部分还原氧化石墨烯强化异化Fe(III)还原菌降解丁基黄药的作用机理研究

Xanthate collecters are a class of toxic refractory flotation reagents, residual xanthate in the flotation wastewater has caused serious harm to the ecological environment and human health. Dissimilatory iron-reducing bacteria have great advantage of degradation of toxic refractory organic pollutant and remediation of heavy metal. There have been few studies focusing on the enhanced degradation of pollutants by dissimilatory iron-reducing bacteria with PrGO as redox mediator. The influence factors, dynamical process for degradation of butyl xanthate are discussed, and the abilities of tolerance and immobilization heavy metal, degradation of butyl xanthate by dissimilatory iron-reducing bacteria mediated by PrGO are illustrated. Furthermore, the change of activities of NADH dehydrogenase, cytochrome C reductase, cytochrome C oxidase and EPS content are investigated in order to reveal mechanism for enhanced degradation of butyl xanthate by dissimilatory iron-reducing bacteria mediated by PrGO. A new method for efficiently treating floatation wastewater containing xanthate is proposed, and the method can efficiently degrade xanthate collectors. What is more, dissimilatory iron-reducing bacteria can use a variety of heavy metal ions as electron acceptors, which can be use for immobilization and harmless treatment of heavy metal ions in floatation wastewater. The results will provide theory basis for biological treatment of flotation wastewater, which has important scientific significance and potential application value.

黄药类捕收剂是一类有毒难降解浮选药剂，残留在浮选废水中的黄药给生态环境和人类健康造成了严重的危害。异化Fe(III)还原菌在降解有毒难降解污染物和修复重金属污染方面有很大优势。目前很少有部分还原氧化石墨烯(PrGO)作为氧化还原介体强化异化Fe(III)还原菌降解污染物的研究报道。本项目研究PrGO强化异化Fe(III)还原菌降解丁基黄药的影响因素、动力学，明确其抗重金属、固化重金属能力和对丁基黄药降解能力；研究NADH脱氢酶、细胞色素C还原酶、细胞色素C氧化酶活性和EPS变化，揭示PrGO强化异化Fe(III)还原菌降解丁基黄药的作用机理。提出一种高效处理黄药浮选废水新方法，该法不仅能快速降解浮选废水中的黄药捕收剂，而且异化Fe(III)还原菌还能利用重金属离子作为电子受体来固定及无害化浮选废水中重金属离子。项目实施将为生物法处理浮选废水提供理论依据，具有重要的科学意义和潜在的应用价值。

残留在浮选废水中的黄药和重金属Cr(VI)给生态环境和人类健康造成了严重的危害。异化Fe(III)还原菌在降解有毒难降解污染物和修复重金属污染方面有很大优势。本项目从尾矿库底泥沉积物中分离出四株对丁基黄药具有高效降解能力和对铁具有较好还原能力的异化Fe(III)还原菌，并对其中一株铁还原能力最强的菌进行鉴定；采用一种环保的方法制备了氧化还原介体PrGO，揭示了制备条件对表面含氧基团和催化活性的影响；研究了PrGO强化异化Fe(III)还原菌降解丁基黄药的影响因素、动力学，揭示了其对丁基黄药的降解能力和抗重金属的能力；研究了异化Fe(III)还原菌同时降解浮选废水丁基黄药和还原固定重金属Cr(VI) 的能力。研究结果表明：PrGO可以显著提高异化Fe(III)还原菌降解丁基黄药的生物降解速率（降解速率常数是不加PrGO的3.5倍）。异化Fe(III)还原菌不仅可以高效降解浮选废水中的丁基黄药，而且还具有较好抗重金属、还原固定Cr(VI)的能力，Cr(Ⅵ)主要是以Cr2O3和Cr(OH)3沉淀从溶液中分离。最后揭示了PrGO作为氧化还原介体加速电子传递的机理和丁基黄药的降解机理：即PrGO作为氧化还原介体是通过电子传递链上的细胞色素C还原酶、NADH脱氢酶和EPS的响应，以及PrGO表面上的醌基和羟基的循环转换加速电子从异化Fe(III)还原菌到Fe(III)的传递速率，从而提高氧化还原速率。通过分析丁基黄药降解过程中的产物，推测出丁基黄药两种可能的降解机理。本项目提出的方法可以同时高效、快速去除浮选废水中的丁基黄药和重金属Cr(VI)复合污染。本项目的实施为生物法处理浮选废水提供了一种新思路，具有重要的环境效益和良好的应用前景。