Recent Developments in ZnS-Based Nanostructures Photocatalysts for Wastewater Treatment

Abstract

The continuous growth of the world population has led to the constant increase of environmental pollution, with serious consequences for human health. Toxic, non-biodegradable, and recalcitrant organic pollutants (e.g., dyes, pharmaceuticals, pesticides) are discharged into water resources from various industries, such as textiles, leather, pharmaceuticals, plastics, etc. Consequently, the treatment of industrial wastewater, via a sustainable technology, represents a great challenge for worldwide research. Photocatalytic technology, an innovative technique based on advanced oxidation process (AOP), is considered a green technology with promising prospects in the remediation of global environmental issues. In photocatalysis, a very important role is attributed to the photocatalyst, usually a semiconductor material with high solar light absorption capacity and conductivity for photogenerated-charge carriers. Zinc sulfide (ZnS), as n-type semiconductor with different morphologies and band gap energies (Eg = 3.2–3.71 eV), is recognized as a promising photocatalyst for the removal of organic pollutants from wastewater, especially under UV light irradiation. This review deals with the recent developments (the last five years) in ZnS nanostructures (0D, 1D, 3D) and ZnS-based heterojunctions (n-n, n-p, Z scheme) used as photocatalysts for organic pollutants’ degradation under simulated (UV, Vis) and sunlight irradiation in wastewater treatment. The effects of different synthesis parameters (precursors’ type and concentration, capping agents’ dosages, reaction time and temperature, metal doping, ZnS concentration in heterostructures, etc.) and properties (particle size, morphology, band gap energy, and surface properties) on the photocatalytic performance of ZnS-based photocatalysts for various organic pollutants’ degradation are extensively discussed.

A Comparative Study of ZnS–ZnO Nanocomposite Assembly for Photocatalytic Removal of Crystal Violet Dye

“…In the present NC system, the VBE and CBE of ZnO lie well below ZnS which are shown in Figure and the electronic band positions were taken from literature to understand the generic electronic transitions. [ 35–38 ]…”

“…In the present NC system, the VBE and CBE of ZnO lie well below ZnS which are shown in Figure 13 and the electronic band positions were taken from literature to understand the generic electronic transitions. [35][36][37][38] Interfacial contact between both ZnO and ZnS might lead to passivation of defect states, introducing nonradiative recombination centers. Also, the photoexcited electrons at CBE ZnS will be transferred to CBE ZnO due to their positioning and holes will be transferred from VBE ZnO to VBE ZnS to provide different reactive oxidative (RO) species for photochemical reactions.…”

Recent Developments in Porphyrin-Based Metal–Organic Framework Materials for Water Remediation under Visible-Light Irradiation

“…However, the technologies required to perform it efficiently are not affordable worldwide. This has led to growing scientific investigations by environmentalists and researchers to develop strategies for the environmental remediation of wastewater [4][5][6][7][8][9][10][11].…”

Comparative Investigation of the Spectroscopic Behavior Based on High-Concentrated Solution in Nitrogen and Air Atmospheres

“…The conflict between industrial development and environmental pollution has caused worldwide concern [ 1 ]. The process industry has promoted the rapid growth of the global economy; however, the low resource utilization rate and environmental pollution associated with the process industry are the key difficult issues faced by all countries, which restrict local environmental protection and economic development [ 2 , 3 ]. The feedback, adjustment and control of mass concentration balance in the process industry based on real-time monitoring technology are the key to addressing the low resource utilization rate and pollution of the process industry [ 4 , 5 ].…”