Exceptional adsorption properties of amino-carboxylic acid chelating fibers for calcium, magnesium, and strontium ions

• Published in: Desalination and water treatment Vol. 312; pp. 158 - 165
• Main Authors: Liu, Da-Xin, Xu, Gang, Chen, Zhao-Wen, Wang, Li, Wu, Ming-Hong
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-11-2023
• Subjects: Amino carboxylic acid fibers; Calcium; Chelation; Magnesium; Rapid adsorption; Strontium; Strontium; Chelation; Magnesium; Calcium; Rapid adsorption; Amino carboxylic acid fibers
• ISSN: 1944-3986
• DOI: 10.5004/dwt.2023.29939

In the chlor-alkali industry, the thorough purification of calcium (Ca2+), magnesium (Mg2+), and strontium ions (Sr2+) presents a considerable challenge. In this context, we developed novel amino carboxylic acid fibers in this study by using laboratory-synthesized polyacrylonitrile–polyethyleneimine amino fibers as the matrix. The amino carboxylation process was achieved by introducing chloroacetic acid under mild alkaline and heating conditions, resulting in the desired amino carboxylic acid fibers (PAN-C-Na). Adsorption experiments demonstrated that the PAN-C-Na fibers reached adsorption equilibrium within 30 s. Additionally, they effectively adsorbed Ca2+ and Mg2+ ions at ultralow concentrations (<0.02 mg/L), exhibiting outstanding adsorption capacities of 0.40 and 0.36 mmol/g, respectively, and exceeding 50% of their saturation adsorption capacities. Moreover, compared to amino-phosphonic acid fibers, which are another type of calcium–magnesium adsorptive fibers, the PAN-C-Na fibers exhibited twice the selectivity for Sr2+ adsorption and proved effective in eliminating residual Sr2+ in brine. These findings highlight the potential of PAN-C-Na fibers as a promising material for the thorough purification of Ca2+, Mg2+, and Sr2+ ions in the chlor-alkali industry.