The lake of water sources for human is a serious problem nowdays and industrial development and release of their pollutant into the waters intensify this problem. So finding methods and improvement of technologies for decontamination of waste waters is necessary. Among different pollutants heavy metals, specially Lead, are very dangerous for livings due to their accumulation in organs and harmful effects on health. Adsorption is one of the widely used processes for heavy metal removal from contaminated water, since it is a flexible and economical method. So far different materials have been used as adsorbent in this process, but mineral materials are more desirable because of their biocompatibility. ?-tricalcium phosphate (?TCP) is a mineral adsorbent with good performance in lead sorption. ?TCP powder in nano-scale has better sorption capacity than larger sizes, but needs high-cost filtration process. In this work nano- ?TCP was fabricated and then shaped using Alginate biopolymer in bead form. Alginate-65%W ?TCP beads were used to decontamination of 900 ppm lead aqueous solution in pH=5 at room temperature. The sorption capacity of this adsorbent was measured to be 208.2 (mg/g) after 1 hour contact time with lead solution. Scanning Electron microscopy, Energy dispersive x-ray analysis and x-ray diffractometery were used to characterization of powder and beads. The main sorption mechanism was detected to be dissolution-precipitation for ?TCP powder and ion-exchange for Alginate biopolymer. The equilibrium behavior of Alginate-65%W ?TCP composite bead was described well by the Langmuir isotherm model and the overall adsorption process was successfully fitted with the pseudo-second-order kinetic model. Key Words : ?Tricalcium phosphate, Alginate, Lead, Adsorption.
