Abstract: An improved process for preparing an aromatic dicarboxylic acid wherein the improvement resides in dehydrating and recovering solvent from a feed stream having from 20% to 40% by weight water via azeotropic distillation with organic phase reflux using an entrainer selected from isobutyl acetate, n-propyl acetate or an entrainer with a boiling point between isobutyl acetate and n-propyl acetate.

Abstract: A is a process for removing water from an alkanesulfonic acid such as methanesulfonic acid or ethanesulfonic acid by mixing an azeotropic excess of a phenolic compound with water and the alkanesulfonic acid, then boiling off substantially all of the water, and leaving as a remnant substantially all the alkanesulfonic acid and some of the phenol. This process is particularly useful for recycling an alkanesulfonic acid for a reaction which requires the phenolic compound as one of the reagents. One such reaction is the alkanesulfonic acid catalyzed condensation reaction of a phenolic compound with an .alpha.haloketone to form a chlorinated intermediate of a dihydroxy-.alpha.-alkylstilbene such as 4,4'-dihydroxy-.alpha.-alkylstilbene (DHAMS).

Abstract: An assembly for prepping sulfuric acid for spectrometric analysis comprised of a vessel member having sleeve members formed with channels disposed about an outer peripheral surface and a cap member including a disc shaped top portion and a lower body portion and further including a gasket member to be positioned between the cap member and the vessel member wherein the lower body portion extending into a chamber of the vessel member and wherein the top portion includes channels to be aligned with the channels of the sleeves of the vessel member for receiving mounting devices for rigidly mounting the cap member to the vessel member.

Abstract: A method of recycling and purifying cleaning chemicals used in the production of semiconductor circuits and containing hydrofluoric acid and or hydrochloric acid. Recycling of such chemicals is accomplished using separation and reconstitution steps Hydrofluoric acid and hydrochloric acid cannot be distilled directly from a chemical solution as they form azeotropes with water. A low vapor pressure substance such as sulfuric acid or phosphoric acid is used to break the azeotrope while increasing the purity of the recovered chemicals and decreasing disposal problems. The method is useable at the point of use of the chemicals.

Abstract: A process for treating an aqueous solution mainly containing nitric acid and hydrofluoric acid. The process involves distilling to provide an aqueous solution concentrated in nitric acid and hydrofluoric acid for the separation thereof, then separating by distillation.

Abstract: Tetranitromethane and other polynitrated methanes can be effectively removed from otherwise substantially organic-free nitric acid streams through the addition of substantially organic-free concentrated sulfuric acid and by, optionally, performing secondary operations such as sparging the mixed acid stream with a gas such as nitric oxide or with an oil.

Abstract: A high efficiency batch sulfuric acid reprocessor system that is capable of producing high purity acid through distillation. Methods of use are also provided. The distillation is monitored and controlled in accordance with temperatures of the system, in particular, the temperature of the column and the temperature of the vapor in a condensing chamber. A stream splitter enables the invention to selectively collect high purity product as well as remove waste or recycle condensate as reflux.

Abstract: Volatile acids containing metal salt impurities, such as metal pickling solutions-are regenerated by a process in which the acid is subjected to sulfuric acid distillation. Resulting volatile acid vapor is condensed and recycled to the pickle tank, while the residual acid mixture is treated in an acid sorption unit, preferably of the acid retardation type. Acid sorbed in the acid sorption unit is periodically eluted with water and recycled, while metal impurities are rejected in a deacidified by-product solution.

Abstract: The present invention provides a method for separating boric acid from a liquid, especially liquid waste obtained from a nuclear power plant. In the process, the waste solution containing the boric acid is contacted with steam in a reactor so that the boric acid evaporates from the liquid and passes into the steam vapor phase. Consequently, the radioactive wastes which are not evaporated with the steam remain in the waste water while the boric acid is removed from the waste water when it passes into the vapor or steam phase. The boric acid can then be separated and recovered from the steam by means of a distillation and fractionating column or a wash column. By removing the boric acid from the liquid waste, it is possible to obtain concentrated radioactive waste having a reduced volume due to the absence of boric acid in the waste.

Abstract: Method and apparatus for the distillation of liquids which is particularly suited for the removal of soluble impurities and insoluble and non-volatile particles of 10 microns to 0.2 micron or less in size. A substantially elongated distillation chamber having walls equipped with axially disposed concentric boiling rings spaced from the walls near the bottom, and a packing stop, packing redirector rings for condensed vapor, and a reflux condenser in the upper part of the distillation chamber provide, during distillation, a smooth convective upward flow of distilling liquid and vapor proximate the walls and boiling rings and a smooth convective downward flow of distilling liquid and vapor substantially centrally of the distillation chamber.

