JP2010184835A - Method for recovering iodine - Google Patents
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本発明は、ヨウ化物イオンと鉄（II)イオンを含有する水溶液からヨウ素を回収する方法に関する。 The present invention relates to a method for recovering iodine from an aqueous solution containing iodide ions and iron (II) ions.
ヨウ素は、医薬品、殺菌・防カビ剤、工業用触媒、感光剤、樹脂安定剤、除草剤、飼料添加剤として、医薬、工業、農業など多岐にわたる分野で利用されている。また近年では、液晶の偏光フィルムや半導体エッチング剤においても利用されており、その需要はますます高まっている。その一方、ヨウ素は産地が偏在する貴重な天然資源であり、安価ではないため、コスト、環境負荷、資源の有効利用の面からこれを効率的に回収する方法が産業上強く求められている。 Iodine is used in various fields such as medicine, industry and agriculture as pharmaceuticals, bactericides and fungicides, industrial catalysts, photosensitizers, resin stabilizers, herbicides and feed additives. In recent years, it is also used in polarizing films for liquid crystals and semiconductor etching agents, and the demand is increasing. On the other hand, iodine is a precious natural resource that is unevenly distributed, and is not inexpensive. Therefore, there is a strong industrial demand for a method for efficiently recovering this from the viewpoint of cost, environmental load, and effective use of resources.
上記のように、ヨウ素は各種の産業で幅広く用いられている結果、それらの産業から排出される廃液にはヨウ化物イオンが含まれる場合が多い。ヨウ化物イオン含有液からヨウ素を回収する方法については、これまでブローアウト法、イオン交換樹脂法、活性炭吸着法、澱粉吸着法、銅法、銀法など種々の方法が提案されている。これらのうち、ブローアウト法は、ヨウ化物イオンを含む天然かん水中のヨウ化物イオンをさらし粉や塩素ガスなどの酸化剤を用いて酸化し、単体ヨウ素にした後、ガス化させることにより回収する方法であり（特許文献１〜３）、ヨウ素をポリイオン化してイオン交換樹脂に吸着させて回収するイオン交換樹脂法と並んでヨウ素回収方法の主流となっている。 As described above, iodine is widely used in various industries. As a result, the waste liquid discharged from these industries often contains iodide ions. Various methods, such as a blowout method, an ion exchange resin method, an activated carbon adsorption method, a starch adsorption method, a copper method, and a silver method, have been proposed so far for recovering iodine from an iodide ion-containing liquid. Among these, the blowout method is a method in which iodide ions in natural brine containing iodide ions are oxidized using an oxidizing agent such as bleaching powder or chlorine gas, converted into simple iodine, and then recovered by gasification. (Patent Documents 1 to 3), which is the mainstream of the iodine recovery method along with the ion exchange resin method in which iodine is polyionized and adsorbed on the ion exchange resin for recovery.
一方、硫化銅鉱やそれに付随する貴金属の湿式製錬において、その浸出速度改善のために様々な添加剤が使用される。その中でも、ヨウ素は温和な酸化剤として作用するほか、配位子として金属の浸出を促進することも知られており、優れた浸出助剤である（特許文献４、非特許文献１）。本発明者も、鉄（III)イオンを酸化剤として硫化銅鉱から銅を浸出させる際に、ヨウ素を触媒として添加する方法を確立している（特願2008-189258号）。ヨウ素をこのような鉱業分野において利用する場合は、その使用量は膨大であり、その回収は非常に重要となってくる。また、上記の硫化銅鉱の浸出に際しては、浸出後の液にヨウ化物イオンのほかに鉄（II)イオンが存在する。ヨウ化物イオンと鉄（II)イオンはともに酸化されやすいために、鉄（II)イオンの存在によってヨウ化物イオンの酸化が妨害されてヨウ素を回収することが困難となる。一般に、２種類以上の物質が共存するとき、一方を選択的に酸化できるのは酸化還元電位が300mV以上離れているときといわれているが、ヨウ化物イオンと鉄（II)イオンは酸化還元電位差が235mVしかなく、また、鉄（II)イオンがヨウ化物イオンに比べて大過剰に存在すればいっそうヨウ化物イオンの酸化は困難となる。 On the other hand, various additives are used to improve the leaching rate in the hydrometallurgy of copper sulfide ore and associated noble metals. Among them, iodine is known to act as a mild oxidant and to promote metal leaching as a ligand, and is an excellent leaching aid (Patent Document 4, Non-Patent Document 1). The present inventor has also established a method of adding iodine as a catalyst when copper is leached from copper sulfide ore using iron (III) ions as an oxidizing agent (Japanese Patent Application No. 2008-189258). When iodine is used in such a mining field, the amount used is enormous, and its recovery is very important. In addition, when leaching the copper sulfide ore, iron (II) ions are present in addition to iodide ions in the leached liquid. Since both iodide ions and iron (II) ions are easily oxidized, oxidation of iodide ions is hindered by the presence of iron (II) ions, making it difficult to recover iodine. In general, when two or more kinds of substances coexist, it is said that one of them can be selectively oxidized when the redox potential is 300 mV or more apart. Is only 235 mV, and if iron (II) ions are present in a large excess compared to iodide ions, the oxidation of iodide ions becomes more difficult.
