First evidence of a photochemical process including an iron-aspartate complex and its use for paracetamol elimination from aqueous solution

Abstract

In this study, the photochemical properties of Fe(III)-Aspartate complex (Fe(III)-Asp) and its performance for the degradation of paracetamol (PC) in aqueous solution under UVA irradiation has been investigated. First, the Fe(III)-Aspartate complex was characterized using UV–vis absorption; the results confirmed that the complex was stable (Log β = 13.81), with molar ratio Fe(III) : Asp = 1:1. Upon irradiation, the Fe(III)-Asp complex undergoes photolysis leading to the formation of reactive oxygen species (ROS) such as HO. Moreover, this photochemical transformation is dependent on the irradiation wavelength and pH. The direct photolysis of paracetamol after 300 min under UVA irradiation showed a negligible effect, while 80 %, 59 %, and 15 % of paracetamol was eliminated in the presence of Fe(III)-Asp complex at pH = 2.05, 3.10, and 4.05; respectively. The degradation was investigated using various parameters such as initial pH, complex concentration, Fe(III):Asp molar ratio, and paracetamol concentration. The use of tert-butyl alcohol as a scavenger confirmed the participation of HO in paracetamol elimination. Addition of Zn (II) and Mn (II) to the system paracetamol-Fe(III)-Asp/UVA showed no significant effect on the degradation, however, Cu (II) had a slightly inhibiting effect. This study highlights the important role that organic iron complexes can play on the fate of pharmaceutical pollutants in aquatic environments.