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Study of continuous lead removal from aqueous solutions by marble wastes: efficiencies and mechanisms Mlayah, A. & Jellali, S. Abstract Lead removal from synthetic solutions and real wastewater by Bianco Gioia marble wastes as abundant, renewable and eco-friendly materials was studied under different experimental conditions in a continuous stirring tank reactor. These marble wastes were found to be very efficient in removing lead for several experimental situations. Indeed, for initial aqueous pH values higher than 3.6, a lead removal efficiency of about 100 % was achieved even for high aqueous concentrations (200 mg L-1), important feeding flow rates (60 mL min-1) and low marble waste dosage (2 g L-1). The best removal capacity (175.7 mg g-1) was obtained for an initial lead concentration of 200 mg L-1, a marble waste dose of 5 g L-1 and an aqueous pH of 5. Even using the real wastewater with low aqueous pH (1.1), lead was also completely removed using 20 g L-1 of the tested marble wastes. According to the energy-dispersive spectroscopy and X-ray diffraction analyses, lead removal seems to be controlled by both precipitation as cerussite (PbCO3) and hydrocerussite (Pb3(CO3)2(OH)2), and adsorption onto the surface particles through cation exchange and complexation. The proposed low-cost material efficiently removes lead present in synthetic solutions and real wastewaters and constitutes an interesting environmental management option. Keywords Dynamic mode; Mineral adsorbents; Precipitation; Wastes management; Water pollutants

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