Excellent photocatalytic performance of PAA/Na2MoO4-Fe3+ hydrogel with Na2MoO4 as sacrificial agent for dye removal

Currently, the majority of photocatalytic materials primarily consist of insoluble semiconductors, whereas soluble semiconductor materials have limited applications in photocatalysis. In this study, it is proposed for the first time to use the soluble semiconductor sodium molybdate (Na 2 MoO 4 ) as a sacrificial agent to fabricate a polyacrylic acid/sodium molybdate-Fe 3+ hydrogel photocatalyst (PAA/Na 2 MoO 4 -Fe 3+ ) through polymerization with Fe 3+ ions and acrylic acid (AA) monomer. The hydrogel photocatalyst was thoroughly characterized and the results revealed that the presence of Na 2 MoO 4 in ionic form within the hydrogel significantly enhanced its adsorption capacity for pollutant molecules. Additionally, Fe 3+ ions coordinated with -COOH ( L ) groups on PAA to form [Fe( L ) 6 ] 3+ ions, which acted as active sites of photocatalytic. Moreover, the PAA/Na 2 MoO 4 -Fe 3+ hydrogel exhibited promising potential as a photocatalyst for the remove of dye pollutants (e.g. MB, MG, RhB and MO) from wastewater. Finally, we also explored and analyzed the photocatalytic mechanism of the hydrogel. It is noteworthy to conclude that the hydrogel possesses immense potential for the practical application of photocatalytic techniques in the treatment of dyes wastewater.