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Ten different soil samples from Basrah and Messan governorates of southern Iraqi were used to study the mechanism of copper (Cu) adsorption. Copper was added at 0 , 4 , 8 , 16 and 32 mg Cu kg-1 soil and two salts (0.01 M CaCl2 and 0.01 M NaCl) with two temperature (25±1 C° and 45±1 C°). Copper adsorption was tested using isothermal equation parameters of Langmuir, Freundlich and D-R as well as thermodynamic parameters (K°, ΔG°, ΔH° and ΔS°). The results showed that the isotherm equations that give the best description of copper adsorption were in the following order: Langmuir > D-R > Freundlich according to their (R2 ) values. The value of activity energy (E) which ranges from 8.006 - 15.823 kJ mol-1 showed that the copper adsorption is an ionic exchange reaction. The value and sign of ΔG° of copper adsorption in the studied soils exhibit that it is a spontaneous process and increases with increasing the temperature. For the positive ΔH° values, Cu at sorption is considered an endothermic reaction and the positive ΔS° indicates the degree of randomness between the solid and liquid phases. There is not any clear effect of soil properties. But there is a general effect of whole soil properties on the calculated parameters. The results also showed that the amount of adsorbed Cu under using 0.01 M CaCl2 on adsorption sites was lower compared to 0.01 M NaCl . [ABSTRACT FROM AUTHOR]

Laboratory experiment was carried out in order to study the adsorption of Fe as FeEDDHA as related to some soil properties in six calcareous soils from the middle of Iraq. Langmuir, Freundlich and Temkin equations were used for describing Fe adsorption. The best equation was chosen according to highest value of r, r2 and t and least value of Standard error of estimate. The results showed that Freunglich equation was more efficient for describing Fe sorption compared with other physicochemical equations used, depending on highest values of, r (0.985), r 2 (0.970) and t ( 20.01) and lower standard error SE.e (0.186). Maximum adsorption capacity in tested soils were 415.2, 393.7, 353.7, 344.2, 318.4 and 306.0 µg Fe g-1 soil while the binding strength were 0.059, 0.046, 0.059, 0.051, 0.059 and 0.064 ml Fe µg-1 for Balad, Al-Khalis, Al-Raaid, Al-Wehda, Al-Mussayib and Al-Rashidaaa. 59.2% of the applied Fe was sorbed on soil while 40.8% remained soluble in soil solution. Freunglich adsorption constants (lnKf and 1/n) significantly correlated with Langmuir maximum adsorption (b) and binding strength (K). Also, the maximum adsorptive capacity (b) of Langmuir models statistically related to soil properties (EC, total and active carbonate and plant available Fe). It can be concluded from this study that Freunglich and Langmuir equations were more suitable for describing Fe adsorption in all tested soils. Tested soils sorbed Fe according to the following arrangement: Balad > Al-Khalis > Al-Raaid > Al-Wehda > Al-Mussayib > Al-Rashidaa. [ABSTRACT FROM AUTHOR]

Laboratory experiment conducted for studying the effect of ionic strength and soil properties in phosphorus adsorption in some Calcareous soils. In this experiment, ten soil sites from different parts in Basrah governorate were collected. These soils were collected from sites as follows: Al-Brazeia, Tanuma, Najibia, Al-Hartha, Al-Deir, Al-Qurna, Al -Fao, Al-Berjesia, Am-Qaser and Khor Al-Zbeir. The laboratory work is done by weighting 2.5 g. from each soil and put them in 50ml conical flask. Then added phosphorus in the form of phosphate mono potassium KH2PO4 on nine levels as follows: (0, 50, 100, 150, 200, 250, 300, 350, 400) μM L-1. As well, it was used three levels of waters (control (distilled water), 0.1 mol L-1 NaCl and 0.2 mol L-1NaCl). The water was added to each treatment to field capacity. Meanwhile, the treatments were shake and left till equilibrium. After that procedure, it was determined the soluble phosphorus after equilibrium and calculated adsorbed quantity of phosphorus on the soil surfaces. The results are tested by linear Langmuir equation and calculation the constants of this equation, (b, k). The results showed that the increase of added water salinity to the soil leads to increase of phosphate adsorption by fine textured soils like silty clay loam and silty clay whereas phosphate adsorption decreased in coarse textured soils like loamy sand and sandy ones and this go in line with adsorption curve where coefficient of correlation was L =0.0026 – 0.854 for all studied treatments. The soil colloids (clay, silt), solid carbonate and soil salinity gave high significant coefficient of correlation (r) with adsorption maxima of phosphorus (b) and with bonding energy constant (k). [ABSTRACT FROM AUTHOR]