Abstract: An apparatus for distilling corrosive compounds under high temperatures, which would include primary vessel chamber, having a first interior annular wall lined with a loose polymer, such as PTFE (or TEFLON), a second annular wall exterior to the first annular wall, and defining an annular space between the interior and the exterior wall; a somewhat rigid porous material for supporting the interior PTFE liner positioned along the interior wall of the vessel; device for drawing air out of the annular space between interior and exterior walls, for creating a vacuum at the annular space, so that the PTFE liner is supported firmly against the somewhat rigid porous support member; next, a second means for drawing air out of the interior of the vessel for creating a vacuum therewithin so that a pressure equilibrium is established between the interior of the vessel and the annular space, and a corrosive material can be heated in the vessel chamber under the vacuum, and the liner be maintained flush against the wall o

Abstract: Aqueous hydrochloric acid of very high purity can be obtained in a process for purifying crude aqueous 5 to 20 wt. % hydrochloric acid. In the purification, process water or a water/HCl mixture is evaporated from the crude aqueous hydrochloric acid at a pressure of from 0.01 to 1.0 bar and a temperature of from 10.degree. to 100.degree. C. until a crude, azeotropic mixture of water and HCl is obtained. The crude, azeotropic mixture of water and HCl is distilled in a distillation apparatus at a pressure of from 0.1 to 1.5 bar and a temperature of from 50.degree. to 110.degree. C. A purified gaseous, azeotropic mixture of water and HCl is recovered from the head of the distillation apparatus and a liquid mixture is left at the bottom of the distillation apparatus. The liquid mixture which is left at the bottom of the distillation apparatus is distilled at a pressure of from 0.5 to 2.5 bar and a temperature of from 80.degree. to 130.degree. C.

Abstract: An apparatus and method for reprocessing waste piranha containing contaminated H.sub.2 SO.sub.4 from, for example, a semiconductor processing operation is described. The apparatus and method include a first distillation flask which is maintained under a substantial vacuum. The first distillation flask includes a first column packed with a column packing material and an input pipe for refluxing to retard loss of H.sub.2 SO.sub.4 in the first distillation. The second distillation flask boils off substantially pure H.sub.2 SO.sub.4 and provides for a continuous automatic purge of the contaminants from the second distillation flask thus improving the purity of the H.sub.2 SO.sub.4. The substantially pure H.sub.2 SO.sub.4 flows through a column which is coupled to a condenser which condenses substantially pure H.sub.2 SO.sub.4.

Abstract: An apparatus and method for reprocessing waste piranha containing contaminated H.sub.2 SO.sub.4 from, for example, a semiconductor processing operation is described. The apparatus and method include a first distillation flask which are maintained under a substantial vacuum. The first distillation flask includes a first column with a column packing means and a reflux means to retard loss of H.sub.2 SO.sub.4 in the first distillation. The second distillation flask boils off substantially pure H.sub.2 SO.sub.4 through a column which is coupled to a condenser which condenses substantially pure H.sub.2 SO.sub.4.

Abstract: An integrated continuous processes for concentrating "weak" nitric acid and concurrently reconcentrating the spent dehydrating agent used to break the nitric acid azeotrope to obtain "strong" nitric acid, the processes involving direct coupling of the nitric acid concentration with the reconcentration of the spent dehydrating agent so that less energy input is required. The major proportion of the feed "weak" nitric acid is vaporized before being fed countercurrently into a column to contact a large volume of the dehydrating agent, this vaporization being one of the two major sources of energy input, the second being through the reboiler at the bottom of the column. Energy input is balanced by energy rejection through condensation of strong nitric acid vapor and water vapor.

Abstract: A two-step distillation process provides semiconductor purity, concentrated hydrofluoric acid. Further, the distillation process, occurring under reduced pressures eliminates essentially pure water after the first distillation step. The product output of the second distillation process provides an acid of weight percent greater than 27 weight percent. The product acid is carefully diluted to the required concentrations during the dilution step.

Abstract: One or more quartz tubes (1) are utilized in apparatus for the concentration of an acid. Each quartz tube is heated from the outside, and the acid is fed in at the upper part of each tube. Concentrated acid is drained off from the lower part of each tube into a vessel (3) and the vapors driven off from the acid during the concentrating rise inside each tube, and are led off from the upper part thereof. Inside each tube, the acid first passes through a rectification zone (A) in the upper part of the tube, and then passes through a liquid film zone and a reservoir zone.

Abstract: System for concentrating and recovering acid comprising in combination a receptacle or storage tank for receiving and containing weak or dilute acid; an evaporating pan including a pipe connected to the receptacle or storage tank and a pump whereby acid may be delivered to the evaporating pan; a second receptacle or storage tank including a pipe connected to the evaporating pan and a pump whereby concentrated acid may be delivered to the second receptacle or storage tank; and an air drier device in the form of a tank containing acid and including an inlet through which air and water vapor may be introduced, and a pipe connection to the tank for weak or dilute acid; wherein the evaporating pan includes a heat collecting surface as a floor thereof and a lens focus top whereby heat energy from the sun's rays will heat and concentrate the acid therein by developing water vapor which is removed with air.