本発明の課題は、上記のような事情に鑑み、ヨウ化物イオンと鉄（II)イオンを含有する溶液からヨウ素を効率良く回収する方法を提供することにある。 In view of the circumstances as described above, an object of the present invention is to provide a method for efficiently recovering iodine from a solution containing iodide ions and iron (II) ions.
本発明者らは、上記課題を解決すべく鋭意研究を重ねた結果、ヨウ化物イオンと鉄（II)イオンを含有する水溶液に塩素系酸化剤を添加し、低ｐＨ条件下で酸化反応を行うことにより、ヨウ化物イオンが選択的に酸化されてヨウ素が生成し、ヨウ素を効率良く回収できることを見出し、本発明を完成させるに至った。 As a result of intensive studies to solve the above problems, the present inventors add a chlorinated oxidant to an aqueous solution containing iodide ions and iron (II) ions, and perform an oxidation reaction under low pH conditions. As a result, it was found that iodide ions are selectively oxidized to produce iodine, and iodine can be efficiently recovered, and the present invention has been completed.
即ち、本発明は以下の発明を包含する。
（１） ヨウ化物イオンと鉄（II)イオンを含有する水溶液に、該水溶液のｐＨを２未満に維持するように制御しつつ塩素系酸化剤を添加し、該水溶液中のヨウ化物イオンを選択的に酸化する工程と、前記工程で生成したヨウ素を回収する工程を含むことを特徴とする、ヨウ素の回収方法。
（２） 前記塩素系酸化剤が、次亜塩素酸ナトリウムまたはさらし粉である、（１）に記載の方法。
（３） 前記塩素系酸化剤の添加量が、ヨウ化物イオンに対して有効塩素量換算で４倍モル以上である、（１）または（２）に記載の方法。
（４） 前記ヨウ素の回収がブローアウト法または有機溶媒抽出法により行われる、（１）〜（３）のいずれかに記載の方法。
（５） 前記ヨウ化物イオンと鉄（II)イオンを含有する水溶液が硫化銅鉱の浸出後液である、（１）〜（４）のいずれかに記載の方法。
That is, the present invention includes the following inventions.
(1) Chlorine oxidant is added to an aqueous solution containing iodide ions and iron (II) ions while controlling the pH of the aqueous solution to be less than 2, and iodide ions in the aqueous solution are selected. A method for recovering iodine, characterized by comprising a step of oxidative oxidation and a step of recovering iodine produced in the step.
(2) The method according to (1), wherein the chlorinated oxidant is sodium hypochlorite or bleached powder.
(3) The method according to (1) or (2), wherein the addition amount of the chlorine-based oxidizing agent is 4 times or more moles in terms of effective chlorine amount with respect to iodide ions.
(4) The method according to any one of (1) to (3), wherein the iodine is collected by a blowout method or an organic solvent extraction method.
(5) The method according to any one of (1) to (4), wherein the aqueous solution containing iodide ions and iron (II) ions is a solution after leaching of copper sulfide ore.
