Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D3/00—Halides of sodium, potassium or alkali metals in general
  • C01D3/04—Chlorides
  • C01D3/06—Preparation by working up brines; seawater or spent lyes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D3/00—Halides of sodium, potassium or alkali metals in general
  • C01D3/14—Purification
  • C01D3/18—Purification with selective solvents
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/26—Treatment of water, waste water, or sewage by extraction
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
  • C02F2103/36—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds
  • C02F2103/38—Polymers
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F9/00—Multistage treatment of water, waste water or sewage

Definitions

• the present invention relates to a process for the treatment of saline wastewater, characterized in that an aqueous saline solution is obtained by a certain sequence of acidification, extraction, alkalization and stripping steps, which can be used directly in chlor-alkali electrolysis ,
• Saline wastewater is produced in many chemical processes.
• phase interface process for the production of polycarbonate or the production of diphenyl carbonate also in the phase interface process and many other chemical reactions in which sodium chloride is formed directly or indirectly (see, for example, Schnell, “Chemistry and Physics of Polycarbonates”, polymer
• waste water could be better disposed of.
• a possible option would be the use of such waste water in chlor-alkali electrolysis. Firstly, this would not pollute the environment with salt, secondly, resources would be saved and raw material costs would be saved. For use in chlor-alkali electrolysis, however, only waste water is considered which contains chlorides as anions practically exclusively. Therefore, wastewater, which still contains other anions and organic impurities, must be treated accordingly beforehand.
• wastewater generated in the production of polycarbonate or diaryl carbonate contains carbonate from phosgene hydrolysis in addition to saline concentrations of 2 to 20%.
• organic contaminants are also present. So there are still residues of phenols or bisphenols, catalyst and solvent. All these
• Impurities would have to be reduced to a minimum to enable use in chlor-alkali electrolysis.
• reaction salts containing saline such as are obtained, for example, from the interfacial processes for polycarbonate or diphenyl carbonate synthesis, can be worked up by means of reactive extraction after acidification in such a way that a solution suitable for introduction into the environment is obtained becomes. It is also pointed out that this solution can be used in chlor-alkali electrolysis after appropriate concentration. However, the process described there is not suitable for directly delivering a solution suitable for use in chlor-alkali electrolysis. The residual organic load still present according to this process would also be concentrated if it was concentrated, making the solution unsuitable for chlor-alkali electrolysis.
• saline process wastewater can be treated in such a way that the remaining saline solution can be used directly in the chlor-alkali electrolysis by using the process wastewater acidified with HCI and then degassed with an organic solvent, the aqueous phase alkalized and stripped with steam.
• the salt solution obtained can be used directly in the electrolysis, a concentration is not necessary. In the case of membrane electrolysis, salt cleaning is no longer necessary and the water can be recycled.
• the extracted phenols can be used again as raw materials in the synthesis.
• Reactive extraction are operated. 7.
• the COD value achieved in the treated wastewater is below 30 ppm and thus below the application limit of the COD process. The value is therefore not exactly determinable but very low.
• the wastewater from the reaction is first with HCl, preferably with commercially available 37% aqueous acid, up to a pH of 1-5, preferably from 3 to 4, very particularly preferably 3 acidified.
• the carbonates are thus converted into carbonic acid, which escapes as a gas.
• the carbonic acid can possibly be recovered in order to convert it to CO in a reformer.
• phenolic anions are converted into the corresponding free phenolic compounds.
• Apolar organic solvents such as e.g. Methylene chloride, chlorobenzene or a mixture of these two, MIBK (methyl isobutyl ketone) or ether, preferably methylene chloride, chlorobenzene or a mixture of these two, can be used.
• MIBK methyl isobutyl ketone
• ether preferably methylene chloride, chlorobenzene or a mixture of these two
• Base preferably long chain tertiary amines such as e.g. Use alamin or tri-iso-octyl-amine, especially tri-iso-octyl-amine, as the reactive extractant, dissolved in inert apolar organic solvents such as petroleum fractions, e.g. Shell-Sol AB.
• inert apolar organic solvents such as petroleum fractions, e.g. Shell-Sol AB.
• inert organic solvents is preferred. This removes the phenolic compounds and other organic compounds from the aqueous solution. This extraction takes place in several, preferably 4-10 stages.
• Mixer-settlers or extraction columns, preferably extraction columns, particularly preferably pulsed filling or sieve plate columns, can be used for this purpose, see FIG. z. B. Perry's Chemical Engineering Handbook, Mc Graw Hill, New York,
