Partial Oxidation Strategy to Synthesize WS2/WO3 Heterostructure with Enhanced Adsorption Performance for Organic Dyes: Synthesis, Modelling, and Mechanism.

Guiping Li,Xin Huang,Liang Luo,Yafei Mao,Yongli Wang,Hongxun Hao,Jingtao Bi

doi:10.3390/nano10020278

Abstract

In this work, a facile oxidation strategy was developed to prepare novel tungsten disulfide/tungsten trioxide (WS2/WO3) heterostructures for adsorbing organic dyes efficiently by combining the hydrophilic property of WO3 and the superior dye affinity of WS2. The structural and elemental properties of the synthesized hybrid materials were systematically investigated, and the results demonstrated the retained flower-like morphology of the primitive WS2 and the successful introduction of WO3. Furthermore, surface properties such as a superior hydrophilicity and negative-charged potential were also demonstrated by a water contact angle characterization combined with a Zeta potential analysis. The performance of the obtained WS2/WO3 hybrid materials for removing Rhodamine B (RhB) from wastewater was evaluated. The results showed that the maximum adsorption capacity of the newly synthesized material could reach 237.1 mg/g. Besides, the adsorption isotherms were also simulated by a statistical physics monolayer model, which revealed the non-horizontal orientation of adsorbates and endothermic physical interaction. Finally, the adsorption mechanism and the recyclability revealed that the partial oxidation strategy could contribute to a higher adsorption capacity by modulating the surface properties and could be applied as a highly efficient strategy to design other transition metal dichalcogenides (TMDs) heterostructures for removing organic dyes from wastewater.

Highlights

In the past several decades, it was estimated that millions of tons of dyes were produced annually, and amount of dyes were discarded into water as waste [1,2,3]
A new type of WS2/WO3 heterostructure, which could be used as excellent absorbents, was developed and fabricated by coupling a solvothermal synthesis method with a partial oxidation strategy
Different characterization results confirmed the successful fabrication of WS2/WO3 heterostructures, which possess more negative surface charges and which highly promoted hydrophilicity after a partial oxidation

Summary

Introduction

In the past several decades, it was estimated that millions of tons of dyes were produced annually, and amount of dyes were discarded into water as waste [1,2,3]. These organic dyes, which are toxic, non-biodegradable, and even carcinogenic, had posed serious threats to human health and marine organisms [4]. It is urgent to develop low-cost and efficient methods to remove these organic dyes from wastewater. Adsorption is considered a promising candidate to eliminate dyes from industrial wastewater due to the low capital cost, simplicity of operation, and low introduction of toxic byproducts. A large number of materials have been developed and utilized in adsorption, such as carbon nanotubes, metal-organic framework (MOF), and graphene, which have the advantages of a high surface area, hydrophilic properties, and intense interactions between adsorbents and adsorbates [4,16,17,18,19,20,21]

Methods

Results

Conclusion