Abstract: A linear polyester is made by a process reacting polyols comprising at least two primary alcohol groups and at least one secondary alcohol or amino group and a dicarboxylic acid or a dicarboxylic acid ester in the presence of an effective amount of a lipase derived from Candida cylindracea, Candida lipolytica, Candida rugosa, Candida antarctica, Candida utilis, Chromobacterium viscosum, Geotrichum viscosum, Geotrichum candidum, Mucor javanicus, Mucor miehei, Porcine pancreas, Pseudomonas species, specifically Pseudomonas fluorescens, Pseudomonas cepacia, Pseudomonas pseudoalkaligenes, Pseudomonas alkaligenes, Thermomyces species, Rhizopus arrhizus, Rhizopus delemar, Rhizopus niveus, Rhizopus oryzae, Rhizopus javanicus, Aspergillus niger, Penicillium roquefortii, Penicillium camembertii or an esterase derived from Bacillus species, specifically Bacillus thermoglucosidasius; Mucor miehei, Horse liver, Saccharomyces cerevisiae, Pigs liver or combinations thereof.

Abstract: A process is disclosed for the two-phase extraction of metal ions from phases containing solid metal oxides, which is characterized in that the solid metal oxides are brought into contact with a hydroxamic acid, known per se, dissolved in a hydrophobic organic solvent, the phases containing the solid metal oxides and the organic phase are intensively intermixed over a sufficient contact time, after phase-splitting, the organic phase is separated and the metal ions are re-extracted from the organic phase in a manner known per se and processed.The extracting agent used therein and the use of this extracting agent are also disclosed.