Deactivation of Singlet Oxygen by Titanium Dioxide in Aqueous Solution Studied by Phosphorescence Quenching with Porphyrin Photosensitizers

Dalam kajian ini, ZnO dan TiO2 digunakan sebagai fotomangkin dalam pendegradasian pewarna New Methylene Blue N (NMBN). Kadar fotodegradasi diukur menggunakan alat spektrofotometer UV-Vis. Dalam kajian ini, New Methylene Blue N menunjukkan nilai serapan pada λ = 590 nm dan λ = 286 nm. Lampu UV (λ = 354 nm) digunakan dalam proses fotodegradasi. Dalam proses degradasi menggunakan ZnO menunjukkan 81.42% NMBN terdegradasi pada λ = 590 nm dan 77.75% pada λ = 286 nm. Sebaliknya, degradasi menggunakan TiO2 adalah 25.68% pada λ = 590 nm dan 26.37% pada λ = 286 nm. Peratus degradasi New Methylene Blue N ialah 88.89% dan 68.94% pada masing-masing λ = 590 nm dan λ = 286 nm apabila ditambahkan dengan H2O2. Campuran ZnO dan TiO2 dalam nisbah 85: 15 (0.085 g; 0.015 g) merupakan campuran fotomangkin yang paling optimum iaitu dengan peratus degradasi NMBN sebanyak 96.97% dan 93.61% pada λ = 590 nm dan λ = 286 nm. Penambahan ion logam Cu2+ memberikan peratus degradasi tertinggi berbanding ion logam lain iaitu 83.83% pada λ = 590 nm. Penambahan ion logam Pb2+ memberikan peratus degradasi tertinggi pada λ = 286 nm iaitu 81.25% pewarna terdegradasi. Keadaan optimum dicapai pada pH 5.90, dengan peratus degradasi tertinggi iaitu 92.84% dan 89.30% pada masing-masing λ = 590 nm dan λ = 286 nm. Kata kunci: New Methylene Blue N; fotodegradasi; larutan; ZnO; TiO2 In this study, ZnO and TiO2 are used as photocatalyst to degrade the dye, New Methylene Blue N (NMBN). The photodegradation rate was measured using UV-Visible spectrophotometer. In this study, New Methylene Blue N showed absorption values at λ = 590 nm and λ = 286 nm. UV lamp (λ = 354 nm) is used in the photodegradation process. Results showed that ZnO is a better photocatalyst compared to TiO2. The degradation by ZnO showed that 81% of NMBN was degraded at λ = 590 nm and 77.75% at λ = 286 nm. In contratst, the degradation using TiO2 was 25.68% at λ = 590 nm and 26.37% at λ = 286 nm. The percent degradation of New Methylene Blue N is 88.89% and 68.94% at λ = 590 nm and λ = 286 nm respectively when H2O2 was added. A mixture of ZnO and TiO2 in the ratio of 85: 15 (0.085 g: 0.015 g) is the most optimum ratio for the mixed photocatalyst where the degradation percentage of NMBN are 96.97% and 93.61% at λ = 590 nm and λ = 286 nm. The addition of Cu2+ metal ion gave the highest percentage of degradation (83.83% at λ = 590 nm) compared to other metal ions. The addition of Pb2+ gave the highest percentage of degradation at λ = 286 nm with 81.25% degradation of the dye. The optimum condition was achieved at pH 5.90, which gave the highest percentage degradation, 92.84% and 89.30% at λ = 590 nm and λ = 286 nm respectively. Key words: New Methylene Blue N; photodegradation; aqueous; ZnO; TiO2

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Direct Observation and Quantitative Characterization of Singlet Oxygen in Aqueous Solution upon UVA Excitation of 6-Thioguanines

The Journal of Physical Chemistry B ◽

10.1021/jp109590t ◽

2011 ◽

Vol 115 (8) ◽

pp. 1889-1894 ◽

Cited By ~ 34

Author(s):

Yazhou Zhang ◽

Xianchun Zhu ◽

Joshua Smith ◽

Makeisha T. Haygood ◽

Ruomei Gao

Keyword(s):

Aqueous Solution ◽

Singlet Oxygen ◽

Direct Observation ◽

Quantitative Characterization

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IMMOBILIZATION OF STRONTIUM FROM AN AQUEOUS SOLUTION USING THE CRYSTALLINE HYDROUS TITANIUM DIOXIDE FIBERS

Chemistry Letters ◽

10.1246/cl.1981.957 ◽

1981 ◽

Vol 10 (7) ◽

pp. 957-960 ◽

Cited By ~ 5

Author(s):

Takayoshi Sasaki ◽

Yu Komatsu ◽

Yoshinori Fujiki

Keyword(s):

Aqueous Solution ◽

Titanium Dioxide ◽

Titanium Dioxide Fibers

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Effect of two formulations of 10% sodium ascorbate on fracture resistance of endodontically treated tooth submitted to dental bleaching with hydrogen peroxide associated titanium dioxide nanoparticles

Journal of Research in Dentistry ◽

10.19177/jrd.v2e1201413-21 ◽

2014 ◽

Vol 2 (1) ◽

pp. 13

Author(s):

Francisco Carlos Bontorim ◽

Milton Carlos Kuga ◽

Sabrina Spinelli Cioffi ◽

Marcus Vinicius Reis Só ◽

Gisele Faria ◽

...

Keyword(s):

Aqueous Solution ◽

Hydrogen Peroxide ◽

Titanium Dioxide ◽

Fracture Resistance ◽

Composite Resin ◽

Positive Control ◽

Sodium Ascorbate ◽

Resistance Testing ◽

Dental Bleaching ◽

Endodontically Treated Tooth

PURPOSE: This study evaluated the effect of 10% sodium ascorbate (10SA), in gel (10SAg) or aqueous solution (10SAs) formulations, on fracture resistance of endodontically treated tooth submitted to dental bleaching procedures with 15% hydrogen peroxide associated with titanium dioxide (15HP-TiO2) nanoparticles and photoactivated by LED-laser. MATERIAL AND METHODS: Forty maxillary premolars were endodontically-treated and embedded in acrylic resin up to the cement-enamel junction. The specimens were divided into four groups (n=10): G1 (negative control): no bleaching, coronal access restored with composite resin; G2 (positive control): three dental bleaching sessions using 15HP-TiO2 and LED-laser photoactivation and restored with composite resin (positive control); G3 (10SAg): similar procedures to G2, but applied 10SA, in gel formulation, for 24 hours before restoration; G4 (10SAs): similar procedures to G3, but applied 10SA, in aqueous solution formulation. The 15HP-TiO2 was applied on buccal and lingual surfaces of the crown tooth and inside the pulp chamber and photoactivated by LED-laser. Between each bleaching session, the teeth were maintained in artificial saliva, at 37oC, for 7 days. In sequence, the teeth were submitted to fracture resistance testing using an eletromechanical machine test. The data was analyzed using Kruskal Wallis test (p = 0.05) RESULTS: There are no differences significant among the groups in relation to fracture resistance of endodontically treated teeth (p>0.05). CONCLUSIONS: The use of 10% sodium ascorbate, in gel or aqueous solution formulations, did not interfered on the fracture resistance teeth after dental bleaching using 15HP-TiO2 and LED-laser photoactivation.

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