Mathematic modeling of exchange kinetics for NH4+ adsorption on K saturated clinoptilolite

Homoionic k-clinoptilolite was evaluated as a reservoir for NH4+ and a source of nutrients such as K+. Kinetic studies of the NH4 adsorption and consequently K-release on K-clinoptilolite were performed aiming to throw more light on the mechanism of NH4+ adsorption-desorption process in aqueous media. Several models [zero-, first-, second-order, parabolic diffusion, Elovich and power function equations] were applied to the kinetic data to select the most suitable model for the description of the ammonium exchange process on the surface of zeolite minerals

Microdetermination of aminophenols and cresols via their reactions with bromine

The oxidation of aminophenols [APs] and cresols [CRs] with bromine in aqueous solution was investigated and used for microdetermination of these reductants under selected optimum conditions of pH, temperature, catalyst, time of contact of reactants and concentration ratios. The potentiometric-argentimetric titration of the librated bromide using silver amalgam electrode was found to be independent of the bromine concentration. Possible schemes, for the course of these reactions were simply suggested. The reactions were quantitative at concentration ranges of APs, 9.80 to 22.24 mg, percent recovery 98 to 103 percent and SD = 0.11 to 0.023 at [Br[2]]/[APs] ratio 2 to 4 and CRs in the concentration range 3.24 to 25.95 mg, percent recovery = 96.6 to 104.8 percent and SD = 0.19 to 0.03 at Br[2]]/[APs] ratio 2 to 6. The reaction between Br[2] and APs was fast in the order p-AP > o-AP > m-AP and with CRs it was in the order O-CR > m-CR > P-CR under the selected optimum conditions

Reaction kinetics of bromine and aminophenols

The kinetics of reactions of bromine and aminophenols has been studied at different temperatures. The overall order of the reactions determined from the half-life times was found to be 2.1, 2.12 and 2.4 for, 0-, m- and p-aminophenol, respectively. The thermodynamic parameters of activations were calculated and discussed. The final products of the reactions were investigated by elemental analysis, IR and mass spectra. Proposed schemes for these reactions were presented

Reactions of di-and tri-hydric phenolic drugs with trioxalato ferrate [III] reagent and their analysis in aqueous media

Simple rapid and reliable spectrophotometric procedures were adopted for microdetermination of catechol, dopamine hydrochloride [drug] and pyrogallol using trioxalatoferrate [III] complex [A] as a coloring reagent via formation of colored mixed ligand chelates with these phenolic drugs. A series of experiments were performed covering a wide range of concentration of the abovementioned drugs in the suitable conditions. The standard deviation was calculated and found to be 0.1 to 1.22. The obtained results indicated the successful application of complex [A] as selective indicator for microdetermination of dopamine in its pharmaceutical ampules and total catecholamines in urine samples of some tumor Egyptian patients

catalyzed reactions between iodine and cresols microdetermination of cresols

The oxidation of three isometric cresols with iodine in potassium iodide solutions in the presence and in absence of silver ions as a catalyst was investigated and used for microdetermination of these vital reductants. The study of these redox reactions and microdetermination of the methylphenols was performed by volumetric and spectrophotometric methods. The spectrophotometric method was more accurate than potentiometric and volumetric and can be used for determination of these reductants in microrange [4 to 240 ug]. The volumetric methods used silver ions as catalysts. Possible schemes for the course of the redox reactions were suggested. One and two electron processes for oxidation of cresols have been indicated