CN115180699B - Salting-out treatment method for alkali-reduced fiber-opening wastewater of microfiber fabric - Google Patents

Salting-out treatment method for alkali-reduced fiber-opening wastewater of microfiber fabric Download PDF

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CN115180699B
CN115180699B CN202210851164.XA CN202210851164A CN115180699B CN 115180699 B CN115180699 B CN 115180699B CN 202210851164 A CN202210851164 A CN 202210851164A CN 115180699 B CN115180699 B CN 115180699B
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alkali
wastewater
salting
opening
fiber
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CN115180699A (en
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钱能
钱国春
董爱学
钱红飞
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Zhejiang Meisheng New Materials Co ltd
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Zhejiang Meisheng New Materials Co ltd
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    • 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
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • 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
    • C02F2103/30—Nature of the water, waste water, sewage or sludge to be treated from the textile industry

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Inorganic Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Removal Of Specific Substances (AREA)

Abstract

The invention belongs to the technical field of alkali reduction wastewater recovery, and discloses a salting-out treatment method of alkali reduction fiber-opening wastewater of a microfiber fabric. According to the invention, anhydrous calcium chloride is added into alkali-reduced fiber-opening wastewater, and the molar ratio of the anhydrous calcium chloride to the terephthalate is 0.5-2.5: 1, adding acid to adjust the pH value to 5-8 after mixing, and standing; then, carrying out solid-liquid separation to obtain supernatant and solid; and washing the solid with water and drying to obtain the terephthalic acid product. The invention adopts a salting-out method to treat alkali-reduction fiber-opening wastewater under near neutral condition, can realize the precipitation of terephthalic acid at normal temperature and normal pressure, has high recovery rate, less consumption of acid, alkali and salt and low comprehensive treatment cost; the total CODcr value of the obtained wastewater is greatly reduced, the burden of subsequent wastewater treatment is lightened, and the wastewater treatment efficiency is improved.

