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New Insight into GO, Cadmium(II), Phosphate Interaction and Its Role in GO Colloidal Behavior

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journal contribution
posted on 01.08.2016, 00:00 by Xuemei Ren, Qunyan Wu, Huan Xu, Dadong Shao, Xiaoli Tan, Weiqun Shi, Changlun Chen, Jiaxing Li, Zhifang Chai, Tasawar Hayat, Xiangke Wang
This study establishes the relationship between the graphene oxide (GO) colloidal behavior and the co-adsorption of Cd­(II) and phosphate (P­(V)) on GO. Results reveal that the interactions among GO, Cd­(II), and P­(V) exhibit a significant dependence on solution chemistry and addition sequences and that these interactions subsequently affect the GO colloidal behavior. The GO aggregation is pH-dependent at pH < 4.0 and depends apparently on the binding ability of Cd­(II) to GO at pH > 4.0. When the components were added simultaneously, the presence of P­(V) enhances the GO binding capacity toward Cd­(II), confirmed by theoretical calculation, resulting in the greater destabilizing influence of Cd­(II) + P­(V) on GO than Cd­(II) at pH 3.0–9.5, while the formation of Cd3(PO4)2 precipitate leads to a lower destabilizing influence of Cd­(II) + P­(V) on GO than Cd­(II) at pH > 9.5. Both pH and addition sequence affect the destabilizing ability of Cd­(II) + P­(V). These new insights are expected to provide valuable information not only for the application of GO as a potential adsorbent in multicomponent systems for heavy metal ion and oxyanion co-removal but also for the fate and risk assessment of GO after serving as heavy metal ion and oxyanion carrier.