阅读说明：本技术 一种类芬顿试剂用于分析测定有机成核剂中铝含量的方法 (Method for analyzing and determining aluminum content in organic nucleating agent by Fenton-like reagent ) 是由 代燕琴 林福华 张咪 王克智 李训刚 张建军 毛晨曦 李向阳 王晶 王晨 王凯 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种类芬顿试剂用于分析测定有机成核剂中铝含量的方法,所述方法包括以下步骤：A)用类芬顿试剂对样品进行氧化消解,消解液澄清透明无颗粒；B)对消解液进行特殊处理,使Fe<Sup>2+</Sup>全部转化为Fe<Sup>3+</Sup>；C)采用乙二胺四乙酸二钠(EDTA)络合-氟盐置换滴定法对铝的含量进行滴定。本发明改变了传统的用高浓度强酸或强碱高温浸取样品的预处理方法,采用类芬顿试剂作为样品消解用氧化剂,使样品的消解变得简便易行,避免了使用高浓度酸碱带来的操作危险性；本发明采用EDTA络合滴定中的置换滴定,屏蔽了芬顿试剂中的铁离子对铝含量测定的影响,准确检测出有机成核剂中的铝含量,与电感耦合等离子发射光谱法(ICP-OES)的数据相比,误差＜1.5％。(The invention discloses a method for analyzing and determining aluminum content in an organic nucleating agent by using a Fenton-like reagent, which comprises the following steps of: A) carrying out oxidation digestion on the sample by using a Fenton-like reagent, wherein digestion liquid is clear and transparent and has no particles; B) subjecting the hydrolysate to special treatment to obtain Fe 2+ All conversion to Fe 3+ (ii) a C) And titrating the content of the aluminum by adopting an Ethylene Diamine Tetraacetic Acid (EDTA) complexation-villaumite replacement titration method. The method changes the traditional pretreatment method for leaching the sample at high temperature by using high-concentration strong acid or strong base, adopts the Fenton-like reagent as the oxidizing agent for sample digestion, ensures that the digestion of the sample becomes simple and easy, and avoids the operation danger caused by using high-concentration acid and alkali; the invention adopts replacement titration in EDTA complexation titration, shields the influence of iron ions in Fenton reagent on the determination of aluminum content, accurately detects the aluminum content in organic nucleating agent, and emits light with inductively coupled plasmaThe data for the spectroscopy (ICP-OES) were compared with an error of < 1.5%.)

1. A Fenton-like reagent is used for analyzing and determining the aluminum content in an organic nucleating agent, and comprises the following steps:

A) carrying out oxidation digestion treatment on the organic nucleating agent sample by using a Fenton-like reagent until digestion liquid is clear, transparent and particle-free;

B) treating the digestion liquid obtained in the step A) to ensure that Fe in the digestion liquid²⁺All conversion to Fe³⁺；

C) Masking off Fe in Fenton reagent by EDTA complexation-villaumite replacement titration method³⁺The influence on the complexometric titration, the content of aluminum can be accurately determined by titration with a zinc chloride standard solution.

2. The method for analyzing and measuring the aluminum content in the organic nucleating agent by using the Fenton-like reagent as claimed in claim 1, wherein the organic nucleating agent is a nucleating agent of aluminum carboxylate and aluminum phosphate.

3. The method for analyzing and measuring the aluminum content in the organic nucleating agent by using the Fenton-like reagent as claimed in claim 2, wherein the aluminum carboxylate salt nucleating agent is bis [ 4-di-tert-butylbenzoic acid ] aluminum hydroxide, the aluminum organophosphate salt nucleating agent is 2,2' -methylene-bis (4, 6-di-tert-butylphenyl) aluminum hydroxide phosphate, and the compound nucleating agent comprising the two.

4. The method of claim 1, wherein the Fenton-like reagent is a combination of iron powder and hydrogen peroxide.

5. The method for analyzing and determining the aluminum content in the organic nucleating agent by using the Fenton-like reagent according to claim 1, wherein the specific steps of oxidizing digestion in the step A) comprise:

mixing organic nucleating agent sample, excessive iron powder and dilute HNO₃Mixing, heating to 85 + -2 deg.C in water bath, maintaining the temperature for 2 hr, and dropwise adding 30% of excessive H at the beginning of the maintaining and 1hr after maintaining₂O₂And (4) until the digestion solution is colorless, clear and transparent liquid, and the sample digestion is finished.

