Investigation on the adsorption of Mn(II) on surfactant-modified alumina: Batch and column studies

•Surfactant-modified alumina is successfully used for Mn(II) removal from water.•The kinetic data was described by a pseudo-second order kinetic model.•Freundlich isotherm was followed at three different temperatures.•The adsorption phenomenon was a spontaneous, favorable and endothermic process.•Column operation was carried out for Mn(II) removal and logit model was applied.

Surface modification of solids can have much influence on adsorptive removal of solutes. The removal of Mn(II) from aqueous solution on prepared surfactant-modified alumina (SMA) has been extensively studied in the present work. The bilayer of sodium dodecyl sulfate (SDS; an anionic surfactant), formed on alumina surface, can adsolubilize Mn(II) in a rapid process. The effects of contact time, initial concentration of adsorbate, adsorbent dose, pH, temperature, agitation speed have been studied by using the batch mode. The adsorption follows Freundlich isotherm model best at different temperatures. Various kinetic models such as pseudo-first order, pseudo-second order, intra-particle diffusion and liquid-film diffusion models have been studied. Thermodynamic properties (ΔG0, ΔH0, ΔS0) have been calculated and the process is found to be endothermic, favorable and spontaneous. The adsorbent SMA is used for the removal of Mn(II) ions from the Mn(II)-spiked industrial wastewater, obtained from steel product manufacturing industries. Column operation and the applicability of logit model on the system showed promise for Mn(II) removal by SMA.

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