Copper-PANI-graphite HB2 composite for eco-friendly efficient degradation of textile dyes: Advancements in wastewater treatment enhanced by solar radiation

Abstract

This research aimed to assess the potential of Cu50PANI@UG composite for sunlight drive photocatalytic dye degradation, targeting specifically Thymol Blue (TB) and Black NT (BNT) dyes and their mixture (DM). The Cu50PANI@UG composite was successfully synthesized via electropolymerization in acetonitrile/sulfuric acid mixture under atmospheric conditions. Photocatalytic experiments were conducted by exposing aqueous dye solutions to sunlight. N,N-dimethyl-p-nitrosoaniline (RNO) served as a molecular probe for detecting hydroxyl radicals (•OH). Additionally, experiments capturing free radicals were performed to identify active components, with a concomitant proposal of plausible degradation reaction mechanism for the Photo-Fenton-Like degradation into the Cu50PANI@UG composite + H2O2 + hv reaction system. Various operating parameters affecting dye degradation were evaluated, including catalyst dosage (from 0.27 to 0.67 g L−1), H2O2 concentration (from 16 to 64 mM), pH (from 3.0 to 9.0), and dye concentration (from 25 to 100 mg L−1). Optimization of key parameters such as pH, catalyst dosage, and H2O2 concentration was conducted. The highest degradation efficiency, ca. 100% of DM dye, was achieved within 35 min under optimized conditions, using Cu50PANI@UG composite as a catalytic precursor. These conditions were determined as follows: Catalyst dosage = 0.67 g L−1, pH = 3.0–6.0, H2O2 = 32–64 mM, and irradiation time of 35 min. The degradation percentage under the Response Surface Methodology (RSM) was utilized as a statistical tool to correlate influential parameters. Four consecutive reusability trials were performed to assess catalyst stability.