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.