Filtration of solution containing heavy metals and dyes by means of ultrafiltration membranes deposited on support made of Moroccan clay

The use of inorganic membranes in pollution treatment is actually limited by the cost of such membranes. Advantages of inorganic membranes over organic ones are their chemical, thermal and pH resistance. In this study, low cost ZnAl2O4-TiO2 ultrafiltration membranes were tested for removing Cd(NO3)2, Pb(NO3)2, Cr(NO3)3, methylene blue and orange acid from water. The electrical interactions between ionic species and surface material govern the rejections of heavy metals and charged species. Retentions of dyes methylene blue and orange acid are also important but the adsorption of the species leads to fouling when the concentration increases.

The performances of a low cost TiO2/ZnAl2O4 ultrafiltration membrane deposited on a tubular support made of Moroccan clay were studied. The membrane presents interesting retention properties with regard to the heavy metal ions and dyes, their retention depends strongly on the concentration and on the pH of the filtered solution. The retention evolution for the different species can be interpreted by taking into account the electric interactions between the ions and the residual charges on the surface of the filtering material. Such membranes will be tested now for removing polluting metallic species in wastewater produced by surface treatment industry. This should find interesting applications for the treatment of liquid effluents in emergent countries.