Retention of arsenic using alkali- and acid-bonded low temperature ceramics

ABSTRACT Immobilisation of AsIII and AsV using alkali- and acid-bonded low temperature ceramics (LTCs), respectively, has been investigated. Arsenic was loaded into these matrices as solubilised arsenic or as a solid via precipitation with a metal nitrate. Where appropriate, samples were heated to 1000°C to consolidate their microstructure and reduce their open porosity. Samples were assessed according to microstructural characterisation and standard leaching protocols. Alkali-bonded LTCs, even after the application of a thermal treatment, did not bind arsenic sufficiently to pass a TCLP protocol, whereas acid bonded LTCs showed better potential for immobilising As. At a loading of 5 wt% As2O5, a TCLP leach test on an acid bonded LTC resulted in As levels of 7 ppm, close to the regulatory limit of 5 ppm As.