Elaboration and properties of new ceramic microfiltration membranes from natural and synthesised apatite

In this work, we were interested in the development and the characterisation of new mineral microfiltration membranes coated on apatite macroporous supports which are prepared and characterised beforehand. The choice of material is based primarily on its low cost (considering its abundance in the Tunisian layers for natural apatite) and its thermal and chemical resistance. The active layers were prepared from lacunary hydroxyapatite synthesised (HA) and from natural apatite (AB). The membranes were deposited on the tubular support basing of natural apatite, already prepared by the “slip-casting” process. The thermal treatment consists of drying at room temperature for 24 h then a sintering at 600°C for the membrane with HA (MS) and at 750°C for the membrane with AB (MB). The surface and the cross-section morphologies observed through a scanning electron microscope (SEM) are homogeneous and do not present any macro defects (cracks, etc.). The average pore diameters of the active layer are approximately 0.25 μm and 0.2 μm for the MS and MB membrane respectively. The obtained membrane was used to treat cuttlefish effluents generated from the conditioning seawater product industry which consumes a great amount of water where the washing baths are discharged in the littoral of Sfax (Tunisia) (about 1000 m³/d). Cross-flow microfiltration was performed then, in order to reduce the turbidity and chemical oxygen demand (COD). The result showed a high retention of turbidity (99%), conductivity and COD (85%).