JPH0436143B2 - - Google Patents
Info
- Publication number
- JPH0436143B2 JPH0436143B2 JP15808483A JP15808483A JPH0436143B2 JP H0436143 B2 JPH0436143 B2 JP H0436143B2 JP 15808483 A JP15808483 A JP 15808483A JP 15808483 A JP15808483 A JP 15808483A JP H0436143 B2 JPH0436143 B2 JP H0436143B2
- Authority
- JP
- Japan
- Prior art keywords
- acid
- terephthalic acid
- sulfuric acid
- crystals
- svi
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims description 62
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 40
- 238000000034 method Methods 0.000 claims description 15
- -1 alkali metal salt Chemical class 0.000 claims description 9
- 238000003916 acid precipitation Methods 0.000 claims description 7
- 229910052783 alkali metal Inorganic materials 0.000 claims description 6
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 239000013078 crystal Substances 0.000 description 22
- 238000006243 chemical reaction Methods 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 239000002253 acid Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-M hydrogensulfate Chemical compound OS([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 description 6
- 229920000728 polyester Polymers 0.000 description 6
- 238000010494 dissociation reaction Methods 0.000 description 5
- 230000005593 dissociations Effects 0.000 description 5
- 239000000835 fiber Substances 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 230000004580 weight loss Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 238000005904 alkaline hydrolysis reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- VIQSRHWJEKERKR-UHFFFAOYSA-L disodium;terephthalate Chemical group [Na+].[Na+].[O-]C(=O)C1=CC=C(C([O-])=O)C=C1 VIQSRHWJEKERKR-UHFFFAOYSA-L 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
Description
【発明の詳細な説明】
技術分野
本発明は、テレフタル酸のアルカリ金属塩水溶
液よりテレフタル酸を回収する方法に関する。DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for recovering terephthalic acid from an aqueous solution of an alkali metal salt of terephthalic acid.
従来技術
テレフタル酸のアルカリ金属塩水溶液よりテレ
フタル酸を酸析反応により回収する方法において
は、中和反応であるため極めて反応速度が速く、
且つ生成するテレフタル酸の溶解度が室温で約
15ppmと非常に小さいため、生成するテレフタル
酸の結晶が極めて微細で、通常2μ程度の粒子径
しか得られない。このように微細なテレフタル酸
の結晶は、反応液中に懸濁して沈降せず、固液分
離に際して150％程度の含有率しか得られず、ま
た洗浄も困難であり、さらに乾燥の負荷を増大さ
せるためテレフタル酸を回収するにあたり大きな
障害となつている。Prior Art In the method of recovering terephthalic acid from an aqueous solution of an alkali metal salt of terephthalic acid by acid precipitation reaction, the reaction rate is extremely fast because it is a neutralization reaction.
Moreover, the solubility of the terephthalic acid produced is approximately
Because it is extremely small at 15ppm, the crystals of terephthalic acid that are produced are extremely fine, and the particle size is usually only about 2μ. These fine terephthalic acid crystals are suspended in the reaction solution and do not settle, resulting in a content of only about 150% during solid-liquid separation, which is difficult to clean, and further increases the burden of drying. This poses a major obstacle in recovering terephthalic acid.
発明の目的・構成及び効果の説明
本発明者等は近年急速な発展をとげたポリエス
テル繊維のアルカリ加水分解による風合改善処理
（以下、ポリエステル繊維の減量加工と称する）
の排液よりテレフタル酸を回収する方法を検討し
たが、上記障害を改良しなければ工業的な実施が
困難であるため鋭意検討の結果、本発明をなすに
いたつたものである。ポリエステル繊維の減量加
工とは、アルカリ金属水酸化物の水溶液を使用し
てポリエステル分子鎖を加水分解し、適度に脆化
させることによりポリエステル繊維の剛直なる風
合を改善するもので、その排液中には高純度のテ
レフタル酸がアルカリ金属塩の形で多量に含まれ
ている。本発明は、ポリエステル繊維の減量加工
排液よりテレフタル酸を回収する方法に関して特
に有効であるが、あらゆるテレフタル酸のアルカ
リ金属塩水溶液について適用することができ、ポ
リエステル繊維の減量加工排液からテレフタル酸
の回収に限定されるものではない。Description of the purpose, structure, and effects of the invention The present inventors have developed a treatment for improving the feel of polyester fibers by alkaline hydrolysis (hereinafter referred to as weight loss processing of polyester fibers), which has been rapidly developed in recent years.
