JP2013003113A - Method for quantitating reducing agent in aqueous solution - Google Patents

Method for quantitating reducing agent in aqueous solution Download PDF

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JP2013003113A
JP2013003113A JP2011137742A JP2011137742A JP2013003113A JP 2013003113 A JP2013003113 A JP 2013003113A JP 2011137742 A JP2011137742 A JP 2011137742A JP 2011137742 A JP2011137742 A JP 2011137742A JP 2013003113 A JP2013003113 A JP 2013003113A
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reducing agent
iodine
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aqueous solution
sulfur dioxide
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Manabu Manabe
学 真鍋
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JX Nippon Mining and Metals Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

PROBLEM TO BE SOLVED: To provide a method for quickly and accurately quantitating a reducing agent such as sulfite and sulfur dioxide in an aqueous solution in an actual operation level in order to solve such problems that although it is important to quantitate unreacted reducing agent in each step in iodide ion collecting operation, reducing agents of sulfite and sulfur dioxide used widely are unstable in an acidic solution and easily subject to oxidation by air and thereby quick and accurate quantification is required, however installation of a large-scale precision apparatus is not realistic in an actual operation site.SOLUTION: The concentration of a reducing agent is quantitated by adding a solution to be quantitated to an iodine-starch mixture in a degree capable of suppressing disappearance of blue-violet and performing back titration of residual iodine.

Description

本発明は、水溶液中に含まれる亜硫酸や二酸化硫黄等の還元剤の定量法に関する。   The present invention relates to a method for quantifying a reducing agent such as sulfurous acid or sulfur dioxide contained in an aqueous solution.

湿式製錬法においては、鉱酸に難溶性を示す黄銅鉱等の硫化銅鉱に対して、その溶解のため、ヨウ素又はヨウ化物イオン及びＦｅ3+を添加すると、銅の浸出が著しく促進される（特許文献１）。 In the hydrometallurgical process, leaching of copper is remarkably promoted by adding iodine or iodide ions and Fe 3+ to copper sulfide ores such as chalcopyrite, which are hardly soluble in mineral acids, for dissolution. (Patent Document 1).

浸出後の貴液には比較的高価なヨウ素が含まれており、これを回収して再利用するには活性炭による吸着−溶離が好ましい。   The precious solution after leaching contains relatively expensive iodine, and adsorption-elution with activated carbon is preferable to recover and reuse it.

ヨウ素の溶離（ストリップ）の際に使用される溶離液は、水溶性の還元剤を含み、これによってヨウ素がヨウ化物イオンとして回収される。還元剤は、亜硫酸塩、二酸化硫黄、チオ硫酸塩等が任意の濃度で用いられるが、価格の面から亜硫酸塩及び二酸化硫黄が用いられることが多い。   The eluent used in iodine elution (strip) contains a water-soluble reducing agent, whereby iodine is recovered as iodide ions. As the reducing agent, sulfite, sulfur dioxide, thiosulfate or the like is used at an arbitrary concentration, but sulfite and sulfur dioxide are often used from the viewpoint of price.

溶離操作において指標となるものは、未反応の還元剤濃度であり、この濃度をモニターすることで反応の終点を知ることができる。   The index in the elution operation is the unreacted reducing agent concentration, and the end point of the reaction can be known by monitoring this concentration.

また、溶離して回収されたヨウ化物イオンは再び硫化銅鉱の浸出に利用されるが、この中には未反応の還元剤が含まれており硫化銅鉱の浸出に影響を与えることから、あらかじめバッキ等によりこれを除いておく必要がある。   The iodide ions recovered after elution are used again for the leaching of copper sulfide ore, but this contains an unreacted reducing agent that affects the leaching of the copper sulfide ore. It is necessary to exclude this by etc.

特開２０１０−０２４５１１号公報JP 2010-024511 A

ヨウ化物イオン回収操作においては、各工程における未反応の還元剤を定量することが重要であるが、広く利用されている亜硫酸塩及び二酸化硫黄の還元剤は、酸性溶液中で不安定であり、容易に空気による酸化を受けることから迅速に精度よく定量しなければならない。   In the iodide ion recovery operation, it is important to quantify the unreacted reducing agent in each step, but the widely used sulfite and sulfur dioxide reducing agents are unstable in acidic solutions, Since it is easily oxidized by air, it must be quantified quickly and accurately.

