Abstract: Provided herein is a method for the removal of soluble metal species consisting of lead, cadmium, zinc and mixtures thereof, present in an aqueous effluent, the method comprising the steps of: a) contacting the aqueous effluent with a organophosphorus salt selected from sodium di-(n-octyl) phosphinate and sodium di-(n-dodecyl) phosphinate or mixtures thereof; b) achieving precipitation of said soluble metal species by reaction with said organophosphorus salts to yield a precipitate; and c) recovering said precipitate by filtration. Preferably, the mole ratio of organophosphorus salt is about 1.5 to 2.5 and most preferably about 2, in relation to the total mole ratio of the said soluble metal species. Preferably, prior to step a), the pH of the aqueous effluent to be treated is adjusted to at least about 3 and most preferably at least about 4.

Abstract: A process is described for removing mineral or ash constituents from heavy hydrocarbon residues, such as those resulting from coal-oil coprocessing, residue hydrocracking or coal liquifaction. The process comprises the steps of: (a) intimately mixing the ash-containing heavy hydrocarbon oil residue with a surfactant and a pH-conditioned aqueous solution under high shear mixing conditions to disperse the ash-containing residue in the aqueous phase thereby creating a fine oil-in-water emulsion, (b) adding a strong oxidizing agent to the emulsion to thereby break the emulsion and release the ash into the aqueous phase and (c) separating the ash-containing aqueous phase from the oil phase. The HLB method for characterizing the emulsion forming activity of a surface active material is described in M. J. Rosen, Surfactants and Interfacial Phenomena, John Wiley & Sons, New York (1989), incorporated herein by reference.