Irreversible ammonia adsorption on asphaltite bottom ash: A thermodynamic approach

Surface area (20 m(2)g(-1)) and pore volume (0.015 cm(3)g(-1)) estimate for the bottom ash of an asphaltite from Sirnak/Turkey deposit, were determined using the nitrogen adsorption/desorption isotherms at 196 degrees C. The shape and location of the adsorption/desorption isotherms of ammonia on the ash at 0, 50, 100, and 200 degrees C revealed that the irreversible chemical adsorption was more effective than the accompanied physical one. The overall and chemical adsorption capacities increased with the increasing temperature, whereas the physical adsorption capacity decreased. Data obtained from the isotherms, adsorption isosteres, and corresponding Van't Hoff graphs were evaluated thermodynamically to estimate the isosteric enthalpy (Delta H) and entropy changes (Delta S) for the overall ammonia adsorption. Decrease in Delta H and Delta S is caused due to a drop in the endothermic chemical adsorption, whereas increasing exothermic physical adsorption is correlated to the progression of the reaction.

Automated summary

This study investigated the surface area and pore volume of bottom ash from an asphaltite deposit in Sirnak, Turkey using nitrogen adsorption/desorption isotherms. The results showed that chemical adsorption was more effective than physical adsorption at different temperatures, with overall and chemical adsorption capacities increasing with temperature while physical adsorption capacity decreased. Thermodynamic evaluation revealed changes in enthalpy and entropy for ammonia adsorption, with a decrease in endothermic chemical adsorption and an increase in exothermic physical adsorption as temperature increased.