Hybrid Advanced Oxidation Processes Involving Ultrasound: An Overview.

Jagannathanmadhavan Jagannathanmadhavan,Sallasunitha Sallasunitha,Muthupandianashokkumar Muthupandianashokkumar,Jayaramantheerthagiri Jayaramantheerthagiri,Dhandapanibalaji Dhandapanibalaji,Choi Choi

doi:10.3390/molecules24183341

Abstract

Sonochemical oxidation of organic pollutants in an aqueous environment is considered to be a green process. This mode of degradation of organic pollutants in an aqueous environment is considered to render reputable outcomes in terms of minimal chemical utilization and no need of extreme physical conditions. Indiscriminate discharge of toxic organic pollutants in an aqueous environment by anthropogenic activities has posed major health implications for both human and aquatic lives. Hence, numerous research endeavours are in progress to improve the efficiency of degradation and mineralization of organic contaminants. Being an extensively used advanced oxidation process, ultrasonic irradiation can be utilized for complete mineralization of persistent organic pollutants by coupling/integrating it with homogeneous and heterogeneous photocatalytic processes. In this regard, scientists have reported on sonophotocatalysis as an effective strategy towards the degradation of many toxic environmental pollutants. The combined effect of sonolysis and photocatalysis has been proved to enhance the production of high reactive-free radicals in aqueous medium which aid in the complete mineralization of organic pollutants. In this manuscript, we provide an overview on the ultrasound-based hybrid technologies for the degradation of organic pollutants in an aqueous environment.

Highlights

Environmental pollutioncaused distinctively by anthropogenic sources is a common concern for the human race over the past few decades that have led to the exhaustion of the natural resources, viz., air, water, land, and soil, etc
The respective sonolysis degradation was studied in terms of total organic carbon (TOC), chemical oxygen demand (COD) reduction and ion chromatography (IC) and high-performance liquid chromatography (HPLC)
H2O2flow rate from 14 to 60 mL/h, a four-fold improvement in the TOC removal from 11% to 38%

Summary

Introduction

Environmental pollutioncaused distinctively by anthropogenic sources is a common concern for the human race over the past few decades that have led to the exhaustion of the natural resources, viz., air, water, land, and soil, etc. Designing of more eco-friendly techniques to eradicate these environmental pollutants has turned into a challenging assignment for researchers worldwide In this regard, advanced oxidation processes (AOPs) are recognised as an efficient method for the degradation of organic pollutants as they rely on the generation of highly reactive HO (hydroxyl radical) via chemical, solar or other types of energy options [9,10,11]. These radicals subsequently react with contaminants through a series of multi-step reactions to form low molecular weight carboxylic acids as end products and these products will further be mineralized into CO2 and H2 O [12]. The application of ultrasound is used in the preparation of active catalysts but has been extensively applied in wastewater treatment applications [58]

Sonolysis

Sonocatalysis

Sonophotocatalysis

Findings

Summary