Photocatalytic reduction of Cr(VI) by PVA-alginate encapsulated γFe2O3 magnetic beads using different types of illumination lamp and light

In this study the toxic Cr(VI) which is a common pollutant to the environment is removed from the aqueous solution using the one step photocatalytic reduction to Cr(III) using PVA-alginate encapsulated γFe2O3 magnetic beads. The photocatalytic reduction of Cr(VI) by PVA-alginate encapsulated γFe2O3 magnetic beads was examined under sunlight and other 4 types of lamp: xenon lamp, black light bulb (BLB) lamp, light emitting diode (LED) lamp and fluorescent lamp. The experiments were performed at pH 1, initial Cr(VI) = 50 mg/L and the photocatalyst dosage of maghemite nanoparticles was kept at 8% (v/v). Removal of Cr(VI) was best under sunlight; 100% removal in 30 min, followed by xenon lamp; 100% removal in 100 min, BLB lamp; 70% removal in 100 min. LED and fluorescent lamp have about the same removal rate; 50% removal in 100 min. The Cr(VI) reduction using PVA-alginate magnetic beads fitted the Langmuir–Hinshelwood (L–H) kinetics model with a correlation coefficient (R2) of 0.972. The PVA-alginate magnetic beads were capable of treating industrial chromium waste containing 300 mg/L Cr(VI) within 2 h under sunlight.