We investigated a method for recovering terephthalic acid from the effluent, but it would be difficult to implement it on an industrial scale unless the above-mentioned obstacles were corrected.As a result of intensive research, we have arrived at the present invention. Weight loss processing for polyester fibers involves hydrolyzing the polyester molecular chains using an aqueous solution of alkali metal hydroxide to make them moderately brittle, thereby improving the rigid texture of the polyester fibers. It contains a large amount of highly purified terephthalic acid in the form of an alkali metal salt. The present invention is particularly effective with respect to a method for recovering terephthalic acid from the waste water from the weight loss process of polyester fibers, but it can be applied to any aqueous alkali metal salt solution of terephthalic acid. It is not limited to the collection of
本発明によれば、テレフタル酸結晶の大きさは
40μ以上になり、その結果回収したテレフタル酸
は沈降分離が可能で、脱水工程でも水分率50％以
下のケーキが容易に得られ、乾燥工程のエネルギ
ーも大いに軽減される。テレフタル酸の粒子が大
きくなつた結果は純度面にもあらわれ、微細粒子
ではどうしても除去できなかつた塩の混入が解決
し、回収したテレフタル酸を特に精製することな
く再利用に供することが可能である。 According to the present invention, the size of terephthalic acid crystals is
As a result, the recovered terephthalic acid can be separated by sedimentation, and a cake with a moisture content of less than 50% can be easily obtained during the dehydration process, and the energy required for the drying process is greatly reduced. The result of larger terephthalic acid particles is also seen in terms of purity, which solves the problem of salt contamination that could not be removed with finer particles, making it possible to reuse the recovered terephthalic acid without any particular purification. .
テレフタル酸のアルカリ金属塩水溶液よりテレ
フタル酸を回収するには、酸を使用してアルカリ
金属イオンと水素イオンとを置換することにより
達成される。本発明者等は先に酸としてpKa＝
1.5〜5.0の弱い酸を使用して連続的に酸析反応を
行なうことによりテレフタル酸の回収が容易に行
なわれることを見い出した（特願昭58−53816
号）。これによれば、pKa＝1.5〜5.0の弱い酸を使
用して、pH＝2.0〜4.0にコントロールしながら連
続的に酸析反応を行なうことにより、粒子径が大
きく且つ純度の高いテレフタル酸が回収可能であ
る。即ち、硫酸の第２段目の解離pKa＝1.92）を
適度な酸強度を持つ酸としてとらえ、硫酸水素塩
の使用を要件としたのである。しかし、さらに詳
しく検討してみれば、pH2.0〜4.0にコントロール
される系内においては硫酸そのものが硫酸水素イ
オンの解離過程にあり、広義に解釈すれば硫酸の
使用を前記出願の発明に包含するものとみなすこ
とができる。しかしながら、本発明者等は硫酸を
使用してテレフタル酸を回収する場合、生成する
結晶の大きさが不安定に変動することを確認して
おり、前記特許出願においては比較例として例示
するにとどめた。しかして、本発明においては、
このように不安定な結晶生成状況を見せる硫酸の
使用について詳しく検討を加え、安定に結晶が成
長する条件を見い出し本発明を完成するにいたつ
たものである。なお、本発明において結晶の大き
さは、沈澱のSVIを測定することにより評価し
た。SVIとは、活性汚泥法の管理パラメーターと
してよく知られる指数であるが、ここでは次式に
より定義するものとし、第１図に示すとうり結晶
の大きさとの間に明瞭なる相関関係がある。 Recovery of terephthalic acid from an aqueous solution of an alkali metal salt of terephthalic acid is achieved by replacing alkali metal ions with hydrogen ions using an acid. The present inventors previously determined that pKa=
It has been discovered that terephthalic acid can be easily recovered by carrying out a continuous acid precipitation reaction using a weak acid of 1.5 to 5.0 (Japanese Patent Application No. 58-53816).
issue). According to this, terephthalic acid with large particle size and high purity can be recovered by performing acid precipitation reaction continuously using a weak acid with pKa = 1.5 to 5.0 while controlling pH = 2.0 to 4.0. It is possible. That is, the second-stage dissociation pKa of sulfuric acid (pKa = 1.92) was regarded as an acid with appropriate acid strength, and the use of hydrogen sulfate was a requirement. However, upon further examination, it is found that in a system controlled at pH 2.0 to 4.0, sulfuric acid itself is in the process of dissociating hydrogen sulfate ions, and if interpreted in a broad sense, the use of sulfuric acid is included in the invention of the above application. It can be regarded as something that does. However, the present inventors have confirmed that when terephthalic acid is recovered using sulfuric acid, the size of the generated crystals fluctuates unstablely, and the above patent application is limited to illustrating it as a comparative example. Ta. However, in the present invention,
We conducted detailed studies on the use of sulfuric acid, which exhibits such unstable crystal formation conditions, and found conditions for stable crystal growth, leading to the completion of the present invention. In the present invention, the crystal size was evaluated by measuring the SVI of the precipitate. SVI is a well-known index as a control parameter of activated sludge method, but here it is defined by the following formula, and as shown in Figure 1, there is a clear correlation between SVI and crystal size.
