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Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
Polymerization of Silica in Water-Effect of Ultrasonic Waves on Coagulation and Sedimentation
Nezameddin
Daneshvar
Hossein
Salavati
Polymerization rates of silica at various concentrations and pHs have been studied via nephelometry. The ability and potency of ultrasonic radiation on the coagulation process in aqueous samples with and without silica colloidal particles have been extensively investigated. Factors affecting the rate and filtration volume such as silica concentration, time of radiation, temperature, and frequency of radiation have also been studied. The results indicate that ultrasonic radiation has two folded effect: on the one hand it breaks down the large flocs and on the other it results in the flocculation of small particles. The above mentioned effects lead to a reduced uniformity coefficient for the filter beds made of such coagulated particles.
Silica polymerization
Silica colloidal particles
Ultrasonic Waves
Coagulation
sedimentation
Flocculation
Filtration rate
Nephelometry
1992
12
01
1
7
Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
Base Catalyzed Cyclization and Isomerization of 3-Propargylmercapto-1, 2,4-Triazine to Thiazolo [3,2-b][1,2,4]-Triazines
Majid
Heravi
Transformation of 3-propargylmercapto-6 methyl-1, 2,4-triazin- 5 (2H)- one (1; R=CH3) to 3,6- dimethyl-7H- thiazolo [3,2-b] [1, 2, 4] triazin -7- one (2) is performed under basic condition. The formation of (2) may be mainly due to the high reactivity of acetylenes towards nucleophiles and isomerization of the intermediate.
Cyclization
Isomerization
3-Propargylmercapto-1
2
4- triazine
Thiazolo [3
2-b][1
4]- triazine
1992
12
01
8
11
Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
Complexation of Hydronium Ion with Several Crown Ethers in Nitromethane Solution
Mihammad Kazem
Amini
The interaction between hydronium ion and several crown ethers was studied via conductometry in nitromethane at 25 °C and 1H-NMR techniques. The stabilities of the resulting 1:1 complexes were determined from the conductance data and found to vary in the order DC18C6 > 18C6 > DB30C10 > DB24C8 > DB18C6 > ~B15C5 > DB21C7. For the first time, evidences for the formation of a 2:1 sandwich complex between the smaller crown ethers (i. e. B15C5 and 18 crowns) and hydronium ion in solution were observed by monitoring the molar conductance of hydronium ion as a function of the ligand to cation mole conductance of hydronium ion as a function of the ligand to cation mole ratio. The 1H-NMR data support the existence of such 2:1 adduct in solution.
Hydronium ion
Crown ether
Nitromethane
Conductometry
NMR
1992
12
01
12
18
Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
Determination of the Stability Constant of Vanadium (V) with Alaine
Saeed
Abedini Khorrami
Farrokh
Gharib
Karim
Zare
Hossein
Aghai
Formation equilibria of dioxy vanadium (V) complex with alanine in acidic media (pH<2.3) has been investigated potentiometrically and spectrophotometrically. In this condition the 1:1 complex has the formula VO2Y, where Y¯ represent the fully dissociated aminocarboxylate anion. The stability constant of VO2Y was determined as log KVO2Y=11.32±0.35 at 25±0.1 °C and I=1 mol per liter of sodium perchlorate. The protonation constant of alanine was also determined poteniumetrically under above condition.
Stability constant
sodium meta vanadate
Alanine
Dioxy vanadium complexes
Vanadium aminocarboxylates
1992
12
01
19
24
Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
Isobaric vapor-Liquid Equilibrium of Ethyl-Acetate+ 2-Propanol and Ethyl Acetate+ Ethanol Mixtures at 84.8 kPa
Mohamad Taghi
Zafarani Moattar
Abdorreza
Mirhoseni
Accurate vapor-liquid equilibrium data have been obtained for ethyl acetate + 2-propanol and ethyl acetate + ethanol mixtures at 84.8 kPa, and the results are discussed thermodynamically. The vapor-liquid equilibrium data are correlated with redlich-Kister, Margules, Van-Laar and Ortega, equations the parameters and standard deviation of which are calculated and reported. The best correlation is found in the case of the Ortega's equation.
Vapor-Liquid Equilibrium
Azeotropes
Ethyl acetate-2-Propanol
Ethyl acetate-Ethanol
1992
12
01
25
28
Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
Comparative Gas Chromatography of Halides Using Different Substituted Phenylboronic Acids as Derivatizing Reagents
Ali
Sarafraz Yazdi
W.I.
Stephen
The GC of halides (chloride, bromide and iodide) using phenylboronic acid (PBA), 4-bromophenylboronic acid (BPBA), 3, 5 bis (trifluoromethyl) phenylboronic acid (FPBA) and 2,4- dichlorophenylboronic acid (CPBA) as derivatizing reagents are compared. The reactions are carried out in the presence of mercuric salts. The detection systems used are FID and ECD. The thermal analysis of the compounds are studied prior to GC to get an indication of the likely operating temperatures. The unsubtituted phenylboronic acid show better volatility and FID response, but substituted phenylboronic acids exhibit better responses using ECD system. Finally FPBA is examined for the possible use in quantitative determination of chloride, bromide and iodide using solvent extraction procedure and ECD detection system. Detection limits for chloride, bromide and iodide are reported in the range of 0.29-0.35 pg.
Halides
Substituted phenylboronic acid
Gas-Liquid-Chromatography
Derivatization
1992
12
01
29
34
Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
Polymer Gel-Liquid Equilibria Using Uniface-FV
Hamid
Modarress
Ali
Eliassi
Based on Gibbs-Duhem law and using UNIFAC-FV computer algorithm, the activity of polymer component in polymer-solvent systems is determined. The variation of activity of components with concentration at different temperatures are used to find the equilibrium concentration, UCST, and LCST for the systems. Also by generalization of the method, Gel-Liquid equilibrium is studied in some three component systems: polymer-solvent-solvent..
Uniface
Uniface-FV
Group contribution
Polymer solution
Phase equilibria
Activity
1992
12
01
35
42
Iranian Journal of Chemistry and Chemical Engineering
Iran. J. Chem. Chem. Eng.
1021-9986
1021-9986
1992
11
2
A Correlation for the Prediction of the Adiabatic Joule-Thomson Coefficient of Pure Gases and Gas Mixtures
Mohsen
Edalat
Ramin
Bozorgmehri Boozarjomehry
Jalal
Basiri Parsa
A correlation based on the general form of cubic equations of state has been derived. This equation provides a convenient mathematical form of the Joule-Thomson coefficient in terms of the state variable V and T. The Joule-Thomson coefficient calculated by this correlation has been compared with experimental data. It has been shown that the Redilich-Kwang equation of state is a suitable equation for prediction of Jule-Thomson coefficient of non-hydrocarbon compounds. The joule-Thomson coefficient of light hydrocarbons can be obtained with greater accuracy through the use of the Soave-Redich-Kwang equation of state. As hydrocarbon compounds become heavier the Joule-Thomson coefficient correlation based on the Peng-Robinson equation of state gives more accurate results. In the superheat region and for simple and quantum compounds the Redlich-Kwang equation of state is superior. Because of the complexity of the Joule-Thomson coefficient the correlation obtained by the Lee-Kessler equation of state and based on the high average percent error resulting from this correlation, the Lee-Kessler equation of state is not recommended for prediction of the Joule-Thomson coefficient.
Joule-Thomson coefficient
Heat capacity Non-ideality
Mixing rules
Cubic equations
Lee-Kessler
Non-hydrocarbon
1992
12
01
43
49