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Computerised flow injection coupled with potentiometric stripping analysis (FIPSA) was employed for examination of the adsorption behaviour of Pb(II), Cd(II) and Zn(II) ions onto diatomite modified with manganese oxides. Signal optimisation was undertaken with respect to flow rate, deposition time, deposition potential, oxidising agent concentration, thickness of mercury film, solution pH and metal ion concentration. Examination of the column adsorption characteristics was facilitated by introduction of an adsorption microcolumn, as a complementary component of the flow injection system. The resulting breakthrough curves were employed to calculate parameters including adsorption capacity and adsorption rate constant, taking into consideration initial ion concentration, flow rate, mass and particle size of adsorbent, and column internal diameter. Adsorption capacities, determined using the Thomas mathematical model, showed that manganese modified Jordanian diatomite had an efficiency towards the removal of heavy metal ions from aqueous solutions; Cd(II)>Zn(II)≉Pb(II). The relative adsorption rates of the ions followed the order: Pb(II)>Zn(II)≉Cd(II). [Copyright &y& Elsevier]

Diatomite and manganese oxide modified-diatomite (Mn-diatomite) were tested for heavy metal removal from wastewater. Impregnating the diatomite surface with 0.38 g g−1 of manganese oxide gave a 2.4-fold increase in the adsorbent surface area. Equilibrium studies demonstrated that diatomite has a higher removal capacity for Pb2+, Cu2+ and Cd2+ from water than untreated diatomite. Furthermore, the adsorption capacity of Mn-diatomite increased by decreasing the quantity of manganese oxides deposited on the surface. Electronic microscopy was carried out to study the effect of heterogeneity, modification and diatomite frustule type on adsorption. Both centric and pennate types of diatomite were present. The scanning micrographs also indicated the birnessite structure of manganese oxides, which is characterised by a platy-like-crystal structure. Adsorption kinetics confirmed the effectiveness of the manganese chemical treatment, which also significantly improved the diatomite filtration properties. [Copyright &y& Elsevier]