Photo-Fenton-like degradation of direct blue 15 using fixed bed reactor containing bimetallic nanoparticles: Effects and Box–Behnken optimization

Abstract

This study involved the treatment of textile wastewater contaminated with direct blue 15 dye (DB15) using a heterogeneous photo-Fenton-like process. Bimetallic iron/copper nanoparticles loaded on bentonite clay were used as heterogeneous catalysts and prepared via liquid-phase reduction method using eucalyptus leaves extract (E-Fe/Cu@B-NPs). Characterization methods were applied to resultant particles (NPs), including SEM, BET, and FTIR techniques. The prepared NPs were found with porous and spherical shapes with a specific surface area of particles was 28.589 m 2 /g. The effect of main parameters on the photo-Fenton-like degradation of DB15 was investigated through batch and continuous fixed-bed systems. In batch mode, pH, H2O2 dosage, DB15 concentration, and UV intensity were investigated. In contrast, the flow rate, E-Fe/Cu@B-NPs height, DB15 concentration, and UV intensity were examined in the fixed-bed column. The response surface methodology based on the Box–Behnken design (BBD) was used to optimize both studied systems. The batch results showed that 100 mg/L of DB15 was completely degraded within 60 min with optimum pH 3.5, H 2 O 2 dosage of 7.5 mmol/L, and UV intensity of 15 W/m 2 . The kinetic study indicated that the DB15 degradation was fitted to the second-order kinetic model. The optimized parameters for the fixed-bed system were determined as 1mL/min, 1 cm, 100 mg/L, and 15 W/m 2 for flow rate, E-Fe/Cu@B-NPs height, DB15 concentration, and UV intensity. • The bentonite-supported Fe/Cu nanoparticles were synthesized by the green method. • The nanoparticle has a spherical shape with a specific surface area of 28.6 m 2 /g. • A heterogeneous catalyst was used in the photo-Fenton-like process. • Batch and fixed-bed techniques used for degradation of dye-contaminated wastewater. • The second-order kinetic model fitted the dye degradation.