The Evaluation of Zinc Adsorption by Using The Constants of ( Q / I ) Relationship For Four Gypsoferous Soils

Abstract

gypsum content 50 , 80 , 140 , 180 gm gysum.kg soil-1. samples represents these soils have been taken from different sites of Tikrit university fields to evaluate Zinc adsorption using the constants of the relationship between intensity and quantity Q/I . Samples were divided into two parts . natural soil and washed soil with 0.01 moler of HCl solution. Fourty ml of ZnCl2 has been added at concentration. ( 0 , 1 , 2 , 3 , 4 , 5 , 10 , 25 , 50 , 100 , 500 , 1000 ) mg.L-1 to 2 mg soil . Results showed increase in soil Buffering capacity with values ranged between ( 2.32 – 3.28 ) mole.gm-1 for natural soil , while the values of washed soils ranged between ( 0.5 – 0.97 ) mole.gm-1 , this results caused washed soils , the values ranged between ( 0.33 – 0.4 ) and ( 0.26 – 0.30 ) mole.kgm-1 respectively . The increase in gypsum content of soil also caused increase in the value of exchangeable free energy at ARZn° for both natural and washed soils , the values ranged between ( -21.95 to -22.33 ) and ( -18.7 to -19.97 ) K.Jole.mole-1 ,respectively . Values of Gibbs free energy ranged between ( -30.56 to -31.41 ) and ( -26.80 to -28.41 ) K.Jole.mole-1 for natural and washed soils respectively .