Novel Persulfate Activation Methods And Their Degradation Property Of Atrazine

Water, is the source of life and an essential premise to our human beings. Water is related to the sustainable development of human and society directly. However, with the rapid development of the economy, water pollution is getting more and more serious and it has been a threat to human health. So how to deal with the issue has become a focus of the society. Generally speaking, water pollution treatment methods includes biological method, physical method and chemical method. Among these methods, the advanced oxidation technology is the most popular method. In recent years, sulfate radical based advanced oxidation processes are regarded as an effective technology for hazardous organic pollutants control and become a research hot spot. The activation of persulfate is the main source of sulfate radical. Generally, the activation methods includes thermal activation, photochemical activation, transition metal ions activation, etc.. However, these methods have some deficiencies, thus, the research about sulfate radical based advanced oxidation processes are focused on how to effectively activate oxidants. In this paper, we studied two novel homogeneous ways for the effective activation of persulfate.First, we demonstrated that ascorbic acid (AA) could activate sodium persulfate (PS) and significantly enhance the degradation of atrazine. We interestingly found that the addition of ascorbic acid could increase the atrazine degradation rate by 20 times in the AA/PS oxidation system. We studied the degradation efficiency in different pH value conditions. The capture experiments indicated that both hydroxyl radical and sulfate radical are the main species contributed to the degradation of atrazine. We tested the active oxygen species by ESR and we used LC-MS and GC-MS to detect the intermediates of ascorbic acid and atrazine. Comparing some reducing substances and some ascorbic acid similar-structured materials activation property of persulfate, we demonstrate that this enhancement of atrazine degradation was attributed to the dienol structure in the ascorbic acid molecule, which has a strong reducing capacity and can effectively activate persulfate to accelerate the generation of active oxygen species. Finally, we proposed a possible activation mechanism in AA/PS system. The modified system provide a simple and effective technology for the decomposition of refractory organics in water and also shed new light into the possible roles of some dienol acids in the transformation of the organic contaminants in natural aquatic environment.In the second part, we studied the activation of peroxymonosulfate by phosphate. We studied the influence of different ratio of phosphate and peroxymonosulfate on the degradation of atrazine. We also simulated the dissociated ions and the speciation of phosphate and peroxymonosulfate under different pH values. We studied the effect of pH on the atrazine degradation. According to the experimental results, we supposed that the activation of peroxymonosulfate by phosphate is related with their structure. There may be a hydrogen bond between them which induced the activation of peroxymonosulfate. We also measure the generation of reactive oxygen species in the PBS/PMS system. The results showed that hydroxyl radical and sulfate radical contributed to the degradation of atrazine simultaneously. In addition, the phosphate is also a pollutant in water. Calcium chloride was used to remove excessive phosphate. The developed PBS/PMS system has great potential in phosphorus wastewater treatment.