الفهرس 
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Abstract
The interactions between humic acid (HA) and smectite are important for modeling the geochemical fate and transport of pollutants in soil upon changes of environmental parameters such as pH and ionic strength. Mixed ionic strength could be causing more closed behavior to natural effects. Thence, kinetic study of humic acid adsorption onto smectite has been studied under various conditions. Impact of pH and individual and mixed ionic strength on the rate of adsorption has been investigated. The rate and amount of adsorbed HA on smectite improved with raised background electrolyte concentration, declining pH, and in existence Ca2+. The rate of adsorption order was in the presence of CaCl2 > mix (CaCl2 and KCl) > KCl. The adsorption isotherm was L-shap in the presence of CaCl2 and KCl while was S-shap in presence mix (CaCl2 and KCl). Moreover, the data revealed that the adsorption behavior of HA might be pronounced more obviously by Freundlich model than Langmiur. The results clarified that HA adsorption on smectite was following to pseudo second order model under various conditions. Kinetics of Cu2+, Zn2+ and Ni2+ ions adsorption on smectite in the absence and presence of humic acid have been investigated under various conditions in order to evaluate the influence of humic acid. The rate and the amount of adsorbed Cu2+ > Zn2+ > Ni2+ ions on smectite in the absence and presence of humic acid and increased with decreasing ionic strength, increasing pH and in the presence of the background electrolyte K+ > mix (CaCl2 and KCl) > CaCl2. In addition, humic acid enhanced the rate and the amount of adsorbed Cu2+, Zn2+ and Ni2+ onto smectite. The adsorption equilibrium data showed that adsorption behavior of Cu2+ , Zn2+ and Ni2+could be described more reasonably by Langmiur adsorption isotherm than
ABSTRACT
II
Freundlich isotherm and more conforming to pseudo second order kinetics in the absence and presence of humic acid. In case of competitive adsorption, The rate and the amount of competitive adsorption of heavy metal ions on smectite in the absence and presence of humic acid increased at ionic strength (0.001), at pH=5 and in the presence of the background electrolyte K+ > mix (CaCl2 and KCl) > CaCl2. In addition, humic acid enhanced the rate and the amount of competitive adsorption of heavy metal ions on smectite .The adsorption equilibrium data showed that competitive adsorption of heavy metal ions on smectite could be described more reasonably by Langmiur adsorption isotherm than Freundlich isotherm and more conforming to pseudo second order kinetics in the absence and presence of humic acid. The rate and the amount of competitive adsorption of heavy metal ions on smectite in the absence and presence of humic acid increased ionic strength (0.001), at pH=5 and in the presence of the background electrolyte K+ > mix (CaCl2 and KCl) > CaCl2. In addition, humic acid enhanced the rate and the amount of competitive adsorption of heavy metal ions on smectite. The adsorption equilibrium data showed that competitive adsorption of three heavy metal ions on smectite could be described more reasonably by Langmiur adsorption isotherm than Freundlich isotherm and more conforming to pseudo second order kinetics.in the absence and presence of humic acid. Keyword: Adsorption, humic acid, clay, copper, zinc, nickel , kinetics