Zero-Waste Approach: Assessment of Aluminum-Based Waste as a Photocatalyst for Industrial Wastewater Treatment Ecology

Abstract

Alum sludge (AS) is produced in inevitable amounts from drinking water treatment plants. Also, dye-contaminating wastewater is usually discharged from textile industries that must be treated to meet the environmental authorities; thus, Fenton’s reagent is a suitable candidate. However, reducing the quantity of chemicals used in Fenton reactions can be partly achieved by an industrial ecology approach. This paper is introducing alum sludge waste as a photocatalyst, (termed as AS-Fenton), that is prepared under mild experimental conditions. Thermogravimetric and differential thermogravimetric analyses were conducted to attain full illustrations of the thermal treatment steps. Its chemical composition and morphology is revealed using X-Ray Diffraction and Scanning Electron Microscope. Thus, this research is of great significance for the application of a waste by-product for being a Fenton source for photocatalytic removal of Levafix Blue dye effluent. A new modified Fenton reagent was applied with the addition of 1.0 g/L and 800 mg/L of catalyst and H2O2, respectively, at pH 3.0 shows high potential for the dye removal. The starting concentration of the Levafix Blue CA was halved during the first 5 min under the UV illumination. The most effective operating variables are optimized through Response Surface Methodology. The kinetics of the dye removal was investigated and the reaction following the pseudo-first-order regime with the kinetic constant (KF), ranged in 0.04–0.57 min−1. Thermodynamic parameters reveal that the reaction is a non-spontaneous and endothermic in nature. Hence, toxicity of the dye is significantly reduced via Fenton reaction to non-toxic end products.