本発明の方法によれば、ヨウ化物イオンを含む水溶液にヨウ化物イオンの酸化の妨害となる鉄（II)イオンが存在しても、当該溶液中のヨウ化物イオンが選択的に酸化されてヨウ素を高収率で回収することが可能となる。本発明の方法は、ヨウ素を添加剤として使用する硫化銅鉱の浸出後液の処理に用いることができ、ヨウ素の再利用という点で経済的であり、かつ、環境負荷を低減させることができる。 According to the method of the present invention, even if iron (II) ions that interfere with the oxidation of iodide ions are present in an aqueous solution containing iodide ions, the iodide ions in the solution are selectively oxidized to produce iodine. Can be recovered in a high yield. The method of the present invention can be used for the treatment of a solution after leaching of copper sulfide ore using iodine as an additive, is economical in terms of reuse of iodine, and can reduce the environmental burden.
本発明のヨウ素の回収方法は、ヨウ化物イオンと鉄（II)イオンを含有する水溶液に、該水溶液のｐＨを２未満に維持するように制御しつつ塩素系酸化剤を添加し、該水溶液中のヨウ化物イオンを選択的に酸化する工程と、前記工程で生成したヨウ素を回収する工程を含むことを特徴とする。 In the method for recovering iodine of the present invention, a chlorine-based oxidizing agent is added to an aqueous solution containing iodide ions and iron (II) ions while controlling the pH of the aqueous solution to be less than 2. The method includes a step of selectively oxidizing the iodide ion, and a step of recovering iodine generated in the step.
本発明の方法の対象となる水溶液は、ヨウ化物イオンと鉄（II)イオンを含有する水溶液であれば特に限定はされない。ヨウ化物イオンと鉄（II)イオンを含有する水溶液としては、代表的には、鉱業から排出される廃液であるが、その他の産業、例えば電子工業、薬品産業から排出される水溶液でもよい。具体的には、ヨウ素イオンと鉄（III)イオンとを含有する硫酸溶液を浸出液として用いて硫化銅鉱の浸出処理を行った液（廃液）が挙げられる。 The aqueous solution to be subjected to the method of the present invention is not particularly limited as long as it is an aqueous solution containing iodide ions and iron (II) ions. The aqueous solution containing iodide ions and iron (II) ions is typically a waste liquid discharged from the mining industry, but may be an aqueous solution discharged from other industries such as the electronics industry and the pharmaceutical industry. Specifically, the liquid (waste liquid) which performed the leaching process of the copper sulfide ore using the sulfuric acid solution containing an iodine ion and iron (III) ion as a leaching liquid is mentioned.
本発明の方法において、ヨウ素の酸化に用いる酸化剤としては単体ヨウ素（I2）より酸化還元標準電極電位が上位のものならば理論的に使用可能ではあるが、酸化力、反応速度、共存物質の影響を考慮すると塩素系酸化剤が好ましい。塩素系酸化剤としては、好適には、無機塩素系酸化剤、例えば、次亜塩素酸ナトリウム、次亜塩素酸カリウム、次亜塩素酸カルシウム（さらし粉）、亜塩素酸ナトリウム、亜塩素酸カリウムなどが挙げられるが、次亜塩素酸ナトリウムが好ましい。 In the method of the present invention, the oxidizing agent used for the oxidation of iodine can be theoretically used as long as the oxidation-reduction standard electrode potential is higher than that of elemental iodine (I 2 ). Considering the influence of the above, a chlorinated oxidant is preferable. As the chlorine-based oxidant, preferably, an inorganic chlorine-based oxidant such as sodium hypochlorite, potassium hypochlorite, calcium hypochlorite (bleaching powder), sodium chlorite, potassium chlorite and the like. Although sodium hypochlorite is preferable.
塩素系酸化剤はｐＨが低くなるにつれその酸化能力が増すことが知られており、また、鉄（II)イオンはｐＨが低くなるにつれ安定性が増すので、処理する水溶液のｐＨを低くなるように制御すればヨウ化物イオンのみの選択的酸化が可能である。従って、本発明の方法において、ヨウ化物イオンと鉄（II)イオンを含有する水溶液のｐＨは２．０未満、好ましくは１．２〜１．６とする。ｐＨは、当該水溶液への酸化剤添加時の初期ｐＨのみならず、酸化反応終了まで上記範囲に維持されるよう制御することが好ましい。 Chlorine oxidizers are known to increase in oxidation capacity as pH decreases, and iron (II) ions become more stable as pH decreases, so the pH of aqueous solutions to be treated is lowered. If controlled to, selective oxidation of only iodide ions is possible. Therefore, in the method of the present invention, the pH of the aqueous solution containing iodide ions and iron (II) ions is less than 2.0, preferably 1.2 to 1.6. The pH is preferably controlled so as to be maintained in the above range until the end of the oxidation reaction as well as the initial pH at the time of addition of the oxidizing agent to the aqueous solution.
