Chloride converts lead slag into a bifunctional material to remove heavy metals

Gang Zhi; Xianjin Qi; Guizhi Yan; Yongkui Li; Junfeng Wang; Pengna Huang; Heng Wang; JiaHao Shi; Jianhua Wang

doi:10.1016/j.jenvman.2023.118631

Chloride converts lead slag into a bifunctional material to remove heavy metals

J Environ Manage. 2023 Oct 15:344:118631. doi: 10.1016/j.jenvman.2023.118631. Epub 2023 Jul 15.

Authors

Gang Zhi¹, Xianjin Qi², Guizhi Yan¹, Yongkui Li¹, Junfeng Wang¹, Pengna Huang¹, Heng Wang¹, JiaHao Shi¹, Jianhua Wang¹

Affiliations

¹ State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
² State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, China. Electronic address: qixianjin_1@163.com.

PMID: 37459815
DOI: 10.1016/j.jenvman.2023.118631

Abstract

Efficient and safe removal of arsenic and lead from industrial wastewater is essential for ecological protection. In this study, we developed a novel method using lead slag as a purifying agent and sodium chloride as a reinforcing agent to remove arsenic and lead from industrial wastewater. Through a combination of experiments and simulations, we elucidated the mechanisms involved in this reaction. The initial concentrations of As and Pb ions in the industrial wastewater were 4333 and 188 mg/L, respectively. After the reaction at 25 °C and a pH ranging from 9.7 to 10, the concentrations of arsenic and lead were reduced to 4.9 mg/L and 0.008 mg/L, respectively, achieving a removal rate of 99.9%. Our experimental results demonstrated that Pb²⁺ and AsO₄^3- ions released from the lead slag and industrial wastewater reacted with Cl^- ions to form Pb₅(AsO₄)₃Cl precipitates, thus effectively eliminating a significant amount of As and Pb species. Simulation studies indicated that Pb₅(AsO₄)₃Cl exhibited exceptional stability below 400 °C and could be directly stored. Additionally, the lead slag, which is rich in silica, played a crucial role in removing and stabilizing As and Pb ions. Under alkaline conditions, silica encapsulated the As and Pb species, adhering to the surface of the Pb-As co-precipitates and forming dense, irregular, small particles with internal and external structures that impeded the efflux of As and Pb ions. This phenomenon was confirmed through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The kinetics of As and Pb ion removal was consistent with the pseudo-second-order kinetic model, indicating that the removal process was primarily governed by chemical interactions. Lead slag exhibits significant potential and advantages in the removal of As and Pb. This innovative method offers an effective approach to address heavy metal contamination in industrial wastewater, thus contributing to ecological protection.

Keywords: Industrial wastewater; Lead slag; Pb(5)(AsO(4))(3)Cl; Removal of heavy metals; Thermodynamics.

MeSH terms

Adsorption
Arsenic*
Chlorides
Hydrogen-Ion Concentration
Kinetics
Lead
Metals, Heavy* / chemistry
Silicon Dioxide
Wastewater
Water Pollutants, Chemical* / chemistry

Substances

Wastewater
Chlorides
Lead
Arsenic
Metals, Heavy
Silicon Dioxide
Water Pollutants, Chemical