JP7315160B2 - Fluorine insolubilizer, method for producing same, treated gypsum, method for treating fluorine-containing contaminated soil and contaminated water - Google Patents
Fluorine insolubilizer, method for producing same, treated gypsum, method for treating fluorine-containing contaminated soil and contaminated water Download PDFInfo
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Description
本発明は、石膏中、汚染水中又は汚染土壌中のフッ化物イオンを安定な鉱物であるフッ素アパタイト(ＦＡｐ）として不溶化し、長期的な安定性を担保するフッ素不溶化剤、その製造方法、処理石膏、フッ素含有汚染土壌及び汚染水の処理方法に関するものである。 The present invention relates to a fluorine insolubilizing agent that insolubilizes fluoride ions in gypsum, contaminated water, or contaminated soil as a stable mineral, fluoroapatite (FAp), to ensure long-term stability, a method for producing the same, a method for treating treated gypsum, fluorine-containing contaminated soil, and contaminated water.
フッ素は、先端技術産業の分野で広く使用されており、それに伴って排水や土壌のフッ素汚染が深刻な問題となっている。このフッ素汚染土壌は、我が国の汚染土壌では２番目にサイト数が多いものとなっている。このため、排水中又は土壌中のフッ素（フッ化物イオン）を安定なフッ素アパタイト(ＦＡｐ）として不溶化する技術が多数、提案されている。 Fluorine is widely used in the field of high-tech industries, and along with this, fluorine contamination of wastewater and soil has become a serious problem. This fluorine-contaminated soil has the second largest number of sites among contaminated soils in Japan. For this reason, many techniques have been proposed for insolubilizing fluorine (fluoride ions) in waste water or soil as stable fluoroapatite (FAp).
従来、このようなフッ素不溶化剤としては、各種アルミニウム化合物やカルシウム化合物の他に、リン酸ナトリウム（Ｎａ３ＰＯ４）、リン酸水素二ナトリウム（Ｎａ２ＨＰＯ４）、リン酸二水素ナトリウム（ＮａＨ２ＰＯ４）、リン酸水素カルシウム二水和物（ＣａＨＰＯ４・２Ｈ２Ｏ）、水酸アパタイト（Ｃａ５（ＰＯ４）３ＯＨ）等、各種のリン酸化合物が知られている。 Conventionally, various phosphoric acid compounds such as sodium phosphate (Na3PO4), disodium hydrogen phosphate (Na2HPO4), sodium dihydrogen phosphate (NaH2PO4), calcium hydrogen phosphate dihydrate (CaHPO4 2H2O), and hydroxyapatite (Ca5(PO4)3OH) have been known as such fluorine-insolubilizing agents in addition to various aluminum compounds and calcium compounds.
この中、リン酸水素カルシウム二水和物（以下、単に「ＤＣＰＤ」との言う。）は、直接フッ化物イオンと反応するのではなく、反応初期に粒子表面に数十ｎｍのリン酸カルシウム系前駆体を生成し、それがトリガーとなってＦＡｐを生成することが見いだされている（非特許文献１）。この前駆体相の生成には数時間の誘導時間（遅れ時間）を必要とし、さらにこの前駆体相生成は、例えばＭｇイオン、Ｃｄイオン、フッ化物イオンなどの共存イオンによって容易に妨害される（非特許文献２等）という問題がある。 Among them, it has been found that calcium hydrogen phosphate dihydrate (hereinafter simply referred to as "DCPD") does not directly react with fluoride ions, but produces a calcium phosphate-based precursor of several tens of nanometers on the particle surface in the early stage of the reaction, which triggers the production of FAp (Non-Patent Document 1). The formation of this precursor phase requires an induction time (lag time) of several hours, and the formation of this precursor phase is easily disturbed by coexisting ions such as Mg ions, Cd ions, and fluoride ions (Non-Patent Document 2, etc.).
ＤＣＰＤとフッ化物イオンとの反応に見られる遅れ時間を改善する技術として、例えば、国際公開番号ＷＯ２０１０/０４１３３０号（特許文献１）には、ＤＣＰＤを水あるいは温水処理により前駆体相を表面に誘起する方法が開示されている。また、特開２０１１－２５６３５６号公報（特許文献２）には、ＤＣＰＤと水酸アパタイト（ＨＡｐ）の混合物であるフッ素不溶化剤が開示されている。また、非特許文献３には、ＤＣＰＤを人の体液と同じイオン濃度を有する擬似体液に浸漬して、ＨＡｐを粒子表面に析出させる方法が開示されている。 As a technique for improving the lag time seen in the reaction between DCPD and fluoride ions, for example, International Publication No. WO2010/041330 (Patent Document 1) discloses a method of inducing a precursor phase on the surface by treating DCPD with water or warm water. Further, Japanese Patent Application Laid-Open No. 2011-256356 (Patent Document 2) discloses a fluorine insolubilizer which is a mixture of DCPD and hydroxyapatite (HAp). Non-Patent Document 3 discloses a method of immersing DCPD in a simulated body fluid having the same ion concentration as that of a human body fluid to deposit HAp on the particle surface.
しかしながら、これら従来の方法は、未だＤＣＰＤとフッ化物イオンとの反応に見られる遅れ時間を改善するには不十分であるか、あるいはＤＣＰＤの活性化が不十分であり、フッ素汚染土壌中のフッ素の不溶化という点では、満足がいくものではなかった。また、疑似体液を用いる方法は、疑似体液の調製や保管が難しいという問題がある。また、ＤＣＰＤとＨＡｐの混合物であるフッ素不溶化剤の場合、実際には、ＤＣＰＤは合成したものを使用しており、限られた用途にしか適用できなかった。このため、例えば、汚染土壌の処理現場において、市販のＤＣＰＤを簡単に処理して得られるフッ素不溶化剤が求められていた。 However, these conventional methods are still insufficient to improve the lag time observed in the reaction between DCPD and fluoride ions, or the activation of DCPD is insufficient, and the insolubilization of fluorine in fluorine-contaminated soil is unsatisfactory. Moreover, the method using the simulated body fluid has a problem that the preparation and storage of the simulated body fluid are difficult. In addition, in the case of a fluorine insolubilizing agent that is a mixture of DCPD and HAp, DCPD was actually synthesized and could only be applied to limited applications. For this reason, there has been a demand for a fluorine-insolubilizing agent that can be obtained by simply treating commercially available DCPD, for example, at a contaminated soil treatment site.
