The electrochemical advanced oxidation processes (EAOPs) have received significant attention among the many other water and wastewater treatment technologies. However, achieving a desirable removal effect with a single technique is frequently difficult. Therefore, the integration of ultrasound technique with other processes such as electrocoagulation, electro-Fenton, and electrooxidation is a critical way to achieve effective organic pollutants decomposition from wastewater. This review paper is focused on ultrasound-assisted electrochemical (US/electrochemical) processes, so-called sonoelectrochemical processes of various organic pollutants. Emphasis was given to recently published articles for discussing the results and trends in this research area. The use of ultrasound and integration with electrochemical processes has a synergistic impact owing to the physical and chemical consequences of cavitation, resulting in enhancing the mineralization of organic pollutants. Various types of sonoelectrochemical reactors (batch and continuous) employed in the US/electrochemical processes were reviewed. In addition, the strategies to avoid passivation, enhanced generation of reactive oxygen species, and mixing effect are reviewed. Finally, concluding remarks and future perspectives on this research topic are also explored and recommended. 

Recent progress on ultrasound-assisted electrochemical processes: A review on mechanism, reactor strategies, and applications for wastewater treatment

Recent progress on ultrasound-assisted electrochemical processes: A review on mechanism, reactor strategies, and applications for wastewater treatment.

Water contamination is an environmental burden for the next generations, calling for advanced methods such as adsorption to remove pollutants. For instance, unwanted biowaste and invasive plants can be converted into biosorbents for environmental remediation. This would partly solve the negative effects of invasive plants, estimated at 120 billion dollars in the USA. Here we review the distribution, impact, and use of invasive plants for water treatment, with emphasis on the preparation of biosorbents and removal of pollutants such as cadmium, lead, copper, zinc, nickel, mercury, chromate, synthetic dyes, and fossil fuels. Those biosorbents can remove 90-99% heavy metals from aqueous solutions. High adsorption capacities of 476.190 mg/g for synthetic dyes and 211 g/g for diesel oils have been observed. We also discuss the regeneration of these biosorbents. 

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Invasive plants as biosorbents for environmental remediation: a review

Fe3+-citric acid/sodium alginate hydrogel: A photo-responsive platform for rapid water purification.

Malachite green (MG) dye has various applications as a dyeing material, medical disinfectant and biocide but is also recognized as a teratogenic, carcinogenic, mutagenic and respiratory toxic material which creates dire effects on human beings, aquatic flora and fauna. Hence, the main objective lies in the removal of MG dye from an aqueous stream. In the current investigation, emulsion liquid membrane (ELM) technique was used and the effect of different factors like concentration of carrier, surfactant, stripping phase and its type and volume ratio of membrane to stripping solution on the removal of MG dye were studied. MG extraction efficiency of 94.99% was achieved using emulsion consisting of 2% w/v Span 80, 2% w/v D2EHPA, 0.1 N HCl and membrane phase to stripping phase volume ratio 1. Microscopic studies of the emulsion revealed the formation of well-defined and large number of globules with very less coalescence which resulted in high removal of MG dye. The physical stability of the emulsion was analysed and the phase separation was comparatively less at various time intervals suggesting that the conditions used for preparing the emulsions are suitable. Fourier transform infrared spectroscopy established the bonding and presence of various functional groups. The current study intends to fulfill the gap by exploring the removal of MG dye by ELM technique. 

Application of emulsion liquid membrane for removal of malachite green dye from aqueous solution: Extraction and stability studies

Ultrasonic assisted electrochemical degradation of malachite green in wastewater

The 1-(3-sulfopropyl)-3-vinylimidazole inner salt was prepared through the reaction of 1-vinylimidazole and 1,3-propanesultone, and then, it was mixed with different acids to synthesize three kinds of vinylimidazole acidic ionic liquids. The three ionic liquids (ILs) were used as catalysts for the catalytic synthesis of trimethylolpropane trioleate, and the effects of the catalyst amount, reaction time, reaction temperature, and molar ratio of reactants on the catalytic activity were studied. The esterification rates obtained using the three ILs as catalysts could reach 95.82%, 95.37%, and 97.88%. The catalytic kinetics of the synthesized ionic-liquid catalyst was studied, and the activation energies of the forward and reverse reactions were 13.9872 kJ mol−1 and 13.9918 kJ mol−1, and the pre-exponential factors were 2.781 × 10–2 L mol−1 h−1 and 4.835 × 10–5 L mol−1 h−1, respectively. The vinylimidazole acidic ILs showed good catalytic activity in the esterification reaction; thus, the catalysts are suitable for esterification reaction systems and valuable for research. Moreover, the existence of double bonds paves a way for the subsequent research on polymerized ionic liquids.

Yinghao Xue

Papers

Ultrasonic assisted electrochemical degradation of malachite green in wastewater

Preparation of a novel ionic liquid and its application in the synthesis of trimethylolpropane trioleate