Ali Mohammad Sanati

In this study, a CaCl2-treated biomass of the Padinasanctae-crucis algae was used for bio-adsorption of lead, cadmium, and nickel removal from aqueous solution. The properties of bio-adsorbent were analyzed using SEM, FTIR, and methylene blue surface area. The effect of physical parameters on the bio-adsorption process was investigated and it was revealed that the solution pH has the most effective role in the bio-adsorption process. The increasing of temperature led to an increase in the bio-adsorption efficiency of nickel, lead,and cadmium. Bio-adsorption kinetics showed that the pseudo second order model can describe the kinetics of the process better than the pseudo first order model. The adsorption diffusion model stated that the bio-adsorption of metal ions was controlled by the intra-particle diffusion model. Based on the Langmuir model, the maximum bio-adsorption capacity of lead, nickel, and cadmium was determined to be 80.64, 78.74, and 93.45 mg/g, respectively. After desorption of toxic metals, the spent bio-adsorbent was recycled six times. A leather factory wastewater was successfully treated by the P.sanctae-crucis bio-adsorbent. The results revealed that the adsorption process was spontaneous and endothermic and temperature increase can improve the spontaneous degree of the process.