Upcycling of Wastewater via Effective Photocatalytic Hydrogen Production Using MnO2 Nanoparticles-Decorated Activated Carbon Nanoflakes.

Sankar Sekar,Thirumavalavan Santhakumar,Kaliyappan Mohan Kalirajan,Sejoon Lee,Sutha Sadhasivam,Preethi Vijayarengan,Saravanan Sekar

doi:10.3390/nano10081610

Abstract

In the present work, we demonstrated the upcycling technique of effective wastewater treatment via photocatalytic hydrogen production by using the nanocomposites of manganese oxide-decorated activated carbon (MnO2-AC). The nanocomposites were sonochemically synthesized in pure water by utilizing MnO2 nanoparticles and AC nanoflakes that had been prepared through green routes using the extracts of Brassica oleracea and Azadirachta indica, respectively. MnO2-AC nanocomposites were confirmed to exist in the form of nanopebbles with a high specific surface area of ~109 m2/g. When using the MnO2-AC nanocomposites as a photocatalyst for the wastewater treatment, they exhibited highly efficient hydrogen production activity. Namely, the high hydrogen production rate (395 mL/h) was achieved when splitting the synthetic sulphide effluent (S2− = 0.2 M) via the photocatalytic reaction by using MnO2-AC. The results stand for the excellent energy-conversion capability of the MnO2-AC nanocomposites, particularly, for photocatalytic splitting of hydrogen from sulphide wastewater.

Highlights

Upcycling of wastewater via effective solar-assisted photocatalytic hydrogen production is vital for future green energy technology because this technique would become readily available as an ecofriendly and inexpensive method for treating industrial wastewater as well as developing alternative energy sources
The material preparation and the improved hydrogen production characteristics of the MnO2-activated carbon (AC) nanocomposites are discussed in detail
The MnO2-AC nanocomposites were prepared by using the biomass resources of Brassica oleracea and Azadirachta indica

Summary

Introduction

Upcycling of wastewater via effective solar-assisted photocatalytic hydrogen production is vital for future green energy technology because this technique would become readily available as an ecofriendly and inexpensive method for treating industrial wastewater as well as developing alternative energy sources. Semiconductor materials exhibit the increased potential energy from the photocatalytic reaction because of their flexible constitution and diversity of properties [5]. Many earlier studies reported that biomass AC could improve the catalytic ability for reformation of carbon dioxide [35] and enhance the energy-storage performances [36,37,38,39]. Despite such vast benefits, to our best awareness, no studies on the MnO2-AC nanocomposite-based wastewater treatment have been conducted yet. The material preparation and the improved hydrogen production characteristics of the MnO2-AC nanocomposites are discussed in detail

Synthesis of MnO2 Nanoparticles

Conclusions