Description

Salting-out treatment method for alkali-reduced fiber-opening wastewater of microfiber fabric
Technical Field
The invention relates to the technical field of alkali reduction wastewater recovery, in particular to a salting-out treatment method of alkali reduction fiber-opening wastewater of a microfiber fabric.
Background
Polyesters are high molecular weight compounds formed by polycondensation of terephthalic acid and glycol. The textile fabric made of polyester fiber can make the surface gloss of the fabric become softer through alkali deweighting hydrolysis process, and achieves the special hand feeling and good draping feeling of real silk. The microfiber fabric prepared from the microfiber also needs to be subjected to alkali deweighting treatment to remove the sea-phase polyester part in the original fiber, and only the island phase (the component is polyester or polyamide) is reserved, so that the fiber opening is realized. The polyester polymer and sodium hydroxide undergo multiphase hydrolysis reaction, ester bonds in the polymer undergo nucleophilic reaction hydrolysis cleavage, the hydrolysis reaction is gradually carried out on the surface of the fiber from outside to inside, and hydrolysis products with different polymerization degrees are continuously separated out from the surface of the fiber and enter sodium hydroxide aqueous solution. The wastewater produced by the method has high pH value, contains a large amount of high-concentration terephthalic acid salt, has high CODcr value, and can cause great environmental pollution and resource waste when being directly discharged, and the wastewater treatment system for conventional printing and dyeing wastewater is difficult to degrade terephthalic acid contained in alkali-reduction wastewater, so that all treated wastewater can not reach the discharge standard far.
The traditional recovery method of terephthalic acid in the alkali reduction wastewater is an acid precipitation method, namely, after acid is added to a certain extent, terephthalic acid crystals which are difficult to dissolve in water can be formed, precipitation is performed, and the wastewater is purified. However, the acid precipitation method is adopted to treat the alkali-reduction wastewater, the consumption of acid is large, and a large amount of alkali is additionally added to adjust the pH to be neutral before the obtained waste liquid is discharged into a printing and dyeing wastewater treatment system, so that the comprehensive treatment cost of the alkali-reduction wastewater is increased, and secondary pollution is easily caused if the treatment is improper.
Therefore, how to provide an alkali-reduction wastewater treatment method with low treatment cost and high recovery efficiency of terephthalic acid is of great significance to the subsequent treatment of wastewater, environmental protection and resource recovery and reuse.
Disclosure of Invention
The invention aims to provide a salting-out treatment method for alkali-reduced fiber opening wastewater of a microfiber fabric, which solves the problems existing in the existing alkali-reduced wastewater treatment technology.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a salting-out treatment method of alkali-reduced fiber opening wastewater of a microfiber fabric, which comprises the following steps:
adding anhydrous calcium chloride into the alkali-reduced fiber-opening wastewater, mixing, adding acid to adjust the pH value, and standing; then, carrying out solid-liquid separation to obtain supernatant and solid; and washing the solid with water and drying to obtain the terephthalic acid product.
Preferably, in the salting-out treatment method of the alkali-reduced fiber-opening wastewater of the microfiber fabric, the alkali-reduced fiber-opening wastewater contains terephthalate; the molar ratio of the anhydrous calcium chloride to the terephthalate is 0.5-2.5: 1.
preferably, in the salting-out treatment method of the alkali-reduced fiber-opening wastewater of the microfiber fabric, the pH is adjusted to 5-8.
Preferably, in the salting-out treatment method of the alkali-reduced fiber-opening wastewater of the microfiber fabric, the standing time is 1-3 hours.
Preferably, in the salting-out treatment method of the alkali-reduced fiber opening wastewater of the microfiber fabric, the number of times of water washing is 1-3 times; the drying temperature is 90-120 ℃; the drying time is 60-100 min.
And adding calcium salt into the alkali-reduced fiber-opening wastewater of the microfiber fabric to generate insoluble or insoluble terephthalate precipitate. The pH value of the solution is regulated to realize the maximized precipitation of terephthalic acid, the recovery rate can reach more than 90 percent, and the method has simple process, easy filtration of the product and good sedimentation.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts a salting-out method to treat alkali-reduction fiber-opening wastewater under near neutral condition, can realize the precipitation of terephthalic acid at normal temperature and normal pressure, has high recovery rate, less consumption of acid, alkali and salt and low comprehensive treatment cost; the total CODcr value of the obtained wastewater is greatly reduced, the burden of subsequent wastewater treatment is lightened, and the wastewater treatment efficiency is improved.
Detailed Description
The invention provides a salting-out treatment method of alkali-reduced fiber opening wastewater of a microfiber fabric, which comprises the following steps:
adding anhydrous calcium chloride into the alkali-reduced fiber-opening wastewater, mixing, adding acid to adjust the pH value, and standing; then, carrying out solid-liquid separation to obtain supernatant and solid; and washing the solid with water and drying to obtain the terephthalic acid product.
In the invention, the alkali-reduced fiber-opening wastewater is provided by Zhejiang Mei Cheng new material Co., ltd; wherein, the concentration of the terephthalate is 0.02-0.06 mol/L, and the COD value is 3900-11000 mg/L.
In the invention, the alkali-reduced fiber-opening wastewater contains terephthalate; the molar ratio of the anhydrous calcium chloride to the terephthalate is preferably 0.5-2.5: 1, more preferably 0.7 to 2.1:1, more preferably 1.2:1.
in the present invention, the pH is preferably adjusted to 5 to 8, more preferably 6 to 8, still more preferably 6 to 7; the pH is preferably adjusted to 25 to 98%, more preferably 50 to 98%, and even more preferably 72% by using sulfuric acid.
In the present invention, the time for the standing is preferably 1 to 3 hours, more preferably 1.5 to 2.5 hours, still more preferably 2 hours; the temperature for standing is preferably room temperature.
In the present invention, the solid-liquid separation is preferably centrifugation.
In the present invention, the number of times of the washing with water is preferably 1 to 3 times, more preferably 2 to 3 times, and still more preferably 3 times; the drying temperature is preferably 90 to 120 ℃, more preferably 96 to 113 ℃, still more preferably 107 ℃; the drying time is preferably 60 to 100 minutes, more preferably 70 to 90 minutes, and still more preferably 80 minutes.
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The embodiment provides a salting-out treatment method of alkali-reduced fiber opening wastewater of a microfiber fabric, which comprises the following steps:
selecting 100mL of microfiber fabric alkali deweighting fiber-opening wastewater, wherein the concentration of terephthalate is 0.06mol/L, and the COD value is 11000mg/L; 0.3343g of anhydrous calcium chloride (the molar ratio of the anhydrous calcium chloride to the terephthalate is 0.5:1) is added, after uniform mixing, 50% sulfuric acid is used for regulating the pH value to 5, and then the mixture is kept stand at room temperature for 2 hours; centrifuging after standing to obtain supernatant and solid; washing the solid with water for 3 times in turn, and drying at 100 ℃ for 80min to obtain terephthalic acid solid; the concentration of terephthalic acid salt in the supernatant was measured, and the sedimentation rate of terephthalic acid was calculated.
Wherein, the method for measuring the concentration of the terephthalate in the supernatant fluid comprises the following steps:
the absorbance of the supernatant was measured using an ultraviolet-visible spectrophotometer and substituted into the absorbance-concentration standard curve regression equation of the terephthalate solution (a=13083 x, r 2 =0.9998, a is the absorbance value of the sample solution at 238nm, x is the concentration of terephthalate salt, mol/L), and the concentration of terephthalate salt in the supernatant (i.e., the treated alkali-reduced fiber-opening wastewater) is obtained.
The formula for calculating the sedimentation rate of terephthalic acid is:
precipitation rate of D-solution precipitate (%)
Concentration of terephthalic acid salt in stock solution (mol/L)
Concentration of terephthalic acid salt in C2-supernatant (mol/L)
Examples 2 to 4
Examples 2 to 4 provide a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, and the specific reference is made to example 1, and the difference is that the pH values are respectively adjusted to 6, 7 and 8.
Example 5
The embodiment provides a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, which is specifically referred to in embodiment 1, and is different in that the addition amount of anhydrous calcium chloride is 0.6686g, that is, the molar ratio of the anhydrous calcium chloride to the terephthalate is 1:1.
examples 6 to 8
Examples 6 to 8 provide a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, and the specific reference is made to example 5, and the difference is that the pH values are respectively adjusted to 6, 7 and 8.
Example 9
The embodiment provides a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, which is specifically described in embodiment 1, and is different in that the addition amount of anhydrous calcium chloride is 1.0029g, namely, the molar ratio of the anhydrous calcium chloride to terephthalate is 1.5:1.
examples 10 to 12
Examples 10 to 12 provide a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, and the specific reference is made to example 9, and the difference is that the pH values are respectively adjusted to 6, 7 and 8.
Example 13
The embodiment provides a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, which is specifically described in embodiment 1, and is different in that the addition amount of anhydrous calcium chloride is 1.3373g, namely, the molar ratio of the anhydrous calcium chloride to terephthalate is 2:1.
examples 14 to 16
Examples 14 to 16 provide a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, and the specific reference is made to example 13, and the difference is that the pH values are respectively adjusted to 6, 7 and 8.
Example 17
The embodiment provides a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, which is specifically described in embodiment 1, and is different in that the addition amount of anhydrous calcium chloride is 1.6716g, namely, the molar ratio of the anhydrous calcium chloride to terephthalate is 2.5:1.
examples 18 to 20
Examples 18 to 20 provide a salting-out treatment method for alkali-reduced fiber-opening wastewater of a microfiber fabric, and the specific reference is made to example 17, and the difference is that the pH values are respectively adjusted to 6, 7 and 8.
The sedimentation rate results of terephthalic acid in examples 1 to 20 are shown in Table 1.
TABLE 1 sedimentation Rate results of terephthalic acid
As can be seen from Table 1, the addition of various amounts of calcium chloride and the adjustment of the pH of the wastewater have a great influence on the recovery rate of terephthalic acid from the wastewater. When the molar ratio of anhydrous calcium chloride to terephthalate is 0.5, the pH value of the wastewater needs to be reduced to 5 so that 99.13 percent of reaction products are separated out; the molar ratio of the anhydrous calcium chloride to the terephthalate is 1, when the pH value is 7, the sedimentation rate is 89.81 percent, and the COD value is reduced to 1780mg/L; at pH 6, the product had 96.80% sedimentation; the sedimentation rates of 97.12%, 97.96% and 99.35% are respectively obtained when the molar ratio of anhydrous calcium chloride to terephthalate is 1.5, 2 and 2.5 and the pH value is 7. Considering that the alkali decrement wastewater can be discharged and treated only by adjusting the wastewater to be nearly neutral, when the molar ratio of anhydrous calcium chloride to terephthalate is 0.5, the optimal process needs to additionally add alkali to adjust the pH of the wastewater, and when the molar ratio of the anhydrous calcium chloride to the terephthalate is 1.5, 2 and 2.5, the wastewater has higher sedimentation rate under the neutral condition, but the use amount of the calcium chloride is large, so that the wastewater treatment cost can be increased. Therefore, from the economic factor, the molar ratio of the anhydrous calcium chloride to the terephthalic acid salt is 1, and the pH value is adjusted to 6, so that the process is a better process, the recovery rate of the terephthalic acid is higher under the condition, the dosage of the input medicament is small, the overall process is more economical, the treatment difficulty of alkali reduction wastewater discharge can be solved, and the process can also contribute to the recycling economy and sustainable development.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (3)