従って、本発明の目的は、ＤＣＰＤとフッ化物イオンとの反応に見られる遅れ時間を改善し、ＤＣＰＤの高い活性化を有するフッ素不溶化剤、より単純な組成の溶液を使用して施工現場で調製可能なフッ素不溶化剤の製造方法、処理石膏及びフッ素含有汚染土壌又は汚染水の処理方法を提供することにある。 Accordingly, it is an object of the present invention to provide a fluorine-insolubilizing agent that improves the lag time observed in the reaction between DCPD and fluoride ions and has high activation of DCPD, a method for producing a fluorine-insolubilizing agent that can be prepared at the construction site using a solution with a simpler composition, and a method for treating treated gypsum and fluorine-containing contaminated soil or contaminated water.
かかる実情において、本発明者等は、フッ素不溶化剤の製造方法について、鋭意検討を行った結果、ＤＣＰＤの表面に前駆体を形成する溶液である弱酸性溶液において、疑似体液のＣａ２＋イオンとＨＰＯ４ ２－イオンに着目し、更にこれらのイオンに、不溶化の対象物であるフッ化物イオンを併存させるという逆転の発想に基づき作成された溶液を使用し、ＤＣＰＤの表面にフッ素アパタイトを予め積極的に形成してフッ素不溶化剤を得たところ、ＤＣＰＤとフッ化物イオンとの反応に見られる遅れ時間を大きく改善でき、ＤＣＰＤが高い活性化を示すことを見出し、本発明を完成するに至った。 Under such circumstances, the present inventors conducted intensive studies on a method for producing a fluorine-insolubilizing agent, and as a result, focused on Ca 2+ ions and HPO 4 2- ions in simulated body fluids in a weakly acidic solution that forms a precursor on the surface of DCPD. When the insolubilizing agent was obtained, it was found that the lag time observed in the reaction between DCPD and fluoride ions could be greatly improved, and DCPD exhibited high activation, leading to the completion of the present invention.
すなわち、本発明は、リン酸水素カルシウム二水和物の表面に、フッ素アパタイトが付着してなることを特徴とするフッ素不溶化剤を提供するものである。 That is, the present invention provides a fluorine-insolubilizing agent comprising calcium hydrogen phosphate dihydrate and fluoroapatite adhering to the surface thereof.
また、本発明は、Ｃａ２＋イオン２．０～５．０ｍｍｏｌ/ｌ、ＨＰＯ４ ２－イオン０．５～２．０ｍｍｏｌ/ｌ及びＦ－イオン１．０～３．０ｍｍｏｌ/ｌを含有する弱酸性溶液に、リン酸水素カルシウム二水和物を浸漬させ、リン酸水素カルシウム二水和物の表面に、フッ素アパタイトを沈着させる第１工程を有すること特徴とするフッ素不溶化剤の製造方法を提供するものである。 The present invention also provides a method for producing a fluorine-insolubilizing agent, comprising a first step of immersing calcium hydrogen phosphate dihydrate in a weakly acidic solution containing 2.0 to 5.0 mmol/l of Ca 2+ ions, 0.5 to 2.0 mmol/l of HPO 4 2- ions, and 1.0 to 3.0 mmol/l of F − ions to deposit fluoroapatite on the surface of calcium hydrogen phosphate dihydrate.
また、本発明は、前記不溶化剤が添加された石膏であり、フッ素の溶出を低減したことを特徴とする処理石膏を提供するものである。 The present invention also provides a treated gypsum, which is gypsum to which the insolubilizing agent has been added, and which is characterized by reduced elution of fluorine.
また、本発明は、前記フッ素不溶化剤を、フッ化物イオンで汚染された土壌に添加することを特徴とする汚染土壌の処理方法を提供するものである。 The present invention also provides a method for treating contaminated soil, which comprises adding the fluorine-insolubilizing agent to soil contaminated with fluoride ions.
また、本発明は、前記フッ素不溶化剤を、フッ化物イオンで汚染された汚染水に添加することを特徴とする汚染水の処理方法を提供するものである。 The present invention also provides a method for treating contaminated water, which comprises adding the fluorine-insolubilizing agent to contaminated water contaminated with fluoride ions.
本発明によれば、ＤＣＰＤとフッ化物イオンとの反応に見られる遅れ時間を改善し、ＤＣＰＤの高い活性化を有するフッ素不溶化剤を提供できる。また、本発明によれば、より単純な組成の溶液を使用して施工現場で調製可能なフッ素不溶化剤の製造方法を提供できる。また、本発明によれば、フッ素不溶化剤を直接または水に混合したものを、汚染土壌や汚染水に添加するという簡単な工程の実施のみで汚染土壌や汚染水中のフッ化物イオンを効率よく不溶化できる。 According to the present invention, it is possible to improve the lag time observed in the reaction between DCPD and fluoride ions and to provide a fluorine insolubilizing agent with high activation of DCPD. Moreover, according to the present invention, it is possible to provide a method for producing a fluorine-insolubilizing agent that can be prepared at the construction site using a solution with a simpler composition. In addition, according to the present invention, fluoride ions in contaminated soil and contaminated water can be efficiently insolubilized simply by performing a simple step of adding a fluorine insolubilizing agent directly or mixed with water to contaminated soil or contaminated water.
（フッ素不溶化剤）
本発明のフッ素不溶化剤は、ＤＣＰＤの表面に、フッ素アパタイト（以下、単に「ＦＡｐ」とも言う。）が付着してなるものであり、例えば、このＦＡｐは、ＤＣＰＤ粉末の表面を被覆しているものが挙げられる。ＤＣＰＤは、Ｘ線分析及び示差熱分析で特定することができる。ＤＣＰＤは、汚染土壌や汚染水中の汚染物であるフッ化物イオンと反応し、最終的には、ＦＡｐに転換される。
(Fluorine insolubilizer)
The fluorine-insolubilizing agent of the present invention is obtained by attaching fluoroapatite (hereinafter also simply referred to as "FAp") to the surface of DCPD. For example, the FAp covers the surface of DCPD powder. DCPD can be identified by X-ray analysis and differential thermal analysis. DCPD reacts with fluoride ions, which are contaminants in contaminated soil and contaminated water, and is finally converted to FAp.
