溶磷微生物改性生物炭吸附重金属的机理研究

利用磷溶菌（PSB）对稻壳（RB）和污泥（SB）生物炭进行不同时间的改性，研究了其对水体中Pb²⁺和Cd²⁺（1000mg/L）的修复机制.主要通过测定改性生物炭的理化特性和重金属含量，并利用结构方程模型研究了微生物改性生物炭对重金属的吸附机理.结果表明，PSB显著改善生物炭的孔径结构、比表面积BET （增加了12.5%~175.0%）和表面官能团.特别是还增加了生物炭中C和P元素的释放，促进了生物炭表面的生物矿化机制.PSB改性显著提高了生物炭对Pb²⁺和Cd²⁺的吸附作用（RB提高：Pb²⁺=9.5%~34.5%，Cd²⁺=34.7%~219.9%，SB提高：Pb²⁺=65.3%~101.3%，Cd²⁺=106.6%~248.6%）.通过Pb和Cd的修复差异，发现不同重金属对微生物的胁迫是导致改性生物炭对重金属的修复反应路径相反的原因.此外，结构方程模型证实6~12h的PSB改性效果最好，且BET不是主要影响因素.不同的生物质炭改性后的修复机制也存在明显差异，孔径结构（R_max²=0.99）是改性RB的主要吸附途径，化学沉淀（R_max²=0.99）是改性SB的主要吸附途径.

Adsorption mechanism of heavy metals by phosphate-solubilizing microorganism modified biochar.

Rice husk (RB) and sludge (SB) biochars were modified by phosphorus-solubilizing bacteria (PSB) with different times. The materials were added to 1000mg/L Pb²⁺ and Cd²⁺ aqueous solution. The physicochemical properties and heavy metal content of the modified biochar were measured. Structural equation model was then applied to study the adsorption mechanism of heavy metals by modified biochar. Microbial modification significantly improved the pore size, specific surface area (BET) (12.5%~175.0%), and functional groups of biochar. In particular, the release of C and P from the biochars was significantly increased, which promoted the mineralization of heavy metals on the biochars. The adsorption of Pb²⁺ and Cd²⁺ by the two biochars was evidently improved after modification of PSB (RB increased:Pb²⁺=9.5%~34.5% and Cd²⁺=34.7%~219.9%, SB increased:Pb²⁺=65.3%~101.3% and Cd²⁺=106.6%~248.6%). In addition, the different stress of Pb and Cd lead to the distinct reaction pathway of heavy metal adsorption on the modified biochar. Moreover, the structural equation model results showed that 6~12h incubation had the best effect on PSB modifications. Meanwhile, the BET surface area was not the primary factor. Furthermore, there is also evident contrast regarding the mechanism of remediation by the different biochars. Therefore, this study proposes that the pore structure (R_max²=0.99) was the main adsorption pathway of modified RB, while chemical precipitation (R_max²=0.99) was the main adsorption pathway after modified SB.