Simultaneous degradation of methyl orange and indigo carmine dyes from an aqueous solution using nanostructured WO3 and CuO supported on Zeolite 4A

Abstract

In this study, a novel composite catalyst system, Zeolite 4A/WO 3 /CuO with a Z-scheme design, was synthesized for photocatalysis, sonocatalysis, and sono-photocatalysis methyl orange (MO) and indigo carmine (IC) dyes simultaneously. The properties of the Zeolite 4A/WO 3 /CuO composite were thoroughly investigated using various techniques, and the results confirmed the synthesis of the desired catalyst system. In the sonophotocatalytic process, using the Zeolite 4A/WO 3 /CuO composite, the maximum efficiency for MO (99.12 %) and IC (97.24 %) was achieved at pH of 2 and 3, with a catalyst dosage of 0.15 g/L, a dye concentration of 10 mg/L, a contact time of 25 min, and H 2 O 2 dosage of 30 mu L/100 mL. The dye elimination efficiency using the sono-photocatalytic process was reduced in the presence of Cl - and PO 4 3- in the distilled water. The efficiency also declined in the medium of river and well water resources. Moreover, the Zeolite 4A/WO 3 /CuO catalyst maintained over 90 % of its performance even after five reuse cycles. Based on the kinetic study, the sonophotocatalytic process exhibited higher activation for the removal of MO (k: 0.1946 min -1 and t 1/2 : 3.561) and IC (k: 0.1433 min -1 and t 1/2 : 4.836) than other processes. The synergy values for the MO and IC degradation using the Zeolite 4A/WO 3 /CuO composite were determined to be 2.167 and 2.303, respectively. The impact of various scavengers demonstrated that in the degradation processes of the target dyes using the sonophotocatalytic process, different active species like OH center dot , e - , h + , and O 2 -center dot are involved. The purification of dyeladen water using the sono-photocatalytic process was not toxic for plant germination, microorganisms, and fish, highlighting the successful biocompatibility of the process for dye removal.