ヨウ化物イオンと鉄（II)イオンを含有する水溶液への塩素系酸化剤の添加量は、上記のｐＨ範囲に制御する限りヨウ化物イオンに対して有効塩素量換算で４倍モル以上であれば特に制限はないが、好ましくは４〜２２倍モルである。４倍モルより少ないとヨウ素回収率が５０％に至らず実操業上好ましくない。 As long as the amount of the chlorine-based oxidizing agent added to the aqueous solution containing iodide ion and iron (II) ion is controlled within the above pH range, it is 4 times mol or more in terms of effective chlorine amount with respect to iodide ion. Although there is no restriction | limiting in particular, Preferably it is 4-22 times mole. When the amount is less than 4 times mole, the iodine recovery rate does not reach 50%, which is not preferable in actual operation.
上記酸化反応により生成したヨウ素の回収は、ヨウ素を気化させた後、還元吸収するブローアウト法により行うことができる。具体的には、酸化反応終了後の液に空気または水蒸気を吹き込むことにより、ヨウ素を反応系から遊離させ、蒸発遊離したヨウ素を亜硫酸水素ナトリウムなどの還元剤を含む水溶液にて吸収する。またヨウ素は単体では水に難溶であるが有機溶媒には易溶である。従って、この性質を利用して、上記酸化反応により生成したヨウ素を有機溶媒と接触させて有機相に抽出する溶媒抽出法によりヨウ素を濃縮回収することもできる。ここで、使用する有機溶媒としては、ヘキサン、キシレン、トルエン、ベンゼンなどが挙げられる。 The iodine produced by the oxidation reaction can be collected by a blowout method in which iodine is vaporized and then reduced and absorbed. Specifically, by blowing air or water vapor into the liquid after completion of the oxidation reaction, iodine is liberated from the reaction system, and the evaporated and liberated iodine is absorbed in an aqueous solution containing a reducing agent such as sodium bisulfite. In addition, iodine is hardly soluble in water alone, but is easily soluble in organic solvents. Therefore, utilizing this property, iodine can be concentrated and recovered by a solvent extraction method in which iodine produced by the oxidation reaction is brought into contact with an organic solvent and extracted into an organic phase. Here, examples of the organic solvent to be used include hexane, xylene, toluene, and benzene.
以下、実施例によって本発明を更に具体的に説明するが、これらの実施例は本発明を限定するものでない。
（実施例１）各種酸化剤によるヨウ素の酸化
硫酸銅５水和物（Cu濃度：1g/l)と硫酸鉄（II）７水和物(Fe2+濃度：3g/l）を含む水溶液100mlを硫酸でpH1.6に調整した後、ヨウ化カリウム水溶液（KI濃度：10 g/l）を1ml混合した。この水溶液を300ml容量の分液ロートに注ぎ、下記の酸化剤Ａ〜Ｄを添加して軽く攪拌し、さらにトルエン100mlを注いだ後、手で一分程度激しく振とうした。また、酸化剤を添加しない場合についても上記操作を同様に行った。
（酸化剤Ａ）次亜塩素酸ナトリウム液（有効塩素5％以上）0.5ml
（酸化剤Ｂ）さらし液（高度さらし粉50g/l、不完全溶解）2ml
（酸化剤Ｃ）予め液中のFe3+を硫酸鉄（III）にて10g/lに調整
（酸化剤Ｄ）過酸化水素水（30％）1ml
上記操作後、トルエン中に分配されたヨウ素の濃度を吸光光度測定器で測定した。また水相のFe2+濃度を二クロム酸カリウム滴定法で決定した。ヨウ素濃度から換算したヨウ素回収率、およびFe2+酸化率を下記表１に示す。
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but these examples do not limit the present invention.
