Combined electrosorption and chemisorption of low concentration Pb(II) from aqueous solutions with molybdenum disulfide as electrode

In order to develop a more effective method for removal of heavy metals with low concentration and explore the feasibility of using MoS2 as a super electrode material, removal of Pb(II) at low concentration was studied with combined electrosorption and chemisorption (CEC) by using molybdenum disulfide electrode. The experimental results indicated that Pb(II) could be highly removed by using CEC method when the initial concentration of Pb(II) was less than 6 mg/L. MoS2 electrode achieved 86.26 mg/m2 uptake capacity of Pb(II) with CEC, which was almost five times of that with pure chemisorption. The great improvement was attributed to the cooperation of electrosorption and chemisorption. The electric field helped to attract positively charged Pb(II) to the surface of the cathode and thus concentrated Pb(II) in the electric double layer (EDL) of MoS2 electrode, while the intrinsic S atoms on the surface of MoS2 immobilized Pb(II) on the electrode through the formation of Pb-S complex. It is suggested that CEC might be a promising process to immobilize heavy metals with low concentration from aqueous solutions.