Cr(III) removal from synthetic and industrial wastewaters by using co-gasification chars of rice waste streams

Blends of rice waste streams were submitted to co-gasification assays. The resulting chars (G1C and G2C) were characterized and used in Cr(III) removal assays from a synthetic solution. A Commercial Activated Carbon (CAC) was used for comparison purposes. The chars were non-porous materials mainly composed by ashes (68.3–92.6% w/w). The influences of adsorbent loading (solid/liquid ratio – S/L) and initial pH in Cr(III) removal were tested. G2C at a S/L of 5 mg L⁻¹ and an initial pH of 4.50 presented an uptake capacity significantly higher than CAC (7.29 and 2.59 mg g⁻¹, respectively). G2C was used in Cr(III) removal assays from an industrial wastewater with Cr(III) concentrations of 50, 100 and 200 mg L⁻¹. Cr(III) removal by precipitation (uptake capacity ranging from 11.1 to 14.9 mg g⁻¹) was more effective in G2C, while adsorption (uptake capacity of 16.1 mg g⁻¹) was the main removal mechanism in CAC.