(Example 1) Oxidation of iodine with various oxidizing agents 100 ml of an aqueous solution containing copper sulfate pentahydrate (Cu concentration: 1 g / l) and iron (II) sulfate heptahydrate (Fe 2+ concentration: 3 g / l) After adjusting the pH to 1.6 with sulfuric acid, 1 ml of an aqueous potassium iodide solution (KI concentration: 10 g / l) was mixed. The aqueous solution was poured into a separating funnel having a capacity of 300 ml, the following oxidizing agents A to D were added, and the mixture was lightly stirred. In addition, the above operation was performed in the same manner when no oxidizing agent was added.
(Oxidizing agent A) Sodium hypochlorite solution (effective chlorine 5% or more) 0.5ml
(Oxidizing agent B) bleaching solution (50g / l advanced bleaching powder, incomplete dissolution) 2ml
(Oxidizing agent C) Fe 3+ in the liquid was adjusted to 10 g / l with iron (III) sulfate in advance (oxidizing agent D) Hydrogen peroxide (30%) 1 ml
After the above operation, the concentration of iodine distributed in toluene was measured with an absorptiometer. And the Fe 2+ concentration in the aqueous phase was determined by potassium dichromate titration method. The iodine recovery rate and the Fe 2+ oxidation rate converted from the iodine concentration are shown in Table 1 below.
表１に示されるように、次亜塩素酸ナトリウム液とさらし液はヨウ素イオンを選択的にかつ効率的に酸化できることがわかった。これに対し、Fe3+では酸化力が不足し、過酸化水素水ではfenton反応により共存物質であるFe2+が優先的に酸化された。 As shown in Table 1, it was found that the sodium hypochlorite solution and the exposure solution can selectively and efficiently oxidize iodine ions. In contrast, insufficient Fe 3+ in oxidizing power, are Fe 2 + is a coexisting substance by fenton reaction was preferentially oxidized in the hydrogen peroxide solution.
（実施例２）ヨウ素の酸化に対するFe2+濃度と酸化剤添加量の影響
本実施例では酸化剤として次亜塩素酸ナトリウム液を用いた。初期Fe2+濃度と次亜塩素酸ナトリウム液の添加量を以下の条件とする以外は、実施例１と同様の操作で水溶液からヨウ素を回収した。
（条件Ａ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：0.1 ml
（条件Ｂ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：0.2 ml
（条件Ｃ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：0.3 ml
（条件Ｄ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：0.4 ml
（条件Ｅ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：0.5 ml
（条件Ｆ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：1 ml
（条件Ｇ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：2 ml
（条件Ｈ）Fe2+濃度：3 g/l、次亜塩素酸ナトリウム液添加量：5 ml
（条件Ｉ）Fe2+濃度：0 g/l、次亜塩素酸ナトリウム液添加量：1 ml
（条件Ｊ）Fe2+濃度：5 g/l、次亜塩素酸ナトリウム液添加量：1 ml
（条件Ｋ）Fe2+濃度：10 g/l、次亜塩素酸ナトリウム液添加量：1 ml
（条件Ｌ）Fe2+濃度：15 g/l、次亜塩素酸ナトリウム液添加量：1 ml
条件Ａ〜Ｌによる反応後、トルエン中に分配されたヨウ素の濃度を吸光光度測定器で測定した。また水相のFe2+濃度を二クロム酸カリウム滴定法で決定した。ヨウ素濃度から換算したヨウ素回収率、Fe2++酸化率、および酸化後の液のpHを下記表２に示す。
(Example 2) Effect of Fe 2+ concentration and addition amount of oxidant on oxidation of iodine In this example, sodium hypochlorite solution was used as the oxidant. Iodine was recovered from the aqueous solution in the same manner as in Example 1, except that the initial Fe 2+ concentration and the amount of sodium hypochlorite solution added were as follows.