本発明のフッ素不溶化剤において、ＦＡｐは、針状体の集合物であり、この針状体は、最大長さ５μｍ、好ましくは最大長さ０．５μｍである。また、針状体のアスペクト比（長辺と短辺の比）としては、１：１００～１：５０である。ＦＡｐは、Ｘ線分析及び示差熱分析で特定でき、その針状形状及び長さ寸法は、電子顕微鏡で特定できる。 In the fluorine-insolubilizing agent of the present invention, FAp is an aggregate of needle-like bodies, and the needle-like bodies have a maximum length of 5 μm, preferably a maximum length of 0.5 μm. Moreover, the aspect ratio (ratio of long side to short side) of the needle-shaped body is 1:100 to 1:50. FAp can be identified by X-ray analysis and differential thermal analysis, and its acicular shape and length dimension can be identified by electron microscopy.
本発明のフッ素不溶化剤において、ＦＡｐの含有量は、フッ素不溶化剤中、０．１質量％以上、好ましくは１．０～３０．０質量％以上、更に好ましくは５．０～４０．０質量％である。フッ素不溶化剤中、ＦＡｐの含有量は、上記数値範囲内において、多い方が汚染物であるフッ化物イオンとＤＣＰＤとの反応に見られる遅れ時間の改善効果が高い。図１のフッ素不溶化剤は、フッ素不溶化剤中、ＦＡｐの含有量が１０．０質量％のものであり、図２のフッ素不溶化剤は、フッ素不溶化剤中、ＦＡｐの含有量が１８．０質量％のものである。 In the fluorine-insolubilizing agent of the present invention, the content of FAp in the fluorine-insolubilizing agent is 0.1% by mass or more, preferably 1.0 to 30.0% by mass or more, and more preferably 5.0 to 40.0% by mass. Within the above numerical range, the greater the content of FAp in the fluorine-insolubilizing agent, the greater the effect of improving the delay time seen in the reaction between fluoride ions, which are contaminants, and DCPD. The fluorine-insolubilizing agent in FIG. 1 has a FAp content of 10.0% by mass in the fluorine-insolubilizing agent, and the fluorine-insolubilizing agent in FIG. 2 has a FAp content of 18.0% by mass in the fluorine-insolubilizing agent.
本発明のフッ素不溶化剤は、汚染物であるフッ素を含んだ石膏、汚染水あるいは汚染土壌に対し、直接または水に混合して添加することで、フッ化物イオンとＤＣＰＤとの反応における遅れ時間を短縮して、汚染物のフッ素を不溶化できる。 The fluorine-insolubilizing agent of the present invention can be added directly or mixed with water to fluorine-containing gypsum, contaminated water, or contaminated soil as contaminants, thereby shortening the lag time in the reaction between fluoride ions and DCPD and insolubilizing the fluorine in the contaminants.
（フッ素不溶化剤の製造方法）
本発明の第１の実施の形態におけるフッ素不溶化剤の製造方法は、Ｃａ２＋イオン２．０～５．０ｍｍｏｌ/ｌ、好ましくは、２．５ｍｍｏｌ/ｌ、ＰＯ４
２－イオン０．５～２．０ｍｍｏｌ/ｌ、好ましくは、１．０ｍｍｏｌ/ｌ、及びＦ－イオン１．０～３．０ｍｍｏｌ/ｌ、好ましくは１．２～３．０ｍｍｏｌ/ｌを含有する弱酸性溶液に、ＤＣＰＤを浸漬させ、ＤＣＰＤの表面に、ＦＡｐを沈着させる第１工程を有する方法である。
(Method for producing fluorine insolubilizer)
In the method for producing a fluorine-insolubilizing agent according to the first embodiment of the present invention, DCPD is immersed in a weakly acidic solution containing 2.0 to 5.0 mmol/l, preferably 2.5 mmol/l, of Ca 2+ ions, preferably 2.5 mmol/l, 0.5 to 2.0 mmol/l, preferably 1.0 mmol/l of PO 4 2- ions, and 1.0 to 3.0 mmol/l, preferably 1.2 to 3.0 mmol/l of F − ions. The method has a first step of depositing p.
Ｃａ２＋イオンとしては、塩化カルシウム、硝酸カルシウム又は酢酸カルシウムが使用でき、ＰＯ４ ２－イオンとしては、リン酸ナトリウム、リン酸アンモニウム又はリン酸が使用でき、Ｆ－イオンとしては、フッ化ナトリウム、フッ化水素酸又はフッ化アンモニウムが使用できる。カルシウム化合物、リン酸化合物及びフッ化化合物の添加順序は特に制限されず、純水中に、一度に添加してもよく、別個に添加してもよい。この際、沈殿が生じないよう、ｐＨ調整しながら行う。弱酸性溶液には、上記イオンの他、例えばマグネシウムイオン、ナトリウムイオン、カリウムイオンなどが含まれていてもよい。 Calcium chloride, calcium nitrate or calcium acetate can be used as Ca 2+ ions, sodium phosphate, ammonium phosphate or phosphoric acid can be used as PO 4 2- ions, and sodium fluoride, hydrofluoric acid or ammonium fluoride can be used as F - ions. The order of adding the calcium compound, the phosphoric acid compound and the fluoride compound is not particularly limited, and they may be added at once or separately to the pure water. At this time, the pH is adjusted so as not to cause precipitation. The weakly acidic solution may contain, for example, magnesium ions, sodium ions, potassium ions, etc., in addition to the above ions.
弱酸性溶液のｐＨは、２．５～６．５、好ましくは３．５～６．５である。すなわち、ＤＣＰＤの表面に、ＦＡｐを沈着させた後の溶液のｐＨが６．１となるように、該弱酸性溶液のｐＨを調整すればよい。ｐＨがこの範囲であれば、溶液の沈殿は起こらず、溶解状態を保持することができる。弱酸性溶液のｐＨが小さ過ぎると、ＤＣＰＤが溶解して原料の損失が大きくなり、ｐＨが大き過ぎると、溶液中に白濁が生じて分化するため、いずれも好ましくない。 The weakly acidic solution has a pH of 2.5-6.5, preferably 3.5-6.5. That is, the pH of the weakly acidic solution may be adjusted so that the pH of the solution after depositing FAp on the DCPD surface is 6.1. If the pH is within this range, precipitation of the solution does not occur and the dissolved state can be maintained. If the pH of the weakly acidic solution is too low, DCPD will dissolve and the raw material will be greatly lost.