6. The method for analyzing and determining the aluminum content in the organic nucleating agent by using the Fenton-like reagent according to claim 1, wherein the specific steps of the treatment in the step B) comprise:

after digestion, the temperature is continuously raised until the water bath is boiled, and the temperature is kept for 3 minutes to eliminate redundant H₂O₂Cooling to room temperature, wherein the liquid is turbid, and then adding 20% diluted H dropwise₂SO₄Shake with stirring until the solution is just clear, then transfer the whole sample into a 250ml conical flask for titration.

7. The method for analyzing and determining the aluminum content in the organic nucleating agent by using the Fenton-like reagent according to claim 1, wherein the specific steps of EDTA complexation-villaumite replacement titration in the step C) comprise:

using xylenol orange as an indicator, adjusting the pH value of the digestion solution obtained in the step B), transferring an excessive EDTA standard solution into a conical flask, and complexing Fe3+ with EDTA to generate a complex; cooling, adding hexamethylenetetramine, adjusting the pH value of the solution, and titrating by using a zinc chloride standard solution until the solution is rose red, namely, the residual EDTA is completely complexed by Zn, which is the 1 st end point; adding fluoride, shaking, heating and boiling for 3min, taking down and cooling to room temperature, adding 1-2 drops of xylenol orange indicator, adjusting the pH value of the solution at the 3 rd time, titrating with a zinc chloride standard solution until the solution is rose red, and recording the volume v (ml) of the zinc chloride standard solution consumed by the titration at the 2 nd end point.

Technical Field

The invention belongs to the technical field of chemical analysis, and particularly relates to a method and a technology for testing the aluminum content of an organic nucleating agent.

Background

The aryl carboxylic acid metal salt and organic phosphate metal salt organic nucleating agent both belong to alpha-crystal form polyolefin nucleating agent, are used as excellent modification auxiliary agents of polyolefin, can endow resin with good rigidity, surface gloss and heat deformation resistance, have good compatibility with the resin, are easy to disperse and resist extraction, and are widely applied in the fields of high-rigidity PP special materials, vehicle PP accessories and the like; the aluminum salt nucleating agent becomes the most main general variety of polyolefin resin, the production and consumption are steadily increased, but the industry does not have a uniform quality index which is proper in cost, simple in operation and easy to popularize so that the product quality is uneven; therefore, the invention provides a conventional detection method which is simple and convenient to operate, economical and practical, and is very important. The Al combined in the compound is shown by the structural formulas of aluminum carboxylate and aluminum organophosphate³⁺The method is quantitative, and can realize quantitative analysis of the two types of nucleating agents by establishing a quantitative analysis and detection method of the aluminum content.

For the analysis and detection of organic matters, the most common digestion method of the current sample pretreatment technology is a wet digestion method, which mainly comprises an electric hot plate method, a microwave digestion method, a full-automatic graphite digestion method and the like; the electric hot plate method has simple equipment and low price, but has large acid consumption, long time consumption and environmental pollution; the microwave digestion method and the graphite digestion method have the advantages of thorough digestion and good repeatability, but the equipment is expensive, the cost is high, and the method cannot be popularized. The fenton-like reagent is used as the oxidant for sample digestion, so that the defects of the digestion methods are overcome, the digestion of the sample is simple and easy to implement, the temperature is only (85 +/-2) DEG C, the digestion can be easily realized in a water bath, the time is shortened to 2 hours, the operation danger caused by using high-concentration acid and alkali is avoided, special equipment is not needed, and the method is extremely easy to popularize.

The Fenton reagent is hydrogen peroxide and Fe²⁺The combination results in a strong oxidizing agent, while the combination of hydrogen peroxide with other metal ions is called fenton-like reagent. Hydrogen peroxide in Fe²⁺Or hydroxyl free radical OH & lt- & gt with high reaction activity is generated under the catalytic action of other metal ions, the OH & lt- & gt has high electronegativity and strong addition reaction characteristics, can react with most organic matters without selectivity, has high oxidation rate and thorough reaction, and finally oxidizes and decomposes organic matters into micromolecular matters, carbon dioxide and water, wherein the Fenton reaction formula is as follows:

H₂O₂+Fe²⁺→Fe³⁺+OH·+OH·

the Fenton reagent and the Fenton reaction are widely applied to the treatment aspect of industrial wastewater at present, and are not reported in the aspect of digestion of organic matters.

