Development of a hydroxyl group-mediated biosynthetic schwertmannite as a persulfate activator for efficient degradation of RhB and Cr(VI) removal

Recently, sulfate radical-based advanced oxidation processes (SR-AOPs) have shown broad potential for restoring the water environment. However, the application of SR-AOPs to simultaneously remove organic pollutants and Cr(VI) has rarely been reported. Herein, we developed a modified schwertmannite (Sch-PVA) synthesized via the mediation of Acidithiobacillus ferrooxidans in the introduction of polyvinyl alcohol (PVA). This modification significantly changed the morphology and structure of the schwertmannite (Sch). The specific surface area and the density of functional sites also increased. Sch-PVA significantly increased the persulfate (PDS) activation efficiency. Even in 100 mg L-1 rhodamine B (RhB) conditions, 96.3% of RhB was eliminated by 0.5 g L-1 SchPVA and 6 mM PDS in 120 min. Moreover, excellent performance was exhibited over a wide pH range. The dissolution of the passivation layer facilitated the exposure of new adsorption and reduction sites, thereby enhancing the simultaneous removal of RhB and Cr(VI). Quenching experiments and electron spin resonance (ESR) measurements verified that sulfate and hydroxyl radicals were generated. The hydroxyl groups on the SchPVA surface played a key role in the bonding with and the activation of PDS. In conclusion, Sch-PVA provides new insights into the catalyst application for simultaneous removal of organic pollutants and Cr(VI).

Automated summary

The study developed a modified schwertmannite (Sch-PVA) which showed promising results in removing organic pollutants and Cr(VI) simultaneously. Sch-PVA improved the activation efficiency of persulfate and enhanced the simultaneous removal of RhB and Cr(VI). The research provides new insights into the application of novel catalyst for water environment restoration.