Standard free energy of formation of borate minerals in Zubair Wells of irrigation water

الملخص EN

An empirical method has been developed to estimate the standard free energy of formation (Δ GRf,298R) values for hydrated borate minerals in twenty one wells in Zubair location.

Water samples were analyzed for pH, electrical conductivity(E.CRiwR), Calcium, Magnesium, Sodium and Boron concentrations.

Ionic strength of water samples was calculated from electrical conductivity, and ionic activity taking into account ion pairs that were likely to be present in these samples.

Solubility data for a number of alkali borate minerals, Pinnonite Mg[BR2RO(OH)R6R], Inderite Mg[BR3ROR3R(OH)R5R].

5HR2RO, Inyoite Ca[BR3ROR3R(OH)R5R].

4HR2R0, and Borax NaR2RBR4RO7.10HR2RO were compiled and analyzed according to Bassett(2).

Data of experimental data and the standard free energy of formation were compared with findings of other researchers.

Results indicated that borate mineral Pinnonite Mg[BR2RO(OH)R6R], Inderite Mg[BR3ROR3R(OH)R5R].5HR2RO, Inyoite Ca[BR3ROR3R(OH)R5R].4HR2R0, and Borax NaR2RBR4RO7.10HR2RO) were not founded in the studied wells water because the standard free energy of their formation was less than the values of standard free energy of formation founded by Bassett(2) and Mattigod & Sposito(11).

The method is completely general, and the parameter used in the computation is the number of Boron atoms in the polyanion unit of mineral.

The standard free energy of formation value appeared that some borate minerals are dissolve and this will the problem of boron toxicity in well irrigation water.

Results indicated that Boron concentration was ranged between 0.0231 to 0.462 mM.LP -1 P in the mean value of 0.158 mM.LP -1 P and equal to 0.254 to 5.082 mg.LP -1P with the mean value of 3.477 mg.LP -1P, that means most of studies wells water (80.95% of total wells ) are above the critical level concentration of boron and toxicity symptoms may appear on plants when it may irrigated with it.