Abstract
Arsenic (As) is a naturally occurring element in the environment that poses significant risks to human health. Several treatment technologies have been successfully used in the treatment of As-contaminated waters. However, limited literature has explored advanced electrocoagulation (EC) processes for As removal. The present study evaluates the As removal performance of electrocoagulation, electrochemical peroxidation (ECP), and photo-assisted electrochemical peroxidation (PECP) technologies at circumneutral pH using electroactive iron electrodes. The influence of As speciation and the role of oxidants in As removal were investigated. We have identified the ECP process to be a promising alternative for the conventional EC with around 4-fold increase in arsenic removal capacity at a competitive cost of 0.0060 $/m3. Results also indicated that the rate of As(III) oxidation at the outset of electrochemical treatment dictates the extent of As removal. Both ECP and PECP processes reached greater than 96% As(III) conversion at 1 C/L and achieved 86% and 96% As removal at 5 C/L, respectively. Finally, the mechanism of As(III) oxidation was evaluated, and results showed that Fe(IV) is the intermediate oxidant generated in advanced EC processes, and the contribution of •OH brought by UV irradiation is insignificant.
Highlights
Arsenic (As) is one of the top ten pollutants associated with water quality violations.Arsenic contamination of groundwater has been reported from over 70 countries, affecting around150 million people worldwide [1]
Decreasing values of circulated charges of 27.6 charge loading (C/L), 6.7 C/L, and 4.9 C/L were required for EC, electrochemical peroxidation (ECP), and photo-assisted electrochemical peroxidation (PECP), respectively
ItEC MFe nFv where MFe is the molar mass of Fe (55.85 g/mol), n is the number of electrons involved in the oxidation/reduction reaction, and F is Faraday’s constant (96,485 C/mol). Both ECP and PECP processes are more effective than EC in reducing the
Summary
Arsenic (As) is one of the top ten pollutants associated with water quality violations.Arsenic contamination of groundwater has been reported from over 70 countries, affecting around150 million people worldwide [1]. Arsenic (As) is one of the top ten pollutants associated with water quality violations. Arsenic contamination of groundwater has been reported from over 70 countries, affecting around. 150 million people worldwide [1]. 110 million of those who are affected live in South and South-east Asia [2]. In the Philippines, a case of chronic arsenic poisoning was reported to the Department of Health in 2014 [3]. It was found that 215 people had consulted with similar dermatological symptoms since 2010. Groundwater quality tests conducted showed arsenic concentrations greater than 10 μg/L, which is the maximum limit set by the Philippine National
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