Preparation of High-Performance CdS@C Catalyst Using Cd-Enriched Biochar Recycled From Plating Wastewater.

Rui-Zhi Xing,Zhi Chen,Shun-Gui Zhou,Xing-Gui Yang,Jia-Xin Li,Zhi-Xuan Chen,Ze-Wei Chen,Rong Huang

doi:10.3389/fchem.2020.00140

Rui-Zhi Xing, Zhi Chen + Show 6 more

Open Access

https://doi.org/10.3389/fchem.2020.00140

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Abstract

Biochar is widely used for the adsorptive removal of Cd from water and soil, but the Cd-enriched biochar produced carries a risk of secondary pollution. In this work, biochar derived from rice straw was used to adsorb Cd from plating wastewater. The Cd-enriched biochar showed a saturated adsorption capacity of about 63.5 mg/g and could be recycled and used in a mesoporous carbon-supported CdS (CdS@C) photocatalyst after pyrolysis carbonization and a hydrothermal reaction. The results demonstrated that the as-prepared CdS@C photocatalyst contained mixed cubic and hexagonal CdS phases, with a considerably lower band gap (2.1 eV) than pure CdS (2.6 eV). CdS@C exhibited an enhanced photocatalytic performance for the degradation of organic dyes under visible light irradiation compared with pure CdS due to its excellent light-harvesting capacity and efficient electron-hole separation. Moreover, the continuous formation of active species (h+, •OH, and O2•−) was responsible for the photodegradation of organic dyes using CdS@C. This work provides new insights for the safe disposal of Cd-enriched wastewater and for improving the economic viability of Cd-contaminated resources by recovering a value-added photocatalyst.

Highlights

Cadmium (Cd) is extremely toxic to plants and poses a serious threat to humans and animals when it enters the food chain (Clemens et al, 2013; Zhao et al, 2015; Gong et al, 2019; Hussain et al, 2019)
The Cd equilibrium adsorption of the biochar was achieved in 30–40 min and reached about 63.5 mg/g (Figure S2)
The EDX elemental analysis suggested that the particles on the SCHEME 1 | Diagram of the route for CdS@C synthesis route

Summary

INTRODUCTION

Cadmium (Cd) is extremely toxic to plants and poses a serious threat to humans and animals when it enters the food chain (Clemens et al, 2013; Zhao et al, 2015; Gong et al, 2019; Hussain et al, 2019). The carbon carrier prevented the aggregation and photocorrosion of catalyst particles and facilitated the transport and contact of substrates between the support and the active sites (Gao et al, 2011; Han et al, 2011; Huang et al, 2018; Chen et al, 2019c) In light of these advantages, biochar-supported CdS composites may greatly enhance the photocatalytic activity and stability of the catalysts (Ma et al, 2017; Huang et al, 2018, 2019; Bantawal et al, 2019; Cao et al, 2019; Hu et al, 2019). Hydroxyl radicals ( qOH) generated during the photocatalytic reaction could react with terephthalic acid (TA) to produce highly fluorescent 2hydroxyterephthalic acid (TAOH), and the fluorescence was detected by fluorescence spectroscopy

RESULTS AND DISCUSSION

CONCLUSION

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