"Over the past years, a large number of statistical expressions used as a measure of accuracy, collectively referred to as error functions. These functions use to determine the best fitting data. Since accurate adsorption equilibrium information are necessary for the analysis and design of adsorption, error functions are used to valuation the validity of the adsorption mathematical models with experimental results by finding the most appropriate isotherm. Therefore, this overall review provides a definition of a number of common error function and explains the use of these functions in determine optimal adsorption data and chose the right isotherm.

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5- Amino -3- [4- O- hydroxypheny Ithiosemi carbazido ] -1,2,4-thiadiazole compound has been prepared by the reaction of ( 3-mercapto -5- ami,2,4- thiadiazole) with ( O-hydroxyphenyl thiosemicarbazide) in mole ratios of (1:1) .The ligand has been  characterized and its structure was elucidated depending upon the spectral data of  IR and U.V-Vis spectra . Lanthanum complex of the formula  [La( C9H10N6S2O)2Cl2]Cl was prepared through the reaction of the prepared ligand with lanthanum chloride in mole ratios (2:1) respectively . The mode of bonding and overall geometry of the complex was determined through physicochemical and spectroscopic methods . The kinetic of the photo-degradation of the prepared complex was investigated and it was the first order and the rate constant (Kd) determined at (25oC ) Further more primary  quantum yields (Φ) has been also calculated.

In this work the photo degradation of glibinclamide is studied by UV light and different concentrations using solvents (water and ethanol) and different times. The reaction kinetic is studied and found that the photo degradation reaction of glibinclamide is (first-order) reaction and the thermodynamic properties (ΔHo, ΔSo and ΔGo) for glibinclamide were calculated and it was found to be (endothermic and spontaneous reaction).

Photo decomposition of 920 (DB2) dye have been performed at (nm) in deionized water at 25C˚.Under irradiation Uv Lamp. The absorbance spectrum for this dye have been recorded with the time of irradiation in order to examine the kinetics of photo decay. The specific rate constant the (Kd) for the first order reaction have been calculated and found to be (Kd = 0.0248 min -1 ). Study the effect of various parameters such as catalyst loading, pH of the medium and initial dye concentration. On photodecomposition of 920 (DB2).