Modification of ultrasound-pretreated montmorillonite using poly(diallyldimethylammonium chloride) for W and Mo separation and the sequential application in removal of heavy metals

Xiaojie Hu; Ting Xiao; Qidong Huang; Shichen Liu; Hongxia Liu; Sili Ren; Dandan Gong; Wuhui Luo

doi:10.1016/j.ultsonch.2024.106773

Modification of ultrasound-pretreated montmorillonite using poly(diallyldimethylammonium chloride) for W and Mo separation and the sequential application in removal of heavy metals

Ultrason Sonochem. 2024 Feb:103:106773. doi: 10.1016/j.ultsonch.2024.106773. Epub 2024 Jan 18.

Authors

Xiaojie Hu¹, Ting Xiao¹, Qidong Huang², Shichen Liu³, Hongxia Liu¹, Sili Ren¹, Dandan Gong¹, Wuhui Luo⁴

Affiliations

¹ Jiangxi Key Laboratory of Environmental Pollution Prevention and Control in Mining and Metallurgy, Ganzhou 341000, PR China; School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, PR China.
² Jiangxi Key Laboratory of Environmental Pollution Prevention and Control in Mining and Metallurgy, Ganzhou 341000, PR China; Heyuan Hospital for Occupational Disease Prevention and Treatment, Heyuan 517000, PR China.
³ College of Life Sciences, Gannan Normal University, Ganzhou 341000, PR China.
⁴ Jiangxi Key Laboratory of Environmental Pollution Prevention and Control in Mining and Metallurgy, Ganzhou 341000, PR China; School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, PR China. Electronic address: luo070221@126.com.

Abstract

The use of a resin to selectively separate thiomolybdate from a tungsten (W) feed solution is a well-known protocol for achieve high-purity W products; however, the regeneration of saturated resin is laborious. In this study, poly(diallyl dimethyl ammonium chloride) (PDADMA) was used to modify ultrasound-pretreated montmorillonite (Mt) for W and molybdenum (Mo) separation for the first time, and the resultant tetrathiomolybdate (MoS₄^2-)-loaded composite was further tested to remove heavy metals instead of regeneration. Among the three variables of ultrasound pretreatment, that is, Mt concentration, ultrasound power, and treatment time, the Mt concentration exhibited the most significant influence followed by ultrasound power on the separation performance of W and Mo. Compared to the distance of the interlayer space and the surface charge of the modified Mt, the PDADMA content showed a closer correlation with the W/Mo separation coefficient. Assisted by Box-Behnken design, with Mt concentration of 6.9 g/L, ultrasound power of 593.8 W, and treatment time of 13.8 min, the composite with the greatest separation coefficient was obtained. The adsorption of Cu(II) on the optimal W/Mo separation-derived composite was ascribed to the formation of Cu-S complexes, while that of Pb(II) was attributed to complexation and surface precipitation. In contrast, ion exchange with the initially loaded anions, reduction by sulfide to Cr(III), and formation of Cr(III)-S complexes accounted for Cr(VI) removal. The adsorption of Cu(II) and Pb(II) equilibrated faster and showed higher acid-resistance than that of Cr(VI). The adsorption capacities for Cu(II), Pb(II), and Cr(VI) were 0.535, 1.398, and 0.882 mmol/g, respectively. Applying PDADMA to modify Mt as a reagent for W/Mo separation was feasible, and the derived composite was capable of removing cationic and anionic heavy metals.

Keywords: Heavy metal removal; Modification; Montmorillonite; Ultrasound; W and Mo separation.