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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]

Highlights: [•] The uptake capacity order was: Pb2+ >Cu2+ >Ni2+. [•] The thermodynamic constants were endothermic and spontaneous for Pb2+ and Cu2+. [•] The thermodynamic constants were exothermic and non-spontaneous for Ni2+. [•] The adsorption mechanisms are affected by metal ion hydration and other factors. [•] Different functional groups are responsible on the metals binding. [Copyright &y& Elsevier]