Heavy metal contamination of water bodies by anthropogenic activities is inevitable. Therefore, the development of a cost effective and efficient treatment method is immensely important. Biochar is a promising candidate for the removal of heavy metal contaminants and has received great attention in the scientific community due to its inherent low cost of production and high absorption capacity. Douglas fir biochar (DFBC) produced from fast pyrolysis was impregnated with 5% aluminum sulfate and magnesium chloride. The resulting biochar was characterized by point of zero charge, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. The BET surface area reduced from 535 m2/mg to 316 m2/mg following the metal ion loading. Energy Dispersive X-ray spectroscopy provided evidence for the facile impregnation of Al and Mg into the biochar. Batch sorption investigation of chromium solution on Al/Mg biochar was carried out at pH values ranging from 2 to 10 while the adsorbate concentration varied from 5 to 300 mg/L. The sorption of chromium was monitored by UV-visible spectroscopy at 370 nm. The effect of temperature on sorption was studied at 25, 35, 45 and 550C and adsorption isotherms were analyzed at different temperatures, ranging from 25-55 0C using Langmuir, Freundlich, Redlich-Peterson, Toth, and Sips isotherm models. Langmuir adsorption isotherms give a maximum adsorption capacity of 66 mg/g at pH 6.5 and at 450C. It can be concluded that Al/Mg Douglas fir biochar is a more effective adsorbent for chromium ion removal compared to untreated Douglas fir biochar.

Chromium ion removal from aqueous media by aluminum and magnesium impregnated biochar

255th National Meeting (2018)

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