(Condition A) Fe 2+ concentration: 3 g / l, sodium hypochlorite solution addition amount: 0.1 ml
(Condition B) Fe 2+ concentration: 3 g / l, Sodium hypochlorite solution addition amount: 0.2 ml
(Condition C) Fe 2+ concentration: 3 g / l, Sodium hypochlorite solution addition amount: 0.3 ml
(Condition D) Fe 2+ concentration: 3 g / l, Sodium hypochlorite solution added amount: 0.4 ml
(Condition E) Fe 2+ concentration: 3 g / l, Sodium hypochlorite solution addition amount: 0.5 ml
(Condition F) Fe 2+ concentration: 3 g / l, sodium hypochlorite solution addition amount: 1 ml
(Condition G) Fe 2+ concentration: 3 g / l, sodium hypochlorite solution addition amount: 2 ml
(Condition H) Fe 2+ concentration: 3 g / l, Sodium hypochlorite solution addition amount: 5 ml
(Condition I) Fe 2+ concentration: 0 g / l, Sodium hypochlorite solution addition amount: 1 ml
(Condition J) Fe 2+ concentration: 5 g / l, Sodium hypochlorite solution addition amount: 1 ml
(Condition K) Fe 2+ concentration: 10 g / l, sodium hypochlorite solution addition amount: 1 ml
(Condition L) Fe 2+ concentration: 15 g / l, Sodium hypochlorite solution addition amount: 1 ml
After the reaction under the conditions A to L, the concentration of iodine distributed in toluene was measured with an absorptiometer. And the Fe 2+ concentration in the aqueous phase was determined by potassium dichromate titration method. Table 2 below shows the iodine recovery rate converted from the iodine concentration, the Fe 2+ + oxidation rate, and the pH of the solution after oxidation.
表２に示されるように、初期Fe2+濃度が3 g/lの条件下で次亜塩素酸ナトリウム液の添加量を増加させた場合（条件Ａ〜Ｈ）、次亜塩素酸ナトリウム液の添加量が0.1ml（ヨウ素に対して２倍モル）ではヨウ素回収率が約40％（条件Ａ）、0.2ml（ヨウ素に対して４倍モル）ではヨウ素回収率が約60％（条件Ｂ）、0.4ml（ヨウ素に対して８倍モル）ではヨウ素回収率が約80％（条件Ｄ）、0.5ml（ヨウ素に対して１１倍モル）ではヨウ素回収率が97％と最も高くなった（条件Ｅ）。しかしながら、次亜塩素酸ナトリウム液の添加量が1ml（ヨウ素に対して２２倍モル）ではヨウ素回収率がピーク時に比べると低下し（条件Ｆ）、2.0mlを超えると、本条件下ではその強いアルカリ性のためpHの上昇をひきおこし、その結果鉄（II）イオンが優先的に酸化されてしまいヨウ素の酸化および抽出が不能となった（条件Ｇ、Ｈ）。 As shown in Table 2, when the amount of sodium hypochlorite solution added was increased under the conditions of initial Fe 2+ concentration of 3 g / l (conditions A to H), the sodium hypochlorite solution When the added amount is 0.1 ml (2 times mole with respect to iodine), the iodine recovery rate is about 40% (condition A), and when 0.2 ml (4 times mole with respect to iodine), the iodine recovery rate is about 60% (condition B). In 0.4 ml (8 times mole with respect to iodine), iodine recovery was about 80% (Condition D), and 0.5 ml (11 times mole with respect to iodine) gave the highest iodine recovery rate of 97% (conditions). E). However, when the amount of sodium hypochlorite solution added is 1 ml (22 moles relative to iodine), the iodine recovery rate is lower than at the peak (Condition F), and when it exceeds 2.0 ml, it is strong under this condition. Due to alkalinity, the pH was raised, and as a result, iron (II) ions were preferentially oxidized, making it impossible to oxidize and extract iodine (conditions G and H).
一方、次亜塩素酸ナトリウム液の添加量が1 mlの条件下で、初期Fe2+濃度を増加させた場合（条件Ｉ〜Ｌ）、初期Fe2+濃度が増加するにつれてヨウ素回収率が下がる傾向にあるが、いずれも高い回収率でヨウ素を得ることができた。 On the other hand, when the initial Fe 2+ concentration is increased under conditions where the amount of sodium hypochlorite solution added is 1 ml (conditions I to L), the iodine recovery rate decreases as the initial Fe 2+ concentration increases. Although tending, iodine could be obtained with a high recovery rate.
以上の結果から、Fe2+濃度に関わらず、次亜塩素酸ナトリウム液の添加量が0.2ml〜1.0ml（ヨウ素に対して４倍モル〜２２倍モル）とすると、ヨウ素を効率よく回収できることが確認できた（条件Ｂ、Ｃ、Ｄ、Ｅ、Ｆ、Ｊ、Ｋ、Ｌ）。 From the above results, iodine can be efficiently recovered when the amount of sodium hypochlorite solution added is 0.2 ml to 1.0 ml (4 to 22 times moles of iodine) regardless of the Fe 2+ concentration. Was confirmed (conditions B, C, D, E, F, J, K, and L).
