Abstract: The invention relates to a process for treating an aqueous solution containing ?-caprolactam, ammonium sulphate and one or more other impurities, comprising one or more organic impurities from a caprolactam production process and optionally other salts than ammonium sulphate, by means of a membrane process, thereby obtaining a retentate and a permeate, in which process the membrane used is selected from the group of polyether sulphone membranes, sulphonated polyether sulphone membranes, polyester membranes, polysulphone membranes, aromatic polyamide membranes, polyvinyl alcohol membranes, polypiperazine membranes, cellulose acetate membranes, titanium oxide membranes, zirconium oxide membranes and aluminium oxide membranes, having a molecular weight cut off in the range of 100-1000 g/mol; and wherein more than 60 wt. % of the caprolactam in the aqueous solution is passed through a membrane to the permeate side, to obtain a purified caprolactam containing permeate stream, and wherein at least 50 wt.

Abstract: The invention relates to a method for the preparation of porous polymeric fibres comprising functionalized or active particles. By extruding a mixture of one or more dissolved polymers with particulate material a porous fibre is obtained in which the particulate material is entrapped. Extrusion of the fibre occurs under two-step phase inversion conditions. In particular the porous fibres can be used for the isolation of macromolecules such as peptides, proteins, nucleic acids or other organic compounds from complex reaction mixtures, in particular from fermentation broths. Another application is the immobilization of a catalyst in a reaction mixture.