摘要:
Concentrated dithionite solutions are produced by cathodic reduction of an aqueous solution, containing sulfite and/or bisulfite, which is circulated by pumping. The cathode and anode chambers are separated from one another by a permselective cation exchanger membrane. The catholyte must be circulated at least 10 times per hour and the selective catholyte volume outside the cell, defined asa = V.sub.total -V.sub.C /V.sub.total,Should be less than 0.9.
摘要:
Thermoplastic molding compositions comprise A) from 30 to 96% by weight of a polyester B) from 1 to 30% by weight of melamine cyanurate C) from 1 to 30% by weight of at least one phosphorus-containing flame retardant D) from 0.01 to 5% by weight of at least one ester or amide derived from a saturated or unsaturated aliphatic carboxylic acid having from 10 to 40 carbon atoms and a saturated aliphatic alcohol or &mine having from 2 to 40 carbon atoms E) from 0 to 60% by weight of other additives and processing aids where the total of the percentages by weight of components A) to E) is 100%.
摘要:
The invention relates to a process for recycling diaphragms, in particular a process for recycling used asbestos-free diaphragms from alkali metal chloride electrolysis, the diaphragm material being comminuted, the diaphragm material being washed with a wash substrate and a reusable material being obtained.
摘要:
A process for preparing a silane of the formula I R.sup.1.sub.n SiR.sup.2.sub.m (I) where R.sup.1 is --O--Y, n is an integer from 1 to 3, R.sup.2 is ##STR1## m is an integer from 1 to 3 and n+m=4, and Y and Z are each, independently of one another, unsubstituted or mono- or polyhalo-substituted C.sub.1 --C.sub.20 -alkyl, C.sub.2 --C.sub.20 -alkenyl, C.sub.2 --C.sub.20 -alkynyl and --(CH.sub.2).sub.p --A, where p is an integer from 0 to 6 and A, which is unsubstituted or substituted by one or more C.sub.1 -C.sub.6 -alkyls, is a 3- to 20-membered hydrocarbon ring entails reacting a halosilicon compound of the formula II SiX.sub.4 (II) where X is fluorine, chlorine, bromine and iodine, with compounds of the formula III and IV, or with an anhydride of the formula V and the compound of the formula IV ##STR2## where R.sup.1 and R.sup.2, and Z have the above meanings, M is a metal of main group one and two.
摘要:
Alkali metal nitrates are prepared by supplying the anode space of an electrolysis cell, separated from the cathode space by a perm-selective cation exchange membrane, with alkali metal chloride solution and at the same time supplying the cathode space with a nitric acid/alkali metal nitrate solution whose alkali metal nitrate concentration is not less than 10% by weight and whose HNO.sub.3 concentration is of from 0.1 to 10% by weight, and withdrawing from the cathode space a solution whose pH does not exceed 5.
摘要:
In a process for the manufacture of sodium dithionite by reacting sulfur dioxide with sodium formate and aqueous sodium hydroxide solution in the presence of methanol, an aqueous methanolic solution of sodium formate is first produced by reacting carbon monoxide with sodium hydroxide solution in an aqueous medium, containing from 1 to 50% by weight of methanol, based on the amount of water, at from 80 to 120.degree. C. under a pressure of from 10 to 40 bars. The resulting aqueous methanolic solution can be reacted directly, in the conventional manner, with sulfur dioxide and aqueous sodium hydroxide solution to give sodium dithionite.
摘要:
A process for welding membranes of fluorinated polymers which contain groups with exchangeable H-ions. To carry out the process, the polymer in at least one of the membranes to be welded together must be in the H-form.
摘要:
Phosphorus-containing iron powder is prepared by mixing carbonyl iron powder or whiskers with elemental phosphorus, heating the mixture and comminuting the product obtained to give a powder. The powder of the present invention has a particularly low content of extraneous elements.
摘要:
The invention relates to a method for preparing silicon-containing iron powders by thermal decomposition of a gas mixture comprising iron pentacarbonyl and, as a volatile silicon compound, a silane or a halogen-free organosilane in which the gas mixture flows through a heated reaction chamber and heating of the gas mixture is effected by thermal conduction. The silicon-containing iron powders obtained are distinguished by a particularly low impurity element content. The silicon-containing iron powders can be used for the fabrication of cores, magnets and radar-absorbing materials.
摘要:
Silanes of the general formula I ##STR1## wherein n is an integer of from 1 to 5, at least one of the residues R represents a hydrolyzable residue selected from the group of substituents consisting of halogen, alkoxy, sec. amino and oxycarbonyl hydrogen or oxycarbonyl alkyl, and the other residues represent alkyl, cycloalkyl, aryl or one of the said hydrolyzable residues, a process for their preparation, and their use.