Abstract: A process for purifying a crude composition includes a monoterpene compound selected from the group consisting of monocyclic monoterpene alcohols, monocyclic monoterpene ketones, bicyclic epoxy monoterpenes and mixtures of two or more of the aforementioned compounds, such as preferably a monocyclic monoterpene alcohol. The process comprises performing a layer crystallization with a melt of the crude composition, and the melt of the crude composition subjected to the layer crystallization includes oxygen-containing solvent in a concentration of 20 ppm to 2% by weight. The oxygen-containing solvent is selected from the group consisting of water, C1-6-alcohols, C1-6-carboxylic acids, C1-6-ketones, C1-6-aldehydes, C1-12-ethers, C1-12-esters and mixtures of two or more of the aforementioned solvents.

Abstract: A process for purifying a crude composition includes a monoterpene compound selected from the group consisting of monocyclic monoterpene alcohols, monocyclic monoterpene ketones, bicyclic epoxy monoterpenes and mixtures of two or more of the aforementioned compounds, such as preferably a monocyclic monoterpene alcohol. The process comprises performing a layer crystallization with a melt of the crude composition, and the melt of the crude composition subjected to the layer crystallization includes oxygen-containing solvent in a concentration of 20 ppm to 2% by weight. The oxygen-containing solvent is selected from the group consisting of water, C1-6-alcohols, C1-6-carboxylic acids, C1-6-ketones, C1-6-aidehydes, C1-12-ethers, C1-12-esters and mixtures of two or more of the aforementioned solvents.

Abstract: The present invention is directed to dye mixtures comprising structures of formula and their production and their use for dyeing textiles and in particular for dyeing aramid fibres.

Abstract: The invention relates to mixtures of fiber-reactive Triphendioxazine dyes with other fiber-reactive azo dyes and their use for the dyeing of hydroxyl- and especially carboxamide-containing material in blue and navy shades.

Abstract: A process for desalinating water is disclosed. The process comprises the steps of passing a feed stream of saline solution 2? in a first desalination step through a reverse osmosis membrane desalination plant 3? comprising at least one reverse osmosis desalination unit 4? to form a first product water stream 5? having a reduced salt concentration relative to that of the feed stream of saline solution 2? and a first byproduct stream 6? having an increased salt concentration relative to that of the feed stream of saline solution 2? characterized in that the first byproduct stream 6? is passed in a second desalination step through a falling film crystallization unit 7 to form a second product water stream 8 having a reduced salt concentration relative to that of the first byproduct stream 6? and a second byproduct stream 9 having an increased salt concentration relative to that of the first byproduct stream 6?. The invention further relates to an apparatus 1 for carrying out said process.

Abstract: The present invention relates to a method for purifying a crude benzoic acid (32) containing 5 to 20% by weight of byproducts and 80 to 95% by weight of benzoic acid, by means of distillation, wherein the distillation is performed in a plant comprising a first distillation system (54), which comprises a divided wall column (10).

Abstract: The invention relates to a process for purification of a stream containing a cyclic ester of an alpha-hydroxycarboxylic acid of formula (I), wherein each R independently represents hydrogen or an aliphatic hydrocarbon having 1 to 6 carbon atoms comprising the steps of: (a) separating the cyclic ester-containing stream into one or more cyclic ester-containing vapor fractions and one or more cyclic ester-containing liquid fractions; (b) condensing a cyclic ester-containing vaporized fraction as obtained in step (a) to obtain a cyclic ester-containing condensate; (c) subjecting at least part of the cyclic ester-containing condensate as obtained in step (b) to melt crystallization to obtain a purified cyclic ester-containing stream and a residue stream; and (d) recovering the purified cyclic ester-containing stream as obtained in step (c). The invention further relates to an apparatus suitable for carrying out the present process.

