The reactions between Fe(Phen) 2þ 3 [phen=tris-(1,10) phenanthroline] and Co(CN) 5 X 3) (X=Cl, Br or I) have been studied in aqueous acidic solutions at 25°C and ionic strength in the range I=0.001-0.02 mol dm )3 (NaCl/HCl). Plots of k 2 versus p I, applying Debye-Huckel Theory, gave the values )1.79±0.18, )1.65±0.18 and 1.81±0.10 as the product of charges ðZ A Z B Þ for the reactions of Fe(Phen) 2þ 3 with the chloro-, bromo-and iodo-complexes respectively. Z A Z B of % À2 suggests that the charge on these Co III complexes cannot be )3 but is )1. This suggests the possibility of protonation of these Co III complexes. Protonation was investigated over the range [H + ]=0.0001 )0.06 mol dm )3 and the protonation constants K a obtained are 1.22 · 10 3 , 7.31 · 10 3 and 9.90 · 10 2 dm 6 mol )3 for X=Cl, Br and I, respectively.

Aggregation of sodium lauroylsarcosinate (SLS) in aqueous solutions of methanol, ethanol, propanol and ethylene glycol at 288-313 K has been determined from conductivity measurement in the range 0-20% v/v of additives. The precise values of the critical micelle concentration (CMC) and the degree of counter-ion dissociation of micelles were obtained at each temperature by fitting the specific conductivitysurfactant concentration curve to the integrated form of the Boltzmann-sigmoid equation. The CMC was found to increase with increase in additive concentrations in the case of methanol and ethylene glycol, while it decreases with increase in ethanol and propanol concentration. The equilibrium model of micelle formation was applied to obtain the thermodynamic parameters of micellisation. The Gibbs free energies were observed to vary only slightly with temperature and additive concentrations. Enthalpyentropy compensation was observed for all the systems with a constant compensation temperature of ≈300 K and negative compensation enthalpy.

The sponge of Luffa cylindrical (LFC), a fibrous material, was employed as adsorbent for the removal of Brilliant Green (BGD) from aqueous effluent via batch studies. The optimum removal of BGD was found at pH 8.2 and the equilibrium was attained within 3 hours. The kinetic data are analyzed using several models including pseudo-first-order, pseudo-second-order, power function, simple elovich, intraparticle diffusion, and liquid film diffusion. The fitting of the different kinetics models to the experimental data, tested by error analysis, using the linear correlation coefficient ( 2 ) and chi-square analysis ( 2 ), showed that the mechanism of adsorption process was better described by pseudo-second-order and power function kinetic models. The equilibrium isotherm data were analyzed using Langmuir, Freundlich, and Temkin models and the sorption process was described by the Langmuir isotherm with maximum monolayer adsorption capacity of 18.2 mg/g at 303 K. The thermodynamic properties Δ 0 , Δ 0 , and Δ 0 showed that adsorption of BGD onto LFC was spontaneous, endothermic, and feasible within the temperature range of 303-313 K.

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