Thermodynamics, Kinetics, and Mechanisms of the Co-Removal of Arsenate and Arsenite by Sepiolite-Supported Nanoscale Zero-Valent Iron in Aqueous Solution

Meihaguli Ainiwaer; Xibai Zeng; Xianqiang Yin; Jiong Wen; Shiming Su; Yanan Wang; Yang Zhang; Tuo Zhang; Nan Zhang

doi:10.3390/ijerph191811401

Thermodynamics, Kinetics, and Mechanisms of the Co-Removal of Arsenate and Arsenite by Sepiolite-Supported Nanoscale Zero-Valent Iron in Aqueous Solution

Int J Environ Res Public Health. 2022 Sep 10;19(18):11401. doi: 10.3390/ijerph191811401.

Authors

Meihaguli Ainiwaer^{1

2}, Xibai Zeng^{1

2}, Xianqiang Yin², Jiong Wen³, Shiming Su¹, Yanan Wang¹, Yang Zhang¹, Tuo Zhang^{1

4}, Nan Zhang¹

Affiliations

¹ Key Laboratory of Agro-Environment, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agriculture Sciences, Ministry of Agriculture and Rural Affairs, Beijing 100081, China.
² College of Natural Resources and Environment, Northwest A&F University, Yangling, Xianyang 712100, China.
³ Scientific Observation and Experiment Station of Yueyang, Ministry of Agriculture, Yueyang Agricultural Research Academy, Yueyang 414021, China.
⁴ College of Environmental Science & Engineering, China West Normal University, Nanchong 637009, China.

Abstract

In this study, a newly synthesized sepiolite-supported nanoscale zero-valent iron (S-nZVI) adsorbent was tested for the efficient removal of As(III) and As(V) in aqueous solution. Compared with ZVI nanoparticles, the As(III) and As(V) adsorption abilities of S-nZVI were substantially enhanced to 165.86 mg/g and 95.76 mg/g, respectively, owing to the good dispersion of nZVI on sepiolite. The results showed that the adsorption kinetics were well fitted with the pseudo-second-order model, and the adsorption isotherms were fitted with the Freundlich model, denoting a multilayer chemical adsorption process. The increase in the initial solution pH of the solution inhibited As(III) and As(V) adsorption, but a weaker influence on As(III) than As(V) adsorption was observed with increasing pH. Additionally, the presence of SO₄^2- and NO₃^- ions had no pronounced effect on As(III) and As(V) removal, while PO₄^3- and humic acid (HA) significantly restrained the As(III) and As(V) adsorption ability, and Mg²⁺/Ca²⁺ promoted the As(V) adsorption efficiency. Spectral analysis showed that As(III) and As(V) formed inner-sphere complexes on S-nZVI. As(III) oxidation and As(V) reduction occurred with the adsorption process on S-nZVI. Overall, the study demonstrated a potential adsorbent, S-nZVI, for the efficient removal of As(III) and As(V) from contaminated water.

Keywords: adsorption; arsenate; arsenite; nZVI; sepiolite.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adsorption
Arsenates
Arsenites*
Humic Substances / analysis
Iron / chemistry
Kinetics
Magnesium Silicates
Thermodynamics
Water
Water Pollutants, Chemical* / analysis

Substances

Arsenates
Arsenites
Humic Substances
Magnesium Silicates
Water Pollutants, Chemical
Water
magnesium trisilicate
Iron
arsenite
arsenic acid

Grants and funding

This work was financially supported by the National Natural Science Foundation of China (NSFC) (Project No. U19A2048), the Natural Science Foundation of Sichuan Province (NSFSC) (Project No. 2022NSFSC1059), the Agricultural Science and Technology Innovation Program (ASTIP) and the Central Public-interest Scientific Institution Basal Research Fund (Project No. BSRF202213).