Enhanced removal of humic acid from aqueous solution by combined alternating current electrocoagulation and sulfate radical

Fatemeh Rajaei; Ensiyeh Taheri; Sousan Hadi; Ali Fatehizadeh; Mohammad Mehdi Amin; Nasim Rafei; Saeid Fadaei; Tejraj M Aminabhavi

doi:10.1016/j.envpol.2021.116632

Enhanced removal of humic acid from aqueous solution by combined alternating current electrocoagulation and sulfate radical

Environ Pollut. 2021 May 15:277:116632. doi: 10.1016/j.envpol.2021.116632. Epub 2021 Feb 10.

Authors

Fatemeh Rajaei¹, Ensiyeh Taheri², Sousan Hadi¹, Ali Fatehizadeh³, Mohammad Mehdi Amin², Nasim Rafei², Saeid Fadaei², Tejraj M Aminabhavi⁴

Affiliations

¹ Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran; Student Research Committee, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran.
² Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran; Environment Research Center, Research Institute for Primordial Prevention of Non-Communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran.
³ Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran; Environment Research Center, Research Institute for Primordial Prevention of Non-Communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran. Electronic address: a.fatehizadeh@hlth.mui.ac.ir.
⁴ Department of Chemistry, Karnatak University, Dharwad, 580 003 India.

PMID: 33640826
DOI: 10.1016/j.envpol.2021.116632

Abstract

Application of alternating current in electrocoagulation and activation of persulfate (AEC-PS) for the effective removal of humic acid (HA) from aqueous solution was evaluated. In order to optimize the removal efficiency HA by the AEC-PS process, several influencing parameters such as pH, reaction time, PS dose, current density (CD), concentration of NaCl, initial concentration of HA, and coexisting cations and anions influence were investigated. From the batch experiments, the highest HA removal efficiency obtained was 99.4 ± 0.5% at pH of 5, reaction time of 25 min, CD of 4.5 mA/cm², PS dose of 200 mg/L, and NaCl concentration of 0.75 g/L for an initial HA concentration of 30 mg/L. When CD increased from 1.25 to 4.5 mA/cm², the HA removal efficiency was improved from 88.8 ± 4.4% to 96.1 ± 1.5%. In addition, the type of coexisting cations and anions exerted a significant role, leading to a reduction in the removal efficiency of HA. To investigate the dominant free activated radical, radical scavengers such as tert-butyl alcohol and ethanol were employed. It was observed that both OH and SO₄^- radicals substantially contributed to the removal of HA, and the contribution of SO₄^- radical was higher than that of OH radical, suggesting that AEC-PS process could serve as a novel and effective treatment technique for the removal of organic matters from aqueous sources.

Keywords: Alternating current; Electrocoagulation; Electrodes; Humic acid; Persulfate.

MeSH terms

Electrocoagulation
Humic Substances
Oxidation-Reduction
Sulfates
Water Pollutants, Chemical* / analysis
Water Purification*

Substances

Humic Substances
Sulfates
Water Pollutants, Chemical
sulfate radical