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The adsorption of Pb(II) ions from aqueous solutions by chitosan flakes and beads was studied. The chitosan beads were prepared by casting an acidic chitosan solution into alkaline solution. Experiments were carried out as a function of pH, agitation period and initial concentration of Pb2+ ions. The uptake of Pb2+ ions from aqueous solution was determined from changes in concentration as measured by atomic absorption spectroscopy. The maximum uptake of Pb2+ ions on chitosan beads was greater than that on chitosan flakes. Adsorption isothermal data could be interpreted by the Langmuir equation. The experimental data of the adsorption equilibrium from Pb2+ ion solutions correlated well with the Langmuir isotherm equation. SEM analyses were also conducted for visual examination of the chitosan flakes and beads. Physical properties including surface area and average pore diameter were characterized by N2 adsorption experiment.

This study used common salts (monovalent and divalent salts) and seawater to cause aggregation of an acid dye, AB25 to a particle size large enough to be removed by simple filtration using a filter paper. All the common salts (CaCl2, Mg(NO3)2, KNO3, KCl, NaCl) were able to produce high removal efficiencies of AB25 (100 mg/L, unadjusted pH) at 99.4%, 90.3%, 98.4%, 99.3% and 99.3%, respectively, while a 2.5x dilution of seawater was successful in removing up to 93.8% of AB25. These findings proved the effectiveness of this method which is a much simpler and direct approach to dye wastewater remediation.