しかしながら、実際の操業現場においては大掛かりな精密機器を設置することは現実的ではない。
そこで、本発明はこのような事情に鑑み、実操業レベルで水溶液中の亜硫酸塩や二酸化硫黄等の還元剤を迅速に、且つ、精度良く定量する方法を提供することを課題とする。 However, it is not realistic to install large-scale precision equipment at the actual operation site.
Therefore, in view of such circumstances, an object of the present invention is to provide a method for quickly and accurately quantifying a reducing agent such as sulfite and sulfur dioxide in an aqueous solution at an actual operation level.

本発明者は、上記課題を解決するために鋭意検討した結果、ヨウ素−デンプン混合液に定量対象液を青紫色が消失しない程度添加し、残留ヨウ素を逆滴定するという手段を用いることで、大掛かりな精密機器を用いずに簡易な操作で水溶液中の還元剤を迅速に、且つ、精度良く定量することができることを見出した。   As a result of intensive studies to solve the above-mentioned problems, the present inventor added a liquid to be quantified to the iodine-starch mixed liquid to such an extent that the blue-violet color does not disappear, and used a means for back-titration of residual iodine. It has been found that the reducing agent in the aqueous solution can be quickly and accurately quantified with a simple operation without using a precise instrument.

以上の知見を基礎として完成した本発明は一側面において、ヨウ素−デンプン混合液に定量対象液を青紫色が消失しない程度添加し、残留ヨウ素を逆滴定することにより還元剤濃度を定量する水溶液中の還元剤の定量方法である。   The present invention completed on the basis of the above knowledge, in one aspect, in an aqueous solution in which the concentration of the reducing agent is quantified by adding the liquid to be quantified to the iodine-starch mixed solution to such an extent that the blue-violet color does not disappear, and back titrating residual iodine This is a method for quantifying the reducing agent.

本発明の水溶液中の還元剤の定量方法は一実施形態において、前記還元剤が、亜硫酸及び二酸化硫黄のいずれか、又は、それらの混合物である。   In one embodiment of the method for quantifying a reducing agent in an aqueous solution of the present invention, the reducing agent is any one of sulfurous acid and sulfur dioxide, or a mixture thereof.

本発明の水溶液中の還元剤の定量方法は別の一実施形態において、前記定量対象液を添加する前の前記ヨウ素−デンプン混合液に、ｐＨが４．３〜５の酢酸−酢酸ナトリウム緩衝液を添加しておく。   In another embodiment of the method for quantifying a reducing agent in an aqueous solution of the present invention, an acetate-sodium acetate buffer solution having a pH of 4.3 to 5 is added to the iodine-starch mixed solution before the quantification target solution is added. Add.

本発明によれば、簡便な装置を用いて実操業レベルで水溶液中の亜硫酸塩や二酸化硫黄等の還元剤を迅速に、且つ、精度良く定量する方法を提供することができる。   According to the present invention, it is possible to provide a method for quickly and accurately quantifying a reducing agent such as sulfite and sulfur dioxide in an aqueous solution at an actual operation level using a simple apparatus.

以下に、本発明に係る水溶液中の還元剤の定量方法の実施形態を説明する。   Below, embodiment of the determination method of the reducing agent in the aqueous solution which concerns on this invention is described.

ヨウ素は、その形態が単体ヨウ素のときに最も効率良く活性炭に吸着される。そのため、吸着及び溶離は、式１〜式３に示すようにヨウ素の酸化還元反応によって制御されると考えられる。
吸着時 2I- ＋Ox → I2 （Ox：酸化剤） （式１）
溶離時 I2 ＋ H2O ＋ SO3 2- → SO4 2- ＋2H+ ＋2I- （式２）
I2 ＋ 2H2O ＋ SO2 → SO4 2- ＋4H+ ＋2I- （式３） Iodine is most efficiently adsorbed on activated carbon when its form is simple iodine. Therefore, adsorption and elution are considered to be controlled by the oxidation-reduction reaction of iodine as shown in Formulas 1 to 3.
Adsorption during 2I - + Ox → I 2 ( Ox: oxidizing agent) (Equation 1)
Elution time I 2 + H 2 O + SO 3 2- → SO 4 2- + 2H + + 2I - (Formula 2)
I 2 + 2H 2 O + SO 2 → SO 4 2- + 4H + + 2I - (Formula 3)

溶離後液は酸性であり、ヨウ化物イオンの他に、主な共存物質として未反応還元剤と硫酸イオンが含まれている。   The solution after elution is acidic and contains unreacted reducing agent and sulfate ions as main coexisting substances in addition to iodide ions.

