Wong Man Yung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 106-120). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Figures --- p.xi / List of Plates --- p.xiii / List of Tables --- p.xv / Abbreviations --- p.xvi / Equations --- p.xviii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Water disinfection --- p.1 / Chapter 1.2 --- Bacterial species --- p.2 / Chapter 1.2.1 --- Staphylococcus saprophyticus --- p.2 / Chapter 1.2.2 --- Enterobacter cloacae --- p.3 / Chapter 1.3 --- Disinfection methods --- p.4 / Chapter 1.3.1 --- Physical methods --- p.4 / Chapter 1.3.1.1 --- UV-C irradiation --- p.4 / Chapter 1.3.1.2 --- Solar disinfection --- p.5 / Chapter 1.3.2 --- Chemical methods --- p.6 / Chapter 1.3.2.1 --- Chlorination --- p.6 / Chapter 1.3.2.2 --- Ozonation --- p.7 / Chapter 1.3.2.3 --- Mixed disinfectants --- p.8 / Chapter 1.3.3 --- Other disinfection methods --- p.8 / Chapter 1.4 --- Advanced oxidation processes (AOPs) --- p.9 / Chapter 1.5 --- Photocatalytic oxidation (PCO) --- p.10 / Chapter 1.5.1 --- PCO process --- p.12 / Chapter 1.5.2 --- Photocatalysts --- p.14 / Chapter 1.5.2.1 --- Titanium dioxide (P25) --- p.15 / Chapter 1.5.2.2 --- Silver sensitized P25 (Ag/P25) --- p.16 / Chapter 1.5.2.3 --- Silicon dioxide doped titanium dioxide (SiO2-TiO2) --- p.17 / Chapter 1.5.2.4 --- Copper(I) oxide sensitized P25 (Cu2O/P25) --- p.18 / Chapter 1.5.3 --- Irradiation sources --- p.19 / Chapter 1.5.4 --- PCO disinfection mechanisms --- p.20 / Chapter 1.6 --- Bacterial defense mechanisms against oxidative stress --- p.22 / Chapter 2. --- Objectives --- p.25 / Chapter 3. --- Materials and Methods --- p.26 / Chapter 3.1 --- Chemicals --- p.26 / Chapter 3.2 --- Bacterial culture --- p.26 / Chapter 3.3 --- Photocatalytic reactor --- p.27 / Chapter 3.4 --- PCO efficacy test --- p.30 / Chapter 3.5 --- Optimization of PCO conditions --- p.31 / Chapter 3.5.1 --- Effect of P25 concentrations --- p.31 / Chapter 3.5.2 --- Effect of UV intensities --- p.32 / Chapter 3.5.3 --- Combinational study of P25 concentrations and UV intensities --- p.32 / Chapter 3.5.4 --- Effect of stirring rates --- p.32 / Chapter 3.5.5 --- Effect of initial cell concentrations --- p.33 / Chapter 3.6 --- PCO disinfection using different photocatalysts --- p.33 / Chapter 3.6.1 --- Effect of CU2O/P25 concentrations --- p.33 / Chapter 3.6.2 --- Effect of CU2O powder on the two bacterial species --- p.33 / Chapter 3.7 --- Transmission electron microscopy (TEM) --- p.34 / Chapter 3.8 --- Catalase (CAT) test --- p.37 / Chapter 3.9 --- Superoxide dismutase (SOD) activity assay --- p.39 / Chapter 4. --- Results --- p.40 / Chapter 4.1 --- Efficacy test --- p.40 / Chapter 4.2 --- PCO disinfection under UV irradiation --- p.40 / Chapter 4.2.1 --- Control experiments --- p.40 / Chapter 4.2.2 --- Optimization of PCO conditions using P25 as a photocatalyst --- p.42 / Chapter 4.2.2.1 --- Effect of P25 concentrations --- p.42 / Chapter 4.2.2.2 --- Effect of UV intensities --- p.45 / Chapter 4.2.2.3 --- Combinational study of P25 concentrations and UV intensities --- p.48 / Chapter 4.2.2.4 --- Effect of stirring rates --- p.54 / Chapter 4.2.2.5 --- Effect of initial cell concentrations --- p.57 / Chapter 4.2.3 --- Comparison of PCO inactivation efficiency between S. saprophyticus and E. cloacae --- p.60 / Chapter 4.2.4 --- PCO disinfection using different photocatalysts --- p.62 / Chapter 4.2.4.1 --- Control experiments --- p.62 / Chapter 4.2.4.2 --- Ag/P25 --- p.62 / Chapter 4.2.4.3 --- SiO2-TiO2 --- p.64 / Chapter 4.2.4.4 --- Cu2O/P25 --- p.64 / Chapter 4.3 --- PCO disinfection under visible light irradiation --- p.66 / Chapter 4.3.1 --- Effect of Cu2O/P25 concentrations --- p.67 / Chapter 4.3.2 --- Effect of CU2O powder on the two bacterial species --- p.70 / Chapter 4.4 --- Feasibility use of indoor light (fluorescent