Preparation, characterization and application of polystyrene based activated carbons for Ni(II) removal from aqueous solution

• Activated carbons with decent yield/properties are produced from polystyrene.
• Steam activated carbon performs superior in Ni(II) removal than air activated.
• Adsorption appears to be governed by an exchange and complexation process.
• Maximal reached adsorption capacity is 40.8 mg g− 1.

The production of activated carbon from polystyrene waste is tested in order to limit its negative environmental impact through conversion to value added products. For this purpose modification of the precursor, slow pyrolysis and subsequent activations, i.e. high temperature steam activation and low temperature air oxidation, are applied. The physical/chemical properties as well as adsorption capacities of obtained activated carbons (ACs) towards Ni(II) removal in aqueous solutions are explored.Steam activated carbon S-ACMPS performs superior in Ni(II) removal at applied circumstances. Ni(II) adsorption by this AC has been investigated using different process parameters and occurs through cation exchange mechanism optimal at pH range of initial solution of 4–8. Several reaction based kinetic models, i.e. pseudo-first, pseudo-second and Elovich models, and intra-particle diffusion model, are applied on experimental data. The adsorption kinetics of Ni(II) is best approximated by a pseudo second-order model. The equilibrium adsorption data best fits the Langmuir adsorption isotherm. Calculated maximum adsorption capacity for S-ACMPS is 40.8 mg g− 1.