IMPACT OF ORGANIC WASTES ON ISOTHERM MODELS OF COPPER AND NICKEL ADSORPTION IN SOIL.

A laboratory experiment was conducted to study the effect of filter cake and vinasse on copper and nickel adsorption on a loamy sand soil. To attain this aim, five grams of the soil were placed with 0.5 g of filter cake or vinasse in conical flasks. Then, 10 ml of Cu or Ni solutions containing 44 mg Cu or Ni / 10 ml prepared from CuSO4 5H2O and NiSO4. 6H2O, respectively, plus 25 ml of distilled water were added to the flasks to give the initial concentration of Cu or Ni of 1257 mg L-1. Two control flasks of the soil plus Cu or Ni and the soil with distilled water were used. The treatments were repeated three times.
The soil suspensions in the flasks were shaken at 25 ° C for five shaking periods of 5, 10, 20, 40 and 60 minutes. The results obtained showed that organic materials resulted in increased efficiency the sorption of Cu and Ni on a loamy sand soil compared to control treatment (without organic materials), and the filter cake was more able to absorb both Cu and Ni compared with vinasse with increased shaking intervals. The highest adsorption amount was 8.53 mg g-1 for copper with the non-amended soil at reaction time 60 minute and 4.72 mg g-1 for nickel with filter cake + soil treatment at reaction time 20 minute. The results also showed that the Freundlich equation for Cu and Ni absorption was better than the Langmuir equation due to that Langmuir equation is unsuitable of adsorption equations with high concentrations of heavy metals under study.