An innovative exploration to identify and isolate the dominant-flocculated-species from polytitanium chloride synthesized by electrodialysis

Mingqian Hou; Xu Zhao; Chang Tian; Haibo Li; Weiqiang Zhu; Weiying Xu; Jiazhao Liu; Yuyu Liu; Yanxia Zhao

doi:10.1016/j.watres.2024.121515

An innovative exploration to identify and isolate the dominant-flocculated-species from polytitanium chloride synthesized by electrodialysis

Water Res. 2024 May 15:255:121515. doi: 10.1016/j.watres.2024.121515. Epub 2024 Mar 24.

Authors

Mingqian Hou¹, Xu Zhao¹, Chang Tian², Haibo Li³, Weiqiang Zhu¹, Weiying Xu¹, Jiazhao Liu⁴, Yuyu Liu¹, Yanxia Zhao⁵

Affiliations

¹ School of Water Conservancy and Environment, University of Jinan, Jinan, Shandong 250022, China.
² School of Environmental Science & Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.
³ Shansuyouke (Shenzhen) New Materials Limited, 2015 Shenyan Road, Yantian, Shenzhen 518081, China.
⁴ No.8 Institute of Geology and Mineral Resources Exploration of Shandong Province, Rizhao, Shandong 276826, China.
⁵ School of Water Conservancy and Environment, University of Jinan, Jinan, Shandong 250022, China. Electronic address: Stu_zhaoyx@ujn.edu.cn.

PMID: 38554628
DOI: 10.1016/j.watres.2024.121515

Abstract

Abundance of dominant-flocculated-species is the key to determine coagulation performance of coagulant. Titanium-based coagulants have garnered considerable attention due to their high coagulation efficiency, but with a current challenge of the identification and isolation of the dominant-flocculated-species. Herein, polytitanium chloride (PTC), enriched with dominant-flocculated-species, was successfully synthesized by electrodialysis through accurate micro-interface control of the reaction among Ti-hydrolyzed-species and OH^-. Special attention was paid to a feasible and high-effective strategy to isolate the dominant-flocculated-species from PTC through one-step rapid ultrafiltration. Selective preference was the ultrafiltration membranes (made of polyethersulfone) with a molecular weight cut-off of 5 kDa, which enabled the isolation of the dominant-flocculated-species, named PTC-5k. Results from the electrospray time-of-flight mass spectrometry (ESI-TOF-MS) proved a large proportion of the small and medium-sized hydrolyzed products as dominant-flocculated-species in PTC-5k, with the main signals concentrated between m/z 100 and 500. This composition achieved approximately 15.0% higher removal of organic matter with a 33.0% reduction in dosage compared to PTC. Unique snowflake-like branched structure of PTC-5k enhanced the coagulation mechanisms of sweeping and adsorption-bridging flocculation. Worth noting was the more compact flocs formed by PTC-5k than PTC, which was the probable reason for the mitigated fouling of ceramic membrane when PTC-5k was utilized as pre-treatment methodology. Continuous operation of ceramic membrane filtration up to 30 h, demonstrated 30% improvement in stable flux compared to PTC. This study provides the strategy for the isolation of Ti-dominant-flocculated-species, and lays the foundation for practical application.

Keywords: Coagulation; Dominant-flocculated-species; Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS); Polymerized titanium chloride; Ultrafiltration separation.