Polarography of urea and thiourea derivatives. XIII. Kinetics of base catalysed decomposition of S-substituted thioureas in alkaline solution

1964 ◽  
Vol 29 (9) ◽  
pp. 2115-2133 ◽  
Author(s):  
M. Fedoroňko ◽  
P. Zuman
Keyword(s):  
Alkaline Solution ◽  
Thiourea Derivatives ◽  
Kinetics Of

Reaction Kinetics of Poly-Si Etching in TMAH Solution

2021 ◽  
Vol 314 ◽  
pp. 60-65
Author(s):  
Taegun Park ◽  
Sangwoo Lim
Keyword(s):  
Reaction Kinetics ◽  
Alkaline Solution ◽  
Etching Rate ◽  
Tetramethylammonium Hydroxide ◽  
Dissolved Gas ◽  
Metal Free ◽  
Effect Of Water ◽  
Detailed Kinetics ◽  
Kinetics Of ◽  
Tmah Solution

Tetramethylammonium hydroxide (TMAH) is a metal-free strong alkaline solution which can etch poly-Si. The concentration of dissolved gas as well as the concentration of TMAH affects etching rate of poly-Si. The detailed kinetics of poly-Si etching in TMAH solution is investigated in this study. The effect of water and TMAH concentration on the etching kinetics of poly-Si was investigated by using various concentrations of TMAH solution. It is found that H2O in TMAH solution plays an important role in etching poly-Si. Presence of dissolved CO2 and O2 in TMAH solution tends to inhibit etching of poly-Si. The concentration of dissolved CO2 and O2 in TMAH were reduced by Ar bubbling, thereby the poly-Si etching rate increased.

scholarly journals A novel experimental approach for studying spontaneous imbibition processes with alkaline solutions

2019 ◽  
Vol 89 ◽  
pp. 04004
Author(s):  
T. Chevalier ◽  
J. Labaume ◽  
A. Delbos ◽  
T. Clemens ◽  
V. M. Waeger ◽  
...  
Keyword(s):  
Interfacial Tension ◽  
Alkaline Solution ◽  
Recovery Process ◽  
Oil Field ◽  
Spontaneous Imbibition ◽  
Alkaline Solutions ◽  
Vienna Basin ◽  
Natural Surfactants ◽  
Current Flows ◽  
Kinetics Of

Spontaneous imbibition processes can play an important role in oil production. It can be enhanced or influenced by wettability changes generated by properly designed chemicals or by the natural surfactants resulting from reactive crude oils in the presence of alkaline solutions. The reaction of basic salts with some components of oil can, indeed, lead to the formation of natural soaps that reduces the interfacial tension between oil and brine. The latter scenario is studied herein on samples and oil from the St Ulrich oil field in the Vienna basin. To that end, spontaneous imbibition experiments were performed with two brines differing by the absence or presence of alkali. We first present a general novel technique to monitor saturation changes on small rock samples for the purpose of assessing the efficiency of a given recovery process. Samples of only 15 mm in diameter and 20 mm in length and set at irreducible saturation were fully immersed in the solution of interest, and the evolution of the samples’ saturation with time was monitored thanks to a dedicated NMR technique involving the quantification of the sole oil phase present within the sample. A fully-3D imbibition configuration was adopted, involving counter-current flows through all faces of the sample. The experimental method is fast for two reasons: (i) the kinetics of capillary imbibition process is proportional to the square of sample size, i.e. very rapid if accurate measurements can be acquired on tiny samples, (ii) the present 3D situation also involves faster kinetics than the 1D configuration often used. The NMR technique was crucial to achieve such conditions that cannot be satisfied with conventional volumetric methods. The kinetics of oil desaturation during spontaneous imbibition is interpreted with the help of an analytical 3D diffusion model. For the alkaline solution, the diffusion coefficient is reduced by a factor of only two compared to the non-alkaline brine, although the interfacial tension between the oil and the imbibing solution is reduced by a factor of 10. Hence, a wettability change to a more water wet state has to be assumed when the alkaline solution replaces the non-alkaline solution in the imbibition process. However, no significant impact on the final saturation was observed.

A Review on Heat Released in early Geopolymerization by Calorimetric Study

2019 ◽  
Vol 967 ◽  
pp. 236-240
Author(s):  
Mohamed Rosnita ◽  
A.R. Razak ◽  
Mohd Mustafa Al Bakri Abdullah
Keyword(s):  
Reaction Kinetics ◽  
Chemical Reaction ◽  
Alkaline Solution ◽  
Curing Temperature ◽  
Calorimetric Study ◽  
Calorimetric Data ◽  
Pozzolanic Material ◽  
Exothermic Chemical Reaction ◽  
Kinetics Of ◽  
Heat Released

An exothermic chemical reaction between cement and water or is called as hydration of cement produced heat in which gives significance impact to the cement or concrete produced. This hydration of cement is similar to geopolymerization as in geopolymerization, heat is liberated when any pozzolanic material mixes with alkaline solution. Heat released for both hydration of cement and geopolymerization can be measured in a form of calorimetric data. This paper reviews on the use of heat released information for a better understanding on the reaction kinetics of geopolymerization and correlating the heat released with several factors including concentration of alkaline solution, mixing designation and curing temperature.

Kinetics of Repassivation of Nickel/Copper Alloys in Alkaline Solution

1984 ◽  
Vol 131 (7) ◽  
pp. 1515-1522 ◽  
Author(s):  
R. D. K. Misra ◽  
G. T. Burstein
Keyword(s):  
Alkaline Solution ◽  
Copper Alloys ◽  
Nickel Copper ◽  
Kinetics Of
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