Recent advancements in the sonophotocatalysis (SPC) and doped-sonophotocatalysis (DSPC) for the treatment of recalcitrant hazardous organic water pollutants

Abstract

The review has accomplished a thorough and a critical analysis of sonophotocatalysis (SPC) based on the recently published journals. Recent advancements in the doped sonophotocatalysis (DSPC) and the mechanisms behind synergistic enhancement in the pollutant degradation rate have been discussed with justifications. Besides, the possible future works are suggested for the advancements in sonophotocatalysis based treatment. This review will be beneficial for electing a SPC based method because of the accomplished sharp comparisons among the published results. The review includes current advancements of SPC based methods which aid for a low-cost and a large-scale wastewater treatment application.

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

“… the increased production of hydroxyl radicals in the reaction mixture under UV irradiation and high or low US frequency in the presence of a catalyst (Fenton reagent for example); the enhanced mass transfer between the liquid phase and the catalyst surface; the increased catalytic activity due to ultrasound (depassivation effects, de‐aggregating catalyst particles increasing its surface area, etc) …”

“…the increased catalytic activity due to ultrasound (depassivation effects, de‐aggregating catalyst particles increasing its surface area, etc) …”

“…The synergistic combination of sonocatalysis and photocatalysis, called "sonophotocatalysis"o r" photosonocatalysis" (Figure 1) depending on the focus of the author, has been reported in the literature, especially for the degradation of organic compoundsi nt he aqueous phase, [42][43][44] such as phenol and phenolic compounds, [45,46] 2-propanol, [47] naphthol blue black, [48] methylene blue, [49] reactive red 120, [50] methyl orange, [51] hydrogels, [52] textile industrial effluents, [53] pesticides from waste-water, [54] paracetamol, [55] etc.…”

“…The US irradiation increases turbulence in the liquid phase, decreasing mass transfer limitations and increasing the catalytically active surface area through the deagglomeration and fragmentation of the particles. From a recent review of the literature in the area, Panda and Manickam highlighted the role of the pH of the solution (depending of the type of pollutant), the acoustic power (direct effect on the degradation rates), and individual parameters such as initial concentration of pollutant, catalyst loading, operating temperature, type of sparging gas, incorporation of additives such as Fenton's reagent, hydrogen peroxide, tetrachloromethane and methanol, in the efficiency of degradation . The synergistic effects proposed by sonophotochemical as AOP, coupled to the efficient use of a photocatalyst and eventually a catalyst support and, clearly increases free radicals formation in aqueous solution, increases the formation of cavitation bubbles, accelerates and facilitates mass transfer of pollutant molecules onto the photocatalyst surface as well as remove any impurities from its surface .…”

Photocatalytic degradation and photo-Fenton oxidation of Congo red dye pollutants in water using natural chromite—response surface optimization

“…The physical methods represented by adsorption, coagulation, and filtration. Other methods also were used in the degradation of dyes such as ultrasonic power, hydrodynamic cavitational techniques, sonochemical reactors, and sonophotocatalytic degradation process Pandit 2001, 2002;Gogate et al 2004;Panda and Sivakumar 2017). Adsorption by low-cost materials is efficient in dye removal, but such method produces a lot of solid waste (Sivakumar et al 2013).…”