SVI＝反応懸濁液の５分静置後の沈澱の体
積百分率（％）／テレフタル酸の濃度（％）
硫酸を使用してテレフタル酸を酸析する場合
は、すでに述べたように硫酸水素イオンの解離過
程が重要であり、平衡理論より考えて100×Ka2
mol／以下の硫酸濃度で硫酸水素イオンの解離
過程の重要性が増大する。そこで、9.8重量％
（1mol／）に稀釈した硫酸を使用してテレフタ
ル酸を回収したところ、生成した沈澱のSVIは15
（相当する粒子径は約40μ）であり、この結果は
理論的な予測を充分裏付けるものであつた。次い
で、本発明者等は実験的に硫酸濃度の使用可能上
限について調査し、硫酸濃度が33重量％
（4.2mol／）までほぼ一定のSVIを示して大き
な結晶が得られるが、硫酸濃度がこれ以上のとき
はSVIが大きくなり微細な結晶しか得られないと
いうことを見い出した。 SVI = Volume percentage of precipitate (%) after the reaction suspension was allowed to stand still for 5 minutes / Concentration of terephthalic acid (%) When precipitating terephthalic acid using sulfuric acid, as mentioned above, hydrogen sulfate ion The dissociation process of is important, and considering from equilibrium theory, 100 × Ka 2
At sulfuric acid concentrations below mol/mol, the importance of the dissociation process of hydrogen sulfate ions increases. Therefore, 9.8% by weight
When terephthalic acid was recovered using sulfuric acid diluted to (1 mol/), the SVI of the precipitate formed was 15
(The corresponding particle size was approximately 40μ), and this result fully supported the theoretical prediction. Next, the present inventors experimentally investigated the usable upper limit of sulfuric acid concentration, and found that the sulfuric acid concentration was 33% by weight.
It was discovered that up to 4.2 mol/2, large crystals can be obtained with a nearly constant SVI, but when the sulfuric acid concentration is higher than this, the SVI increases and only fine crystals can be obtained.
無稀釈の硫酸を使用してテレフタル酸を酸析す
る場合、硫酸水素イオンの解離過程が重要である
としても、硫酸の第１段目は完全に解離している
から、硫酸と反応溶液との混合の初期において水
素イオン濃度が高濃度になるため種晶が多発する
ことを避けられず、したがつてある程度結晶が細
かくなることを避けられない。ここで使用する硫
酸の濃度を33重量％以下に稀釈する目的は、種晶
の発生する範囲を限定する効果を持つものと思わ
れ、硫酸の場合には硫酸水素イオンの解離過程で
の結晶成長が期待できるため、最終的に大きな結
晶が生成するものと思われる。 When terephthalic acid is acid-precipitated using undiluted sulfuric acid, even though the dissociation process of hydrogen sulfate ions is important, the first stage of sulfuric acid is completely dissociated, so the interaction between sulfuric acid and the reaction solution is Since the hydrogen ion concentration becomes high in the early stage of mixing, it is unavoidable that a large number of seed crystals occur, and therefore it is unavoidable that the crystals become fine to some extent. The purpose of diluting the concentration of sulfuric acid used here to 33% by weight or less is thought to have the effect of limiting the range in which seed crystals are generated, and in the case of sulfuric acid, crystal growth occurs during the dissociation process of hydrogen sulfate ions. It is expected that large crystals will eventually form.
