The degradation of cyanide, however, remained relatively constant with #PR-171 randurls[1|1|,|CHEM1|]# further increase in the reaction time beyond 180 min, indicating that the catalyst might be deactivated by deposition of the reaction products on the catalyst surface. Figure 7 Photocatalytic degradation

of cyanide using different concentration wt.% of calcined ZnO E . Reaction conditions: 100 ppm KCN(aq), t = 25°C, pH = 8.5. Kinetic photocatalytic degradation of CN- using calcined ZnOE The first order kinetic degradation of CN – (aq) was fitted to the following expression: where [C]t and [C]o represent the concentration in (ppm) of CN¯ (aq) in solution at time zero and at time t of illumination, respectively, and k represents the apparent rate constant (min-1). The kinetic analysis of cyanide photodegradation is depicted in Figure  8, which shows that the rate of photocatalytic reaction depends on the concentration of the catalyst. An excellent correlation to

the pseudo-first-order reaction kinetics (R > 0.99) was found. Obviously, the photodegradation rate of the CN- was found to increase from 19.2 to 42.9 × 10-3 min-1 with increasing ZnO loading from 0.01 to 0.07 wt.% (Table  5). Figure 8 Photodegradation kinetic of cyanide ion over calcined ZnO E . Table 5 Apparent rate constant ( k ) at different concentration wt.% of calcined ZnO E ZnOEconcentration, wt.% k(min × 10-3) 0.01 19.2 0.02 20.8 0.03 33.5 0.05 36.1 0.07 42.9 Conclusion Zinc oxide nanoparticles SB431542 were readily prepared at room

temperature from zinc nitrate Cediranib (AZD2171) hexahydrate and cyclohexylamine either in aqueous or ethanolic medium. The calcined ZnOE had a regular, polyhedra morphology while the calcined ZnOW had irregular spherical morphology, mixed with some chunky particles. The morphology was a key factor in the superior photocatalytic behavior of ZnOE over that of ZnOW. The differences in morphology and photocatalytic behavior are strongly influenced by the physicochemical properties of the synthesis medium. Acknowledgements The authors gratefully thank King Abdulaziz City for Science and Technology (KACST) for financing this work through project No. 29–280. We also thank Dr. Mohamad Mokhtar and Reda Mohammed for their useful discussion, Mr. Emad Addurihem for his technical assistance, Mr. Abdulrahman AL-Ghihab for SEM analysis, and Mr. Muath Ababtain for TEM analysis. References 1. Mudder TI, Botz MM: Cyanide and society: a critical review. Eur J Miner Process Environ Protect 2004, 4:62–74. 2. Young CA: Remediation of technologies for the management of aqueous cyanide species . In Cyanide: Social, Industrial and Economic Aspects. Edited by: Young CA, Tidwell LG, Anderson CG. Warrendale, PA: TMS; 2001:175–194. 3. Zagury GJ, Oudjehani K, Deschenes L: Characterization and variability of cyanide in solid mine tailings from gold extraction plants.