Enhanced Cd(II) biomineralization induced by microalgae after cultivating modification in high-phosphorus culture

• DOI: 10.1016/j.jhazmat.2022.130243
• Publication Date: 2022-10-22T02:54:55Z
• Authors: Ling Xia; Jiaqi Tan; Rong Huang; Zijia Zhang; Keqiang Zhou; Yaxi Hu; Shaoxian Song; Lei Xu; María Eugenia Farías; Rosa María Torres...
• Keywords: Chlorella sorokiniana

In this study, high-phosphorus beared microalgae was prepared by cultivating modification in high-phosphorus culture, and used for the enhanced Cd(II) biomineralization in soil. Batch experiment results showed that Chlorella sorokiniana FK was modified successfully in highly phosphate culture. Both intracellular P (Poly-P, 29.7 mg/kg) and surface P (phosphoryl based functional groups, 3.7 mol/kg) were greatly enhanced, and the Cd(II) removal capacity surged to 45.98 mg/g at equilibrium in the Langmuir simulation. The EXAFS analysis indicated that Cd tended to form a more stable bidentate complex (RPO4)2Cd when bounding with phosphate groups on the surface of the high-phosphorus microalgae. Moreover, high-phosphorus beared microalgae not only had higher immobilization amount of Cd(II), but also promoted immobilized Cd from adsorbed state to mineralized state. After high-phosphate cultured, increased density of P-related groups provided more adsorption sites, while the decomposition of intracellular Poly-P released phosphate ions into cell surface microenvironment, which combined and promoted the formation of Cd3(PO4)2/Cd(H2PO4)2 on cell surface. Cd-contaminated soil remediation experiments applying high-surface-phosphate beared microalgae further showed that more Cd stabilized as a residue fraction within 49 days. This study proposes that the high-phosphate culture strategy is a good way to improve the immobilization of heavy metals in soil induced by microorganisms.