Development of Green catalysts for dye degradation

Abstract

Sustainable waste management boosts national development by converting waste to value-added products. This study targets removing methyl orange (MO) dye from contaminated water using industrial by-products. Two composites, Iron oxide-biochar (BC-Fe) and Iron oxide-zeolite (Z-Fe), were developed from industrial by-products through a solvent-free process. Biochar, derived from biomass via slow pyrolysis, which contained roots and stems of ayurvedic medicinal plants used to produce Dashamoola Kashayam/Arishtam. Spent zeolite from the FCC unit of a nearby refinery was regenerated by treating it with a mixed acid solution followed by sonication. Iron oxide obtained from an acid regeneration plant of TiO2 manufacturing industry was integrated into the biochar and zeolite matrix using a planetary ball mill followed by calcination. Comprehensive characterization through XRD, FTIR, SEM-EDS, TGA, and BET surface area analysis confirmed the successful formation of the composites due to ball milling and calcination. newline newlineThe prepared composites and iron oxide were tested to remove MO dye from dye-laden water through batch experiments. The optimum process variables for maximum removal efficiency were identified using the Box Behnken design of experiments technique. The variables chosen were contact time, catalyst dosage, pH, and initial MO dye concentration. The optimal conditions for the maximum removal efficiency (45%) for Fe were found to be a pH of 2.4, a contact time of 50 minutes, and catalyst loading of 4.7 g/L for a maximum initial MO dye concentration of 100 mg/L. For BC-Fe, optimal conditions for the maximum removal efficiency (95%) were found to be a pH of 2, contact time of 50 minutes, and catalyst loading of approximately 3 g/L for a maximum MO dye dose of 100 mg/L. The optimum conditions for the maximum removal efficiency (91%) using Z-Fe composite was found to be a contact time of 50 min with a catalyst dosage of approximately 4 g/L at a high acidic pH of 2 for 100 mg/L MO dye concentration.