Wastewater decontamination via piezoelectric based technologies: Materials design, applications and prospects

Piezoelectric effect has been widely applied for energy harvesting via constructing nano energy generator in piezoelectric materials, while its application in water treatment is relatively limited. Recently, the piezoelectric effect has been employed to generate reactive species for water decontamination via induced dipole moment in the piezoelectric materials. The piezo-catalytic process can utilize natural mechanical energy, which includes wind, water flow, waves etc., and has drawn lots of attention. Meanwhile, it can be easily coupled with other oxidation process to further improve the performance. On the other hand, the development of piezo-catalytic membrane solves the secondary pollution of the powder materials and has evolved rapidly as a novel technology for water decontamination. This review compiles the latest information on the application of piezoelectric materials in water decontamination, mainly including the organic pollutants degradation and bacterial inactivation. Firstly, the piezoelectric effect was described followed by the summary of different piezoelectric materials employed for water decontamination via piezo, piezo-photo and piezo-persulfate activation processes. Secondly, the preparation and application of piezo-catalytic membrane were revealed, mainly focused on the organic pollutants degradation and membrane fouling elimination. Thirdly, the current challenges including the material synthesis and characterization, process design and reaction mechanism description were described followed by the future research direction recommendation. Overall, the current work could meet the demand of the researchers who are working on the piezoelectric materials for the application of eliminating organic pollutants in wastewater, by providing timely and systematic information on this topic.