Nano-TiO2 enhances the adsorption of Cd(II) on biological soil crusts under mildly acidic conditions

• Published in: Journal of contaminant hydrology 2020-02, Vol.229, p.103583, Article 103583
• Main Authors: Kuang, Xiaolin, Shao, Jihai, Peng, Liang, Song, Huijuan, Wei, Xiangdong, Luo, Si, Gu, Ji-dong
• Format: Article
• Language: English
• Subjects: Biological soil crusts; Heavy metals; Irrigation water; Nanoparticles; Zeta potential
• ISSN: 0169-7722; 1873-6009
• DOI: 10.1016/j.jconhyd.2019.103583

Biological soil crusts (BSCs), which are ubiquitous in paddy fields, are known to remove pollutants from paddy fields systems. The Nano-TiO2 enhanced the removal of Cd(II) by BSC under acidic irrigation water was found, and its mechanism was investigated. After the addition of nano-TiO2, the Cd(II) removal efficiency of BSCS increased by 26.70% than that of pure BSCs, and the Nano-TiO2 induced faster removal velocity as well. Zeta potential and potentiometric titration results revealed that BSCs generated more negative charges and sites concentration after addition of Nano-TiO2 at acidic environment. The carboxyl and amino/hydroxyl groups were the main functional groups on BSC and the BSC + TiO2. The higher concentration of amino/hydroxyl groups in BSC + TiO2 (0.33 ± 0.08 mmol/g) was present than that of pristine BSCs (0.62 ± 0.02 mmol/g), and they were with similar concentration of phosphate groups and carboxyl groups. This result was attributed to the Nano-TiO2 stimulated the BSCs to produce more extracellular polysaccharides and proteins. Our findings would provide novel strategy for the removal of cadmium from acidic irrigation water. [Display omitted] •Nano-TiO2 can promote the adsorption of Cd(II) on BSC at pH 4.•Cadmium was mainly the sorbed and non-EDTA-exchangeable fractions in the BSC.•The nano-TiO2 stimulates BSCs to produce extracellular polysaccharides and proteins.