Abstract: A process for the separation of a substance from a liquid feed mixture and for the purification of the substance by fractional layer crystallization, wherein the liquid feed mixture comprises the substance to be separated and purified in a concentration of less than 50% by weight, which comprises the subsequent steps in the given order: (a) feeding the liquid feed mixture into a crystallization zone, in which at least one surface is provided, so that at least a part of the surface contacts the liquid feed mixture, (b) cooling the at least one surface of the crystallization zone to a temperature below the equilibrium freezing temperature of the liquid feed mixture so that a crystal layer enriched in the substance to be separated and purified is deposited on the at least one cooled surface, whereby a mother liquid having a lower concentration of the substance to be separated and purified than the liquid feed mixture is formed from the liquid feed mixture, (c) removing at least a portion of the mother liquid fro

Abstract: A process for desalinating water is disclosed. The process comprises the steps of passing a feed stream of saline solution 2? in a first desalination step through a reverse osmosis membrane desalination plant 3? comprising at least one reverse osmosis desalination unit 4? to form a first product water stream 5? having a reduced salt concentration relative to that of the feed stream of saline solution 2? and a first byproduct stream 6? having an increased salt concentration relative to that of the feed stream of saline solution 2? characterized in that the first byproduct stream 6? is passed in a second desalination step through a suspension crystallization unit 7 to form a second product water stream 8 having a reduced salt concentration relative to that of the first byproduct stream 6? and a second byproduct stream 9 having an increased salt concentration relative to that of the first byproduct stream 6?. The invention further relates to an apparatus 1 for carrying out said process.

Abstract: Disclosed is a method to prepare a polylactic acid comprising the steps of performing a ring opening polymerization using a catalyst and either a catalyst killer compound or an endcapping additive to obtain a raw polylactic acid of MW greater than 10,000 g/mol, purifying the raw polylactic acid by removing and separating low boiling compounds comprising lactide and impurities from the raw polylactic acid by devolatization of the low boiling compounds as a gas phase stream, and purifying the lactide from the devolatization and removing the impurities from the gas phase stream of evaporated low boiling compounds by means of crystallization by desublimation from the gas phase, wherein the lactide is purified and the removed impurities include a catalyst residue and a compound containing at least one hydroxyl group such that the purified lactide is then polymerized by feeding it back into the ring opening polymerization.

Abstract: The present invention relates to a method for purifying a crude benzoic acid (32) containing 5 to 20% by weight of byproducts and 80 to 95% by weight of benzoic acid, by means of distillation, wherein the distillation is performed in a plant comprising a first distillation system (54), which comprises a divided wall column (10).

Abstract: The invention relates to a process for purification of a stream containing a cyclic ester of an alpha-hydroxycarboxylic acid of formula (I), wherein each R independently represents hydrogen or an aliphatic hydrocarbon having 1 to 6 carbon atoms comprising the steps of: (a) separating the cyclic ester-containing stream into one or more cyclic ester-containing vapour fractions and one or more cyclic ester-containing liquid fractions; (b) condensing a cyclic ester-containing vaporized fraction as obtained in step (a) to obtain a cyclic ester-containing condensate; (c) subjecting at least part of the cyclic ester-containing condensate as obtained in step (b) to melt crystallization to obtain a purified cyclic ester-containing stream and a residue stream; and (d) recovering the purified cyclic ester-containing stream as obtained in step (c). The invention further relates to an apparatus suitable for carrying out the present process.

Abstract: A process for desalinating water is disclosed. The process comprises the steps of passing a feed stream of saline solution 2? in a first desalination step through a reverse osmosis membrane desalination plant 3? comprising at least one reverse osmosis desalination unit 4? to form a first product water stream 5? having a reduced salt concentration relative to that of the feed stream of saline solution 2? and a first byproduct stream 6? having an increased salt concentration relative to that of the feed stream of saline solution 2? characterized in that the first byproduct stream 6? is passed in a second desalination step through a falling film crystallization unit 7 to form a second product water stream 8 having a reduced salt concentration relative to that of the first byproduct stream 6? and a second byproduct stream 9 having an increased salt concentration relative to that of the first byproduct stream 6?. The invention further relates to an apparatus 1 for carrying out said process.

