Role of ferric and ferrous ions in the enhancement of the heterogeneous solar photocatalytic degradation of combined mixture of chlorophenols

The solar photocatalytic degradation of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) was investigated individually and combined in the presence of Fe²⁺ and Fe³⁺ ions. The results revealed that both Fe²⁺ and Fe³⁺ ions enhanced the heterogeneous photocatalytic degradation. Fe³⁺ ions rapidly converted to Fe²⁺ ions as soon as the irradiation started. The intermediates formed during the degradation of 4-CP/2,4-DCP were also monitored and identified. Three main intermediates were observed, hydroquinone, phenol, and 4-chlorocatechol with traces of benzoquinone. The results support a new trend of research by utilising other cheap iron ion sources in the photocatalytic degradation.