微生物溶解载铀赤铁矿及再固定铀的试验研究

将载铀赤铁矿、核黄素(RF)和Sphingomonas sanxanigenens(S. sanxanigenens)同时投加到培养基中,监测培养过程中溶液的总铁、亚铁以及U(VI)浓度的变化,表征载铀赤铁矿还原性溶解前后固相产物中铁和铀的化学形态与价态,分析温度、共存离子对RF介导S. sanxanigenens还原性溶解载铀赤铁矿及再固定铀的影响.结果表明:S. sanxanigenens能够还原性溶解载铀赤铁矿,从而导致铀的释放;RF能够促进S. sanxanigenens还原性溶解载铀赤铁矿,且RF浓度越高越有利于这种还原性溶解;在30℃下RF能显著促进载铀赤铁矿的还原性溶解,且产物中稳定态铀的比例较高;添加2mmol/L Ca²⁺或CO₃^2-对RF介导S. sanxanigenens还原性溶解载铀赤铁矿具有促进作用;添加2mmol/L PO₄^3-能提高残渣态铀的比例,促进铀的固定;RF能够促进S. sanxanigenens对Fe(III)和U(VI)的还原,且反应过程伴随着次生铁矿物的生成.这些研究结果为提出RF介导S. sanxanigenens释放及再固定铀的新方法奠定了基础.

Dissolution of the U(VI)-laden hematite and reimmobilization of uranium by microorganism mediated by riboflavin

U(VI)-laden hematite, riboflavin (RF) and Sphingomonas sanxanigenens (S. sanxanigenens) were simultaneously added to the medium, variations of total Fe, Fe(II) and U(VI) concentrations were monitored during the process of culture, the chemical forms of iron and uranium in solid phase products were analyzed before and after reductive dissolution, and the effect of temperature and coexisted ion on the reductive dissolution of the U(VI)-laden hematite by S. sanxanigenens mediated by riboflavin was analyzed. The results showed that S. sanxanigenens could reductively dissolve U(VI)-laden hematite, leading to release of uranium; the riboflavin could promote the reductive dissolution of U(VI)-loaden hematite by S. sanxanigenens, and the higher concentration of riboflavin is more favorable for this reductive dissolution; the riboflavin could significantly promote the reductive dissolution of U(VI)-loaden hematite and increase the proportion of the stable species of uranium at 30℃; 2mmol/L Ca²⁺ or CO₃^2- had a significant facilitation effect on the reductive dissolution of U(VI)-laden hematite by S. sanxanigenens mediated by riboflavin; 2mmol/L PO₄^3- increased the proportion of uranium species in residual fractions, promting the fixation of uranium; and riboflavin could promote the reduction of Fe(III) and U(VI) by S. sanxanigenens, and the reaction process was accompanied by the formation of the secondary iron minerals. These results laid the foundation for a new method of riboflavin-mediated S. sanxanigenens release and re-fixation of uranium.