Boosting the phosphorus uptake of La2(CO3)3·8H2O based adsorbents via sodium addition: Relationship between crystal structure and adsorption capacity

Excess phosphate contents in water bodies triggers eutrophication, which posts significant challenges to the aquatic ecosystem. Lanthanum-carbonate based adsorbents exhibit excellent phosphate binding properties for remediating eutrophication. However, they suffer from significant adsorption-capacit...

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Bibliographic Details
Published in:Progress in solid state chemistry 2024-12, Vol.76, p.100496, Article 100496
Main Authors: Wang, Zuo-Bei, Ye, Xin, Yang, Jie, Zhang, Yong-Hui, Nan, Zi-Ang, Wang, Yi-Fan, Huang, You-Gui, Wang, Wei
Format: Article
Language:English
Subjects:
Alkaline environments
Lanthanum carbonate
Molecular structure
Phosphate adsorption
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Summary:Excess phosphate contents in water bodies triggers eutrophication, which posts significant challenges to the aquatic ecosystem. Lanthanum-carbonate based adsorbents exhibit excellent phosphate binding properties for remediating eutrophication. However, they suffer from significant adsorption-capacity loss (>85 %) at high pH. Little has been done on understanding this behavior for improving the phosphorus adsorption of lanthanum-carbonate adsorbents in alkaline environments (e.g. eutrophic water bodies). Here, we discover that La2(CO3)3·8H2O, when produced by a conversion reaction from NaLa(CO3)2·xH2O, exhibits high phosphate adsorption capacity in a wide pH window. Under alkaline conditions (e.g. pH = 10), its adsorption capacity decreases by only 8 % compared to the value under neutral pH. By isolating three different lanthanum-carbonate based compounds and analyzing their molecular structures, we find that the trace amount of Na+ residual in our La2(CO3)3·8H2O alters the chemical environment surrounding the La3+ ions, which may significantly boost the phosphate uptake at high pH. Our results provide molecular insights for further tuning the material structure of phosphate adsorbents to achieve robust performances. Less than 1 wt% of Na+ in the structure of La2(CO3)3·8H2O greatly improves the phosphate adsorption at high pH. A molecular mechanism is proposed, attributing the enhancement to the change of connection modes between the CO32− and La3+, induced by Na+. [Display omitted]
ISSN:0079-6786
DOI:10.1016/j.progsolidstchem.2024.100496