HEXAVALENT CHROMIUM ADSORPTION REMOVAL FROM AQUEOUS SOLUTION BY FE-MODIFIED BIOCHAR DERIVED FROM RICE STRAW

Abstract

In this study, Fe-modified biochar (Fe-R-BC) was made from rice straw by modified with FeCl3 through pyrolysis, and used to adsorb Cr(VI) from aqueous solution.The properties of Fe-R-BC and rice straw biochar (R-BC) were characterized by Fe content, Brunauer-Emmett-Teller (BET) analysis, Boehm titration, and Fourier-transform infrared (FT-IR) spectroscopy.The Cr(VI) adsorption removal mechanism and regenerative property of Fe-R-BC were explored with batch adsorption experiment.Compared to those of R-BC, the Fe content, specific surface area (BET), total pore volume, and amount of hydroxyl group of Fe-R-BC increased, while the average pore size and amount of methenyl group decreased.For Fe-R-BC, the maximum Cr(VI) adsorption removal capacity was 94.95 mgg -1 at 313 K.The Cr(VI) adsorption kinetics and isotherms can be well described by the pseudo second order model and the Langmuir-Freundlich model, respectively.The Cr(VI) adsorption removal was spontaneous and endothermic.Low pH was beneficial for the Cr(VI) adsorption removal.SO4 2-showed the largest influence on the Cr(VI) adsorption removal, followed by NO3 -and Cl -.After 4 sorption-desorption cycles, the regenerated Fe-R-BC still maintained 76.27% of adsorption removal ability compared to that of Fe-R-BC in the initial use.Overall, Fe-R-BC can be applied to treat wastewater containing Cr(VI).