Comparative study on the adsorption characteristics of a triazine‐Si hybrid polymer adsorbent and the natural adsorbents for removal of methylene blue from industrial wastewaters

Abstract

This work aims to compare the practical ability of the novel triazine‐based polymer adsorbents (TBPA‐Si hybrid polymer) with those of the natural adsorbents for the adsorption of methylene blue (MB) from the industrial wastewaters. In this regard, a new TBPA‐Si hybrid polymer includes SH, NH, and aromatic ring functional groups for effective interactions with a wide range of organic pollutants was synthesized. In addition, pine leaves, soybean meal (SBM), and wheat bran were selected as representative of the well‐known natural adsorbents. The optimum pH values for natural adsorbents and TBPA‐Si for MB adsorption were 7 and 8, respectively. The optimum time for wheat bran and TBPA‐Si to reach the maximum MB adsorption was 15 min and for pine leaves and SBM was 5 min. The isotherm data for TBPA‐Si hybrid was well fitted to Langmuir isotherm. Pine leaves showed a mix of Langmuir and Temkin isotherms. In addition, SBM and wheat bran also showed Temkin isotherm. During the kinetics investigations, the pseudo‐second‐order kinetics models were observed for all adsorbents. The maximum adsorption capacities for TBPA‐Si and pine leaves were 15.3 and 32.1 mg.g−1, respectively. The empirical adsorption capacity for SBM and wheat brans were 71.6 and 38.3 mg.g−1, respectively. The key advantage of the TBPA‐Si is its ability for removing MB in the presence of high concentrations of electrolytes, where the removal efficiencies of the natural adsorbent were extremely reduced in these conditions. The main advantage of the natural adsorbents is their low cost for removal of MB from the effluents containing very low concentration of electrolytes.