Chiavone Filho, OsvaldoHollanda, Luana Rabelo2019-01-092019-01-092018-07-30HOLLANDA, Luana Rabelo. Estudo da degradação do pesticida atrazina através da redução por cobre de valência zero, e da sua potencialidade como pré-etapa à foto-oxidação com persulfato. 2018. 116f. Dissertação (Mestrado em Engenharia Química) - Centro de Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, 2018.https://repositorio.ufrn.br/jspui/handle/123456789/26442The contamination of waterbodies by pesticides that are resistant to conventional water treatment processes consists a serious environmental problem, making urgent the development of alternative technologies capable of degrading them. Among these pesticides is Atrazine (ATZ), which is of special concern due to its endocrine disrupting character, being classified as a priority substance to be monitored for water quality purposes in the European Union. Advanced oxidation processes (AOP) have been pointed as a promising technology against this kind of pollutant. However, as an organochloride, ATZ contains electron-deficient groups, making it more easy to reduce than to oxidize. Therefore, a pre-reducing step is preferred to an oxidative one for the removal of these class of contaminants. Given that, in this study was investigated the application of zero-valent copper as a reducing agent for the degradation of ATZ. Then, this was combined with a sulfate radical (SO4 ●- )-driven AOP. To study the influence of different operational conditions in the pre-reducing step, a Doehlert experimental design was followed. Then, the mineralization of the solution that presented the highest ATZ degradation was studied by varying the oxidant concentration – sodium persulfate (1, 5 and 10 mmol L-1 ) – and the UV source of radiation (UVC and UVA). During the oxidative stage, samples were collected after 30, 60 and 120 minutes of reaction. Experiments were also performed by applying only the oxidative stage, without the pretreatment. Toxicity assays with the microalgae Chlorella vulgaris and the bacteria Vibrio fischeri were performed with the samples obtained after each step. For the pre-reductive stage, the Doehlert design showed that the best conditions are those that combine low pH and high copper concentration (>0.2% m/v). The oxidative step was then applied on the most degraded solution and about 70% of mineralization was achieved after 2 hours of reaction when 5 mmol L-1 of persulfate and UVC radiation were used, while only 40% of mineralization was observed when only the oxidative stage was performed. Regarding toxicity assays with C. vulgaris, the reduced solution was 30% less toxic than the parentATZ initial solution. For the test with V. fischeri, it was found that ATZ initial solution did not cause inhibitory effects, but a significant increase in toxicity was observed after the reductive step. For both organisms, it was verified that, among the three reaction times tested, the toxicity reached a minimum value after one hour of reaction of the pre-reduced solution with persulfate. In addition, the oxidized sample submitted to the pretreatment presented a lower toxicity when compared to the test performed without the previous stage, both after one hour of reaction. However, for longer reaction times the toxicity has increased again, even though higher mineralization values were achieved. In this way, results indicate that a higher mineralization does not necessarily mean low toxicity and, therefore, additional studies are required to understand the relation between these effects.Acesso AbertoAtrazinaCobre de valência zeroPersulfatoRadiação UVToxicidademasterThesisCNPQ::ENGENHARIAS::ENGENHARIA QUIMICA