Textile Azo Dye Removal Using a Quaternary Ammonium Anion Exchanger Prepared From Sugarcane Bagasse

Abstract

Water contamination with textile dyes is still a prominent environmental challenge today. Sugarcane bagasse (SB) is the largest agro-industrial residue in Brazil, and a chemical modification can transform it into a value-added by-product. This study investigated the adsorption of remazol golden yellow (RGY) RNL on chemically modified SB (STEA) with epichlorohydrin and triethylamine. STEA was characterized by elemental C, H, N, and Cl analysis, 13C solid-state nuclear magnetic resonance spectroscopy, and specific surface area and pore size distribution. The batch kinetics and isotherm were modelled with the intraparticle diffusion, Boyd, and homogeneous surface diffusion models and Langmuir, Redlich–Peterson, and Dubinin–Radushkevich models, respectively. The maximum adsorption capacity of RGY on STEA was 369.2 mg g−1. The interactions between RGY molecules and STEA sites were investigated by infrared spectroscopy. The thermodynamic parameters indicated that adsorption of RGY on STEA was an exothermic (ΔadsH° = −12 ± 5 kJ mol−1), spontaneous (ΔadsG° = −31 ± 3 kJ mol−1), and entropically driven (TΔadsS° = 19 ± 7 kJ mol−1) process. The fixed-bed column packed with STEA was operated for 415, 390, and 315 min in each consecutive cycle, with adsorption capacities of 422, 371, and 332 mg g−1, respectively. Desorption efficiencies ranged between 59 and 72% and re-adsorption efficiencies ranged from 79 to 88%.