| Summary: | The present study aimed at the GO synthesis by a modified Hummers method; and to evaluate the GO's efficiency for heavy metals adsorption in a real surface water sample, collected after a tailing dam rupture in the state of Minas Gerais Brazil. Furthermore, the acute and chronic risks by using a Hazard Quotient (HQ) method was used in order to assess the environmental impact related to raw surface water, and its reduction after GO treatment. The characterization techniques demonstrated that GO had a few-layers (~8 sheets) with micrometric dimensions containing some submicron sized sheets. Furthermore, the BET revealed that the GO had a considerable specific surface area, which favored the adsorption processes. Total dissolved solids and pH met the criteria established by national standards, even after the tailing dam rupture. Conversely, all heavy metal ions presented concentration values greater than recommended. In terms of removal efficiency, higher values were obtained for copper, manganese and aluminum, which were higher than 90.2%. Due to its high concentration in untreated surface water, iron poses a high risk (39.1 mg/L; HQ > 1) in cases of chronical consumption of the contaminated water. After adsorption process, the hazard index value was lower than one, which suggests that population is unlikely to experience adverse health effects. The results reinforce the GO applicability in surface water treatment, even in real and complex aqueous solutions as considered throughout this study.
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