本発明の方法を実施するために使用する反応装
置は連続式反応装置でなければならない。連続式
反応装置内では水素イオン濃度とテレフタル酸イ
オンの濃度のバランスがよくとれており、20分以
上の滞留時間を保つことにより結晶を大きく成長
させることが可能である。反応装置の攪拌は強力
なほどよく、攪拌が弱いときは、ただちに結晶の
大きさに影響し微細になるので注意が必要であ
る。更に、pH4.0以上の場合は酸析が不完全とな
り、pH2.0以下になると結晶が微細になるので好
ましくない。 The reactor used to carry out the process of the invention must be a continuous reactor. In the continuous reactor, the concentration of hydrogen ions and terephthalate ions are well balanced, and by maintaining a residence time of 20 minutes or more, it is possible to grow large crystals. The stronger the stirring in the reactor, the better. Care must be taken, as weak stirring will immediately affect the size of the crystals and make them fine. Furthermore, if the pH is higher than 4.0, acid precipitation will be incomplete, and if the pH is lower than 2.0, the crystals will become fine, which is not preferable.
以下、実施例をあげて本発明に更に説明する。 The present invention will be further explained below with reference to Examples.
実施例
連続式の酸析反応装置を使用し、9.8重量％
（1mol／）〜70重量％（11.5mol／）までの
硫酸水溶液を使用してテレフタル酸の酸析を行な
つた。原排液はテレフタル酸ナトリウム水溶液で
0.6〜1.1重量％の濃度であつた。酸析槽のpHを
2.5〜3.5に調整し、攪拌レイノルズ数を28000に
設定し、滞留時間を30分に選んだ。生成したテレ
フタル酸の結晶をSVIを測定することにより評価
した。結果は第２図に示す。硫酸濃度が33％以下
においては、テレフタル酸のSVIは15でほぼ一定
であることがわかる。このとき相当する結晶の粒
子径は約40μである。Example Using a continuous acid precipitation reactor, 9.8% by weight
Acid precipitation of terephthalic acid was carried out using an aqueous sulfuric acid solution ranging from (1 mol/) to 70% by weight (11.5 mol/). The raw effluent is a sodium terephthalate aqueous solution.
The concentration was 0.6-1.1% by weight. pH of acid analysis tank
2.5-3.5, the stirring Reynolds number was set to 28000, and the residence time was chosen to be 30 minutes. The produced terephthalic acid crystals were evaluated by measuring SVI. The results are shown in Figure 2. It can be seen that the SVI of terephthalic acid is approximately constant at 15 when the sulfuric acid concentration is 33% or less. The particle size of the corresponding crystal at this time is approximately 40μ.
第１図は結晶のSVIと粒子径との関係を示すグ
ラフであり、第２図は硫酸の濃度と結晶のSVIと
の関係を示すグラフである。
FIG. 1 is a graph showing the relationship between SVI of crystals and particle diameter, and FIG. 2 is a graph showing the relationship between sulfuric acid concentration and SVI of crystals.
Claims (1)
レフタル酸を回収する方法において、33重量パー
セント以下の濃度に稀釈した硫酸を使用し、
pH2.0〜4.0の範囲において連続的に酸析処理を行
なうことを特徴とするテレフタル酸の回収方法。1. In a method for recovering terephthalic acid from an aqueous solution of an alkali metal salt of terephthalic acid, using sulfuric acid diluted to a concentration of 33% by weight or less,
A method for recovering terephthalic acid, characterized by carrying out acid precipitation treatment continuously in a pH range of 2.0 to 4.0.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15808483A JPS6051145A (en) | 1983-08-31 | 1983-08-31 | Recovery of terephthalic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15808483A JPS6051145A (en) | 1983-08-31 | 1983-08-31 | Recovery of terephthalic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6051145A JPS6051145A (en) | 1985-03-22 |
| JPH0436143B2 true JPH0436143B2 (en) | 1992-06-15 |
Family
ID=15663942
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15808483A Granted JPS6051145A (en) | 1983-08-31 | 1983-08-31 | Recovery of terephthalic acid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6051145A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0623129B2 (en) * | 1986-02-28 | 1994-03-30 | 三井東圧化学株式会社 | Manufacturing method of cinnamic acids |
| JPH078822B2 (en) * | 1986-05-26 | 1995-02-01 | 三菱レイヨン株式会社 | Phthalic acid recovery method |
| US7915447B2 (en) | 2006-07-19 | 2011-03-29 | Showa Denko K.K. | Process for producing succinic acid |
| JP5052234B2 (en) * | 2006-07-19 | 2012-10-17 | 昭和電工株式会社 | Method for producing succinic acid |
| TWI708761B (en) * | 2019-09-26 | 2020-11-01 | 遠東新世紀股份有限公司 | Method for manufacturing terephthalic acid |
-
1983
- 1983-08-31 JP JP15808483A patent/JPS6051145A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6051145A (en) | 1985-03-22 |
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