例えば、この回収液をそのまま硫化銅鉱の浸出に再使用すると、残存亜硫酸や二酸化硫黄の還元作用によりルイス酸が消費されて浸出に悪影響を及ぼす。そのため、ヨウ素の溶離の終了点は、溶離・回収されたヨウ素液に含まれる未反応還元剤濃度が低く、且つ、ＫＩ濃度が高くない時点としなければならないため、その指標として未反応還元剤濃度を定量する必要がある。   For example, if this recovered solution is reused for leaching copper sulfide ore as it is, Lewis acid is consumed by the reducing action of residual sulfurous acid and sulfur dioxide, which adversely affects leaching. Therefore, the end point of elution of iodine must be a point in time when the unreacted reducing agent concentration contained in the eluted and recovered iodine solution is low and the KI concentration is not high. Need to be quantified.

加えて、亜硫酸や二酸化硫黄は環境負荷が大きく、回収したヨウ化物イオンを再利用するにはあらかじめこれをバッキ等により除いておくことが望ましく、その管理のためには溶離後液に含まれる亜硫酸や二酸化硫黄の濃度を知ることは重要である。   In addition, sulfurous acid and sulfur dioxide have a large environmental impact, and it is desirable to remove the recovered iodide ions in advance in order to reuse the recovered iodide ions. It is important to know the concentration of sulfur dioxide.

ところで、還元剤として亜硫酸や二酸化硫黄を使用した場合は、溶存酸素や空気中の酸素により容易に酸化される（下記式４及び式５）。
O2 ＋ 2SO3 2- → 2SO4 2- （式４）
O2 ＋ 2H2O ＋ 2SO2 → 2SO3 2- ＋ 4H+ （式５） By the way, when sulfurous acid or sulfur dioxide is used as the reducing agent, it is easily oxidized by dissolved oxygen or oxygen in the air (the following formulas 4 and 5).
O 2 + 2SO 3 2- → 2SO 4 2- (Formula 4)
O 2 + 2H 2 O + 2SO 2 → 2SO 3 2- + 4H + (Formula 5)

そのため、定量は迅速に、空気の影響を最小限に留めて行う必要があるが、このような場合、操業現場では不活性ガス置換設備や精密分析機器等を併設することが困難である。   Therefore, quantification needs to be performed quickly and with the influence of air kept to a minimum. In such a case, it is difficult to install an inert gas replacement facility, a precision analysis device, or the like at the operation site.

一方で、ヨウ素は比較的強い酸化力を有し、上記式２及び式３に見られるように、亜硫酸や二酸化硫黄と直ちに反応するものの、単体ヨウ素としては水に対する溶解度が高くない。   On the other hand, iodine has a relatively strong oxidizing power and, as seen in the above formulas 2 and 3, reacts immediately with sulfurous acid and sulfur dioxide, but as a single iodine, its solubility in water is not high.

単体ヨウ素を水に溶解する際には、ヨウ化カリウムを添加し、ヨウ素を三ヨウ化物イオンとして溶解することが知られており、三ヨウ化物イオンも単体ヨウ素と同程度の酸化力を有する。   When dissolving simple iodine in water, it is known that potassium iodide is added and iodine is dissolved as triiodide ions, and triiodide ions have the same level of oxidizing power as simple iodine.

この酸化力を利用したヨウ素や三ヨウ化物イオンの定量法としては、チオ硫酸ナトリウム液を用いたものが広く知られている。当該方法を二酸化硫黄や亜硫酸の定量に適用する場合、逆滴定法になるため、サンプルを過大に分取すると定量が不可能になり、反対に過少に分取した場合は定量精度に問題が生じる。   As a method for quantifying iodine or triiodide ions using this oxidizing power, a method using a sodium thiosulfate solution is widely known. When this method is applied to the determination of sulfur dioxide or sulfurous acid, it becomes a back titration method, so if the sample is excessively sampled, it becomes impossible to determine the amount. .

そこで、あらかじめヨウ素−デンプン混合液に緩衝液を入れておき、そこにサンプルを添加する手法を取れば、サンプル添加量の適不適はヨウ素デンプン反応の青紫色の消失度合いで視認でき、かつ滴定途中の急激なｐＨ変化を抑えつつ溶存酸素や空気酸化による誤差を最小限に留めることが可能になる。   Therefore, if a buffer solution is added to the iodine-starch mixture in advance and a sample is added to the sample, the appropriateness of the sample addition can be visually recognized by the degree of disappearance of the blue-violet color of the iodine starch reaction, and during the titration. It is possible to minimize errors due to dissolved oxygen and air oxidation while suppressing rapid pH changes.

