Molecularly Engineered Aza-Crown Ether Functionalized Sodium Alginate Aerogels for Highly Selective and Sustainable Cu2+ Removal

Long, Teng; El Idrissi, Ayoub; Fu, Lin; Liu, Yufan; Ruan, Banlian; Ma, Minghong; Li, Zhongxun; Lu, Lingbin

doi:10.3390/gels12010078

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Molecularly Engineered Aza-Crown Ether Functionalized Sodium Alginate Aerogels for Highly Selective and Sustainable Cu²⁺ Removal

by

Teng Long

^1,2,3

,

Ayoub El Idrissi

^1,2,3

,

Lin Fu

^1,2,3,

Yufan Liu

^1,2,3,

Banlian Ruan

^1,2,3,

Minghong Ma

^1,2,3,

Zhongxun Li

^1,2,3 and

Lingbin Lu

^1,2,3,*

¹

School of Materials Science and Engineering, Hainan University, Haikou 570228, China

²

State Key Laboratory of Tropic Ocean Engineering Materials and Materials Evaluation, Haikou 570228, China

³

Special Glass Key Lab of Hainan Province, Haikou 570228, China

^*

Author to whom correspondence should be addressed.

Gels 2026, 12(1), 78; https://doi.org/10.3390/gels12010078

Submission received: 1 December 2025 / Revised: 2 January 2026 / Accepted: 14 January 2026 / Published: 16 January 2026

(This article belongs to the Section Gel Processing and Engineering)

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Abstract

Developing sustainable and molecularly selective adsorbents for heavy-metal removal remains a critical challenge in water purification. Herein, we report a green molecular-engineering approach for fabricating aza-crown ether functionalized sodium alginate aerogels (ACSA) capable of highly selective Cu²⁺ capture. The aerogels were synthesized via saccharide-ring oxidation, Cu²⁺-templated self-assembly, and reductive amination, enabling the covalent integration of aza-crown ether motifs within a hierarchically porous biopolymer matrix. Structural analyses (FTIR, ¹³C NMR, XPS, SEM, TGA) confirmed the in situ formation of macrocyclic N/O coordination sites. Owing to their interconnected porosity and chemically stable framework, ACSA exhibited rapid sorption kinetics following a pseudo-second-order model (R² = 0.999) and a Langmuir maximum adsorption capacity of 150.82 mg·g⁻¹. The material displayed remarkable Cu²⁺ selectivity over Zn²⁺, Cd²⁺, and Ni²⁺, arising from the precise alignment between Cu²⁺ ionic radius (0.73 Å) and crown-cavity dimensions, synergistic N/O chelation, and Jahn-Teller stabilization. Over four regeneration cycles, ACSA retained more than 80% of its original adsorption capacity, confirming excellent durability and reusability. This saccharide-ring modification strategy eliminates crown-ether leaching and weak anchoring, offering a scalable and environmentally benign route to bio-based adsorbents that combine molecular recognition with structural stability for efficient Cu²⁺ remediation and beyond.

Keywords: sodium alginate; aza-crown ether; aerogel; copper removal; high selectivity

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MDPI and ACS Style

Long, T.; El Idrissi, A.; Fu, L.; Liu, Y.; Ruan, B.; Ma, M.; Li, Z.; Lu, L. Molecularly Engineered Aza-Crown Ether Functionalized Sodium Alginate Aerogels for Highly Selective and Sustainable Cu²⁺ Removal. Gels 2026, 12, 78. https://doi.org/10.3390/gels12010078

AMA Style

Long T, El Idrissi A, Fu L, Liu Y, Ruan B, Ma M, Li Z, Lu L. Molecularly Engineered Aza-Crown Ether Functionalized Sodium Alginate Aerogels for Highly Selective and Sustainable Cu²⁺ Removal. Gels. 2026; 12(1):78. https://doi.org/10.3390/gels12010078

Chicago/Turabian Style

Long, Teng, Ayoub El Idrissi, Lin Fu, Yufan Liu, Banlian Ruan, Minghong Ma, Zhongxun Li, and Lingbin Lu. 2026. "Molecularly Engineered Aza-Crown Ether Functionalized Sodium Alginate Aerogels for Highly Selective and Sustainable Cu²⁺ Removal" Gels 12, no. 1: 78. https://doi.org/10.3390/gels12010078

APA Style

Long, T., El Idrissi, A., Fu, L., Liu, Y., Ruan, B., Ma, M., Li, Z., & Lu, L. (2026). Molecularly Engineered Aza-Crown Ether Functionalized Sodium Alginate Aerogels for Highly Selective and Sustainable Cu²⁺ Removal. Gels, 12(1), 78. https://doi.org/10.3390/gels12010078

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Molecularly Engineered Aza-Crown Ether Functionalized Sodium Alginate Aerogels for Highly Selective and Sustainable Cu²⁺ Removal

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