lamps) for PCO disinfection --- p.71 / Chapter 4.5 --- Transmission electron microscopy (TEM) --- p.74 / Chapter 4.5.1 --- Morphological changes induced by PCO using P25 as a photocatalyst --- p.74 / Chapter 4.5.2 --- Morphological changes induced by PCO using Cu2O/P25 as a photocatalyst --- p.77 / Chapter 4.6 --- Catalase (CAT) test --- p.80 / Chapter 4.7 --- Superoxide dismutase (SOD) activity assay --- p.82 / Chapter 5. --- Discussion --- p.83 / Chapter 5.1 --- Efficacy test --- p.83 / Chapter 5.2 --- PCO disinfection under UV irradiation --- p.83 / Chapter 5.2.1 --- Optimization study --- p.84 / Chapter 5.2.1.1 --- Effect of P25 concentrations --- p.84 / Chapter 5.2.1.2 --- Effect of UV intensities --- p.85 / Chapter 5.2.1.3 --- Combinational study of P25 concentrations and UV intensities --- p.86 / Chapter 5.2.1.4 --- Effect of stirring rates --- p.86 / Chapter 5.2.1.5 --- Effect of initial cell concentrations --- p.87 / Chapter 5.2.2 --- Comparison of PCO inactivation efficiency between S. saprophyticus and E. cloacae --- p.88 / Chapter 5.2.3 --- PCO disinfection using different photocatalysts --- p.89 / Chapter 5.2.3.1 --- Ag/P25 --- p.89 / Chapter 5.2.3.2 --- SiO2-TiO2 and Cu2O/P25 --- p.90 / Chapter 5.3 --- PCO disinfection under visible light irradiation --- p.90 / Chapter 5.3.1 --- Effect of Cu20/P25 concentrations --- p.91 / Chapter 5.3.2 --- Effect of CU2O powder on the two bacterial species --- p.92 / Chapter 5.4 --- Feasibility use of fluorescent lamps for PCO disinfection --- p.93 / Chapter 5.5 --- Transmission electron microscopy (TEM) --- p.95 / Chapter 5.5.1 --- Morphological changes induced by PCO using P25 as a photocatalyst --- p.95 / Chapter 5.5.2 --- Morphological changes induced by PCO using CU2O/P25 as a photocatalyst --- p.96 / Chapter 5.6 --- Catalase (CAT) test --- p.98 / Chapter 5.7 --- Superoxide dismutase (SOD) activity assay --- p.99 / Chapter 6. --- Conclusion --- p.101 / Chapter 7. --- References --- p.106 / Chapter 8. --- Appendix --- p.121

For the development of a G6PD-deficient mouse model, we introduced the mutant Gpdxa-m1Neu allele (a severe ENU-induced mutation that results in 13-15% G6PD activities of wild type littermates) into the C57L/J background (a strain that constitutively exhibits low G6PD activity) through a breeding program. Of significance is that 78% of the F2 generation had G6PD activities <2 U/g Hb, levels similar to those of severe G6PD deficiency in human. The efficacy of this model was preliminary verified by the known haemolytic agent, naphthalene, as demonstrated by the decrease of GSH/GSSG ratio by 24.6% (P=0.032) and increase of methaemoglobin by 4.5 fold (P=0.8) when compared with the respective control without treatment. / Genetic analysis of 14 mutation hotpots was performed on 98 hemi-/homozygous and 17 heterozygous G6PD-deficient human subjects. We developed a novel Multiplex Primer Extension Reaction (MPER) assay and detected seven specific mutations in 97 subjects: c.1376G>T (33.7%), c.1388G>A (29.6%), c.871G>A + c.1311C>T (12.3%), c.95A>G (9.2%), c.392G>T (7.1%), c.1024C>T (6.2%) and c.1360C>T (1.0%). For the genotyping of 15 heterozygous female, all mutations were identified as follows: c.1376G>T/Normal (33.3%), c.1388G>A/Normal (26.7%), c.871G>A/Normal + c.1311C>T/Normal (20.0%), c.95A>G/Normal (13.3%) and c.392G>T./Normal (6.7%). The c.871G>A and 'silent' mutation c.1311 C>T was newly found to coexist in a high proportion of genotype in our population. / Glucose-6-phosphate dehydrogenase (G6PD)-deficient subjects are vulnerable to chemical-induced haemolysis if exposed to oxidative agents. Little is known, however, of the haemolytic effects of Chinese herbal medicine on G6PD-deficient subjects. Only one case study has reported that a G6PD-deficient newborn developed severe haemolysis after ingestion of Rhizoma