Abstract: Process for working up aqueous nitric acid which is of a concentration above the azeotropic concentration and contains organic compounds in solution for suspension wherein said nitric acid of a concentration about the azeotropic concentration is distilled off in one or more rectification steps until the azeotropic nitric acid is obtained. In the process, certain specified ratios of nitric acid and water to organic constituents must be maintained.

Abstract: The invention procides a circulation evaporator for concentrating mineral acid, particularly sulphuric acid, comprising parts of, or at least coated with, enamel, characterized by a heat exchanger for heating the acid comprising at least one acid feed pipe provided with an enamel layer, means being provided to maintain the compressive stress in the enamel layer under all working conditions, said acid feed pipe being connected at its inlet end to a circulation pump and at its outlet end to a flash evaporator for concentrating the heated acid, this evaporator being connected by a circulation pipe to the pump inlet and to means for introducing the crude acid, for discharging the concentrate and for carrying away the vapors.

Abstract: A method is provided for directly heating a concentrated sulphuric-acid solution by passing alternating electric current between surface-passivated electrodes immersed in the solution and by using electrodes of iron or an iron alloy having a low resistance iron or iron alloy inner core covered by an outer high resistance passivating surface layer which are so surface-passivated that the transition resistance between the electrodes and the concentrated sulphuric-acid solution is at least as great as the resistance exerted by the concentrated sulphuric-acid solution.

Abstract: Concentrated sulphuric acid aqueous solutions, stably clear through the time, are obtained starting from diluted sulphuric acid aqueous solutions containing Mg and possibly other impurities such as Fe, Al, Cr, V and Mn, by evaporation concentration. The process is characterized in that, before filtering, the slurry obtained by evaporation concentration, is cooled down to 10.degree.-25.degree. C. and maintained at this temperature for not less than 12 hours.

Abstract: A multi-stage apparatus suited for concentrating sulphuric acid comprising at least one high temperature stage and one low temperature stage, the high temperature stage including a surrounding wall defining a flue gas channel, means for delivering hot flue gas to said channel, and means for withdrawing from said channel cooled flue gas, the flue gas heating said surrounding wall which in turn imparts heat to material to be heated thereby, the low temperature stage including a heat exchanger with a first flow path for a heating agent and a second flow path for a material to be heated thereby, means for supplying the said second flow path material to be heated, means for withdrawing from said second flow path material after having been heated therein, and means for withdrawing from said first flow path spent heating agent, the means for withdrawing cooled flue gas from said flue channel of said high temperature stage forwarding heat from said cooled flue gas to said first flow path of said low temperature stage

Abstract: The invention has as its object a method for simultaneously concentrating and purifying phosphoric acid. It consists in bringing into contact, in a tower, the acid to be concentrated and purified divided into fine droplets with a current of hot gases and in collecting, at the bottom of the tower, the concentrated and purified acid. Previously, the acid has been mixed, with water and with a fraction of the said concentrated and purified acid. The invention is implemented for the producing of phosphoric acid having a very low fluorine content, suitable for being used for the synthesis of phosphate foodstuffs.

Abstract: In the processing of a corrosive liquid mixture, such as 50 to 80% aqueous sulfuric acid, by its passage over one surface of a wall of inert heat resistant material, and heating the other surface of said wall, thereby to evaporate from said corrosive liquid mixture the more volatile component thereof, the improvement which comprises heating said wall by contact with an inert liquid material, and heating said inert liquid material indirectly through heat exchange with a normally solid molten material. Desirably the wall of inert material is a pipe surrounded by a molten metal in a first annular jacket and a molten salt in a second annular jacket.

Abstract: A two step process for concentrating and desalting dilute sulfuric acid including, first indirectly countercurrently contacting and heating the dilute acid with steam from a second step, removing overhead water vapor and withdrawing concentrated acid, and second further concentrating the acid by directly countercurrently contacting and heating the acid with superheated steam, removing overhead steam and additional water vapor, which is used in the first heating step. Acid of a higher concentration is withdrawn and cooled to crystallize and remove salts and the more highly concentrated sulphuric acid recovered.

Abstract: Dilute solutions of corrosive products, such as sulphuric or phosphoric acid, are concentrated by pre-concentrating the dilute solution and then introducing the pre-concentrated solution into a tunnel in which it flows in a thin layer over successive cascades while being heated, preferably by indirect radiant heating. An installation for carrying out the process is also described.

Abstract: In the processing of a corrosive liquid mixture, such as 50 to 80% aqueous sulfuric acid, by its passage over one surface of a wall of inert heat resistant material, and heating the other surface of said wall, thereby to evaporate from said corrosive liquid mixture the more volatile component thereof, the improvement which comprises heating said wall by contact with an inert liquid material, and heating said inert liquid material indirectly through heat exchange with a normally solid molten material. Desirably the wall of inert material is a pipe surrounded by a molten metal in a first annular jacket and a molten salt in a second annular jacket.