（実施例３）ヨウ素の酸化に対するpHの影響
実施例２の結果に示されるように、過剰の次亜塩素酸ナトリウム液の添加はpHの上昇を引き起こし、ヨウ素の優先的酸化を妨害した（条件Ｇ、Ｈ）。そこで、酸化剤として次亜塩素酸ナトリウム液0.5mlを用い、水溶液の初期pHを以下の条件とする以外は、実施例１と同様の操作で水溶液からヨウ素を回収した。
（条件Ｍ）pH1.0
（条件Ｎ）pH1.2
（条件Ｏ）pH1.4
（条件Ｐ）pH1.6
（条件Ｑ）pH1.8
（条件Ｒ）pH2.0
（条件Ｓ）pH2.2
（条件Ｔ）pH2.4
条件Ｍ〜Ｔによる反応後、トルエン中に分配されたヨウ素の濃度を吸光光度測定器で測定した。また水相のFe2+濃度を二クロム酸カリウム滴定法で決定した。ヨウ素濃度から換算したヨウ素回収率、Fe2+酸化率、および酸化後の液のpHを表３に示す。
Example 3 Effect of pH on Iodine Oxidation As shown in the results of Example 2, the addition of excess sodium hypochlorite solution caused an increase in pH and prevented the preferential oxidation of iodine (conditions G, H). Therefore, iodine was recovered from the aqueous solution in the same manner as in Example 1 except that 0.5 ml of sodium hypochlorite solution was used as the oxidizing agent and the initial pH of the aqueous solution was set as follows.
(Condition M) pH 1.0
(Condition N) pH 1.2
(Condition O) pH1.4
(Condition P) pH 1.6
(Condition Q) pH1.8
(Condition R) pH 2.0
(Condition S) pH 2.2
(Condition T) pH 2.4
After the reaction under conditions MT, the concentration of iodine distributed in toluene was measured with an absorptiometer. And the Fe 2+ concentration in the aqueous phase was determined by potassium dichromate titration method. Table 3 shows the iodine recovery rate converted from the iodine concentration, the Fe 2+ oxidation rate, and the pH of the solution after oxidation.
表３に示されるように、次亜塩素酸ナトリウム液の添加から酸化反応終了までの水溶液のpHを2未満に維持することにより、ヨウ素を効率よく回収できることが確認できた（条件Ｍ〜Ｑ）。 As shown in Table 3, it was confirmed that iodine can be efficiently recovered by maintaining the pH of the aqueous solution from addition of the sodium hypochlorite solution to the end of the oxidation reaction to less than 2 (conditions M to Q). .
Claims (5)
The method according to any one of claims 1 to 4, wherein the aqueous solution containing iodide ions and iron (II) ions is a solution after leaching of copper sulfide ore.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016124774A (en) * | 2015-01-07 | 2016-07-11 | 日宝化学株式会社 | Iodine recovery method |
| JP2021511304A (en) * | 2018-01-14 | 2021-05-06 | コリディオン，インコーポレイテッド | Compositions, kits, methods, and uses for cleaning, disinfection, sterilization, and / or treatment |
| CN115232084A (en) * | 2022-07-28 | 2022-10-25 | 新乡市博源生物科技有限公司 | Method for recycling and applying iodine in isoxazole synthesis process |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016124774A (en) * | 2015-01-07 | 2016-07-11 | 日宝化学株式会社 | Iodine recovery method |
| JP2021511304A (en) * | 2018-01-14 | 2021-05-06 | コリディオン，インコーポレイテッド | Compositions, kits, methods, and uses for cleaning, disinfection, sterilization, and / or treatment |
| JP7379342B2 (en) | 2018-01-14 | 2023-11-14 | コリディオン，インコーポレイテッド | Compositions, kits, methods, and uses for cleaning, disinfection, sterilization, and/or treatment |
| CN115232084A (en) * | 2022-07-28 | 2022-10-25 | 新乡市博源生物科技有限公司 | Method for recycling and applying iodine in isoxazole synthesis process |
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