Adsorption Properties of Tropical Soils from Awka North Anambra Nigeria for Lead and Cadmium Ions from Aqueous Media

Soils consist of various components that can influence significantly heavy metal control in the environment. Understanding the adsorption characteristic of soil is important in combating pollution problems around farming areas. This work explored the sorption characteristics and retention of Pb and Cd by soils from Isu Aniocha farming area in Anambra state, Nigeria. The influence of temperature, metal concentration, pH and time on the sequestration of Pb2+ and Cd2+ was evaluated by batch sorption technique. Physicochemical properties of the soil were determined by standard techniques. Isotherm evaluation was performed by the Langmuir, Tempkin and Freundlich models. Pb (II) ion showed higher adsorption characteristics on the soil than Cd (II) from the maximum uptake capacity obtained. The maximum adsorption values for Pb range from 38.46 to 47.62 mg/g, while that for Cd range from 30.30 to 41.46 mg/g. Kinetic evaluation was conducted by the application of the pseudo first order, pseudo second order and intraparticle diffusion rate equations. The best fit on metal removal on the soils was achieved with the pseudo-second order model. The results showed that soils from a farming area can be effective in decreasing heavy metals pollution, especially Pb and Cd ions from solution phase.