• Sodium hydroxide solution in a concentration of 1-30%, preferably 5 to 20% NaOH, re-extracted.
• the alkaline aqueous phase is used in a significant deficit as an extractant in order to achieve the highest possible phenolate concentrations in the alkaline aqueous phase.
• a ratio of aqueous sodium hydroxide solution to organic phase of about 1:50 to 1: 1000, preferably 1: 400 to 1: 1000, would suffice. The exact However, ratios depend on the concentration of phenol in the organic phase to be worked up, since it is a reactive extraction in which approx.
• Partial flow to mass flow of the extracted organic phase now corresponds to the above-mentioned ratio.
• the aqueous extract obtained in this way can be treated further in order to recover phenols.
• a preferred procedure is that the re-extraction with sodium hydroxide solution is carried out in two stages.
• extralation is carried out with an aqueous sodium hydroxide solution / phenolate solution, which is formed from the partial stream removed in the second extraction stage with the addition of additional NaOH to restore the concentration of 1-30%, preferably 5 to 20%, as described above.
• the partial stream obtained in this stage is fed directly to the phenol recovery and a corresponding amount of lye from the second stage as fresh lye, with the addition of additional NaOH to restore the concentration of 1-30%, preferably 5 to 20% NaOH, again.
• a concentration of 1-30%, preferably 5 to 20% NaOH is extracted with NaOH, as described above, the partial stream removed being replaced by fresh liquor and this partial stream, with the addition of additional NaOH, to restore the concentration of 1-30 %, preferably 5 to 20% NaOH, is added as a fresh extractant to the first stage.
• a concentrated aqueous-alkaline solution of the phenolates is obtained, from which simply by neutralizing with
• HCI two phases arise, which are separated in a simple separation container can. In this way you get an upper phase, which contains about 90% of the phenane amount, and which can either be used again in a synthesis (eg DPC) or otherwise eliminated.
• the other phase consists of an aqueous saline solution slightly contaminated with phenol and is returned to the reaction wastewater to be processed.
• the content of phenolic compounds in the organic phase is reduced to below 1 ppm by this re-extraction.
• the organic phase thus freed from phenolic compounds is returned to the extraction of the reaction waste water as the extraction agent.
• the two-stage re-extraction can be designed, for example, in the form of a countercurrent extraction. These re-extractions are preferably carried out in a mixer-settler, e.g. as described in Perry's Chemical Engineering Handbook, Mc Graw Hill, New York, 1999, 15-22 to 15-29.
• the extracted saline process wastewater largely freed from phenolic and other organic compounds, is now alkalized with aqueous sodium hydroxide solution of any concentration, for example 1-50% NaOH, to a pH of 7-13, preferably 8-12, and with steam at 1- 4, preferably 2-3, particularly preferably 2.5 bar in a stripping column, see. e.g. "Azeotropic Distillation" in Perry's Chemical
• the amount of water vapor is related to the amount of solution to be stripped, such as 1-5, preferably 2-4, particularly preferably 3-3.5 to 100.
• both the catalyst and the residual solvent are removed.
• the top gases of the column therefore contain the catalyst and residual solvent, are condensed and can be returned to the synthesis reaction.
• the bottom product is a pure saline solution, which can now be used directly in chlor-alkali electrolysis.
• the content of residual organics in the saline solution thus prepared is ⁇ 0.3, preferably ⁇ 0.1 ppm, bisphenols and catalyst residues are no longer detectable and the residual content of organic solvents is ⁇ lppm, preferably ⁇ 0.1 ppm.
• Wastewater from diphenyl carbonate production contains 200 ppm phenol, 30 ppm ethyl piperidine (EPP), 2 ppm diphenyl carbonate and 0.25% sodium carbonate.
• EPP ethyl piperidine
• the phenol concentration in the wastewater after the extraction column is ⁇ 200 ppb.
• the ratio of wastewater to extractant (methylene chloride) is 2: 1.
• the COD is 28 ppm and can therefore no longer be measured reproducibly because the sensitivity of the method is insufficient.
• the high NaCl content of the solution also leads to increased measured values so that the actual COD is still significantly lower.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Inorganic Chemistry (AREA)
• Physical Water Treatments (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Degasification And Air Bubble Elimination (AREA)
• Extraction Or Liquid Replacement (AREA)

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• 2002
  • 2002-02-22 DE DE10207442A patent/DE10207442A1/de not_active Withdrawn
• 2003
  • 2003-02-10 WO PCT/EP2003/001282 patent/WO2003070639A1/de not_active Ceased
  • 2003-02-10 US US10/505,196 patent/US20050115901A1/en not_active Abandoned
  • 2003-02-10 JP JP2003569557A patent/JP2005517624A/ja not_active Withdrawn
  • 2003-02-10 EP EP03702616A patent/EP1483204A1/de not_active Withdrawn
  • 2003-02-10 AU AU2003205750A patent/AU2003205750A1/en not_active Abandoned
  • 2003-02-10 CN CNA038091208A patent/CN1646429A/zh active Pending
  • 2003-02-21 TW TW092103586A patent/TW200306952A/zh unknown

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