Abstract: A process for desalinating water is disclosed. The process comprises the steps of passing a feed stream of saline solution 2? in a first desalination step through a reverse osmosis membrane desalination plant 3? comprising at least one reverse osmosis desalination unit 4? to form a first product water stream 5? having a reduced salt concentration relative to that of the feed stream of saline solution 2? and a first byproduct stream 6? having an increased salt concentration relative to that of the feed stream of saline solution 2? characterized in that the first byproduct stream 6? is passed in a second desalination step through a suspension crystallization unit 7 to form a second product water stream 8 having a reduced salt concentration relative to that of the first byproduct stream 6? and a second byproduct stream 9 having an increased salt concentration relative to that of the first byproduct stream 6?. The invention further relates to an apparatus 1 for carrying out said process.

Abstract: Disclosed is a method to prepare a polylactic acid comprising the steps of: performing a ring opening polymerization using a catalyst and either a catalyst killer compound or an endcapping additive to obtain a raw polylactic acid of MW greater than 10,000 g/mol, purifying the raw polylactic acid by removing and separating low boiling compounds comprising lactide and impurities from the raw polylactic acid by devolatization of the low boiling compounds as a gas phase stream, purifying the lactide from the devolatization and removing the impurities from the gas phase stream of evaporated low boiling compounds by means of condensing the evaporated gas phase stream to give a condensed stream and a subsequent melt crystallization of the condensed stream, wherein the lactide is purified and the removed impurities include a catalyst residue and a compound containing at least one hydroxyl group such that the purified lactide is polymerized by feeding it back into the ring opening polymerization.

Abstract: Disclosed is a method to prepare a polylactic acid comprising the steps of: performing a ring opening polymerization using a catalyst and either a catalyst killer compound or an endcapping additive to obtain a raw polylactic acid of MW greater than 10,000 g/mol, purifying the raw polylactic acid by removing and separating low boiling compounds comprising lactide and impurities from the raw polylactic acid by devolatization of the low boiling compounds as a gas phase stream, purifying the lactide from the devolatization and removing the impurities from the gas phase stream of evaporated low boiling compounds by means of condensing the evaporated gas phase stream to give a condensed stream and a subsequent melt crystallization of the condensed stream, wherein the lactide is purified and the removed impurities include a catalyst residue and a compound containing at least one hydroxyl group such that the purified lactide is polymerized by feeding it back into the ring opening polymerization.

Abstract: Disclosed is a method to prepare a polylactic acid comprising the steps of performing a ring opening polymerization using a catalyst and either a catalyst killer compound or an endcapping additive to obtain a raw polylactic acid of MW greater than 10,000 g/mol, purifying the raw polylactic acid by removing and separating low boiling compounds comprising lactide and impurities from the raw polylactic acid by devolatization of the low boiling compounds as a gas phase stream, and purifying the lactide from the devolatization and removing the impurities from the gas phase stream of evaporated low boiling compounds by means of crystallization by desublimation from the gas phase, wherein the lactide is purified and the removed impurities include a catalyst residue and a compound containing at least one hydroxyl group such that the purified lactide is then polymerized by feeding it back into the ring opening polymerization.

Abstract: The present invention relates to a method for the purification of an ionic liquid by means of fractional crystallization in which a part of the ionic liquid is crystallized and the crystallizate formed is separated from the liquid remainder. In this respect the ionic liquid is charged with a certain amount of at least one entrainer substance.

Abstract: The present invention relates to a method of purifying an ionic liquid by means of fractional crystallization in which a part of the ionic liquid is crystallized and the crystals formed are separated off from the residual liquid. In this process a certain amount of at least one entrainer substance is added to the ionic liquid.

Abstract: In the process according to the invention for fractionating substances, particularly paraffins, oils, fats and waxes, which, when crystallized, have poor adhesion to the substantially vertical crystallization surfaces (39) of a crystallizer, screen-like supporting structures, e.g. perforated metal sheets (31) bent in a zig-zag, are disposed between the crystallization surfaces (39) of a crystallizer. The crystals (51) becoming detached from the crystallization surfaces (39) during the sweating phase are left suspended in horizontal strips in the triangular zones (41) on the perforated sheet (31) and remain in thermal contact with the crystallization surface (39) and sweat out the liquid phase (55). The mother liquor (55) drips off, in some cases also between the crystals (51) and the crystallization surface (39), with the result that drip channels are melted by the heated mother liquor and thus opened.