Removal of calcium ions from water by selective electrosorption using target-ion specific nanocomposite electrode

Jun Kim; Amit Jain; Kuichang Zuo; Rafael Verduzco; Shane Walker; Menachem Elimelech; Zhenghua Zhang; Xihui Zhang; Qilin Li

doi:10.1016/j.watres.2019.05.016

Removal of calcium ions from water by selective electrosorption using target-ion specific nanocomposite electrode

Water Res. 2019 Sep 1:160:445-453. doi: 10.1016/j.watres.2019.05.016. Epub 2019 May 6.

Authors

Jun Kim¹, Amit Jain², Kuichang Zuo¹, Rafael Verduzco², Shane Walker³, Menachem Elimelech⁴, Zhenghua Zhang⁵, Xihui Zhang⁵, Qilin Li⁶

Affiliations

¹ Department of Civil and Environmental Engineering, Rice University, 6100 Main Street MS 519, Houston, TX, 77005, USA; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, 6100 Main Street MS 6398, Houston, TX, 77005, USA.
² Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, 6100 Main Street MS 6398, Houston, TX, 77005, USA; Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS 362, Houston, TX, 77005, USA.
³ Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, 6100 Main Street MS 6398, Houston, TX, 77005, USA; Department of Civil Engineering, The University of Texas at El Paso, El Paso, TX, 79968, USA.
⁴ Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, 6100 Main Street MS 6398, Houston, TX, 77005, USA; Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, 06520, USA.
⁵ Graduate School of Shenzhen, Tsinghua University, Tsinghua Campus, The University Town, Shenzhen, 518055, PR China.
⁶ Department of Civil and Environmental Engineering, Rice University, 6100 Main Street MS 519, Houston, TX, 77005, USA; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, 6100 Main Street MS 6398, Houston, TX, 77005, USA; Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS 362, Houston, TX, 77005, USA. Electronic address: qilin.li@rice.edu.

PMID: 31174072
DOI: 10.1016/j.watres.2019.05.016

Abstract

Technologies capable of selective removal of target contaminants from water are highly desirable to achieve "fit-for-purpose" treatment. In this study, we developed a simple yet highly effective method to achieve calcium-selective removal in an electrosorption process by coating the cathode with a calcium-selective nanocomposite (CSN) layer using an aqueous phase process. The CSN coating consisted of nano-sized calcium chelating resins with aminophosphonic groups in a sulfonated polyvinyl alcohol hydrogel matrix, which accomplished a Ca²⁺-over-Na⁺ selectivity of 3.5-5.4 at Na⁺:Ca²⁺ equivalent concentration ratio from 10:1 to 1:1, 94 - 184% greater than the uncoated electrode. The CSN coated electrode exhibited complete reversibility in repeated operation. Mechanistic studies suggested that the CSN coating did not contribute to the adsorption capacity, but rather allowed preferential permeation of Ca²⁺ and hence increased Ca²⁺ adsorption on the carbon cathode. The CSN-coated electrode was very stable, showing reproducible performance in 60 repeated cycles.

Keywords: Calcium-selective removal; Capacitive deionization; Desalination; Electrosorption; Nanocomposite coating.

MeSH terms

Adsorption
Calcium
Electrodes
Ions
Nanocomposites*
Water
Water Purification*

Substances

Ions
Water
Calcium