Photocatalytic degradation of carcinogenic Congo red dye in aqueous solution, antioxidant activity and bactericidal effect of NiO nanoparticles

Abstract: Face-centered cubic structure of nickel oxide (NiO) nanoparticles with 30 nm average size was synthesized by co-precipitation method with some modification in synthesis, calcination time period and temperature. The morphology, particle size, surface area and pore size of NiO nanoparticles were determined by TEM, XRD and BET. FTIR and UV–visible analysis confirmed the formation of NiO nanoparticles. NiO nanoparticles have been used as photocatalyst for Congo red (CR) degradation from aqueous solution. The photocatalytic degradation of CR dye was analyzed by four parameters such as the concentration of CR dye, the effect of contact time, the effect of pH and dose of NiO nanoparticle catalyst. The maximum degradation of CR dye (84%) by NiO nanoparticles was determined with respect to contact time. Antioxidant activity increases as the NiO nanoparticle concentration increases. The concentration of NiO nanoparticles efficiently enhances the bacterial inhibition against gram-positive and gram-negative bacteria. The bacterial strains such as K. pneumonia 700603 and B. subtilis 5902 showed maximum zone of inhibition (15 mm) at 40 mg/ml concentration, and minimum inhibitory concentration 62.5 μg/ml by NiO nanoparticles, respectively. The photocatalytic degradation of CR and antibacterial study acknowledge that the NiO nanoparticles are efficient photocatalysts for degradation of CR dye and inhibition against different bacterial strains. NiO nanoparticles will be used to provide clean and low-cost drinking water without harmful dyes and pathogenic microbes generated in industrial wastewater. Graphic abstract: [Figure not available: see fulltext.].