Mechanisms of nC60 removal by the alum coagulation-flocculation-sedimentation process

This study explored the mechanisms for nC(60) removal in pure water and filtered saline wastewater by the alum coagulation-flocculation-sedimentation process through analyzing the hydrolyzed aluminum species and exploring the complexation of nC(60) with aluminum hydroxide precipitates. Sweep flocculation (enmeshment and adsorption) with Al-c is the most dominant mechanism contributing to the nC(60) removal in pure water. In filtered saline wastewater, hetero-precipitation of Al-b with nC(60), colloids, and dissolved solids also contributes to the nC(60) removal. Alkalinity affected the nC(60) removal by changing the hydrolyzed aluminum species distributions. XPS, FTIR, and SEM evidences suggest that the enmeshment and adsorption of nC(60) onto the aluminum hydroxide precipitates can be described as the inner-sphere complexation. Based on the above observations, conceptual models for nC(60) removal by the alum coagulation-flocculation-sedimentation process in the different water matrices are proposed. (C) 2013 Elsevier Inc. All rights reserved.