Lanthanum hydroxide: a highly efficient and selective adsorbent for arsenate removal from aqueous solution
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RESEARCH ARTICLE
Lanthanum hydroxide: a highly efficient and selective adsorbent for arsenate removal from aqueous solution Yulong Wang 1,2,3 & Yanhong Liu 4 & Tianqi Guo 1 & Hupeng Liu 1 & Jiale Li 1 & Shaofeng Wang 2 & Xuhui Li 1,3 & Xin Wang 2 & Yongfeng Jia 2 Received: 17 April 2020 / Accepted: 20 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In the present work, a lanthanum hydroxide adsorbent was prepared by a simple precipitation process, and its arsenic removal performances and adsorption mechanisms were investigated by batch experiments and various techniques including field emission scanning electron microscopy with energy-dispersive X-ray spectrophotometry (FESEM–EDX), Brunauer–Emmett–Teller (BET) analysis, powder X-ray diffraction (p-XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The influence of pH on arsenic removal showed that the lanthanum hydroxide adsorbent can effectively remove As(V) from solution, whereas the As(III) removal was very low, indicating that the lanthanum hydroxide adsorbent can selectively remove As(V) but not As(III). The isotherm study showed that the maximum adsorption capacities of As(V) at pH 5.0 and 9.0 were 299.4 and 192.3 mg/g, respectively, much higher than those of the widely used ferrihydrite. Significant interference on As(V) removal was caused by the presence of phosphate and natural organic acids (NOAs), such as citric acid. Powder XRD, FTIR, and XPS analysis showed that the lanthanum hydroxide was almost transformed into lanthanum arsenate after As(V) adsorption at pH 4.0, while a portion of lanthanum hydroxide remained after As(V) adsorption at pH 6.0 and 9.0. Furthermore, ligand exchange between the hydroxyl groups of the adsorbent and As(V) and the formation of inner-sphere surface complexes could play a central role in arsenic removal which needs further investigation. Keywords Arsenic . Arsenate . Removal . Lanthanum hydroxide . Selectivity
Highlights • As(V) can be selectively removed by the adsorbent. • As(V) adsorption capacity at pH 5.0 reached 299.4 mg/g. • The presence of phosphate and citric acid greatly retards As(V) removal. • Most lanthanum hydroxide was converted to lanthanum arsenate after As(V) adsorption. Responsible editor: Tito Roberto Cadaval Jr Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-10240-1) contains supplementary material, which is available to authorized users. * Yulong Wang [email protected] * Shaofeng Wang [email protected] * Xuhui Li [email protected] Yanhong Liu [email protected] Tianqi Guo [email protected]
Hupeng Liu [email protected] Jiale Li [email protected] Xin Wang [email protected] Yongfeng Jia [email protected] Extended author information available on the last page of the article
Environ Sci Pollut Res
Introduction Arsenic (As) contamination in natural environment has posed a considerable risk to humans worldwide due to its high toxicity and carcinogen
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