The conventional chemical methods for measuring aluminum comprise a photometric method, an EDTA (ethylene diamine tetraacetic acid) complexation titration method, an atomic absorption spectrometry method, an inductively coupled plasma emission spectrometry method and the like. Although the instrumental analysis method has high sensitivity and good selectivity, the instrumental analysis method is expensive, high in measurement cost, complex in detection process, difficult to operate and high in requirements on experiment operators, and is not suitable for daily detection of small enterprises. And the EDTA titration method has few interference factors, stable determination process and wide determination range, is more suitable for mass enterprises and is easy to popularize. The method adopts a Fenton oxidation digestion-EDTA complexation-villaumite replacement titration method to establish the detection method of the aluminum content with simple and convenient operation, accurate result and good reproducibility, thereby realizing the quantitative analysis of the nucleating agent.

Disclosure of Invention

In view of the above-mentioned deficiencies in the prior art, the present invention provides a Fenton-like reagent for analyzing and determining the aluminum content in an organic nucleating agent, comprising the following steps:

A) carrying out oxidation digestion treatment on the organic nucleating agent sample by using a Fenton-like reagent, wherein the digestion solution is clear and transparent and has no particles;

B) treating the digestion liquid obtained in the step A) to lead Fe²⁺All conversion to Fe³⁺；

C) Masking off Fe in Fenton reagent by EDTA complexation-villaumite replacement titration method³⁺The influence on the complexometric titration is realized, and the aluminum content is accurately determined.

Wherein, the organic nucleating agent is preferably aryl aluminum carboxylate nucleating agent and organic aluminum phosphate nucleating agent.

The aluminum arylcarboxylate nucleating agent is preferably aluminum benzoate series with different substituent groups, the aluminum organophosphate nucleating agent is preferably phosphate aluminum salt series with methylene bis (2, 4-di-tert-butylphenol) as a framework, the aluminum benzoate series nucleating agent is preferably p-tert-butyl aluminum benzoate, the aluminum phosphate ester series with methylene bis (2, 4-di-tert-butylphenol) as a framework is preferably methylene bis (2, 4-di-tert-butylphenyl) phosphate aluminum salt, and the compound nucleating agent taking the two as a composition.

Wherein the Fenton-like reagent refers to hydrogen peroxide and Fe²⁺The combination of metal ions other than the above-mentioned metal ions means a combination of iron powder and hydrogen peroxide in the present invention.

Wherein, the oxidation digestion conditions of the organic nucleating agent sample in the step A) are preferably as follows:

mixing organic nucleating agent sample, excessive iron powder and dilute HNO₃Mixing, heating to 85 + -2 deg.C in water bath, maintaining the temperature for 2 hr, and adding 30% H dropwise twice (at the beginning of the temperature maintenance, at 1 hr)₂O₂(sufficient excess) until colorless clear transparent liquid is present in the tube and the sample digestion is complete.

The main reaction equation in the step A) is as follows:

excess iron powder and dilute nitric acid: 3Fe +8HNO₃(rare) ═ 3Fe (NO)₃)₂+2NO↑+4H₂O

Fenton reaction: h₂O₂+Fe²⁺→Fe³⁺+OH·+OH·

And selecting a sufficient excess of H₂O₂Mixing Fe²⁺And the excess iron powder is completely oxidized to Fe³⁺At this time, Fe in the digestion solution³⁺Is the only form of iron present.

The conditions for treating the digestion solution in the step B) are preferably as follows:

after the digestion is finished, the temperature is continuously raised until the water bath is boiled, and the temperature is kept for 3 minutes to eliminate redundant H₂O₂Cooling to room temperature, wherein the liquid is turbid, and then adding 20% diluted H dropwise₂SO₄Shake with stirring until the solution is just clear, then transfer the whole sample into a 250ml conical flask for titration.

The turbidity phenomenon of the liquid generated in the step B) is caused by: h₂O₂OH formed during decomposition^-With Fe in the liquid³⁺Reaction to produce Fe (OH)₃And (4) precipitating.