以上のことから、ヨウ素−デンプン混合液に適当量の定量対象液を添加し、残存するヨウ素を滴定すれば、簡便な装置により、迅速に精度良く還元剤を定量することが可能となる。より詳細には、本発明は、ヨウ素−デンプン混合液に定量対象液をヨウ素−デンプンの青紫色が消失しない程度添加し、残留ヨウ素を逆滴定することにより還元剤濃度を定量する。ここで、青紫色が消失しない程度の添加量とは、定量対象液を添加する際の、ヨウ素−デンプン混合液の青紫色が目視により消失する直前の添加量をいう。また、このとき、ヨウ素−デンプン混合液に添加する酢酸−酢酸ナトリウム緩衝液がｐＨを４．３〜５に調整されていると、定量精度がより良好となる。   From the above, it is possible to quickly and accurately quantify the reducing agent with a simple device by adding an appropriate amount of the liquid to be quantified to the iodine-starch mixed liquid and titrating the remaining iodine. More specifically, in the present invention, the reducing agent concentration is quantified by adding the liquid to be quantified to the iodine-starch mixed liquid to such an extent that the blue-violet color of iodine-starch does not disappear, and back titrating residual iodine. Here, the addition amount to such an extent that the blue-violet color does not disappear refers to the addition amount immediately before the blue-violet color of the iodine-starch mixed solution disappears visually when adding the liquid to be quantified. At this time, if the pH of the acetic acid-sodium acetate buffer solution added to the iodine-starch mixed solution is adjusted to 4.3 to 5, the quantitative accuracy becomes better.

以下、実施例により本発明をさらに具体的に説明する。但し、本発明はこれらに限定されるものではない。   Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these.

〔例１：実施例１及び比較例１に係る還元剤の定量〕
（実施例１：還元剤の定量）
単体ヨウ素を１０ｇ／Ｌのヨウ化カリウム溶液に溶解し、４ｍｍｏｌ／Ｌのヨウ素溶液を調整した。このヨウ素溶液４ｍＬを正確に量り取り、コニカルビーカーに移した。
１０ｇ／Ｌの可溶性デンプン１０ｍＬと酢酸−酢酸ナトリウム緩衝液（弱酸性域ｐＨ４．３〜５）５ｍＬとを上記コニカルビーカーに添加した。
さらに、希釈した亜硫酸水（市販品）を液の青紫色が消失しない程度（１ｍＬ）量りとり上記コニカルビーカーに添加した。
次に、上記コニカルビーカーに正確に調整したチオ硫酸ナトリウム液０．８ｍｍｏｌ／Ｌを滴下していき、溶液の青紫色が消失した点を終点として容量法により残留ヨウ素を定量した。
残留ヨウ素の量から希釈亜硫酸に含まれる亜硫酸と二酸化硫黄の合計をすべて亜硫酸として換算した量を算定した。 [Example 1: Determination of reducing agent according to Example 1 and Comparative Example 1]
(Example 1: Determination of reducing agent)
A simple iodine was dissolved in a 10 g / L potassium iodide solution to prepare a 4 mmol / L iodine solution. 4 mL of this iodine solution was accurately weighed and transferred to a conical beaker.
10 mL of 10 g / L soluble starch and 5 mL of acetic acid-sodium acetate buffer (weakly acidic range pH 4.3-5) were added to the conical beaker.
Further, diluted aqueous sulfite (commercial product) was weighed to the extent that the liquid blue-violet color did not disappear (1 mL) and added to the conical beaker.
Next, 0.8 mmol / L of sodium thiosulfate solution accurately adjusted was dropped into the above conical beaker, and the residual iodine was quantified by the volumetric method with the point where the blue-violet color of the solution disappeared as the end point.
From the amount of residual iodine, the total amount of sulfurous acid and sulfur dioxide contained in diluted sulfurous acid was calculated as sulfurous acid.

