Abstract: Acid Mine Drainage (AMD) generated from mining activities is strongly acidic,containing high concentrations
of Fe²⁺ along with metal(loid) pollutants. To efficiently treat AMD,a proton exchange membrane (PEM) electrolysis system
was developed. Under the optimal process parameters (iridium titanium mesh anode,platinum plate cathode,15 g/ L SO^2-
4 ,60mA),this system reduced the metal(loid) concentrations in AMD with a pH of 2. 5~3. 5,an initial Fe²⁺ concentration of 200
~800 mg/ L,and containing 50 mg/ L of Fe³⁺ ,Mn²⁺ ,Cr³⁺ ,Cu²⁺ ,Zn²⁺ or As⁵⁺ to meet the drinking water standards within 290
min. The removal efficiency of Fe in AMD by PEM electrolysis technology was positively correlated with the initial pH (2. 5~
4. 5) and negatively correlated with the initial Fe²⁺ concentration (200 ~ 800 mg/ L). 50 mg/ L of Fe³⁺ ,Cu²⁺ ,and Zn²⁺ in
wastewater inhibited the removal of Fe,while Mn²⁺ and Cr³⁺ promoted it. As⁵⁺ showed no significant effect. Products characterization
showed that during the initial stage,part of the Fe²⁺ in the wastewater was oxidized by dissolved oxygen to (hydro) ferric
oxide,while another portion hydrolyzed to form (hydrogen) ferrous hydroxide. In the final stage,these intermediates dissolved
and recrystallized into Fe₃O₄;Fe³⁺ ,Mn²⁺ ,Cr³⁺ ,Cu²⁺ and Zn²⁺ co-precipitated with Fe²⁺ as mixed metal oxides;As⁵⁺ was
adsorbed onto the iron minerals formed.