The Effect of Fe(II), Fe(III), Al(III), Ca(II) and Mg(II) on Electrocoagulation of As(V)

Niels Michiel Moed,Young Ku

doi:10.3390/w14020215

Abstract

The interaction between metal chlorides and electrocoagulation was tested. Precipitation of As(V) was found to be optimal at pH 4.9 using FeCl2, 2.6 for FeCl3, 3.8 using AlCl3, 11.6 using CaCl2 and 8.6 using MgCl2. As(V) removal through electrocoagulation went down as initial pH (pHi) of the solution increased. Addition of FeCl2 increased removal of As(V) at all pHi but was not able to achieve full removal at pHi 7. FeCl3 had a similar effect but a lower Fe(III) concentration of 30 mg/L was not sufficient for full removal at pHi 5 either. AlCl3 addition reduced removal efficiency at pHi 3 but removed all or most As(V) through precipitation at pHi 5 and 7, with complete removal followed through electrocoagulation. The addition of CaCl2 and MgCl2 resulted in nearly identical behavior. Addition of either at pHi 3 had no influence, but at pHi 5 and 7 caused complete removal to take place.

Highlights

The element arsenic is responsible for a wide range of health problems [1,2]
AlCl3 addition reduced removal efficiency at pHi 3 but removed all or most As(V) through precipitation at pHi 5 and 7, with complete removal followed through electrocoagulation
Precipitation is a common way to remove arsenic from aqueous waste streams [5]

Summary

Introduction

The element arsenic is responsible for a wide range of health problems [1,2]. Removal of arsenic from water and ground can prevent exposure to humans and animals, and is possible through various methods such as adsorption on iron oxides [3] and by use of membrane filtration [4]. Precipitation is a common way to remove arsenic from aqueous waste streams [5]. In coprecipitation an extra element is used that bonds to a pollutant and decreases the overall solubility. Coprecipitation of arsenic with other metals such as iron [6,7], aluminum [8,9,10], calcium [11,12] and magnesium [13,14] can greatly reduce its solubility. Whereas chemical precipitation is simple to operate and is cheap in initial investment, operating costs are high due to chemical usage and sludge disposal [15]

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Results

Conclusion