Removal of cadmium and lead from aqueous solutions by thermal activated electrolytic manganese residues

Mengyu Ma; Yaguang Du; Shenxu Bao; Jia Li; Hua Wei; Ying Lv; Xiaolong Song; Tiancheng Zhang; Dongyun Du

doi:10.1016/j.scitotenv.2020.141490

Removal of cadmium and lead from aqueous solutions by thermal activated electrolytic manganese residues

Sci Total Environ. 2020 Dec 15:748:141490. doi: 10.1016/j.scitotenv.2020.141490. Epub 2020 Aug 4.

Authors

Mengyu Ma¹, Yaguang Du¹, Shenxu Bao², Jia Li³, Hua Wei¹, Ying Lv¹, Xiaolong Song¹, Tiancheng Zhang⁴, Dongyun Du¹

Affiliations

¹ School of Resource and Environmental Science, South-Central University for Nationalities, Wuhan, Hubei, China, 430074.
² School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, Hubei, China, 430070.
³ School of Resource and Environmental Science, South-Central University for Nationalities, Wuhan, Hubei, China, 430074; School of Forestry & Environmental Studies, Yale University, New Haven, CT, USA, 06511. Electronic address: jiajiali1982@aliyun.com.
⁴ Civil and Environmental Engineering Department, College of Engineering, University of Nebraska-Lincoln, Omaha, NE, USA, 68182.

PMID: 32810808
DOI: 10.1016/j.scitotenv.2020.141490

Abstract

Electrolytic manganese residues (EMR) is produced from the electrolysis manganese industry. In this study, the thermal activated EMRs (T-EMR) were used to adsorb cadmium and lead from aqueous solution. X-ray diffractometer (XRD), scanning electron microscope-Energy Dispersive Spectrometer (SEM-EDS), X-ray photoelectron spectroscopy (XPS) were adopted to characterize EMR before and after the modification, and the performance and adsorption mechanisms of T-EMR for cadmium and lead were determined. Results show that the pH has a strong influence on the adsorption of cadmium and lead and the maximum adsorption capacity can be achieved at pH 6. The adsorption of Cd(II) can be better fitted by the Lagergren pseudo-first-order dynamic model, while that of Pb(II) fits the pseudo-second-order kinetic model better. The Freundlich isotherm model fits the adsorption of two metals better than Langmuir model. The thermodynamic results demonstrate that the adsorption of Cd(II) or Pb(II) on T-EMR is endothermic and spontaneous. As the nitric acid with pH 0.5 was used, nearly all of the adsorbed Cd(II) and 75% Pb(II) can be desorbed from the loaded T-EMR. It is concluded that the adsorption of Cd(II) and Pb(II) on T-EMR is in virtue of electrostatic attraction, ion-exchange and surface precipitation. The heavy metals are mainly adsorbed on ferric and manganese oxides and silicate minerals in T-EMR by electrostatic attraction. In addition, cadmium and lead also can be adsorbed via the ion exchange reaction. Moreover, some Pb(II) are adsorbed by forming lead sulfate. Thus, T-EMR may be an environmentally-friendly, effective adsorbent for the removal of heavy metals from aqueous solution.

Keywords: Adsorption; Cadmium; Electrolytic manganese residue; Lead; Thermal activation.