New insights into the fate and interaction mechanisms of hydrolyzed aluminum-titanium species in the removal of aged polystyrene

Beibei Liu; Kangying Guo; Qinyan Yue; Yue Gao; Baoyu Gao

doi:10.1016/j.jhazmat.2023.133010

New insights into the fate and interaction mechanisms of hydrolyzed aluminum-titanium species in the removal of aged polystyrene

J Hazard Mater. 2024 Feb 15:464:133010. doi: 10.1016/j.jhazmat.2023.133010. Epub 2023 Nov 16.

Authors

Beibei Liu¹, Kangying Guo¹, Qinyan Yue¹, Yue Gao², Baoyu Gao³

Affiliations

¹ Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 26600, PR China.
² Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 26600, PR China. Electronic address: ygao@sdu.edu.cn.
³ Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 26600, PR China. Electronic address: baoyugao_sdu@aliyun.com.

PMID: 37984144
DOI: 10.1016/j.jhazmat.2023.133010

Abstract

Polyaluminum-titanium chloride composite coagulant (PATC) has been demonstrated to be a promising coagulant in microplastics (MPs) treatment. However, the interaction process between the dominant species of PATC and MPs remains unclear, which will hinder our understanding of the coagulation mechanisms. Here, the species transformation of PATC during its interaction with aged polystyrene powder (APSp) was studied. The results showed that the rise of O-containing functional groups in APSp increased the possibility of forming C-O-M coordination bonds and hydrogen bonds between APSp and PATC, which improved the removal of PSp. Furthermore, Al₁₃(OH)₅₃Ti₁₃O₁₇(H₂O)₂₀⁴⁺ (Al₁₃Ti₁₃) was considered to be the most effective species of PATC. At pH 4, electrostatic attraction brought Al₁₃Ti₁₃ approached APSp first, followed by hydrogen bonding and complexation occurred, respectively. However, the Al₁₃Ti₁₃-APSp complexes were easily converted to monomers and dimers during coagulation, which influenced the coagulation efficiency. With the increase of pH, OH^- in the solution would further polymerize the depolymerized Al₂Ti into oligomers and mesomers. Under weakly acid conditions, the diversity of PATC hydrolysates and the increase in APSp binding sites correspondingly led to the maximum APSp removal of 75%. When the pH further increased to 10, PATC interacted with APSp mainly by hydrogen bonding and sweeping effect.

Keywords: 2D-FTIR-COS; Composite coagulant; Dominant species; Interaction process; PS microplastics.