Aqueous removal of diclofenac by plated elemental iron: Bimetallic systems

The aqueous removal of diclofenac (DF) by micrometric iron particles (Fe0) and amended Fe0 (Me0(Fe0)) under oxic and anoxic conditions was investigated. Bimetallic systems were obtained by plating the surface of Fe with Co, Cu, Ir, Ni, Pd and Sn. Experimental results confirmed the superiority of (Me0(Fe0)) for DF removal except for IrFe (oxic) and SnFe (anoxic). Under anoxic conditions, Pd was by far the most efficient plating element followed by Ir, Ni, Cu, Co and Sn. However, under oxic conditions, Pd and Cu showed almost the same efficiency in removing DF followed by Ni, Co, Sn and Ir. Oxidative and reductive DF transformation products were identified under oxic and anoxic conditions respectively. In some systems (e.g. CoFe and SnFe oxic/anoxic; PdFe oxic; NiFe anoxic), no transformation products could be detected. This was ascribed to the nature of the plating element and its impact on the process of the formation of metal corrosion products (MCPs). MCPs are known for their high potential to strongly adsorb, bond, sequestrate and enmesh both the original contaminant and its reaction products. Obtained results corroborate the universal validity of the view, that aqueous contaminants are basically removed by adsorption and co-precipitation.