Application of impregnated biocarbon produced from soybean hulls in dye decolorization

Abstract

Waste soybean hulls (WSH) were investigated as a Fe-support in two forms: raw and carbonized (i.e. biocarbon, BC), as possible value-added materials. Fe-impregnation was implemented in order to produce heterogeneous Fenton catalysts for Reactive Blue 4 dye degradation. Materials characterization demonstrated a rise in the specific surface area due to decomposition of WSH constituents during carbonization (to obtain BC) and thermal activation (to obtain Fe-WSH and Fe-BC), thus producing catalysts with high mesoporosity and hematite as the active site for Fenton reaction. Among the investigated materials, Fe-WSH showed the greatest ability for •OH production in acidic medium. Next, the hetero-geneous Fenton process was optimized by using response surface methodology, which resulted in selection of the following reaction conditions: 3 mM H2O2, 100 mg Fe-WSH, reaction time of 180 min, at a constant pH 3, RB4 concentration of 50 mg dm-3 and at room temperature. The achieved dye removal and mineralization were 85.7 and 66.8 %, respecti-vely, while the catalyst showed high stability and the reaction intermediates formed during the oxidation process had a low inhibitory effect on Vibrio fischeri bacteria.

Keywords

• valorization
• fe(iii)-impregnation
• response surface methodology
• reactive blue 4
• reuse