Sulfo-group intercalated-layered double hydroxide array grown on carbon cloth membrane for selective adsorption of phosphate from contaminated water

• Published in: Separation and purification technology 2025-07, Vol.360, p.131076, Article 131076
• Main Authors: Zou, Yan, Tong, Qiuwen, Cheng, Peng, Chen, Haoyu, He, Yu, Jiao, Zhaojie, Ao, Liang, Fu, Wenyang, Lv, Xiaoshu, Jiang, Guangming
• Format: Article
• Language: English
• Subjects: Adsorbent recovery; Intercalated layered double hydroxide; Phosphate removal; Selective adsorption
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.131076

[Display omitted] •NiAl-LDH-CC features sulfo-group intercalated NiAl-LDH arrays grown on carbon cloth.•NiAl-LDH-CC affords highly selective adsorption of P in presence of competing anions.•The selective adsorption of P by NiAl-LDH relies on hydrogen bonding with sulfo group.•Adsorbent residue in water is never an issue for NiAl-LDH-CC.•NiAl-LDH-CC is used for P removal from natural water as a membrane module. Layered double hydroxides (LDHs) are recognized for their potential in phosphate (P) adsorption from water, generally achieved through ionic exchange between P and the anions intercalated in LDHs. Nevertheless, their broad applications are challenged by low P selectivity owing to competitive adsorption of other anions (e.g., SO42-, CO32–, NO3–, Cl-) and the difficulty in collecting LDH powders after use. Herein, we developed a facile approach for in-situ growth of p-toluenesulfonic acid-intercalated NiAl-LDH arrays on carbon cloth (NiAl-LDH-CC), forming an integrated membrane for P adsorption. It afforded an adsorption capacity of 75.42 mg gLDH-1 and demonstrated minimal drop in removal efficiency of P (∼3%) even in the presence of competing anions. It was regenerable in 1.0 M NaOH solution, retaining 91.9 % of its initial adsorption capacity after multiple regeneration cycles. More intriguingly, the growth of NiAl-LDH on carbon cloth facilitated their collection after use, addressing the issues of adsorbent residue in water. Mechanistic studies suggested that the enhanced selectivity for P was result from a shift in the adsorption mode from traditional ionic exchange to binding via hydrogen bonding between P and the sulfo-group of p-toluenesulfonic acid. The NiAl-LDH-CC was finally employed for adsorptive removal of P from the natural water samples in a continuous-flow mode. It could reduce the P concentration from feeding 1.00 mg/L to