Aiming to expand the utilization of porous silicate minerals in the remediation of heavy metal contaminated soil,the mesoporous material SBA-15 was successfully synthesized by using sodium silicate as silica source in this study.And the obtained SBA-15 samples were characterized by TEM,X-ray diffraction,N2 adsorption-desorption and FTIR.Furthermore,characterization of Cd (Ⅱ) adsorption and sealing performance onto SBA-15 were evaluated through batch experiment,and the remediation potential of Cd (Ⅱ) contaminated soil was investigated by brassica planting in a pot experiment.The results showed that SBA-15 had the mesoporous structure with surface area of 507.3 m2·g-1 and pore size of 7.38 nm.The maximum Cd (Ⅱ) adsorption capacity was 76.43 mg·g-1 at pH above 7.0 with the adsorption isotherm fitting the Langmuir model in the solution of 100 mg·L-1 Cd (Ⅱ).The increase in ionic strength reduced the Cd (Ⅱ) adsorption capacity.The Cd (Ⅱ) loaded SBA-15 could be regenerated with 0.1 mol·L-1 HNO3,while Cd (Ⅱ) could be strongly sealed in the pore structure after introduction of sodium silicate into the system.The pot experiment proved that the addition of SBA-15(4.5 g·kg-1) into Cd-contaminated soil could reduce Cd (Ⅱ) availability,enhance the transformation of soluble and exchangeable Cd (Ⅱ) fractions into carbonate and Fe-Mn oxides bounded forms,inhibit the Cd (Ⅱ) accumulation in the plant tissue and improve the brassica growth.Based on these results,it can be concluded that combination of the SBA-15 particle with sodium silicate has great potential to remediate Cd (Ⅱ) contaminated soil through adsorption and sealing properties.
Keywords: Cd(Ⅱ); SBA-15; XRD; adsorption and sealing; contaminated soil.