本発明のフッ素不溶化剤の製造方法において、ＤＣＰＤとしては、工業用、化粧品用、食品添加物用、医薬品用等の各種グレードの市販品が使用できる。また、ＤＣＰＤは、例えば、消石灰の水分散液とリン酸とを、ｐＨ４～５に調整した水系媒体中で反応させることで製造する公知の方法で得たものを使用することができる。 In the method for producing the fluorine-insolubilizing agent of the present invention, DCPD of various grades commercially available for industrial use, cosmetics use, food additive use, pharmaceutical use, and the like can be used. In addition, DCPD can be obtained by a known method of producing, for example, by reacting an aqueous dispersion of slaked lime and phosphoric acid in an aqueous medium adjusted to pH 4-5.
次に、ＤＣＰＤを上記弱酸性溶液に浸漬する。ＤＣＰＤと弱酸性溶液の固液比（質量/体積）は、１/１００～１/５、好ましくは１/５０～１/１０である。固液比が小さ過ぎると、ＤＣＰＤが溶解して原料の損失が生じ、大き過ぎると弱酸性溶液に供給できるカルシウム、リン、フッ素量が少なる結果、ＦＡｐの生成量が少なくなり、いずれも好ましくない。 Next, DCPD is immersed in the weakly acidic solution. The solid-liquid ratio (mass/volume) of DCPD and the weakly acidic solution is 1/100 to 1/5, preferably 1/50 to 1/10. If the solid-liquid ratio is too small, DCPD will dissolve and the raw materials will be lost, and if it is too large, the amount of calcium, phosphorus and fluorine that can be supplied to the weakly acidic solution will be small, resulting in a small amount of FAp being produced.
浸漬条件としては、弱酸性溶液とＤＣＰＤが十分、混合されれば、特に制限されず、例えば、１０～３０℃、好ましくは室温下、撹拌又は振とう下、１日～１０日間、好ましくは、１日～７日間、混合処理する方法が挙げられる。 The immersion conditions are not particularly limited as long as the weakly acidic solution and DCPD are sufficiently mixed.
上記浸漬により、ＤＣＰＤの表面に、ＦＡｐが沈着する。ＤＣＰＤの表面へのＦＡｐの沈着の終了は、液中のフッ素濃度の低下をイオン選択性電極や比色分析により判断する（以上が第１工程）。液中のフッ素濃度は、０．１ｍｍｏｌ/ｌまで低下すれば、第１工程終了と判断してよい。 By the above immersion, FAp is deposited on the surface of DCPD. The completion of the deposition of FAp on the surface of DCPD is determined by the decrease in fluorine concentration in the liquid using an ion-selective electrode or colorimetric analysis (the above is the first step). If the fluorine concentration in the liquid decreases to 0.1 mmol/l, it may be judged that the first step is finished.
ＤＣＰＤの表面にＦＡｐの沈着が完了した固液相は、公知の固液分離により、固相を得る（第２工程）。特に、固液分離後、固相を脱水、乾燥して粉末の不溶化剤として得ることが好ましい。脱水方法としては、デカンテーション、濾過、遠心分離などの公知の方法を使用すればよい。乾燥した粉末のフッ素不溶化剤は、活性化に実質的に影響はなく、保管、運搬及び使用の際、都合がよい。 The solid-liquid phase in which the deposition of FAp on the surface of DCPD is completed is subjected to a known solid-liquid separation to obtain a solid phase (second step). In particular, after solid-liquid separation, the solid phase is preferably dehydrated and dried to obtain a powdery insolubilizer. As a dehydration method, a known method such as decantation, filtration or centrifugation may be used. The dry powder fluorine insolubilizer has substantially no effect on activation and is convenient in storage, transportation and use.
次に、本発明の第２の実施の形態におけるフッ素不溶化剤の製造方法について説明する。第２の実施の形態における製造方法において、第１の実施の形態における製造方法と同一構成要素については、その説明を省略し、異なる点について主に、説明する。すなわち、第２の実施の形態の製造方法において、第１の実施の形態の製造方法と異なる点は、第１の実施の形態における製造方法で得られた固相を再度、又は更に引き続き、直前で得られた固相を弱酸性溶液に浸漬する浸漬繰り返し工程を複数回行い、ＤＣＰＤの表面へのＦＡｐの沈着量を増やす点にある。 Next, a method for producing a fluorine-insolubilizing agent according to the second embodiment of the present invention will be described. In the manufacturing method of the second embodiment, descriptions of the same components as those of the manufacturing method of the first embodiment will be omitted, and differences will be mainly described. That is, the manufacturing method of the second embodiment is different from the manufacturing method of the first embodiment in that the solid phase obtained by the manufacturing method of the first embodiment is again or further followed by repeating the immersion step of immersing the solid phase obtained immediately before in a weakly acidic solution a plurality of times to increase the amount of FAp deposited on the surface of DCPD.
