Effect of Microwave Power on the Zn2SnO4 Synthesis and Its Use for Photodegradation of Phenol

Spinel structure Zn2SnO4 was successfully synthesized by microwave-assisted hydrothermal process. The effects of the microwave power on the formation and physical properties of the Zn2SnO4 particles are discussed. The products were characterized by X-ray diffraction, atomic force microscopy, infrared spectroscopy, and N2 adsorption. The results indicated that the microwave power had important influence on the formation of the spinel phase. The results also revealed that the physical properties of Zn2SnO4 particles did not change with the increase of the microwave power above 600 W, with 20 min of reaction time. Furthermore, the photocatalytic activity of the Zn2SnO4 particles for the phenol degradation under sunlight was also investigated.

Treatability studies of naphthalene in soil,water and air with persulfate activated by iron(Ⅱ)

Chemical oxidation was applied to an artificially contaminated soil with naphthalene(NAP).Evaluation of NAP distribution and mass reduction in soil,water and air phases was carried out through mass balance.Evaluation of NAP distribution and mass reduction in soil,water and air phases was carried out through mass balance.The importance of the air phase analysis was emphasized by demonstrating how NAP behaves in a sealed system over a 4 hr reaction period.Design of Experiments method was applied to the following variables:sodium persulfate concentration[SP],ferrous sulfate concentration[FeS04],and pH.The system operated with a prefixed solid to liquid ratio of 1:2.The following conditions resulted in optimum NAP removal[SP]=18.37 g/L,[FeSO4]=4.25 g/L and pH=3.00.At the end of the 4 hr reaction,62%of NAP was degraded.In the soil phase,the chemical oxidation reduced the NAP concentration thus achieving levels which comply with Brazilian and USA environmental legislations.Besides the NAP partitioning view,the monitoring of each phase allowed the variabilities assessment over the process,refining the knowledge of mass reduction.Based on NAP distribution in the system,this study demonstrates the importance of evaluating the presence of semi-volatile and volatile organic compounds in the air phase during remediation,so that there is greater control of the system as to the distribution and presence of the contaminant in the environment.The results highlight the importance of treating the contaminant in all its phases at the contaminated site.