Magnetic separation of magnetic activated carbons for water treatment and reuse

Purpose– The aim of this paper is the study of the magnetic separation of pollutants from water by means of a magnetic filter. A magnetic activated carbons nanometric powder that combines the well-known pollutants absorbent capacity of activated carbons with the magnetic properties of magnetite (Fe3O4) is used. Design/methodology/approach– The considered magnetic filter is made of stainless steel spheres, magnetized by an external flux density field provided by permanent magnets. Flux density and fluid velocity fields are evaluated using volume integral equation method. The modelling of the particles trajectories inside the filter allows calculating its capture efficiency. Findings– The results of the model are tested on the experimental data obtained using two different setups. A removal of the powder larger than 90 percent is achieved in both cases. The pollutant removal efficiency is checked on surfactants (water diluted). Their adsorption on magnetic activated carbons leads to residual concentration below the limit for the reuse in agriculture (according to the Italian legislation) for all the tested surfactants. Originality/value– The proposed process combines efficiently a physico-chemical phase of adsorption and a magnetic phase of filtration due to the particular properties of magnetic activated carbons.