すなわち、本発明の第２の実施の形態における製造方法は、Ｃａ２＋イオン２．０～５．０ｍｍｏｌ/ｌ、ＨＰＯ４ ２－イオン０．５～２．０ｍｍｏｌ/ｌ及びＦ－イオン１．０～３．０ｍｍｏｌ/ｌを含有する弱酸性溶液に、該第２工程で得られた固相を浸漬させ、リン酸水素カルシウム二水和物の表面に、更にフッ素アパタイトを沈着させる浸漬繰り返し工程と、を有する方法（都合２回の浸漬方法）が挙げられ、更に、Ｃａ２＋イオン２．０～５．０ｍｍｏｌ/ｌ、ＨＰＯ４ ２－イオン０．５～２．０ｍｍｏｌ/ｌ及びＦ－イオン１．０～３．０ｍｍｏｌ/ｌを含有する弱酸性溶液を使用した浸漬繰り返し工程を、更に複数回繰り返し行う方法（都合３回以上の浸漬方法）が挙げられる。合計の浸漬回数は、最大１０回、好ましくは最大５回、特に好ましくは最大３回である。合計の浸漬回数が、多過ぎても、ＦＡｐの沈着量はそれほど増えず、効率が悪くなり、また、すくな過ぎても、ＦＡｐの沈着量を増やすことができない。 すなわち、本発明の第２の実施の形態における製造方法は、Ｃａ ２＋イオン２．０～５．０ｍｍｏｌ/ｌ、ＨＰＯ ４ ２－イオン０．５～２．０ｍｍｏｌ/ｌ及びＦ －イオン１．０～３．０ｍｍｏｌ/ｌを含有する弱酸性溶液に、該第２工程で得られた固相を浸漬させ、リン酸水素カルシウム二水和物の表面に、更にフッ素アパタイトを沈着させる浸漬繰り返し工程と、を有する方法（都合２回の浸漬方法）が挙げられ、更に、Ｃａ ２＋イオン２．０～５．０ｍｍｏｌ/ｌ、ＨＰＯ ４ ２－イオン０．５～２．０ｍｍｏｌ/ｌ及びＦ －イオン１．０～３．０ｍｍｏｌ/ｌを含有する弱酸性溶液を使用した浸漬繰り返し工程を、更に複数回繰り返し行う方法（都合３回以上の浸漬方法）が挙げられる。 The total number of immersions is at most 10, preferably at most 5 and particularly preferably at most 3. If the total number of immersions is too large, the deposition amount of FAp will not increase so much, and the efficiency will be poor.
すなわち、本発明の第２の実施の形態における製造方法において、再度及び複数回の浸漬処理を行う際、使用する弱酸性溶液は、常に当初濃度を有する、Ｃａ２＋イオン２．０～５．０ｍｍｏｌ/ｌ、好ましくは、２．５ｍｍｏｌ/ｌ、ＰＯ４ ２－イオン０．５～２．０ｍｍｏｌ/ｌ、好ましくは、１．０ｍｍｏｌ/ｌ、及びＦ－イオン１．０～３．０ｍｍｏｌ/ｌ、好ましくは１．２～３．０ｍｍｏｌ/ｌを含有する溶液である。一度、ＤＣＰＤを浸漬した使用済みの弱酸性溶液は、それぞれのイオン濃度が低減しており、使用できない。また、再度及び複数回の浸漬処理を行う際、浸漬される固相は、直前で浸漬処理された固相である。すなわち、例えば３回目の浸漬処理で使用する固相は、２回目の浸漬処理で得られた固相であり、４回目の浸漬処理で使用する固相は、３回目の浸漬処理で得られた固相である。第２の実施の形態例では、再度及び更に複数回の浸漬処理を行うことで、処理前のフッ素不溶化剤と比べて、処理後のフッ素不溶化剤は、ＦＡｐの沈着量が多くなる。 That is, in the manufacturing method according to the second embodiment of the present invention, when the immersion treatment is performed again and multiple times, the weakly acidic solution used always has an initial concentration of 2.0 to 5.0 mmol/l for Ca 2+ ions, preferably 2.5 mmol/l, 0.5 to 2.0 mmol/l for PO 4 2- ions, preferably 1.0 mmol/l, and 1.0 to 3.0 mmol/l for F − ions, preferably 1.2 to 3.0 mmol/l. is a solution containing A used weakly acidic solution in which DCPD has been immersed once has a reduced ion concentration and cannot be used. Moreover, when the immersion treatment is performed again or multiple times, the solid phase to be immersed is the solid phase that was immersed immediately before. That is, for example, the solid phase used in the third immersion treatment is the solid phase obtained in the second immersion treatment, and the solid phase used in the fourth immersion treatment is the solid phase obtained in the third immersion treatment. In the second embodiment, by performing the immersion treatment again and more times, the fluorine insolubilizer after the treatment has a larger deposition amount of FAp than the fluorine insolubilizer before the treatment.
本発明の実施の形態におけるフッ素不溶化剤の製造方法において、ＤＣＰＤは、市販品を使用できること、使用する弱酸性溶液は簡単な組成であること、ＤＣＰＤの浸漬条件は、室温下でできる簡単な操作であることから、現場の施工場所において製造可能であり、フッ素不溶化剤の用途の拡大が図れる。 In the method for producing a fluorine-insolubilizing agent according to the embodiment of the present invention, a commercially available DCPD can be used, the weakly acidic solution used has a simple composition, and DCPD can be immersed in a simple operation that can be performed at room temperature.
（処理石膏）
次に、本発明に係る含有フッ素の溶出を低減させた処理石膏について説明する。本発明において石膏は、フッ素を含有するものであれば、特に制限されず、二水塩、半水塩、無水塩が挙げられ、この内、半水塩が入手し易い点で好ましい。石膏の具体例としては、天然石膏、排煙脱硫処理によって副生する石膏、天然無水石膏、ふっ酸の製造過程で副産するふっ酸無水石膏等が挙げられる。
(treated gypsum)
Next, the treated gypsum with reduced fluorine-containing elution according to the present invention will be described. In the present invention, the gypsum is not particularly limited as long as it contains fluorine, and includes dihydrate, hemihydrate, and anhydrous salt. Of these, the hemihydrate is preferred because it is readily available. Specific examples of gypsum include natural gypsum, gypsum by-produced by flue gas desulfurization treatment, natural anhydrous gypsum, hydrofluoric anhydride gypsum by-produced in the process of producing hydrofluoric acid, and the like.
