Chemical-Vapor-Deposited Copper on Acid-Activated Bentonite Clay as an Applicable Heterogeneous Catalyst for the Photo-Fenton-like Oxidation of Textile Organic Pollutants

A heterogeneous Cu/clay catalyst was synthesized by dispersing copper onto the surface of bentonite clay through chemical vapor deposition (CVD). To resolve the copper leaching problem during the catalyst's application in aqueous reaction, a critical pretreatment step, acid activation by H2SO4, was applied to the original bentonite clay. Such manufactured Cu/clay catalyst was characterized and evaluated in the photo-Fenton-like degradation of an azo organic dye, Acid Black 1 (AB1). It was found that the acid activation process of clay could significantly reduce the leaching problem by almost 72% and improve the catalytic activity. These improvements came from the active site and the addition of sulfonate functional group on the clay surface. It was also observed that the adsorption and desorption properties of the Cu/acid-activated clay play an important role in the catalytic reaction and that its catalytic performance is better than Fe/clay at pH 7 and 9. It also has a comparable activity to that of Fe/clay at pH 3. This advantage increases the potential of the catalyst in the treatment of organic contaminated wastewater. The optimum reaction conditions in a 1-L reactor equipped with 8 W UVC light were determined to be 0.1 mM AB1, 6.4 mM H2O2, 0.5 g/L catalyst loading, pH 3, at ambient temperature of 30 °C. It was also found that splitting the required dosage of H2O2 could minimize the H2O2 scavenging effect and results in a higher total organic carbon (TOC) removal.