Wherein, the step C) of EDTA complexation-villiaumite replacement titration is preferably as follows:

transferring the excess EDTA standard solution into a conical flask, Fe³⁺Firstly, complexing with EDTA to generate a corresponding complex, taking xylenol orange as an indicator, and carrying out complexing reaction after adjusting the pH value of the solution for the first time; cooling, adding hexamethylenetetramine, adjusting the pH value of the solution for the 2 nd time, and titrating by using a zinc chloride standard solution until the solution is rose red, namely, the residual EDTA is completely complexed by Zn, which is the 1 st end point; adding fluoride, shaking, heating and boiling for 3min, taking down and cooling to room temperature, adding 1-2 drops of xylenol orange indicator, adjusting the pH value of the solution at the 3 rd time, titrating with a zinc chloride standard solution until the solution is rose red, and recording the volume v (ml) of the zinc chloride standard solution consumed by the titration at the 2 nd end point.

In the step C) of EDTA complexation-villiaumite displacement titration, the pH value of the solution is adjusted for the 1 st time, and the conditions of the complexation reaction are preferably: neutralizing with 1+3 ammonia water until the solution turns purple red, immediately adjusting to orange yellow with 1+1 hydrochloric acid, adding 2 drops of hydrochloric acid, controlling pH at 3.5-4.0, boiling for 3min, and at this time, adding EDTA and Al³⁺Take place ofComplexing reaction to generate EDTA-Al³⁺The highest percentage.

In the step of EDTA complexation-villiaumite replacement titration in step C), the pH values of the 2 nd and 3 rd adjusting solutions and the optimal pH conditions of EDTA complexation titration are preferably as follows: adjusting pH of the liquid to 5.5-5.9 (orange yellow) with 1+1 hydrochloric acid, wherein the indicator is xylenol orange and Zn²⁺The ions form a stable red complex, and in the pH range, xylenol orange is not only an acid-base indicator, but also a complexometric titration indicator, so that the phenomenon of color development confusion caused by adding more than 2 indicators is avoided, and a satisfactory detection result is obtained.

Wherein in the step of EDTA complexation-villiaumite replacement titration in the step C), villiaumite refers to ammonium fluoride solid, and EDTA-Al can be completely captured when the addition amount is 0.5g³⁺Al in the Complex³⁺AlF with more stable generation of fluoride ion₆ ^3-By substitution of Al with³⁺Equivalent amount of EDTA, and EDTA-Fe³⁺The high stability of the complex can not be destroyed by ammonium fluoride, namely can not be replaced, the replaced EDTA is titrated by zinc chloride standard solution, and the aluminum content in the sample can be calculated by the consumption volume of the zinc standard solution.

The invention relates to a method for analyzing and determining the aluminum content in an organic nucleating agent by using a Fenton-like reagent, wherein the calculation formula of the determined aluminum content is as follows:

wherein X represents the content of aluminum (mg/kg) in the sample;

v- -volume (mL) of zinc chloride standard solution consumed for the 2 nd titration;

c- - -the exact value of the concentration of the zinc chloride standard titration solution (mol/L);

m — molar mass of aluminum (g/mol) (M ═ 26.98);

m- -weight the sample (g).

The invention has the beneficial effects that: the Fenton reagent is applied to the aspect of organic sample digestion, not only is the raw material easily available, the operation is simple, the equipment is civilian and the effect is good, but also the EDTA complexation-villiaumite replacement titration method is adopted, the interference of iron ions is ingeniously shielded, the measured aluminum content result is very close to the measured result of the inductively coupled plasma emission spectrometer, and the method is suitable for the public and is easier to popularize.

Detailed Description

The following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and the experimental methods without specific conditions noted in the following examples are generally performed according to conventional conditions.

1. Using the following reagents:

nitric acid: 10% solution.

Hydrogen peroxide: 30% solution.

Metallic iron powder

Sulfuric acid: 20% solution.

Ammonia water solution: 1+3.

Hydrochloric acid solution: 1+1

Disodium ethylenediamine tetraacetate standard solution c (EDTA) 0.05 mol/L.

Xylenol orange indicator liquid 5 g/L: 0.5g of xylenol orange is weighed and dissolved by adding 100ml of water.

Hexamethylenetetramine solution: 20% (mass fraction) of aqueous solution.

Zinc chloride standard titration solution: c (ZnCl)₂)＝0.01mol/L。