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Sulfide and ferrous iron preferentially target specific surface O-functional groups of graphene oxide: implications for accumulation of contaminants
Environmental Science: Nano ( IF 5.8 ) Pub Date : 2019/12/19 , DOI: 10.1039/c9en01217f Fanfan Wang 1, 2, 3, 4, 5 , Xinlei Liu 5, 6, 7, 8, 9 , Xuguang Li 5, 6, 7, 8, 9 , Chuanjia Jiang 5, 6, 7, 8, 9 , Tong Zhang 5, 6, 7, 8, 9 , Wei Chen 5, 6, 7, 8, 9
Environmental Science: Nano ( IF 5.8 ) Pub Date : 2019/12/19 , DOI: 10.1039/c9en01217f Fanfan Wang 1, 2, 3, 4, 5 , Xinlei Liu 5, 6, 7, 8, 9 , Xuguang Li 5, 6, 7, 8, 9 , Chuanjia Jiang 5, 6, 7, 8, 9 , Tong Zhang 5, 6, 7, 8, 9 , Wei Chen 5, 6, 7, 8, 9
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Carbonaceous nanomaterials, such as graphene oxide (GO), are susceptible to environmental reduction that affects their fate and impact in aquatic environments. Here, we demonstrate that sulfide and ferrous iron, the most prevalent natural reductants, significantly alter the surface properties of GO, which can enhance the accumulation of both organic and inorganic contaminants on GO. Strikingly, these two reductants target different surface O-functional groups while diminishing the overall surface O-functionality of GO (i.e., C/O ratio) to a similar extent at a given reductant concentration. Hence, the two reductants have distinctly different effects on the adsorption of organics vs. heavy metals onto GO. At the same reductant concentration, iron and sulfide reduction increases the adsorption of naphthalene, 1,2,4,5-tetrachlorobenzene and 2,4-dichlorophenol comparably, as the adsorption of polar and nonpolar organic contaminants on GO is driven primarily by hydrophobic effects and π–π interactions, which correlate reasonably with the C/O ratio of GO. Interestingly, while iron reduction significantly promotes the adsorption of heavy metals, sulfide reduction has essentially no effect. Iron reduction apparently increases the abundance of GO carboxyl groups and consequently promotes the binding of mercury and lead via inner-sphere complexation. The increasing content of carbonyl groups induced by sulfide reduction may enhance metal adsorption on GO, but this effect is probably offset by the simultaneous decrease of carboxyl groups and decreasing negative charges of GO. This research highlights the importance of understanding the specific reduction pathway of carbonaceous nanomaterials when assessing their impact on the environmental behavior of metals.
中文翻译：
硫化物和二价铁优先靶向氧化石墨烯的特定表面O-官能团：对污染物积累的影响
碳纳米材料，例如氧化石墨烯（GO），容易受到环境的影响，这会影响其在水生环境中的命运和影响。在这里，我们证明硫化物和亚铁是最普遍的天然还原剂，它们显着改变了GO的表面性质，这可以增强GO上有机和无机污染物的积累。令人惊讶的是，这两种还原剂以不同的表面O-官能团为目标，同时在给定的还原剂浓度下将GO的整体表面O-官能度（即C / O比）降低到相似的程度。因此，两个还原剂对的有机物吸附明显不同的效果对比重金属进入GO。在相同的还原剂浓度下，铁和硫化物的还原可相比地增加萘，1,2,4,5-四氯苯和2,4-二氯苯酚的吸附，因为极性和非极性有机污染物在GO上的吸附主要是由疏水作用驱动和π-π相互作用，与GO的C / O比合理相关。有趣的是，虽然铁的还原显着促进了重金属的吸附，但硫化物的还原基本上没有作用。铁还原显然增加GO羧基的丰度，并因此促进汞和铅的结合通过内球络合。硫化物还原引起的羰基含量的增加可能会增强金属在GO上的吸附，但是这种效果可能被同时降低的羧基和降低GO的负电荷所抵消。这项研究强调了评估碳纳米材料对金属环境行为的影响时，了解碳纳米材料特定还原途径的重要性。
更新日期：2020-02-20
中文翻译：
硫化物和二价铁优先靶向氧化石墨烯的特定表面O-官能团：对污染物积累的影响
碳纳米材料，例如氧化石墨烯（GO），容易受到环境的影响，这会影响其在水生环境中的命运和影响。在这里，我们证明硫化物和亚铁是最普遍的天然还原剂，它们显着改变了GO的表面性质，这可以增强GO上有机和无机污染物的积累。令人惊讶的是，这两种还原剂以不同的表面O-官能团为目标，同时在给定的还原剂浓度下将GO的整体表面O-官能度（即C / O比）降低到相似的程度。因此，两个还原剂对的有机物吸附明显不同的效果对比重金属进入GO。在相同的还原剂浓度下，铁和硫化物的还原可相比地增加萘，1,2,4,5-四氯苯和2,4-二氯苯酚的吸附，因为极性和非极性有机污染物在GO上的吸附主要是由疏水作用驱动和π-π相互作用，与GO的C / O比合理相关。有趣的是，虽然铁的还原显着促进了重金属的吸附，但硫化物的还原基本上没有作用。铁还原显然增加GO羧基的丰度，并因此促进汞和铅的结合通过内球络合。硫化物还原引起的羰基含量的增加可能会增强金属在GO上的吸附，但是这种效果可能被同时降低的羧基和降低GO的负电荷所抵消。这项研究强调了评估碳纳米材料对金属环境行为的影响时，了解碳纳米材料特定还原途径的重要性。
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