Mullite effect on the ceramic filters effectiveness in the removal of arsenic from borehole water from Burkina Faso

Abstract

In recent years, porous ceramics have been widely studied because of their excellent technological properties. The intrinsic technological characteristics depend on the forming process and the application for which the materials are intended. A clay raw material (75 mass%) which is rich in melting oxides and waste peanut shells (25 mass%) were used to manufacture porous ceramics for the removal of arsenic from borehole water in Burkina Faso. A borehole water analysis shows a concentration of arsernic of 39 μg L⁻¹ above the WHO standard. The porous ceramics were obtained from samples shaped by unidirectionnal pressing and after sintering at 900 °C (MKOR9) or 1100 °C (MKOR11). Unlike MKOR9 materials, MKOR11 materials consist of 27 % mullite phases. MKOR9 and MKOR11 porous materials presented a diametrical compression stress to rupture greater than 0.15 MPa, as recommended in the literature for ceramic filters. The obtained permeability value of MKOR11 ceramic materials (53,802 L/h.m2.bar) is much higher than that of MKOR9 (18596 L/h m² bar), although its open porosity (61 %) is lower than that of MKOR9 materials (65 %). The removal rate obtained with MKOR9 is 24 % compared to 95 % for MKOR11. MKOR11 filters almost completely reduce arsenic concentration below the WHO limit values, which is not the case for MKOR9 materials. The adsorption kinetics and thermodynamic parameters showed that the adsorption process is the chemisorption. This work has shown that MKOR11 ceramic filters have a very impressive effectiveness, and they could be manufactured for the benefit of the remote population.