本発明において、フッ素を含有する石膏に、本発明のフッ素不溶化剤を添加する方法としては、特に制限されず、両者を粉末状とし、単にそのまま混合すればよい。フッ素含有石膏に対するフッ素不溶化剤の添加量としては、フッ素含有石膏１００質量部に対して、フッ素不溶化剤０．５質量部以上、好ましくは０．５～５質量部である。フッ素不溶化剤の添加量が少な過ぎると、石膏からのフッ素の溶出量を土壌環境基準値以下にするのが難しくなり、フッ素不溶化剤の添加量が多過ぎても、フッ素の溶出低減効果は大きく変わらない。本発明によれば、ＤＣＰＤと石膏中のフッ素（フッ化物イオン）との反応に見られる遅れ時間を改善できるため、石膏中のフッ素を固定化して、溶出フッ化物イオンを低減できる。本発明の処理石膏は、そのまま埋立処分することもできるが、石膏ボード、プラスター、土壌固化材等の原料として再使用することもできる。 In the present invention, the method of adding the fluorine-insolubilizing agent of the present invention to the fluorine-containing gypsum is not particularly limited, and the two may be powdered and simply mixed as they are. The amount of the fluorine-insolubilizing agent added to the fluorine-containing gypsum is 0.5 parts by mass or more, preferably 0.5 to 5 parts by mass, per 100 parts by mass of the fluorine-containing gypsum. If the amount of the fluorine-insolubilizing agent added is too small, it will be difficult to keep the amount of fluorine eluted from the gypsum below the soil environmental standard value, and even if the amount of the fluorine-insolubilizing agent added is too large, the effect of reducing fluorine elution will not change significantly. According to the present invention, the lag time observed in the reaction between DCPD and fluorine (fluoride ions) in gypsum can be improved, so fluorine in gypsum can be immobilized and eluted fluoride ions can be reduced. The treated gypsum of the present invention can be landfilled as it is, but it can also be reused as a raw material for gypsum boards, plaster, soil solidification materials, and the like.
（汚染土壌の処理方法）
次に、本発明に係る汚染土壌の処理方法について説明する。本発明は、フッ化物イオンで汚染された土壌に、本発明のフッ素不溶化剤を添加するものである。本発明において、フッ素汚染土壌に、フッ素不溶化剤を添加する方法としては、特に制限されず、単にそのまま混合する方法、両者の混合前、混合中又は混合後に必要に応じて適宜脱水又は加水して水分調整する方法などが挙げられる。水分調整の場合、混合後の水分が５～２０質量％となるようにするのが好ましい。
(Method for treating contaminated soil)
Next, the method for treating contaminated soil according to the present invention will be described. According to the present invention, the fluorine-insolubilizing agent of the present invention is added to soil contaminated with fluoride ions. In the present invention, the method of adding the fluorine-insolubilizing agent to the fluorine-contaminated soil is not particularly limited, and includes a method of simply mixing the soil as it is, and a method of adjusting the moisture content by appropriately dehydrating or adding water before, during, or after mixing the two as necessary. In the case of water content adjustment, it is preferable to adjust the water content after mixing to 5 to 20% by mass.
本発明において、フッ素汚染土壌に対するフッ素不溶化剤の添加量としては、フッ素汚染土壌の乾燥物１００質量部に対して、フッ素不溶化剤１質量部以上、好ましくは１～２０質量部である。フッ素不溶化剤の添加量が少な過ぎると、フッ素汚染土壌からのフッ素の溶出量を土壌環境基準値以下にするのが難しくなり、フッ素不溶化剤の添加量が多過ぎても、フッ素の溶出低減効果は大きく変わらない。本発明によれば、ＤＣＰＤと汚染土壌中のフッ素（フッ化物イオン）との反応に見られる遅れ時間を改善できるため、汚染土壌中のフッ素を固定化して、溶出フッ化物イオンを低減できる。 In the present invention, the amount of the fluorine-insolubilizing agent added to the fluorine-contaminated soil is 1 part by mass or more, preferably 1 to 20 parts by mass, per 100 parts by mass of the dry matter of the fluorine-contaminated soil. If the amount of the fluorine-insolubilizing agent added is too small, it will be difficult to keep the amount of fluorine eluted from the fluorine-contaminated soil below the soil environmental standard value, and even if the amount of the fluorine-insolubilizing agent added is too large, the effect of reducing fluorine elution will not change significantly. According to the present invention, the lag time seen in the reaction between DCPD and fluorine (fluoride ions) in the contaminated soil can be improved, so the fluorine in the contaminated soil can be fixed and the eluted fluoride ions can be reduced.
（汚染水の処理方法）
次に、本発明に係る汚染水の処理方法について説明する。本発明は、フッ化物イオンで汚染された汚染水に、本発明のフッ素不溶化剤を添加するものである。本発明において、フッ素汚染水に、フッ素不溶化剤を添加する方法としては、特に制限されず、単にそのまま混合する方法が挙げられる。
(Contaminated water treatment method)
Next, a method for treating contaminated water according to the present invention will be described. According to the present invention, the fluorine-insolubilizing agent of the present invention is added to contaminated water contaminated with fluoride ions. In the present invention, the method of adding the fluorine-insolubilizing agent to the fluorine-contaminated water is not particularly limited, and a method of simply mixing the water as it is can be mentioned.
本発明において、フッ素汚染水に対するフッ素不溶化剤の添加量としては、フッ素汚染濃度により変わるため、一概に決定できないものの、例えば、フッ素汚染水１００質量部に対して、フッ素不溶化剤０．１質量部以上、好ましくは１．０～５．０質量部である。フッ素不溶化剤の添加量が少な過ぎると、フッ素汚染水からのフッ素の溶出量を基準値以下にするのが難しくなり、フッ素不溶化剤の添加量が多過ぎても、フッ素の溶出低減効果は大きく変わらない。本発明によれば、ＤＣＰＤと汚染水中のフッ素（フッ化物イオン）との反応に見られる遅れ時間を改善できるため、汚染水中のフッ素を固定化して、溶出フッ化物イオンを低減できる。 In the present invention, the amount of the fluorine-insolubilizing agent to be added to the fluorine-contaminated water varies depending on the fluorine-contaminated concentration and cannot be unconditionally determined. If the amount of the fluorine-insolubilizing agent added is too small, it will be difficult to keep the amount of fluorine eluted from the fluorine-contaminated water below the standard value, and even if the amount of the fluorine-insolubilizing agent added is too large, the effect of reducing fluorine elution will not change significantly. According to the present invention, the lag time observed in the reaction between DCPD and fluorine (fluoride ions) in the contaminated water can be improved, so the fluorine in the contaminated water can be fixed and the eluted fluoride ions can be reduced.