（比較例１：一般にヨウ素滴定法として知られる還元剤の定量）
単体ヨウ素を１０ｇ／Ｌのヨウ化カリウム溶液に溶解し、４ｍｍｏｌ／Ｌのヨウ素溶液を調整した。このヨウ素溶液４ｍＬを正確に量り取り、コニカルビーカーに移した。
上記コニカルビーカーに、希釈した亜硫酸水（市販品）を１ｍＬ添加した。
さらに、上記コニカルビーカーに、酢酸−酢酸ナトリウム緩衝液（弱酸性域ｐＨ４．３〜５）５ｍＬを添加した。
次に、上記コニカルビーカーに正確に調整したチオ硫酸ナトリウム液０．８ｍｍｏｌ／Ｌをヨウ素の褐色が薄くなるまで滴下し、指示薬として１０ｇ／Ｌの可溶性デンプンを添加した後、再び青紫色が消失するまで滴下した。
液の青紫色が消失した点を終点として容量法により残留ヨウ素を定量した。
残留ヨウ素の量から希釈亜硫酸に含まれる亜硫酸及び二酸化硫黄の合計を全て亜硫酸として換算した量を算定した。 (Comparative Example 1: Determination of a reducing agent generally known as an iodometric titration method)
A simple iodine was dissolved in a 10 g / L potassium iodide solution to prepare a 4 mmol / L iodine solution. 4 mL of this iodine solution was accurately weighed and transferred to a conical beaker.
1 mL of diluted aqueous sulfite (commercial product) was added to the conical beaker.
Furthermore, 5 mL of an acetic acid-sodium acetate buffer solution (weakly acidic range pH 4.3-5) was added to the conical beaker.
Next, 0.8 mmol / L of sodium thiosulfate solution accurately adjusted in the above conical beaker is added dropwise until the brown color of iodine becomes thin, and after adding 10 g / L of soluble starch as an indicator, the blue-purple color disappears again. It was dripped until.
Residual iodine was quantified by the volumetric method with the point at which the blue-violet color disappeared as the end point.
From the amount of residual iodine, the total amount of sulfurous acid and sulfur dioxide contained in diluted sulfurous acid was calculated as sulfurous acid.

希釈して約７ｍＭとした亜硫酸（計算値）に対して行った実施例１及び比較例１の操作をそれぞれ１２回繰り返した結果を表１に示す。   Table 1 shows the results of repeating the operations of Example 1 and Comparative Example 1 performed 12 times on diluted sulfurous acid (calculated value) to about 7 mM.

Figure 2013003113
Figure 2013003113

表１の結果から、標準偏差及び最大差ともに、実施例の方が精度良く測定できていることがわかる。これは、滴定途中の急激なｐＨ変化を抑えつつ、溶存酸素や空気酸化による誤差を最小限に留めることが可能になったためである。   From the results in Table 1, it can be seen that both the standard deviation and the maximum difference can be measured with higher accuracy. This is because errors due to dissolved oxygen and air oxidation can be minimized while suppressing a rapid pH change during the titration.

〔例２：種々の亜硫酸濃度による定量の可否の評価〕
実施例１の方法及び比較例１の方法で種々の濃度及び分取量の亜硫酸をサンプルに添加し、そのときの各溶液の着色の有無及び容量法での定量の可否を検討した。その結果を表２に示す。 [Example 2: Evaluation of possibility of quantification with various sulfurous acid concentrations]
Sulfurous acid having various concentrations and fractions was added to the sample by the method of Example 1 and the method of Comparative Example 1, and the presence or absence of coloring of each solution at that time and the possibility of quantification by the volumetric method were examined. The results are shown in Table 2.

Figure 2013003113
Figure 2013003113

実施例１の方法では、濃度未知のサンプル液を添加した時でも溶液が薄青色から青紫色に着色している限り定量可能である。
一方、比較例１の方法では、亜硫酸７ｍＭ、分取量０．５ｍＬのようなサンプル中の亜硫酸量が少ない条件ではヨウ素の褐色に着色するため、着色により定量可能と判断できる。しかしながら、比較例１では、それ以外の条件においては、サンプル添加時にはヨウ素の褐色が消失して透明となり、ヨウ素デンプン反応の青紫色の消失度合いで視認できず、且つ、直ちに容量法による定量可否が判断できず、実際に容量法による分析を実施しないと判断できない。 In the method of Example 1, even when a sample solution of unknown concentration is added, it can be quantified as long as the solution is colored from light blue to blue-violet.
On the other hand, in the method of Comparative Example 1, since it is colored in brown of iodine under the condition that the amount of sulfurous acid in the sample is small such as 7 mM sulfite and the amount of separation is 0.5 mL, it can be determined that the amount can be determined by coloring. However, in Comparative Example 1, under the other conditions, the brown color of iodine disappears and becomes transparent when the sample is added, and it cannot be visually recognized by the degree of disappearance of the blue-violet color of the iodine starch reaction. It cannot be judged, and it cannot be judged unless analysis by the capacity method is actually performed.

