Abstract

This work examines possible new applications for common, clay-based formulations. We processed spray-dried grains of a common clay (ZA-4) and collected fines/rejects from the production of lightweight aggregates (LWA), which were used as filtration beds for removal of Pb2+ and Ni2+ from aqueous solutions. Experiments were performed at different contaminant concentrations and by testing several operational conditions. The removal performance of both tested materials is strongly dependent on the particle-size distribution of the batch, being better for beds made of smaller grain size, since packing density and specific contact area for removal are greater. In general, the efficiency for removal of Pb2+ was greater than for Ni2+. When compared with granular activated carbon, clay-based beds performed well. In particular, finer fractions of LWA show stable behaviour, without saturation after consecutive runs. Saturated beds can potentially be reused, in appropriate amounts, for production of new lightweight aggregates or common ceramic items (e.g. bricks), since retained contaminants will be fixed by firing in the clay matrix. Calcination of pressed pellets made of contaminated filter grains created consolidated ceramic components and sorbed metallic species became inert.

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