scholarly journals Rapid and facile chemical actinometric protocol for photo-microfluidic systems using azobenzene and NMR spectroscopy

RSC Advances ◽  
2017 ◽  
Vol 7 (47) ◽  
pp. 29815-29820 ◽  
Author(s):  
Nassim El Achi ◽  
Youssef Bakkour ◽  
Laëtitia Chausset-Boissarie ◽  
Maël Penhoat ◽  
Christian Rolando
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Yield ◽  
Photon Flux ◽  
Microfluidic Systems

A new protocol for determining the photon flux inside a photomicroreactor is described using (E)-azobenzene and NMR spectroscopy which does not require the determination of the quantum yield of the unstableZisomer.

Determination of photonic efficiency and quantum yield of formaldehyde formation in the presence of various TiO2 photocatalysts

2001 ◽  
Vol 44 (5) ◽  
pp. 279-286 ◽  
Author(s):  
C. Wang ◽  
D.W. Bahnemann ◽  
J.K. Dohrmann
Keyword(s):  
Quantum Yield ◽  
Hydroxyl Radicals ◽  
Critical Concentration ◽  
Photon Flux ◽  
Tio2 Photocatalysts ◽  
Ph Values ◽  
Optimum Ph ◽  
Photonic Efficiency ◽  
True Quantum

Illumination of aqueous TiO2 suspentions yields hydroxyl radicals, which can be trapped by methanol producing formaldehyde (HCHO). In this work, the photonic efficiency and quantum yield of HCHO formation in colloidal TiO2 solutions and, P25 and UV 100 suspensions have been determined. Differences in photocatalytic activity of the three photocatalysts have been found and are discussed. The photonic efficiency of HCHO formation in the presence of P25 and UV 100 depends on the concentration of TiO2 and the pH. The critical concentration is 2.5 g/L. Below this, the photonic efficiency with P 25 is higher than with UV 100, and vice versa. Optimum pH values for P25 and UV 100 giving the maximum photonic efficiency are 7.7 and 10.4, respectively. Compared to P25 and UV 100, the true quantum yield of HCHO formation in colloidal TiO2 solution varies a little with pH and virtually does not change with the amount of loading of TiO2. The true quantum yield varies as the inverse square root of light intensity. The quantum yield increases from 0.02 to 0.08 when the absorbed photon flux decreases from 8.1 × 10-7 Ein/L s to 4.9 × 10-8 Ein/L s. A simple model is presented to explain the experimental observation.

Quantitative Determination of Krill Oil Composition by ATR-FTIR, NIR, and 31P NMR Spectroscopy

2020 ◽  
Author(s):  
Ashraf Ismail ◽  
Sanaz Molaye Moghaddam ◽  
Jean-Pierre MetabanzoulouSarya Aziz ◽  
Jacqueline Sedman ◽  
Mazen Bahadi
Keyword(s):  
Nmr Spectroscopy ◽  
Quantitative Determination ◽  
31P Nmr ◽  
31P Nmr Spectroscopy ◽  
Krill Oil ◽  
Oil Composition

Determination of alcohols in mixtures by 19F NMR spectroscopy using hexefluoroacetone reagent

1982 ◽  
Vol 47 (7) ◽  
pp. 1973-1978 ◽  
Author(s):  
Jiří Karhan ◽  
Zbyněk Ksandr ◽  
Jiřina Vlková ◽  
Věra Špatná
Keyword(s):  
Standard Deviation ◽  
Nmr Spectroscopy ◽  
Standard Method ◽  
Internal Standard ◽  
Internal Standard Method ◽  
Concentration Region ◽  
Experimental Conditions ◽  
Curve Method ◽  
Sample Preparation Procedure

The determination of alcohols by 19F NMR spectroscopy making use of their reaction with hexafluoroacetone giving rise to hemiacetals was studied on butanols. The calibration curve method and the internal standard method were used and the results were mutually compared. The effects of some experimental conditions, viz. the sample preparation procedure, concentration, spectrometer setting, and electronic integration, were investigated; the conditions, particularly the concentrations, proved to have a statistically significant effect on the results of determination. For the internal standard method, the standard deviation was 0.061 in the concentration region 0.032-0.74 mol l-1. The method was applied to a determination of alcohols in the distillation residue from an oxo synthesis.

Determination of Tautomeric Preference of Fenobam in Solution by High Resolution NMR Spectroscopy

2020 ◽  
Author(s):  
Xuming Sha ◽  
Shaodong Chen ◽  
Xiaojing Zheng ◽  
Xin Ye ◽  
Hailu Zhang ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
High Resolution Nmr
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