Coptidis. Besides, recent studies reported that green tea and its constituents exerted pro-oxidative effects on cellular systems in culture. / Glucose-6-phosphate dehydrogenase deficiency is a genetic disorder inherited in the X-linked manner. The condition is prevalent in the Mediterranean region, Africa and Southeast Asia. In Hong Kong, the frequency of G6PD deficiency is around 4.5% in males and 0.3% in females. Over 140 specific mutations of the X-linked gene for G6PD have been characterized in various geographic regions. However, the local mutation pattern has not been clearly determined. / In conclusion, some Chinese herbal medicine, tea and tea polyphenols significantly altered the oxidative status of G6PD-deficient erythrocytes in vitro. Their in vivo effects on G6PD-deficient individuals would be further investigated by the novel G6PD-dificient mouse model. / In this study, we aim (1) to investigate effects of (a) a panel of Chinese Herbal Medicine (CHM), (b) tea and its constituents, on the oxidative status of human G6PD-deficient erythrocytes in vitro ; (2) to characterize the genotype of G6PD-deficiency in the Chinese population and their specific response to oxidative stress; (3) to develop a novel strain of mice as a model for study of chemicals agents on G6PD-deficient red cell in vivo. / Our results showed that six of eighteen CHM significantly reduced GSH levels in the G6PD-deficient erythrocytes (p<0.05, n=10). After exposure to 1 mg/mL of Rhizoma Coptidis, GSH levels in G6PD-deficient erythrocytes was decreased by 48.9 +/- 5.4% (P<0.001, n=10). At 5 mg/mL of Cortex Moutan, Radix Rehmanniae, Radix Bupleuri, Rhizoma Polygoni Cuspidati and Flos Chimonanthi, GSH levels were decreased significantly (P=0.001 to 0.004) by 51.8 +/- 7.6%, 25.9 +/- 6.7%, 21.0 +/- 6.9%, 17.5 $ 6.7% and 8.7 +/- 6.8% respectively. There were noticeable increases in levels of methaemoglobin by 2.8 fold (5 mg/mL, P=0.012) and 3.4 fold (10 mg/mL, P=0.016) in the presence of Rhizoma Coptidis and Cortex Moutan, respectively, in G6PD-deficient erythrocytes. / We also investigated the pro-oxidative effect of tea and its polyphenolic components on G6PD erythrocytes from G6PD-deficient (n=8) and normal adult (n=8) subjects. The tea extracts significantly reduced GSH and increased GSSG levels in G6PD-deficient erythrocytes in a dose-dependent manner (0.5-10 mg/mL), but not in normal erythrocytes. Similar dose-dependent responses to (-)-Epigallocatechin (EGC) and (-)-Epigallocatechin-3gallate (EGCG), but not to the other polyphenols, were observed. In G6PD-deficient cells, GSH was reduced by 43.3% (EGC at 0.05 mg/mL) and 33.3% (EGCG at 0.5 mg/mL), compared with pre-challenged levels. The concentration of methaemoglobin was increased significantly when these cells were challenged with tea extracts, and EGC. Plasma haemoglobin levels were higher in G6PD-deficient samples after exposure to tea extracts, EGCG, EGC and gallic acid, compared with those in normal blood. / Ko Chun Kay. / "August 2006." / Advisers: Tai Fai Fok; Kwai Har Karen Li. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1577. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. xxii-xliii). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

The development of technologies that enable efficient and reliable energy inter-conversion and storage is of key importance for tempering the intermittent availability of renewable energy sources, and thus for developing an energy economy based on sustainable, clean energy production. Solid oxide electrolysis cells (SOECs) may be used to store excess electrical energy as hydrogen, while solid oxide fuel cells (SOFCs) could convert back hydrogen into electricity, thus balancing energy availability and demand. However, the current state-of-the-art hydrogen electrode used in both SOECs and SOFCs, the