1. The salting-out treatment method of the alkali-reduced fiber-opening wastewater of the microfiber fabric is characterized by comprising the following steps of:
adding anhydrous calcium chloride into the alkali-reduced fiber-opening wastewater, mixing, adding acid to adjust the pH value, and standing; then, carrying out solid-liquid separation to obtain supernatant and solid; washing and drying the solid to obtain a terephthalic acid product;
wherein, the alkali-reduced fiber-opening wastewater contains terephthalate; the concentration of terephthalate in the alkali deweighting fiber-opening wastewater is 0.02-0.06 mol/L, and the COD value is 3900-11000 mg/L;
the molar ratio of the anhydrous calcium chloride to the terephthalate salt is 1.5: 1.2:1 or 2.5:1, a step of;
and the pH value is adjusted to 6.
2. The salting-out treatment method for the alkali-reduced fiber opening wastewater of the microfiber fabric of claim 1, wherein the standing time is 1-3 hours.
3. The salting-out treatment method for the alkali-reduced fiber opening wastewater of the microfiber fabric according to claim 1 or 2, wherein the number of times of water washing is 1-3 times; the drying temperature is 90-120 ℃; the drying time is 60-100 min.
CN202210851164.XA 2022-07-20 2022-07-20 Salting-out treatment method for alkali-reduced fiber-opening wastewater of microfiber fabric Active CN115180699B (en)

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* Cited by examiner, † Cited by third party
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JPS58166982A (en) * 1982-03-27 1983-10-03 Ishikawaken Treatment of waste water containing sodium terephthalate
JPH05329487A (en) * 1992-05-29 1993-12-14 Asahi Chem Ind Co Ltd Method for treating waste water of alkali reduction treatment for polyester fiber

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