The arsenic adsorption capacity of a manganese oxide-modified biochar composite (MBC), prepared by
pyrolysis of a mixture of potassium permanganate and biochar, was investigated in red soil. Adsorption
experiments using batch procedures were used to estimate the arsenic adsorption capacities of the
absorbent materials. Adsorption and desorption isotherms, Fourier-transform infrared spectroscopy
(FTIR), and X-ray photoelectron spectroscopy (XPS) were used to characterise the prepared adsorbent
materials, and a plausible mechanism for arsenic removal by MBC was proposed. Arsenic in red soileMBC
mixtures exhibited lower mobility than that in soils amended with pristine biochar. The improved
removal performance of soileMBC mixtures was attributed to a lower H/C ratio, higher O/C ratio, higher
surface hydrophilicity, and higher surface sorption capacity, even though the impregnation of manganese
oxide decreased the specific surface area of the biochar. Arsenic retention increased as the biochar
content increased, mainly owing to an increase in soil pH. Several oxygenated functional groups, especially
OeH, C]O, MneO, and SieO, participated in the adsorption process, and manganese oxides played
a significant role in the oxidation of arsenic. This study highlights the potential of MBC as an absorbent to
immobilise arsenic for use in contaminated land remediation in the red soils region.
The arsenic adsorption capacity of a manganese oxide-modified biochar composite (MBC), prepared bypyrolysis of a mixture of potassium permanganate and biochar, was investigated in red soil. Adsorptionexperiments using batch procedures were used to estimate the arsenic adsorption capacities of theabsorbent materials. Adsorption and desorption isotherms, Fourier-transform infrared spectroscopy(FTIR), and X-ray photoelectron spectroscopy (XPS) were used to characterise the prepared adsorbentmaterials, and a plausible mechanism for arsenic removal by MBC was proposed. Arsenic in red soileMBCmixtures exhibited lower mobility than that in soils amended with pristine biochar. The improvedremoval performance of soileMBC mixtures was attributed to a lower H/C ratio, higher O/C ratio, highersurface hydrophilicity, and higher surface sorption capacity, even though the impregnation of manganeseoxide decreased the specific surface area of the biochar. Arsenic retention increased as the biocharcontent increased, mainly owing to an increase in soil pH. Several oxygenated functional groups, especiallyOeH, C]O, MneO, and SieO, participated in the adsorption process, and manganese oxides playeda significant role in the oxidation of arsenic. This study highlights the potential of MBC as an absorbent toimmobilise arsenic for use in contaminated land remediation in the red soils region.
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