Ni-yttria-stabilised zirconia cermet (Ni-YSZ), is unreliable in conjunction with intermittent energy sources, in particular due to its innate redox instability. This thesis explores the fundamental properties of various inherently redox stable A-site deficient titanate perovskite systems (A1-αBO3, B = Ti), seeking to uncover the principles that enhance their properties so that they may be used to replace Ni-YSZ. In particular, this work demonstrates that the versatility of perovskites with respect to the introduction of lattice defects such as vacancies and cation substitutions enables considerable improvements in the extent of reduction, electronic conductivity and overall electrochemical activity. Most importantly, the defect chemistry context set by the presence of A-site vacancies was found to trigger the exsolution of electrocatalytically active nanoparticles from the parent perovskite, upon reduction. This is an entirely new phenomenon which was explored and exploited throughout this study to produce perovskite surfaces decorated with uniformly distributed catalytically active nanoparticles. As demonstrated in this study, the exsolution phenomenon excels in terms of producing nanoparticles with uniform size, distribution, diverse composition and ‘unconventional' surface anchorage. The resulting enhanced properties, and especially the exsolution phenomenon, contributed coherently towards improving the suitability of the perovskites developed here towards their application as hydrogen electrode materials. Consequently, when integrated into SOEC button cells as hydrogen electrodes, they exhibited a step-change increase in performance compared to other perovskites considered to date. Many of the principles and perovskite defect chemistry explored and exemplified in this study on perovskite titanates may be extended to other perovskites as well. In particular the advanced control and understanding achieved in this work over the exsolution phenomenon may inspire the formulation of new and sophisticated oxide materials with advanced functionality.

Neptunium, with its rich redox chemistry, has a special position in the chemistry of actinides. With a decades-long history of development of aqueous separation methods for used nuclear fuel (UNF), management of neptunium remains an unresolved issue because of its not clearly defined redox speciation. Neptunium is present in two, pentavalent (V) and hexavalent (VI) oxidation states, both in their dioxocation O=Np=O neptunyl form, which differ greatly in their solvent extraction behavior. While the neptunium(VI) dioxocation is being very well extracted, the dioxocation of pentavalent neptunium is practically non-extractable by an organic solvent. As a result, neptunium is not well separated and remains distributed in both organic and aqueous extraction phases. The aim of this study was to develop or enhance the understanding of several key topics governing the redox behavior of neptunium in nitric acid medium, which are of vital importance for the engineering design of industrial-scale liquid-liquid separation systems. In this work, reactions of neptunium(V) and (VI) with vanadium(V) and acetohydroxamic acid - two redox agents envisioned for adjusting the neptunium oxidation state in aqueous separations ��� were studied in order to determine their kinetic characteristics, rate laws and rate constants, as a function of temperature and nitric acid concentration. Further were analyzed the interactions of neptunium(V) and (VI) with nitrous acid, which is formed as a product of radiolytic degradation of nitric acid caused by high levels of radioactivity present in such systems. Once HNO��� is distributed between both the aqueous solutions and organic solvent, nitrous acid is also formed in both phases and has a key influence on redox speciation of neptunium; therefore, the effects of gamma-radiation on the redox speciation of neptunium were investigated. The work also includes the results of examination of scavenging of nitrous acid by hydrogen peroxide, which is generated along with nitrous acid during radiolysis of aqueous solutions of nitric acid, and also by chemical reactions with added scavenging agents (methylurea, acetohydroxamic acid). / Graduation date: 2013

