Room-temperature synthesis of zinc oxide nanoparticles in different media and their application in cyanide photodegradation

Cyanide is an extreme hazard and extensively found in the wastes of refinery, coke plant, and metal plating industries. A simple, fast, cost-effective, room-temperature wet chemical route, based on cyclohexylamine, for synthesizing zinc oxide nanoparticles in aqueous and enthanolic media was established and tested for the photodegradation of cyanide ions. Particles of polyhedra morphology were obtained for zinc oxide, prepared in ethanol (ZnO(E)), while spherical and some chunky particles were observed for zinc oxide, prepared in water (ZnO(W)). The morphology was crucial in enhancing the cyanide ion photocatalytic degradation efficiency of ZnO(E) by a factor of 1.5 in comparison to the efficiency of ZnO(W) at an equivalent concentration of 0.02 wt.% ZnO. Increasing the concentration wt.% of ZnO(E) from 0.01 to 0.09 led to an increase in the photocatalytic degradation efficiency from 85% to almost 100% after 180 min and a doubling of the first-order rate constant (k).