〔例３：緩衝液のｐＨ域を変えた滴定による評価〕
緩衝液として、酢酸−酢酸ナトリウム緩衝液（弱酸性域ｐＨ４．３〜５）５ｍＬ、又は、リン酸−リン酸ナトリウム緩衝液（中性域ｐＨ６〜７．５）５ｍＬ用いて、実施例１の操作を希釈して約７ｍＭ又は約５ｍＭとした亜硫酸（計算値）に対して行い、それぞれ１２回繰り返した結果を表３に示す。なお、表３の空試験は、滴定値から当該空試験値を引いた値を亜硫酸により消失したヨウ素量として求めるために行った。また、精度を高めるため、空試験は４回行った。 [Example 3: Evaluation by titration with different pH range of buffer]
As a buffer, 5 mL of acetic acid-sodium acetate buffer (weakly acidic range pH 4.3-5) or 5 mL of phosphate-sodium phosphate buffer (neutral range pH 6-7.5) was used. Table 3 shows the results obtained by performing the operation on sulfurous acid (calculated value) diluted to about 7 mM or about 5 mM and repeating it 12 times. In addition, the blank test of Table 3 was performed in order to obtain | require the value which subtracted the said blank test value from the titration value as the amount of iodine lose | disappeared by the sulfurous acid. In order to improve accuracy, the blank test was performed four times.

Figure 2013003113
Figure 2013003113

変動係数（％）を比較すると、酢酸緩衝系（弱酸性域）の方が、定量精度が高いことがわかる。   Comparing the coefficient of variation (%), it can be seen that the acetic acid buffer system (weakly acidic region) has higher quantitative accuracy.

Claims (3)

ヨウ素−デンプン混合液に定量対象液を青紫色が消失しない程度添加し、残留ヨウ素を逆滴定することにより還元剤濃度を定量する水溶液中の還元剤の定量方法。   A method for quantifying a reducing agent in an aqueous solution, wherein a liquid to be quantified is added to an iodine-starch mixed solution to such an extent that the blue-violet color does not disappear, and residual iodine is titrated back to titrate. 前記還元剤が、亜硫酸及び二酸化硫黄のいずれか、又は、それらの混合物である請求項１に記載の水溶液中の還元剤の定量方法。   The method for quantifying a reducing agent in an aqueous solution according to claim 1, wherein the reducing agent is any one of sulfurous acid and sulfur dioxide, or a mixture thereof. 前記定量対象液を添加する前の前記ヨウ素−デンプン混合液に、ｐＨが４．３〜５の酢酸−酢酸ナトリウム緩衝液を添加しておく請求項１又は２に記載の水溶液中の還元剤の定量方法。   The reducing agent in the aqueous solution according to claim 1 or 2, wherein an acetic acid-sodium acetate buffer solution having a pH of 4.3 to 5 is added to the iodine-starch mixed solution before the quantification target solution is added. Quantitation method.
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Cited By (3)

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JP2018168054A (en) * 2017-03-29 2018-11-01 住友金属鉱山株式会社 Method for storing and quantifying solution containing thionic acid, and sample solution containing thionic acid and method for making the same
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JP7109647B1 (en) * 2021-12-20 2022-07-29 海渡 本田 Method for calculating iodine clathrate ratio using action of sodium hydroxide solution on iodine clathrate starch solution

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018168054A (en) * 2017-03-29 2018-11-01 住友金属鉱山株式会社 Method for storing and quantifying solution containing thionic acid, and sample solution containing thionic acid and method for making the same
JP7062996B2 (en) 2017-03-29 2022-05-09 住友金属鉱山株式会社 A method for storing and quantifying a solution containing thionic acid, and a method for preparing a sample solution containing thionic acid and its preparation.
CN114296174A (en) * 2021-07-14 2022-04-08 住华科技股份有限公司 Method and system for manufacturing polarizing film
JP7109647B1 (en) * 2021-12-20 2022-07-29 海渡 本田 Method for calculating iodine clathrate ratio using action of sodium hydroxide solution on iodine clathrate starch solution

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