Abstract
This work investigated the adsorption properties of Posidonia oceanica (P.O) with the aim of removing mercury ions from aqueous solutions. The effects of several parameters, including contact time, temperature, pH, adsorbent dose, and initial concentration, on mercury removal efficiency were determined. The thermal gravimetric analysis displayed that the (P.O) powder contains (8.96%) moisture and (2.88%) ash. The batch mode study illustrated that mercury ion removal reached equilibrium in 90 minutes at room temperature, using 0.1 g of absorbent and 25 mL of mercury solution (50 ppb, pH 2). The increase in temperature and pH resulted in lower removal percentage, whereas the increase in ionic strength resulted in higher removal capacity. The activation and enthalpy energies of the reaction were found to be - 0.32 and - 85.20 kJ/ mole respectively, where the maximum monolayer capacity of mercury adsorption was determined to be 3.37 mg/g. The isotherm and kinetic studies showed the reaction agrees with Langmuir and pseudo-second-order models (R2 = 0.99).