Kumar Navneet, Verma Swati, Park Jinsub, Chandra Srivastava Vimal, Naushad Mu
Department of Chemical Engineering, Dr. B.R. Ambedkar National Institute of Technology, Jalandhar, Punjab, 144011, India; Department of Electronic Engineering, Hanyang University, Seoul, 04763, South Korea.
Department of Civil and Environmental Engineering, Hanyang University, Seoul, 04763, South Korea.
Chemosphere. 2022 Jul;298:134281. doi: 10.1016/j.chemosphere.2022.134281. Epub 2022 Mar 10.
Advanced oxidation processes triggered by nanoscale materials are promising owing to the in-situ generation of reactive radicals that can degrade toxic organic pollutants. In the present study, zinc sulfide (ZnS) nanoparticles with polyethylene glycol-4000 (PEG-4000) and polyvinylpyrrolidone (PVP) cappings were prepared using the chemical precipitation method and characterized thoroughly. Optical and structural characteristics of the capped ZnS nanoparticles were investigated and compared with those of uncapped ZnS nanoparticles. Results showed that PVP and PEG capped ZnS nanoparticles exhibited smaller crystallite size of 1.42 and 1.5 nm, respectively, as compared to uncapped ZnS (1.93 nm). Consequently, band gap energies of capped ZnS nanoparticles were higher which enable them to work as solar photocatalyst. The photocatalytic performance of the PEG, PVP-capped, and uncapped ZnS nanoparticles were evaluated against methyl orange (MO) dye and showed 85%, 87%, and 80% dye removal efficiencies, respectively. Degradation rate constant derived using Langmuir-Hinshelwood model revealed faster degradation kinetics bycapped ZnS photocatalysts owing to broader light absorption range. A possible dye degradation mechanism based on the energy levels positions was proposed to explain the route of photocatalytic degradation of MO by ZnS materials. It was inferred that the generation of reactive oxygen species by photogenerated electron-hole pairs facilitate degradation of MO dye molecules under sunlight illumination. It is expected that this work will provide insights into the development of strategies employed to achieve enhanced photocatalysis by nanoscale materials through organic capping.
由纳米材料引发的高级氧化过程很有前景，因为其能原位产生活性自由基，可降解有毒有机污染物。在本研究中，采用化学沉淀法制备了用聚乙二醇-4000（PEG-4000）和聚乙烯吡咯烷酮（PVP）包覆的硫化锌（ZnS）纳米颗粒，并对其进行了全面表征。研究了包覆的ZnS纳米颗粒的光学和结构特性，并与未包覆的ZnS纳米颗粒进行了比较。结果表明，与未包覆的ZnS（1.93 nm）相比，PVP和PEG包覆的ZnS纳米颗粒的微晶尺寸分别更小，为1.42和1.5 nm。因此，包覆的ZnS纳米颗粒的带隙能量更高，这使其能够用作太阳能光催化剂。评估了PEG、PVP包覆和未包覆的ZnS纳米颗粒对甲基橙（MO）染料的光催化性能，其染料去除效率分别为85%、87%和80%。使用朗缪尔-欣谢尔伍德模型得出的降解速率常数表明，由于光吸收范围更广，包覆的ZnS光催化剂具有更快的降解动力学。提出了一种基于能级位置的可能的染料降解机制，以解释ZnS材料对MO的光催化降解途径。据推断，光生电子-空穴对产生活性氧物种有助于在阳光照射下MO染料分子的降解。预计这项工作将为通过有机包覆实现纳米材料增强光催化的策略发展提供见解。