本発明において、処理石膏、汚染土壌及び汚染水に配合されたフッ素不溶化剤は、フッ素を短時間で充分にフッ素アパタイトとして不溶化することができる。すなわち、ＦＡｐが表面に付着したＤＣＰＤにおけるＤＣＰＤ部分は、そのままの形状を保持して、内部までＦＡｐに転化される。このため、ＤＣＰＤに付着していたＦＡｐを含めて、粉末全体が、ＦＡｐを形成することになる。 In the present invention, the fluorine-insolubilizing agent blended in the treated gypsum, contaminated soil and contaminated water can sufficiently insolubilize fluorine as fluoroapatite in a short period of time. That is, the DCPD portion of DCPD with FAp attached to the surface retains its shape and is converted to FAp even inside. Therefore, the entire powder, including the FAp attached to DCPD, forms FAp.
（実施例）
次に、実施例を挙げて本発明を更に具体的に説明する。
(Example)
EXAMPLES Next, the present invention will be described more specifically with reference to Examples.
＜フッ素不溶化剤Ａの調製＞
（ＤＣＰＤ粉末Ａ）
市販品である粉末状のリン酸水素カルシウム二水和物（ＤＣＰＤ粉末Ａ）（米山化学工業社製；特級試薬）を使用した。また、ＤＣＰＤ粉末Ａの電子顕微鏡（ＳＥＭ）写真を図８に、ＸＲＤの結果を図４の符号（４－１）に示した。
<Preparation of fluorine insolubilizer A>
(DCPD powder A)
A commercially available powdery calcium hydrogen phosphate dihydrate (DCPD powder A) (manufactured by Yoneyama Chemical Co., Ltd.; special grade reagent) was used. Further, an electron microscope (SEM) photograph of DCPD powder A is shown in FIG. 8, and the result of XRD is shown by symbol (4-1) in FIG.
（弱酸性溶液Ａの調製）
室温下、超純水に超純水１０００ｍｌ換算で、ＣａＣｌ２を０．２７８ｇ（Ｃａ２＋濃度２．５ｍｍｏｌ）、Ｋ２ＨＰＯ４・３Ｈ２Ｏを０．２２８ｇ（ＨＰＯ４
２－濃度１．０ｍｍｏｌ）及びＮａＦを０．０６６ｇ（Ｆ－濃度１．５ｍｍｏｌ）添加し、更に塩酸を添加することでｐＨ４．６に調整された沈殿物のない弱酸性溶液Ａを得た。
(Preparation of weakly acidic solution A)
At room temperature, 0.278 g of CaCl 2 (Ca 2+ concentration: 2.5 mmol), 0.228 g of K 2 HPO 4 .3H 2 O (HPO 4 2 - concentration: 1.0 mmol), and 0.066 g of NaF (F - concentration: 1.5 mmol) were added to ultrapure water in terms of 1000 ml of ultrapure water at room temperature. A solution A was obtained.
（フッ素不溶化剤Ａの調製）
次に、室温下、容器に入れた弱酸性溶液ＡにＤＣＰＤ粉末Ａを投入し、浸漬した。この際、ＤＣＰＤ粉末Ａと弱酸性溶液Ａの固液比（質量/体積）は、ＤＣＰＤ粉末Ａ１ｇに対して、弱酸性溶液Ａを５０ｍｌ混合したものであり、１/５０であった。混合後、溶液をポリプロピレン製瓶に封入し、毎分８０回にて７日間、振とうさせて混合させた。
(Preparation of fluorine insolubilizer A)
Next, at room temperature, DCPD powder A was put into weakly acidic solution A in a container and immersed. At this time, the solid-liquid ratio (mass/volume) of the DCPD powder A and the weakly acidic solution A was 1/50, which was obtained by mixing 50 ml of the weakly acidic solution A with 1 g of the DCPD powder A. After mixing, the solution was sealed in a polypropylene bottle and shaken at 80 times per minute for 7 days to mix.
７日間の振とう後、得られた懸濁物を０．４５μｍのメンブレンフィルターにて濾過して固相を採取し、更に乾燥して、粉末状のフッ素不溶化剤Ａを得た。フッ素不溶化剤Ａを、粉末Ｘ線回折装置（ＸＲＤ）、粒子表面の形態及び構成相をＳＥＭを用いて調べた。 After shaking for 7 days, the resulting suspension was filtered through a 0.45 μm membrane filter to collect a solid phase, which was further dried to obtain a powdery fluorine-insolubilizing agent A. Fluorine-insolubilizing agent A was examined using a powder X-ray diffractometer (XRD), particle surface morphology and constituent phases using SEM.
上記の調製で得られたフッ素不溶化剤ＡのＳＥＭ写真を図１に、ＸＲＤの結果を図４の符号（２－１）に示した。この結果、フッ素不溶化剤Ａは、ＤＣＰＤの表面にＦＡｐが沈着していることを確認した。この時の弱酸性溶液ＡのｐＨは５．６であった。これは、ＤＣＰＤの一部が溶解してカルシウムイオンとリン酸イオンを溶出し、リン酸イオンの加水分解により溶液のｐＨが５．６程度まで上昇したものであり、これらカルシウムイオンとリン酸イオンは、溶液中のフッ化物イオンと反応して、ＤＣＰＤ粉末の表面上にＦＡｐを生成したものと思われる。また、ＤＣＰＤの表面に沈着したＦＡｐは、針状物が集合したものであった。また、フッ素不溶化剤Ａ中のＦＡｐの含有量を、ＩＣＰ（誘導結合プラズマ）分析により求めたところ、フッ素不溶化剤中、１０．０質量％であった。 A SEM photograph of the fluorine-insolubilizing agent A obtained by the above preparation is shown in FIG. 1, and the result of XRD is shown by reference numeral (2-1) in FIG. As a result, it was confirmed that the fluorine-insolubilizing agent A had FAp deposited on the surface of DCPD. The pH of the weakly acidic solution A at this time was 5.6. This is because part of DCPD dissolved and calcium ions and phosphate ions were eluted, and the hydrolysis of phosphate ions raised the pH of the solution to about 5.6. These calcium ions and phosphate ions are thought to have reacted with fluoride ions in the solution to generate FAp on the surface of the DCPD powder. In addition, the FAp deposited on the surface of DCPD was a collection of needle-like substances. Further, when the content of FAp in fluorine-insolubilizing agent A was determined by ICP (inductively coupled plasma) analysis, it was found to be 10.0% by mass in the fluorine-insolubilizing agent.
