Alkali deweighting wastewater processing method and device

Inactive Publication Date: 2012-12-19
SHAOXING COUNTY JINGSHENG RESIN TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Chinese patent 97106539.x discloses a "treatment method for alkali-reduction wastewater", which is to add ferric salt to alkali-reduction wastewater, and adjust the pH with acid, so that terephthalic acid is precipitated in a solid state, thereby reducing waste water. COD cr value, this method can generally reduce COD cr The value is more than 75%, but the simple precipitation of terephthalic acid has many impurities, which cannot be recycled, and contains secondary pollution caused by solid waste
In addition, the cost of acid precipitation is also high
[0004] Chinese patent (99124266.1) discloses a method for recovering terephthalic acid from alkali reduction wastewater, which can obtain relatively high-purity terephthalic acid, and its resource regeneration can make up for operating costs. However, this type of simple precipitation Terephthalic acid cannot directly and effectively remove residues such as ethylene glycol and sodium sulfate adsorbed by terephthalic acid (acid analysis with sulfuric acid), so its recycling is limited to a certain extent
[0006] In summary, this area lacks an effective method to process alkali reduction waste water

Method used

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  • Alkali deweighting wastewater processing method and device
  • Alkali deweighting wastewater processing method and device

Examples

Experimental program
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Effect test

Embodiment 1

[0127] Take 0.5m of the alkali weight reduction waste water of polyester warp knitted fabric 3 , the measured pH is 14, COD cr At 25000mg / L. Sulfuric acid with a concentration of 98% by weight was added to adjust the pH of the waste water to 7. The amount of acid added was determined by the drop of acid in the filtrate and no terephthalic acid was precipitated. Collect the precipitated solid terephthalic acid, weigh 100g after drying, add 50ml of 98% sulfuric acid and 500ml of methanol, and react at 70°C for 10 hours to obtain DMT crystals. After drying, 50g of crude DMT was poured into 200ml of ethanol solution and heated to 60°C. DMT was dissolved to obtain a cloudy ethanol mixture, which was filtered through activated carbon to obtain a clear solution. The resulting clear solution was frozen to 10°C under ice-bath cooling. At this time, DMT crystals were precipitated.

Embodiment 2

[0129] Take 0.3m of alkali reduction waste water of imitation silk polyester fabric 3 , pH value is 12.1. Add waste sulfuric acid with a concentration of 31wt%, and the pH drops to 6.5. The precipitated solid terephthalic acid was collected and weighed 200 g after drying. Add 58ml of 98% sulfuric acid and 600ml of methanol. At 110°C, 4kgf / cm 2 Under the above conditions, the reaction was carried out for 3 hours to obtain DMT crystals. Weigh 50g, add 200ml of analytical pure ethanol, the crystals are completely dissolved at 50°C, add clay and stir, filter through a ceramic microporous tube to obtain a pure liquid, condense to 10°C, and all DMT crystals are precipitated.

Embodiment 3

[0131] With the waste sulfuric acid concentration of 65% and 200ml of the above test, precipitate the pongee alkali reduction wastewater with pH 14 to obtain 80 grams of terephthalic acid, and undergo esterification (at 70°C under normal pressure) for 12 hours to obtain DMT crystals, which are dissolved in hot ethanol , After adding barium carbonate and stirring, CO2 bubbles appear, and white barium sulfate precipitates. Then add walnut shell filter material, filter through a dense filter cloth, obtain recrystallization at room temperature at 25°C, and after crystallization and drying, distill the DMT purity once to reach 99.6%.

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Abstract

The invention provides a processing method for alkali-minimization wastewater, comprising a plurality of steps: (a) adjusting the PH value of alkali-minimization wastewater into 6.5 to 7, using the method of acid precipitation to obtain liquid phase and the solid phase with terephthalic acid; (b) carrying out esterification reaction for the solid phase from the procedure (a) in the presence of methanol to obtain a crude dimethyl terephthalate product. The method recovering terephthalic acid from alkali-minimization wastewater makes CODcr value of the wastewater removal of more than 75% and modifies the wastewater into Biodegradable industrial wastewater and at the same time changes the phthalic acid into dimethyl terephthalate.

Description

technical field [0001] The invention relates to a treatment method for dyeing and finishing wastewater, in particular to a treatment method for alkali weight reduction wastewater. Background technique [0002] The alkali reduction process is to treat the polyester fabric with alkali (NaOH), and hydrolyze the polyethylene terephthalate (PET) on the surface of the fabric at a higher temperature, so that the fabric becomes soft after weight reduction. . The alkali reduction wastewater produced in the alkali reduction treatment process mainly contains PET hydrolyzate sodium terephthalate, ethylene glycol, titanium dioxide, and some auxiliary agents brought by the spinning and spinning process, and its COD cr The value is generally 8000 ~ 30000mg / l (combined value of reduction and washing wastewater). Because the benzene ring structure molecule of sodium terephthalate is extremely difficult to process with low-cost biodegradation process. [0003] Chinese patent 97106539.x dis...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C69/82C02F103/30C02F101/34
Inventor 陈定良
Owner SHAOXING COUNTY JINGSHENG RESIN TECH CO LTD
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