Green synthesis of Zinc sulphide (ZnS) nanostructures using S. frutescences plant extract for photocatalytic degradation of dyes and antibiotics

Abstract

Pollutants such as dyes and pharmaceuticals have become a problem in the environment, thus there is a need to find multifunctional materials that are safe and can be used for the removal of various pollutants. In this study, we report on the synthesis of Zinc sulphide (ZnS) nanostructures and their use as photocatalysts for the degradation of dyes and various antibiotics. Fourier transform infrared spectroscopy(FTIR) confirmed the functional groups found in plants and these were linked to the biomolecules identified through Liquid chromatography-mass spectrometry (LCMS). Ultraviolet-visible spectroscopy (UV-vis) and X-ray diffraction (XRD) confirmed the formation of the ZnS nanostructures. Thermal Gravimetric Analysis (TGA) and Brunner Emmet Teller (BET) confirmed the material was thermally stable up until 480oC and mesoporous in nature, respectively. Scanning electron microscope (SEM) and transmission electron microscope (TEM) showed that the material is spherical in shape and energy dispersive spectroscopy (EDS) further corroborated their formation. From the degradation analysis, 90% of the malachite green (MG) dye could be degraded in 60 min at optimum conditions (pH 6, 25 mg and 10 mg/L) and the holes were responsible for the degradation. Lastly, when tested against antibiotics, the ZnS material managed to degrade both the sulfisoxazole (SSX) and sulfamethoxazole (SMX). These results showed that the ZnS nanoparticles could be used as a multifunctional material for the degradation of various pollutants.

Fabrication of Carbon‐Based ZnBi2S4 and ZnBi2Se4 Nanocomposites for Photocatalytic and Electrochemical Applications

“…The observed peaks at 1000 cm −1 and 1110 cm −1 are attributed to the C−O stretching bands of nanocomposites, based on Figure 2(a) [38] . Metal sulfide nanoparticle vibration is attributed to the strong band at 500–700 cm −1 [39] . Because of the presence of ambient CO 2 , which may adsorb on the surface of the nanoparticles, the peak at 2365 cm −1 is caused by the C=O stretching modes [40] .…”

“…[38] Metal sulfide nanoparticle vibration is attributed to the strong band at 500-700 cm À 1 . [39] Because of the presence of ambient CO 2 , which may adsorb on the surface of the nanoparticles, the peak at 2365 cm À 1 is caused by the C=O stretching modes. [40] At 1718 cm À 1 , the À COO group is shown to develop during carbonization.…”

Biosynthesis of Gold- and Silver-Incorporated Carbon-Based Zinc Oxide Nanocomposites for the Photodegradation of Textile Dyes and Various Pharmaceuticals

“…The eco-friendly synthesis of ZnO-NPs commenced with the measurement of 4 g of Zn (NO 3 ) 2 6H 2 O salt, which was added to 250 mL conical flasks according to the procedure outlined by Munyai et al [43]. Subsequently, 50 mL of the plant extract was introduced into each flask containing the Zn salt, resulting in a brownish-yellowish solution.…”

“…Additionally, noble metals were reported to slow the rate of e − /h + recombination, while also broadening the absorption spectrum of metal oxides [39][40][41][42]. Silver (Ag) has been reported to be less expensive, easily doped, and to have high conductivity and light absorption capacity [43,44]. Gold (Au) has higher electron affinity, and it is known to collect photogenerated electrons during ZnO photoexcitation, increasing photocatalytic efficiency [45][46][47].…”

A Review of the Green Synthesis of ZnO Nanoparticles Utilising Southern African Indigenous Medicinal Plants

“…The strong biological activity of the synthesised ZnO NPs can be attributed to the small size of the NPs, which translates to a large surface area and the secondary metabolites incorporated in the NPs. L. frutescens has also been investigated for the synthesis of NiO NPs [84], AgO NPs [85], ZnS NPs [86], CdS NPs [87], ZnO/SnO 2 NPs [88] and Ag NPs [89] for various applications such as photodegradation of organic dyes and pharmaceutical pollutants, antibacterial activity, and anticancer activity.…”