Tyrosyl radicals can facilitate proton-coupled electron transfer (PCET) reactions that are linked to catalysis in many biological systems. One such protein system is ribonucleotide reductase (RNR). This enzyme is responsible for the conversion of ribonucleotides to deoxyribonucleotides. The beta2 subunit of class Ia RNRs contains a diiron cluster and a stable tyrosyl radical (Y122*). Reduction of ribonucleotides is dependent on reversible, long-distance PCET reactions involving Y122* located 35 Å from the active site. Protein conformational dynamics are postulated to precede diiron cluster assembly and PCET reactions in RNR. Using UV resonance Raman spectroscopy, we identified structural changes to histidine, tyrosine, and tryptophan residues with metal cluster assembly in beta2. With a reaction-induced infrared spectroscopic technique, local amide bond structural changes, which are associated with the reduction of Y122*, were observed. Moreover, infrared spectroscopy of tyrosine-containing pentapeptide model compounds supported the hypothesis that local amide bonds are perturbed with tyrosyl radical formation. These findings demonstrate the importance of the amino acid primary sequence and amide bonds on tyrosyl radical redox changes. We also investigated the function of a unique tyrosine-histidine cross-link, which is found in the active site of cytochrome c oxidase (CcO). Spectrophotometric titrations of model compounds that mimic the cross-link were consistent with a proton transfer role in CcO. Infrared spectroscopic data support the formation of tyrosyl radicals in these model compounds. Collectively, the effect of the local structure and the corresponding protein dynamics involved in tyrosyl radical-mediated PCET reactions are illustrated in this work.

EPR spectroscopy and isotopic substitution were used to gain increased knowledge about the proton-coupled electron transfer (PCET) mechanism for the reduction of the tyrosine D radical (YD*) in photosystem II. pL dependence (where pL is either pH or pD) of both the rate constant and kinetic isotope effect (KIE) was examined for YD* reduction. Second, the manner in which protons are transferred during the rate-limiting step for YD* reduction at alkaline pL was determined. Finally, high field electron paramagnetic resonance (EPR) spectroscopy was used to study the effect of pH on the environment surrounding both the tyrosine D radical and the tyrosine Z radical (YZ*). At alkaline pL, it was determined that the proton and electron are both transferred in the rate-limiting step of YD* reduction. At acidic pL, the proton transfer occurs first followed by electron transfer. Proton inventory experiments indicate that there is more than one proton donation pathway available to YD* during PCET reduction at alkaline pL. Additionally, the proton inventory experiments indicate that at least one of those pathways is multiproton. High field EPR experiments indicate that both YD* and YZ* are hydrogen bonded to neutral species. The EPR gx component for YD* is invariant with respect to pH. Analysis of the EPR gx component for Yz* indicates that its environment becomes more electropositive as the pH is increased. This is most likely due to changes in the hydrogen bond strength

Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Embargoed. Vita. Bibliography: 97-112.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 135-155.

