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Green Valorization of Seawater via Homogeneous Nucleation Electrochemistry: Synthesis of Nano-CaCO3 and Mg(OH)2 Adsorbents for Heavy Metal Removal

  • Yuchen Zhao 1,   
  • Wenda Kang 1, 2, *,   
  • Shuixiang Xie 3, 4,   
  • Yidong Ruan 1,   
  • Xiang Zhou 1,   
  • Weilong Wang 1,   
  • Yongqian Zhang 5,   
  • Hongtao Yu 1,   
  • Gong Zhang 2

Received: 18 Oct 2025 | Revised: 07 Nov 2025 | Accepted: 14 Nov 2025 | Published: 21 Nov 2025

Abstract

Rapid industrialization posed a serious threat to water safety due to heavy metal pollution, creating an urgent need for a green and efficient remediation solution. This research, leveraging electrocatalytic technology, innovatively proposes an electrochemical homogeneous nucleation strategy for the selective recovery of Ca2+ and Mg2+ from seawater. Through employing pH-controlled sequential precipitation, this strategy enables the synthesis of nano-CaCO3 (BET surface area: 50.4 m2/g) and nano-Mg(OH)2 (109.8 m2/g), which serve as high-performance adsorbents for efficient heavy metal removal. Both adsorbents demonstrated adsorption behaviors well-fitted to the Langmuir model, exhibiting exceptional maximum adsorption capacities for Cu(II) (838.2–1331.0 mg/g), Pb(II) (2180.5–3696.8 mg/g), Cd(II) (1065.3–1997.4 mg/g), and Cr(III) (424.1–637.5 mg/g). When configured as fixed-bed columns, the adsorbents reduced effluent concentrations of Cu(II), Pb(II), Cd(II), and Cr(III) to below 0.7 μg/L, meeting World Health Organization drinking water standards. Life cycle assessment revealed the electrochemical strategy reduced carbon emissions by 50–80% compared to conventional methods, achieving net-negative emissions (−10.428 kg CO2eq per ton of water) when incorporating resource recovery benefits. This approach represents a synergistic solution for both resource utilization and environmental remediation, demonstrating significant potential for sustainable water treatment and circular economy development.

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Supplementary Materials
DOI
10.53941/echem.2025.100005
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Volume 1, Issue 1
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Zhao, Y.; Kang, W.; Xie, S.; Ruan, Y.; Zhou, X.; Wang, W.; Zhang, Y.; Yu, H.; Zhang, G. Green Valorization of Seawater via Homogeneous Nucleation Electrochemistry: Synthesis of Nano-CaCO3 and Mg(OH)2 Adsorbents for Heavy Metal Removal. eChem 2025, 1 (1), 5. https://doi.org/10.53941/echem.2025.100005.
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