Study On The Degradation Of Atrazine By Visible Light-fenton System In The Presence Of Ta(O)N Nanoparticles

It has attracted wide attention that a large number of POPs (persistent organicpollutants, POPs) into environment and lead to ecological and human health risk.Development of efficient, economical POPs purification technology has become one ofthe focus areas of engineering and technology topics. Visible-Fenton like system drivenby tantalum(oxy)nitride (Ta(O)N) can degrade POPs rapidly with energy, saving clean,efficient, ect. The paper prepared nano-Ta2O5as precursors and regulated thecomposition of Ta(O)N by nitride conditions, improving the atrazine degradationefficiency by visible-Ta(O)N-Fenton like system. Also we discussed the atrazinedegradation mechanism and studied its influencing factors, has made the followingfindings:1) Nanocrystalline Ta(O)N particles were synthesized by nitridation of nanosizedTa2O5particles which were synthesized by the wet chemical method through TaCl5using NH3as the reactant gas. The sample was characterized by XRD, XPS andUV-DRS, SEM analyses. The sample prepared at700℃under a NH3flow rate0.15L min-1for12h showed the highest level of photocatalytic activity for Fe3+reduction(about16.14%). XRD and XPS results showed the sample was a mixture of TaON andTa3N5and Ta:O:N ratio of1:1.82:1.11. UV-DRS analysis showed absorption edges ofapproximately620nm.2) The sample possessed the highest level of photocatalytic activity for Fe3+reduction and atrazine degradation under visible light irradiation. The influence ofvarious operational parameters such as the light intensity, input of tantalum(oxy)nitride,temperature, pH, and initial concentrations of Fe3+, H2O2and atrazine were investigated.Atrazine was completely degraded after60mins irradiation by500W Xe lamp underthe conditions of pH=2.6, T=25℃,[atrazine]0=18mg L-1,[H2O2]0=2.5mmol L-1,[Fe3+]0=0.5mmol L-1and the input of tantalum(oxy)nitride=0.3g L-1. 3) We monitored OH and other reactive oxygen species in the visible-Fenton likesystem driven by nano-Ta(O)N catalyst. The results show that the process is mainlythrough the photoelectrons react with the catalyst surface oxygen to form oxygenspecies, which OH is the only active substance to degrade atrazine. At first OH attackside alkyl group to form de-alkylated intermediates, and then removed chlorine to formdechlorination hydroxylated product, and finally to mineralized all atrazine. DOincorporate chain reaction of free radicals in visible-Fenton like system driven bynano-Ta(O)N, and lead to the reduction of OH, thus inhibiting the degradation rate ofatrazine.