Conversion of iron rusty waste into Fe dopant of TiO2 to increase its photocatalytic activity under visible light for photodegradation of rhodamine-B

This present research deals with a systematic study on doping TiO2 with Fe from iron rusty waste to improve the activity under visible light irradiation through gap narrowing in the TiO2 semiconductor structure. The doping was conducted by the sol-gel method by interacting titania tetra isopropoxide (TTIP) with Fe3+ ions dissolved from the iron rusty waste in aqua regia. The concentration of the Fe3+ was varied giving mole ratio to TiO2 as (1:0.04), (1:0.08), (1:0.12), (1:0.16), and (1:0.20). The activity of TiO2–Fe was examined for Rhodamine-B dye photodegradation through batch technique. The influences of the Fe fraction, irradiation time, photocatalyst weight, and solution pH were also evaluated to find the best condition for the dye degradation. The research results attribute that doping TiO2 with Fe3+ from the rusty waste has successfully shifted the band gap energy into the visible regime, which remarkably increases the TiO2 activity under visible light irradiation. The increase is controlled by the Fe fraction in the photocatalyst, and the best performance is shown by TiO2–Fe with a 1:0.12 mol ratio. From the dye photodegradation, it is found that the highest degradation effectiveness (99.20 %) of 5 mg/L Rhodamine B in 50 mL of the solution, can be obtained by using 50 mg of TiO2–Fe (1:0.12), pH 5, in 90 min. The photocatalyst can be reused twice in the photodegradation process without a significant decrease in photoactivity. It is implied that the rusty waste has potential as a Fe dopant source creating a better visible responsive photocatalyst. •Fe(III) from iron rusty waste has been successfully doped into TiO2.•The visible activity of the Fe-doped TiO2 is higher than TiO2.•The activity of TiO2–Fe is controlled by the amount of Fe doped.•TiO2–Fe was examined for the photodegradation of rhodamine B.