DISSERTAÇÃO DE MESTRADO - PROGRAMA DE PÓS-GRADUAÇÃO EM QUIMICA

URI Permanente para esta coleçãohttps://tedebc-teste.ufma.br/handle/tede/881

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Navegando DISSERTAÇÃO DE MESTRADO - PROGRAMA DE PÓS-GRADUAÇÃO EM QUIMICA por Autor "ARAUJO, Adriana Barbosa"

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    Blendas à base de quitosana e poliacrilamida revestidas com ZnO como catalisadores para a fotodegradação do azul de metileno
    (Universidade Federal do Maranhão, 2017-08-31) MAIA, Luziane Freire; BEZERRA, Cícero Wellington Brito; 311.559.103-97; http://lattes.cnpq.br/1474300723265204; ARAUJO, Adriana Barbosa; LUZ, Rita de Cássia
    Textile dyes are recognized as a serious environmental problem due the huge quantity discharged annually in water environments, and its dangerous health risks. Efficient and low cost methods for effluent treatment and recovery of impacted areas are necessary and increasingly researched. The photocatalytic degradation is one of these methods, and this work investigated the feasibility of photocatalytic degradation of the methylene blue (AM) dye from aqueous solutions (5 and 15 mgL-1) in the presence and absence of prepared catalysts (chitosanpolyacrylamide (QT-P), and chitosan-polyacrylamide doped with Zn, QT-P/ZnO). The chitosan and polyacrylamide interaction was studied as a function of the degree of deacetylation of chitosan (64, 82 and 90%), previously obtained from the deacetylation of chitin extracted from shrimp exoskeletons. The QT-P/ZnO heterostructures were characterized by FTIR, XRD and MEV. The photocatalysis experiments were performed considering the effects of pH, contact time and mass variation. AM samples were irradiated with mercury vapor lamp (black light,50W mm-2) and photocatalysis was monitored by UV-Vis spectrophotometry, at the peak wavelength of 665 nm. The results indicated that QT-P interaction is favored by deacetylation. All the materials prepared showed a catalytic effect, but the heteroestructure obtained from the chitosan with the highest degree of deacetylation (QTC-P/ZnO) was the most efficient: 99.2% (AM, 15 mg L-1, 50 min) and 99.8% (AM, 5 mg L-1, 20 min).
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    Detecção fotoeletroanalítica de adrenalina baseada em DNA e nanopartículas de TiO2 sensibilizadas com Bis (Etilenoditio) tetratiofulvaleno explorando luz de led
    (Universidade Federal do Maranhão, 2017-09-11) SANTOS, Thiago Augusto Dias; DAMOS, Flávio Santos; 846.255.703-87; http://lattes.cnpq.br/0915687070195770; ARAUJO, Adriana Barbosa; http://lattes.cnpq.br/1008844766307732; SANTANA, Sirlane Aparecida Abreu; http://lattes.cnpq.br/1052349578152491
    A photoelectroanalytical sensor was developed, based on deoxyribonucleic acid (DNA) and anatase titanium dioxide (TiO2) nanoparticles sensitized with bis(ethylenedithio)tetrathiofulvalene (BEDT-TTF) for determination of the adrenaline, also denominated as epinephrine. The photosensor composite developed was denominated as BEDT-TTF/DNA/TiO2/ITO and shows a high photocurrent for the adrenaline under light emitting diode (LED) irradiation in comparison to each component of the composite material. Under optimized conditions, the BEDTTTF/DNA/TiO2/ITO sensor shows a linear response range from 10 nmol L-1 up to 100 μmol L-1 with a sensitivity of 8,1 nA L μmol-1 and limit of detection of 1 nmol L-1 for the adrenaline. The photoelectrochemical sensor showed high photocurrent to adrenaline in comparison to photocurrent response to ascorbic acid and uric acid. The BEDT-TTF/DNA/TiO2/ITO photoelectrochemical sensor was successfully applied to urine samples, with recovery values between 96 and 106%.