Ionic exchange desorption of mercury from contaminated dredging sludge (at 393K and ambient temperature)

Abstract

ABSTRACTIn this work, we reported results obtained during experimental tests to introduce a new approach to the treatment of dredging sludge polluted by mercury. A slurry of dredging sludge was treated by cationic exchange procedures both at ambient temperature and distilled at 393K with the aid of some different exchange salts: three inorganic (NaCl, CaCl2, and CaI2) and two organic Tetrabutylammonium chloride [(C4H9)4NCl] and Ethyl Viologen diiodide (1,1′-Dietil-4,4′-bipyridinium diiodide) [C14H18I2N2], having different cationic exchangeable part and different molecular weights. A similar (15% w/w) solution was used to treat mercury-polluted sludge considering 2, 24, and 48 h of reaction time.The removal efficiencies of the inorganic/low molecular weight monovalent salts were minimal at the tested temperatures, while higher removal was reached when CaI2 and Viol-I2 were used at ambient temperature with maximum treatment efficiencies over 70% in 48 h treatment. A recovery/reuse of the exchanging solutions was also tested finding good recovery potential of the salt slurry.