A Combined Approach using Sonochemistry and Photocatalysis: How to Apply Sonophotocatalysis for Biomass Conversion?

Abstract

The innovative combination of sonochemistry (power ultrasound) and photocatalysis (UV light) has been extensively investigated in the literature, especially as an advanced oxidation process. Based on these results but with a completely different strategy, the sonophotocatalysis starts to be applied to organic reactions and could represent an innovative way to valorize biomass into fuels or platform molecules. This article discusses this opportunity and proposes some trends and outlooks for further researches in the area.

General and Prospective Views on Oxidation Reactions in Heterogeneous Catalysis

“…In this review, we have provided several types of oxidation reactions (selective/partial or total, gas-solid and liquid-solid phases), of oxidation catalysts and of activation procedures, illustrated by case studies or industrial application, mainly gathered in the last two decades. It is well known that The combination of sonocatalysis with photocatalysis has been widely investigated in the last fifteen years as AOP for the degradation of a large variety of organic pollutants in aqueous phase [56], such as phenolic compounds, dyes, pharmaceuticals, pesticides and textile industrial effluents [94]. The combined effects of such sonophotochemical process (see Section 2.3), coupled to the efficient use of a photocatalyst, result in an increased production of free radicals in aqueous solution and of cavitation bubbles, enhance mass transfer between the pollutants and the photocatalyst, as well as remove any impurities from its surface.…”

“…The combined use of sonochemistry (power ultrasound) and photocatalysis, called sonophotocatalysis, recently found innovative applications in organic compounds reactions and biomass conversion (lignin, chitosan, etc.) to high-added value intermediates [56]. Under coupled UV/US irradiations, an increased amount of radical species is produced in the reaction medium (HO • , O2 •− , and HO2 • ) in the presence of a catalyst.…”

“…intensity and energy efficiency in these combined sonochemical and photocatalytic conditions is also essential prior to further applications in this area. [56].…”

“…Schematic representation of the principle of sonophotocatalysis combining sonocatalysis and photocatalysis[56].…”

Catalytic Conversion of Biomass

“…Wang and co‐workers investigated the role of Lewis and Brønsted acid sites in the conversion of glucose into HMF, while Zhang, Su and co‐workers investigated the role of water in catalyzing proton‐transfer in glucose dehydration into HMF . Chatel, Colmenares and co‐workers investigated the innovative combination of sonochemistry and photocatalysis for the valorization of biomass …”