Haemophilus influenzae encounters niches within the human host that are predicted to differ in availability of oxygen and reactive nitrogen species (RNS: nitrite and nitric oxide), which influence the environmental redox state. Previously reported data has indicated that an altered redox condition could serve as a signal recognized by H. influenzae to optimize its survival within host microenvironments. To elucidate the role of redox signaling in virulence, we examined regulation by the FNR homolog of H. influenzae, whose counterpart in E. coli has been reported to be a direct oxygen sensor and a regulator of genes responsible for RNS metabolism and resistance. Many members of the FNR regulon are subject to coordinated transcriptional control by NarP, a regulator in E. coli that is activated by cognate sensor NarQ in response to environmental nitrite. To study the regulatory activities of FNR and NarQ-NarP in H. influenzae, I targeted a gene predicted to be FNR-regulated, nrfA, which encodes nitrite reductase, a periplasmic cytochrome-c involved in anaerobic respiration. The fnr, narP and nrfA mutants were assayed for nitrite reduction, which implicated the roles of FNR, NarP and NrfA in RNS metabolism. Using Western blot detection of an epitope-tagged reporter protein fused to the endogenous nrf promoter (Pnrf-HA), I demonstrate that FNR and NarP, but not NarQ, are required for full activation of the nrf promoter. Additionally, Pnrf-HA expression increases as oxygen becomes depleted and decreases when exposed to high concentrations of nitrite, implying that the nrfpromoter is modulated by environmental redox signals. FNR of E. coli has been implicated in regulation of resistance mechanisms to a reactive nitrogen species, nitric oxide (NO), which is produced by innate immune cells during infection as a host defense mechanism. A mutant lacking FNR is more sensitive to NO exposure and killing by activated macrophages than wild type H. influenzae after anaerobic pre-growth. Mutants of nrfA and narP have been tested and initial experiments have shown both mutants have a lesser NO sensitivity phenotype as compared to the fnr mutant, suggesting that other factors could be involved in FNR-mediated NO resistance in H. influenzae. Upon examination of potential factors that might be involved to this phenotype, we discovered FNR-regulated gene, ytfE, which contributes to defense against nitrosative stress. The fnr and ytfE mutants are more susceptible to killing by activated macrophages indicating that FNR regulation of ytfE might be important for in vivo infection.

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / In search of a distinctive chemical education, with meaning for social and productive life of young high school students, the present study investigates how the theme "pollution" may facilitate the construction of the teaching and learning process of redox reactions content of high school students under a STSE (Science-Technology-Society-Environment) approach. For this, firstly, we sought theoretical references about the conceptual part of redox reactions and the theme "pollution". Then, we conducted an analysis of papers published in the journal Chemistry at the New School , with the intention of investigating how the redox reactions have been explored, their different approaches and their impact on the teaching of chemistry. From this, we developed a proposal to approach the redox reactions in the classroom, which was assessed through interventions with the second year high school students from a public school of Santa Maria, RS. Interventions in the classroom were carried out in two steps, both based on the methodology of the three pedagogical moments. The first developed inorganic redox content associated with the pollution of soil, whereas the second involved some organic redox reactions through the water pollution, specifically the treatment of effluents. This is a qualitative research. To collect data, we use questionnaires and textual productions, they were analyzed according to the Discursive Textual Analysis. The results allowed us to conclude that the development of redox reactions associated with the theme "pollution" by a STSE perspective favored teaching and learning of chemistry, as we observe an improvement in the construction of students knowledge. / Na busca de um ensino de química diferenciado, com significado para vida social e produtiva de jovens estudantes do nível médio, a presente pesquisa investiga como a temática Poluição pode favorecer a construção do processo de ensino aprendizagem do conteúdo de reações redox para estudantes de nível médio sob um enfoque CTSA (Ciência-Tecnologia-Sociedade-Ambiente). Para isso, primeiramente, buscamos referenciais teóricos a respeito da parte conceitual das reações redox e a temática Poluição . Em seguida, realizamos uma análise dos artigos publicados na revista Química Nova na Escola, com a intenção de investigar como as reações redox estão sendo exploradas, suas diferentes abordagens e sua repercussão no ensino de Química. A partir disso, desenvolvemos uma proposta para abordar as reações redox em sala de aula, que foi avaliada através de intervenções realizadas com estudantes da segunda série do nível médio de um colégio estadual de Santa Maria, RS. As intervenções em sala de aula foram realizadas em duas etapas, ambas baseadas na metodologia dos Três Momentos Pedagógicos. A primeira desenvolveu o conteúdo inorgânico de oxirredução associado à poluição do solo, enquanto que a segunda envolveu algumas reações orgânicas de oxirredução através da poluição da água, especificamente o tratamento de efluentes. A pesquisa é de caráter predominantemente qualitativo. Para a coleta de dados, utilizamos de questionários e produções textuais, analisados de acordo com a Análise Textual Discursiva. Os resultados encontrados nos permitiram concluir que o desenvolvimento das reações redox associadas a temática Poluição por um perspectiva CTSA favoreceram o ensino e a aprendizagem de Química, visto que observamos um avanço na construção do conhecimento dos estudantes.