Insights into the mechanism of Cr(Ⅵ) removal by biogenic jarosite-biomass derived Fe-C material with anti-environmental interference performance

Abstract

Hexavalent chromium (Cr(VI)), an acute toxic, potential carcinogenic and mutagenic substance, is increasingly discharged into wastewater by industrial activities. Therefore, it is urgent to develop efficient and eco-friendly approaches for Cr(VI) treatment from wastewater. Biosynthetic jarosite and/or bagasse mixture were carbonized and used as catalysts (jarosite@BC-300 °C, jarosite-300 ℃ and BC-300 ℃) for Cr(VI) removal. Jarosite and BC acted synergistically to enhance the removal of Cr(VI). The Cr(VI) removal efficiency was up to 79.1 % with the addition of 1 g/L of jarosite@BC-300 °C for 120 min. The Cr(VI) removal was mainly attributed to the heterogeneous reduction of Cr(VI) to Cr(III), accompanied with Cr(III) precipitation and Cr adsorption. Fe(II) on the jarosite@BC-300 °C was the main active sites for Cr(VI) reduction. Biochar as electron donor enhanced Cr(VI) reduction by promoting the regeneration of Fe(II) and the production of superoxide radicals ((O₂^•)^-). The electrochemical experiment demonstrated that jarosite@BC-300 °C had fast ion diffusion performance, which could be used as an electron shuttle to realize rapid ion transfer for accelerating Cr(VI) removal. Additionally, jarosite@BC-300 °C could be used over a wide pH range of 2–11. Coexisting ions experiments showed that the effect of anions (Cl^-, NO₃^-, SO₄^2- and PO₄^3-) on the removal of Cr(VI) by jarosite@BC-300 °C was almost negligible. Hence, the prepared jarosite@BC-300 °C with high-efficiency and low-cost had a promising application in the treatment of Cr(VI) containing wastewater.