Adsorption of volatile organic compounds on activated carbon with included iron phosphate

Abstract

Volatile organic compounds (VOCs) are often hazardous and need commonly to be removed from gas mixtures. Capture on activated carbon (AC) is one approach to achieving this. We hypothesized that the smallest pores on ACs and the inclusion of inorganic phosphates could enhance the low gas pressure uptake of two typical VOCs (acetone and isopropanol). To test this hypothesis, ACs were prepared by chemical activation of hydrochars with H₃PO₄ or a mixture of FeCl₃ and H₃PO₄. The hydrochars had been prepared by hydrothermal carbonization of glucose. The ACs were characterized by XRD, IR, TGA, and the adsorption of N₂, CO₂, H₂O, acetone, and isopropanol. The results showed that the ACs had comparably high adsorption of acetone and isopropanol at low vapor pressures. The low-pressure uptake (at 0.03 kPa) of isopropanol and acetone had values of up to 3.4 mmol/g and 2.2 mmol/g, respectively. This suggests that ACs containing iron phosphate could be of relevance for adsorption driven removal of VOC. It was also observed that the external surface area of the ACs containing iron phosphates increased upon secondary heat treatment in N₂.