An improved air purification adsorbent is disclosed. The air purification adsorbent comprises titanium dioxide (TiO2) impregnated with zinc chloride (ZnCl2). The adsorbent may be used in air purification systems for removing ammonia from air streams. The nanocrystalline (amorphous) structure of the adsorbent results in a higher density of surface defects, higher surface area, and higher reactivity which, when combined with the synergistic effect of ZnCl2 and the nanocrystalline TiO2, provides a significantly longer breakthrough time of ammonia as compared with breakthrough time from unimpregnated nanocrystalline TiO2, the commercial (crystalline) TiO2 impregnated with ZnCl2, pure ZnCL2, and other commercially available adsorbents of ammonia. Other embodiments are described and claimed.