Ocimium lamiifolium leaf extract supported synthesis of ag/cuo nanocomposite for photocatalytic and antibacterial applications

Abstract

Since dye effluents discharged from different industries lead to environmental contamination, their treatment and remediation method is highly desired. Due to the limitation of physical methods like adsorption, the photocatalytic degradation method was used because of its capability to the complete the degradation of dyes. On the other hand, most bacteria have shown resistance to antibiotic drugs. In this regard, nanomaterial has been found to be a promising candidate to overcome the problem of antibiotic (drug) resistance. The main objective of this research was to synthesize CuO NPs and Ag doped CuO NCs by using Ocimium lamiifolium plant extract by precipitation method for photocatalytic and antibacterial applications. Ag/CuO NCs were prepared from ocimium lamiifolium leaf extract, copper nitrate trihydrate, and silver nitrate solution at 70 oC. CuO NPs were synthesized in the same way but without addition of silver nitrate solution. The synthesized CuO NPs and Ag/CuO NCs were characterized by using UV-Vis, XRD, SEM, and FT-IR. From UV-Vis absorption spectrum, the peaks of CuO NPs and Ag/CuO NCs were detected at 308 and 452 nm with Eg of 2.56 and 1.84 eV respectively. FT-IR revealed the presence of carbonyl and hydroxyl groups in the synthesized nanomaterials. The XRD data showed the crystalline structure of CuO NPs and Ag/CuO NCs with crystallite sizes of 29.1 and 38.2 nm respectively. SEM shows some of CuO NPs has a spherical shape and Ag/CuO NCs has a mixture of spherical and rod-like shape. The in-vitro antibacterial test of NPs showed good antibacterial activity, especially at higher concentrations. The result indicates that Ag/CuO NCs showed enhanced antibacterial activity compared to CuO NPs. The photocatalytic performance of Ag/CuO NCs was further assessed by degradation of MB as a model pollutant under visible light (LED lamp, 200 W) irradiation and compared with CuO NPs. The effects of some parameters such as catalyst dosage, contact time, pH, irradiation time, and the effect of initial concentration of MB dye on the activity of the Ag/CuO NCs were also investigated. 88.5 and 76.2% of MB were degraded by Ag/CuO NCs and CuO NPs at 120 min, respectively. The Ag/CuO NCs can also decompose MB in natural sunlight irradiation, and 95.1% was degraded in 60 min, which is promising for future application of solar light-driven photocatalytic degradation of organic pollutants.