Adsorption and desorption of Pb2+ by organic-inorganic complex

In this paper, organic-inorganic complex which is prepared by organically modifying inorganic materials bentonite with natural organic material manure as modifier was used for the adsorption of Pb²⁺ from aqueous solutions. The influence of adsorption time, temperature, pH value and dosage on the removal of Pb²⁺ was evaluated. Then, KNO₃ and HCl were used for desorption of Pb²⁺ to study the adsorption stability of the complex. The results showed that: the organic-inorganic complex has a strong adsorption capacity of Pb²⁺, and the Langmuir adsorption isotherm can be used to describe the adsorption process better than the Freundlich adsorption isotherm. The maximum adsorption capacity was calculated as 15.53mg/g. The adsorption equilibrium reached at 90 min, the optimum temperature is 60°C, the best pH value is 6 and the best dosage is 15g/L. In addition, in the same condition of adsorption, the KNO₃-extractable Pb²⁺ is 4~13 times more than HCl-extractable Pb²⁺, which indicts that organic-inorganic complex has a strong adsorption stability of Pb²⁺.