Self S-doping activated carbon derived from lignin-based pitch for removal of gaseous benzene

In this study, lignin-based pitch extracted from black liquor was used as the precursor for synthesis of activated carbon (AC) with high specific surface area and pore volume through chemical activation with potassium hydroxide (KOH). The effect of the activation temperature on AC properties was also explored. The optimized activated carbon (PAC-5-850-60) was prepared at the activation temperature of 850 °C. At this temperature, the specific surface area and total pore volume of PAC-5-850-60 reached the maximum values of 3652 m2·g−1 and 2.35 cm3·g−1, respectively. The physicochemical properties and structural characteristics of ACs were characterized by N2 adsorption/desorption, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectrometry (FTIR) and X-ray photoelectron spectroscopy (XPS). In the adsorption study, gaseous benzene was selected as the adsorbate. Dynamic adsorption experiment was carried out to explore the adsorption behavior and mechanism of PACs. Under 5000 ppm (or 500 Pa partial pressure), the adsorption capacity and partition coefficient for gaseous benzene on PAC-5-850-60 were 802.06 mg g−1, and 0.20 mol kg−1Pa−1 at 10% breakthrough level and 819.77 mg g−1, and 0.02 mol kg−1Pa−1 at 100% breakthrough level. PAC-5-850-60 exhibited favorable recycling adsorption performance and could be a good absorbent for removal of gaseous benzene.