Adsorption capacity of biochar derived from invasive plant species for hydrogen sulfide removal in biogas purification
摘要
The utilization of biogas for energy production is limited due to the presence of various contaminants. The impurities not only cause operational challenges but also lead to increased maintenance and equipment costs. In this study, the H2S adsorption efficiency of invasive plant biochars, i.e., acacia wood–based biochar (AWB) and lead tree wood–based biochar (LTWB), was studied. Biochar was prepared through slow pyrolysis process at 400 °C. Physical and chemical characteristics of biochar were investigated. BET surface area of AWB and LTWB was determined to be 189.24 m2 g−1 and 223.71 m2 g−1, respectively. The average pore size and total pore volume were estimated to be and 1.98 nm and 0.038 cm3 g−1 for AWB and 2.36 nm and 0.056 and 0.038 cm3 g−1 for LTWB, respectively. The pore size distribution analysis confirmed that these biochars exhibit both microporous and mesoporous structural characteristics. The FTIR analysis results of both biochars showed the existence of carboxylic and hydroxide radical groups which could be responsible for H2S adsorption. The H2S breakthrough capacity of AWB and LTWB was estimated to be 5.07 mg g−1 and 8.44 mg g−1, respectively. The breakthrough time of LTWB was longer than that of AWB for all studied pellet sizes (0.25 cm, 0.50 cm, and 1.00 cm). Smaller pellet sizes exhibited better removal efficiency than larger pallet sizes due to their increased surface area. The SEM/EDX results confirmed the presence of elemental S in both adsorbents after the adsorption, more precisely, higher S content for LTWB. This assured its higher breakthrough capacity and superior adsorption efficiency under similar conditions.
Graphical Abstract