Montmorillonite-mediated electron distribution of zirconium phosphate for accelerating remediation of cadmium-contaminated water and soil

Rapid and efficient remediation of heavy metal-contaminated water and soil bodies has been a hot topic in ecological remediation. However, designing and synthesizing green remediation materials with fast kinetics and high adsorption capacity is still challenging. In this study, a novel heavy metal remediation material (Mt@ZrP) has been prepared using montmorillonite to induce the structural rearrangement of zirconium phosphate (ZrP). The results showed that montmorillonite could mediate the external electron distribution of ZrP, thus increasing its O 1 s binding energy. Distinct from the electrostatic adsorption of bare ZrP, Mt.@ZrP with higher orbital binding energy led to an extra adsorption mode with internal spherical coordination. Such characteristics dramatically shortened the adsorption equilibrium time (23 min) and enhanced the adsorption capacity (275.6 mg/g-ZrP) of Mt.@ZrP for Cd removal in comparison to those of bare ZrP (220 min, 196.1 mg/g-ZrP). As for soil remediation, Mt.@ZrP presented a faster Cd removal rate than bare ZrP. The residual fraction increased from 22.03% (control) to 28.47% (Mt@ZrP, 1 wt%) and 37.54% (Mt@ZrP, 3 wt%), which significantly decreased the biological efficacy of Cd in the soil. These findings could provide a novel strategy for the design and synthesis of excellent remediation materials for the rapid and efficient removal of heavy metals in water and soil.