Mechanism of cadmium removal from soil by silicate composite biochar and its recycling

Biochar added to the soil is generally difficult to separate. In order to solve the problem of separating biochar from soil, this paper applies a hydraulic silicate gel material to the preparation of biochar. Non-magnetic silicate bonded biochar (SBC) and magnetic silicate bonded biochar (MSBC) with hydraulic properties were prepared. The new silicate bonded biochar has good adsorption performance, separation and recovery characteristics. The findings are as follows: (1) after three times of soil remediation, the silicate bonded biochar still had good mechanical properties, and the compressive strength was not attenuated, remaining between 210 and 270 N. (2) After three times of SBC and MSBC remediation, total Cd in soil decreased by 29.33% and 31.82% respectively, and available Cd decreased by 60.82% and 62.74% respectively. (3) After three cycles, the recovery rates of SBC and MSBC both exceeded 94.88%, and the highest adsorption regeneration rates of SBC and MSBC reached 83.09% and 92.06%, respectively. (4) The Cd content of wheat after SBC and MSBC repair was reduced by 29.67-37.36% and 47.25-63.74%, respectively.

Automated summary

The study successfully prepared a new type of silicate bonded biochar with good adsorption performance and separation and recovery characteristics by applying silicate gel materials to the preparation of biochar. The silicate bonded biochar maintained good mechanical properties after three rounds of soil remediation, with compressive strength remaining between 210 and 270 N. The total Cd and available Cd in the soil were significantly reduced, and both SBC and MSBC showed high rates of reuse and adsorption regeneration, effectively decreasing Cd content in wheat.