摘要:
A process for the production of carboxyalkyl celluloses having an average degree of substitution of at least 1.0. The process comprises up to 3 stages, but without any intermediate purification. The preferred suspension medium is isopropanol. In each stage of the process, the carboxyalkylating agent is used in quantities of less than 2.5 moles per mole of anhydroglucose unit and the alkylating agent in quantities of less than 5 moles per mole of anhydroglucose unit. The total water content of the system throughout the reaction as a whole must not exceed 450% by weight, based on the quantity by weight of cellulose used. Water contents of from 80 to 250% by weight are preferred.
摘要:
An improved reactor (and process using the same) comprising multistage stirrer elements and baffles, which has particular dimensional ratios between the reactor diameter, the width and spacing of the stirrer elements, and the baffles. The reactor is particularly adapted for the production of polysaccharide ethers, especially cellulose ethers.
摘要:
A process and apparatus for the separation and purification of cellulose ethers and other cellulose derivatives in a filter unit at relatively high temperatures and with narrow-mesh filters, employing a pressure vessel having candle filters to which pressure is introduced for separation of the suspension liquid, for the removal of residual liquid from the filter cake formed, and also for washing the filter cake.
摘要:
Process and means for purifying cellulose ethers without flocculation points or with relatively high flocculation points (up to 95.degree. C.) and thermoplastic, i.e. highly propoxylated, products made from cellulose in any form, the crude product is first suspended and the suspension liquid subsequently separated in a reverse filter centrifuge a single-stage or multistage wash can be carried out. The filter cake is discharged by reversal of the filter cloth of the centrifuge.
摘要:
A process for working up water-soluble cellulose derivatives, more especially with flocculation points above 85.degree. C., after removal by condensation of readily volatile constituents of the crude product mixture resulting from an etherification reaction, by suspension of the crude product in hot water and subsequent separation of the suspension and washing liquids, wherein the separation of the suspension and washing liquids is carried out at elevated temperature and under pressure applied to the separator as a whole.
摘要:
A process for working up aqueous, electrolyte-containing suspensions of highly swellable layer silicates by which highly swellable layer silicates are isolated substantially free from electrolyte from an aqueous electrolyte-containing suspension in a reasonable time by multi-stage membrane filtration wherein the second and every following membrane stage, the concentrate is diluted, for example with fully deionized water, to maintain pumpability.
摘要:
A process for the production of a surfactant mixture for use in enhanced oil recovery wherein the surfactant mixture comprises an alkyl ether sulfonic acid or salt thereof as a principal constituent and at most a substantially equal quantity of alkoxylated alcohol. The surfactant mixture is prepared by reacting an alkyl ether sulfate with a stoichiometric excess of an alkali metal sulfite solution at about 160.degree. C. to 220.degree. C. under mildly alkaline pH conditions, and then extracting sulfate salt therefrom using a substantially water-insoluble alcohol at a lowered temperature.
摘要:
The development of sludge in phosphating baths is prevented by continuously diverting a partial volume of the baths into a separate device comprising three open chambers: an oxidation chamber where the solution is treated with an O.sub.2 -containing gas to oxidize the iron (II) of the solution of iron (III), which precipitates as phosphate; a conditioning chamber in which the iron (iii) phosphate precipitate formed in the oxidation chamber is agglomerated into a readily sedimented form; and a sedimentation chamber in which the sediment formed in the conditioning chamber is separated from the remaining liquid phosphating solution. This solution is then replenished with phosphate layer-forming components, and the replenished solution is subsequently recycled to the phosphating bath.
摘要:
Unpurified 2-bromo-2-nitro-1,3-propanediol is used as the starting material for a process for the preparation of 5-bromo-5-nitro-1,3-dioxane from 2-nitro-1,3-propanediol without the use of an organic solvent on an industrial scale. This is carried out in such a way that in a first stage a mixture of bromine and aqueous hydrogen bromide solution is cooled and an aqueous solution of an alkali metal or an alkaline-earth metal salt of 2-nitro-1,3-propanediol is added at such a rate that, with cooling, the maximum reaction temperature does not exceed 30.degree. C., and then in a second reaction stage paraformaldehyde and sulfuric acid are added, left to react above room temperature, and the organic phase separated.
摘要:
Process for the conversion of an organophosphonic acid of the formula ##STR1## in which n=3-5 and R=H or C.sub.1 -C.sub.3 alkyl, into an alkali metal or ammonium salt comprising reacting the moist filter cake which accumulates during the production of organophosphonic acids by known processes (water content 10 to 40% by weight) with anhydrous or concentrated aqueous alkali metal hydroxide or ammonia and exposing the paste formed, which has a water content of from 20 to 80% by weight, to intense shear forces in mixing, dispersing, or kneading units, water being removed from the paste under reduced pressure and with application of heat until the paste changes into a free-flowing powder.