adsorbent in a mild reaction condition with energy-efficient manner. Batch experiments for toluidine blue (TB) adsorption were carried out as a function of initial dye concentration, solution pH, contact time, and gel dosage to examine the adsorption capacity, potential mechanism, and removal efficiency. Adsorption behavior exhibited a pH-dependence pattern, which was closely related to their swelling and morphological properties. Adsorption process was in conformity to pseudo-second-order kinetic and Langmuir isotherm models, unlocking a chemical adsorption behavior and monolayer-type removal. The maximum adsorption was 490.2 mg/g, which could be considered a superiorly competing value. Additionally, the UV-gel still showed desirable recyclability and maintained the adsorption effectiveness over 95 % after five regeneration cycles. This study opened up new prospects in preparing high performance adsorbent for TB decontamination and laid the foundation for polysaccharide-based adsorption material research.