Enhanced adsorption of odorous NH₃ using transition metals (Cu, Fe, Ni, Mn, Ce) modified activated carbon

NH₃ with high toxicity and strong corrosion can cause harm to human health and aggravate the corrosion of equipment. In this paper, a series of transition metal salt-modified activated carbon were prepared via an incipient wetness impregnation method, and then used as the adsorbents for the static adsorption of NH₃ in confined space. The physicochemical properties of the adsorbents were characterized by XRD, SEM, EDS, N₂ adsorption/desorption, XPS, FTIR and NH₃-TPD. The effects of transition metal, loading amount, and Ce doping on the adsorption performance were systematically studied. The reusability of the adsorbents was also investigated. Among the various transition metal (Cu, Fe, Mn, and Ce), modification of activated carbon with Cu exhibited the best adsorption performance, which increased the adsorption efficiency from 60% for original activated carbon to 90% within 20 min at a high initial NH₃ concentration (800 ppm) in enclosed spaces. The optimal loading amount of Cu was determined at 5 wt.%. Excess loading would destroy the pore structure and specific surface area, which is unfavorable for NH₃ adsorption. Besides, Ce doping can enhance the NH₃ removal efficiency. Among which, Ce_0.01Cu_0.29/AC exhibited the best adsorption performance with excellent reusability. After three cycles of use, there was no significant decrease in adsorption efficiency, indicating promising practical applications for this adsorbent. This study provides a new insight for the design of high-performance deodorant adsorbents.