Investigation of the sorption potential of rice husk, an agricultural waste, as an adsorbent was carried out. The rice husk was modified with orthophosphoric acid and was used for adsorption of lead (II) ions (Pb2+) from aqueous solution. Physicochemical properties of the modified rice husk were determined. Equilibrium sorption data were confirmed with Langmuir, Freundlich and Temkin adsorption isotherms. On the basis of adsorption isotherm graphs, values were determined to be 0.995, 0.916, and 0.797 for Langmuir, Temkin, and Freundlich isotherms, respectively, indicating that the data fitted well into the adsorption isotherms, but Langmuir isotherm is a better model. The maximum monolayer coverage from Langmuir studies, ？mg/g, Langmuir isotherm constant, ？L/mg, and the separation factor, at 100？mg/L of lead(II) ions indicating that the sorption process, was favourable. The suitability of modified rice husk as an adsorbent for the removal of lead ions from aqueous solution and its potential for pollution control is established. 1. Introduction The pollution of water resources due to the disposal of heavy metal ions has been an increasing worldwide concern for the last few decades. It is well known that some metals are poisonous or otherwise toxic to human beings and ecological environments as reported by Abdel-Halim and coresearchers [1]. Increasing levels of heavy metals and other pollutants in the environment pose serious threats to water quality, human health, and living organisms. Lead(Pb) is considered as one of the priority metals from the point of view of potential health hazards to human, and it is listed by the Environmental Protection Agency (EPA) as one of 129 priority pollutants. The case of recent lead poisoning of hundreds of children in Zamfara State has been identified as the worst lead poisoning in Nigeria’s history [2]. There are various methods of removing heavy metal ions, and they include chemical precipitation, membrane process, ion exchange, solvent extraction, electrodialysis, and reverse osmosis [3]. These methods are noneconomical and have many disadvantages such as incomplete metal removal, high reagent and energy consumption, and generation of toxic sludge or other waste products that require disposal or treatment. In contrast, the adsorption technique is one of the preferred methods for the removal of heavy metal ions because of its efficiency and low cost [4]. For this purpose, in recent years, interest has recently arisen in the investigation of some unconventional methods and low-cost materials for scavenging heavy metal
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