Highly Efficient\nRemoval of Cr(VI) by Biochar Derived\nfrom Vietnamese Young Durian Fruit: Comparison of Traditional and\nMicrowave-Assisted Pyrolysis

This study compares the material characteristics and\nevaluates\nthe Cr(VI) adsorption capacity of biochar derived from a novel byproduct\n(young durian fruit, YDF), synthesized using two pyrolysis methods\n(traditional and microwave-assisted). The optimal pyrolysis conditions\nfor porosity were 800 °C and 800 W for 30 min, respectively.\nThe traditional pyrolysis method yielded a very high surface area\nand pore volume (668 m<sup>2</sup>/g; 0.332 cm<sup>3</sup>/g). XRD\npatterns and FTIR spectra demonstrated structural and functional group\ndifferences, significantly impacting the Cr(VI) removal efficiency\nin water. pH was a critical factor with optimal adsorption at pH 2.0.\nThe adsorption process reached equilibrium at 180 and 100 min at initial\nconcentrations of 100 and 125 mg/L for biochar synthesized by traditional\nand microwave-assisted pyrolysis, respectively. The adsorption mechanisms\nproposed based on modern analytical methods include adsorption-reduction,\nion exchange, electrostatic interaction, and surface complexation.\nIndustrial wastewater containing chromium was effectively treated\nunder natural conditions (pH = 5.88; <i>C</i><sub>o</sub> = 129.9 mg/L) using biochar synthesized via microwave, achieving\na <i>Q</i><sub>e</sub> of 21.41 mg/g. The research results\npave the way for new directions in the synthesis and application of\nbiochar in environmental treatment, specifically using young fruit\nmaterials and microwave methods.