Alginate-pyrolyzed porous carbon as efficient gas phase elemental mercury scavenger

The present research work demonstrates the potential of porous carbon (PC) fabricated through facile one-step method from calcium alginate biomass as a low cost and efficient scavenger for gas phase elemental mercury (Hg°) from natural gas. Performance of the prepared PC at different temperatures (500, 700 and 900 °C) using fixed-bed setup mimicking the plant conditions revealed that PC-900 demonstrated to be a promising adsorbent for removing Hg°. The excellent sorption performance of PC-900 could be attributed to its BET surface area and large pore volume which rendered easy sorption of Hg° into the porous network. The equilibrium adsorption results further confirmed that sorption capacity decreased from 1236 to 1089 μg/g with increase in temperature from 30 to 50 °C, indicating exothermic nature of adsorption. The sorption isotherms well fitted the Langmuir model, with maximum adsorption capacity of 1236 μg/g at 30 °C. A comparison of the sorption capability of bio-derived PC-900 with sulfur impregnated carbon (SIC) at 50 °C affirmed that the uptake capacity of PC-900 (1089.6 μg/g) was much higher than SIC (887.2 μg/g). These results reveal the promising solutions offered by alginate pyrolyzed PC for scavenging Hg° from natural gas, by not only reducing the environmental problems associated with gaseous mercury emissions but also by making the process more economical.