Significance of synthesized digenite phase of copper sulfide nanoparticles as a photocatalyst for degradation of bromophenol blue from contaminated water

Organic pollutants such as phenolic compounds have received global interest since they are harmful, toxic, and carcinogenic. This work aimed to synthesize copper sulfide nanoparticles in digenite phase (Cu 1.8 S) via sol–gel method and apply it as a photocatalyst to remove a phenolic contaminate, bromophenol blue (BPB) dye, from water. The copper sulfide nanoparticles were prepared by the sol–gel technique under different conditions, such as reaction temperature, reactant concentration, and aging time, in the presence of a stabilizing agent (cetyltrimethylammonium bromide, CTAB). The synthesized nanoparticles were then described using different characterization techniques. Then these nanoparticles were applied as a photocatalyst for the degradation of bromophenol blue (BPB) under different conditions, including photo-irradiation time, catalyst dosage, dye concentration and power lamp. The aimed copper sulfide digenite nanoparticles (Cu 1.8 S) were obtained at a 3 h aging time, exhibiting a cubic crystal structure and a size of 8 nm in a 3-dimensional closed-packed structure model with an energy band gap of 1.82 eV. This material has the ability to absorb visible light and thus can be a superior candidate for photocatalysis, demonstrating strong photocatalytic activity towards the degradation of the phenolic dye (i.e., BPB). Excellent results were achieved at a contact time of 3 h, 7 ppm of BPB, 50 mg catalyst dose, and 32 W power lamp. As a consequence, about 96.7% of the contaminants were removed. The photocatalytic degradation was found to obey the Langmuir postulate and exhibit pseudo first order kinetics.