Employing speciation of metals to assess photo-assisted electrochemical efficiency for improving rainwater quality in Tehran, Iran

Abstract

Photo-assisted electrochemical process is a promising technology for a clean ecosystem. It is largely utilized for recovering metals and oxidizing recalcitrant organic compounds. This paper aims to discuss the performance of the photo-oxidation and reduction by applying semiconductor photo-catalysis as the anode and graphite as the cathode for treating rainwater in Tehran, Iran. Organic pollutants and different metals were investigated to study the probable roles of the anodic potential, the gap between electrodes, and the concentration of electrolytes in the possible mechanisms. The laboratory experiments which lasted for 120 min exhibited that the best performance for organic, iron, manganese, and lead removal was at the anodic potential of 10 V and gap of 6 cm. But, for zinc and cadmium, the best performance occurred at the anodic potential of 5.5 V and sodium chloride of 0.65 g/L. The presented reactions and mechanisms demonstrated incidents using the treatment process. They were identical to the presented dendrogram and Pourbaix diagrams. The results of the diagrams showed iron, manganese, and lead were removed by oxidation at the photo-anode. Zinc and cadmium were mainly removed by precipitation. Chemical oxygen demand, iron, manganese, and lead were significantly related and behaved similarly in the treatment process. Their removal was controlled by all the analyzed parameters. This paper may present a cost-effective approach for removing organic and metallic pollutants by photo-assisted electrochemical process. It can be suggested for future evolution of photo-assisted electrochemical on the treatment applications of rainwater.

Photocatalysis over N-Doped TiO2 Driven by Visible Light for Pb(II) Removal from Aqueous Media

“…Hence, there is obvious evidence that the photo-oxidation of Pb(II) yielded of PbO 2 , by following the reaction in Equation ( 4). The formation of PbO 2 from Pb(II) photo-oxidation well agrees with the finding reported previously [8,9]. The formation of the solid PbO 2 is beneficial in terms of solid waste treatment due to the less toxic and handleable waste.…”

“…It is inferred that the photocatalytic removal is i ated and/or accompanied by the adsorption step [18]. The enhancement of the visible tocatalytic-oxidation was promoted by lowering band gap energy (Eg), that allowed to be activated by visible light generating a lot of OH radicals for oxidation [16][17][18][19][20]23 The reactions of the formation of OH radicals and Pb(II) photo-oxidation were prese as Equation (1), Equation (2) [11][12][13][14] and Equation (3) [7][8][9]. The effective photocatal oxidation of Pb(II) under visible light provides a potential and promising method t applied on a larger scale for industrial wastewater treatment.…”

“…Currently, remediation of Pb(II) containing water by the photo-oxidation process through photo-Fenton method [7], under TiO 2 photocatalyst [8], and photo-assisted electrochemical [9] have also been developed. Furthermore, oxidation of Pb(II) by manganese salt has been studied [10].…”

“…Furthermore, oxidation of Pb(II) by manganese salt has been studied [10]. Oxidation seems to be the most interesting method since Pb(II) oxidation resulted in the non-toxic precipitate PbO 2 and is more easily handled [7][8][9][10].…”

Rainwater treatment: an approach for drinking water provision to indigenous people in Ecuadorian Amazon

“…In this study, we believe the action of the wind that carries solid particles that settle on the roof surface affect the original rainwater composition. The presence of excessive iron and manganese in rainwater originated in natural minerals from the soil and dissolved in rainwater has been reported in previous works (Aziz et al 2020;Ebraheim et al 2021).…”