＜フッ素含有汚染水の処理方法Ａ＞
（反応容器）
フッ素不溶化剤Ａと除去対象物であるフッ化物イオンとの反応を調べるために、撹拌用テフロン（登録商標）羽根を備えた反応容器を使用した。反応容器には、フッ化物イオン濃度を測定するフッ化物イオン選択性電極を設置した。
<Method A for treating fluorine-containing contaminated water>
(reaction vessel)
In order to examine the reaction between the fluorine-insolubilizing agent A and the fluoride ions to be removed, a reaction vessel equipped with Teflon (registered trademark) blades for stirring was used. A fluoride ion selective electrode for measuring the fluoride ion concentration was installed in the reaction vessel.
（処理方法及び測定結果）
室温下、反応容器中に超純水を１０００ｍｌ入れ、所定量のフッ化ナトリウム試薬４４ｍｇを溶解させて、フッ化物イオン濃度２０ｍｇ/Ｌのフッ化物溶液（フッ素含有汚染水Ａ）を調製した。ここにフッ素不溶化剤Ａの粉末１．０ｇ（固液比１:１０００）を添加し、撹拌羽根の撹拌速度２００ｒｐｍ下、反応を開始させ、溶液中のフッ化物イオン濃度の変化を経時的にイオン選択性電極で測定した。その測定結果を図３に実施例１として示した。
(Processing method and measurement results)
At room temperature, 1000 ml of ultrapure water was placed in a reaction vessel, and a predetermined amount of 44 mg of sodium fluoride reagent was dissolved to prepare a fluoride solution (fluorine-containing contaminated water A) having a fluoride ion concentration of 20 mg/L. 1.0 g of fluorine-insolubilizing agent A powder (solid-liquid ratio 1:1000) was added thereto, and the reaction was started at a stirring speed of 200 rpm with a stirring blade, and changes in fluoride ion concentration in the solution were measured over time with an ion-selective electrode. The measurement results are shown as Example 1 in FIG.
また、処理時間２４０分後の懸濁液を０．４５μｍのメンブレンフィルターにて濾過して固相を採取し、乾燥させた構成相をＸＲＤ、粒子表面の形態及び構成相をＳＥＭを用いて調べた。ＳＥＭ写真を図５に、ＸＲＤの結果を図４の符号（２－２）に示した。その結果、処理済のフッ素不溶化剤は、全体がＦＡｐと確認できた。また、フッ素不溶化剤ＡのＤＣＰＤ部分は、その形状を保持したまま、ＦＡｐに転換されたものであった。 In addition, after 240 minutes of treatment, the suspension was filtered through a 0.45 μm membrane filter to collect the solid phase, and the dried constituent phase was examined by XRD, and the particle surface morphology and constituent phase were examined by SEM. The SEM photograph is shown in FIG. 5, and the XRD result is shown by reference numeral (2-2) in FIG. As a result, it was confirmed that the treated fluorine-insolubilizing agent was entirely FAp. Also, the DCPD portion of the fluorine-insolubilizing agent A was converted to FAp while retaining its shape.
＜フッ素不溶化剤Ｂの調製＞
固液比１/５０の振とう７日間に代えて、固液比１/１０の振とう１日間としたこと、及びＤＣＰＤ粉末Ａに代えて、粉末状のフッ素不溶化剤Ａを使用し、これを弱酸性溶液Ａに投入し、混合処理したこと以外は、実施例１と同様の方法で、フッ素不溶化剤Ａ-１を調製した。次いで、同様の振とう１日間とし、ＤＣＰＤ粉末Ａに代えて、粉末状のフッ素不溶化剤Ａ-１を使用し、これを弱酸性溶液Ａに投入し、浸漬した以外は、実施例１と同様の方法で、フッ素不溶化剤Ｂを調製した。すなわち、フッ素不溶化剤Ｂは、本発明の第２の実施の形態における製造方法に相当するものであり、２度の繰り返し浸漬、合計３度の浸漬処理を行ったものである。
<Preparation of fluorine insolubilizer B>
Fluorine-insolubilizing agent A-1 was prepared in the same manner as in Example 1, except that 1-day shaking at a solid-liquid ratio of 1/10 was used instead of 7-day shaking at a solid-liquid ratio of 1/50, and powdered fluorine-insolubilizing agent A was used instead of DCPD powder A, and this was added to weakly acidic solution A and mixed. Next, a fluorine insolubilizer B was prepared in the same manner as in Example 1, except that the powdered fluorine insolubilizer A-1 was used instead of the DCPD powder A, and this was added to the weakly acidic solution A and immersed in the same shaking for one day. That is, the fluorine-insolubilizing agent B corresponds to the manufacturing method in the second embodiment of the present invention, and is subjected to repeated immersion twice, ie, a total of three immersion treatments.
実施例２で得られたフッ素不溶化剤ＢのＳＥＭ写真を図２に、ＸＲＤの結果を図４の符号（１－１）に示した。この結果、フッ素不溶化剤Ｂは、ＤＣＰＤの表面にＦＡｐが沈着していることを確認した。また、ＤＣＰＤの表面に沈着したＦＡｐは、針状物が集合したものであった。また、フッ素不溶化剤Ｂにおいて、ＩＣＰ分析の結果よりＦＡｐの含有量を求めたところ、フッ素不溶化剤中、１８．０質量％であった。また、Ｃａ/Ｐ比は、１．１０であった。 The SEM photograph of the fluorine-insolubilizing agent B obtained in Example 2 is shown in FIG. 2, and the result of XRD is shown by symbol (1-1) in FIG. As a result, it was confirmed that the fluorine-insolubilizing agent B had FAp deposited on the surface of DCPD. In addition, the FAp deposited on the surface of DCPD was a collection of needle-like substances. Further, in the fluorine-insolubilizing agent B, the content of FAp was found to be 18.0% by mass in the fluorine-insolubilizing agent as a result of ICP analysis. Also, the Ca/P ratio was 1.10.
＜フッ素含有汚染水の処理方法Ｂ＞
フッ素不溶化剤Ａに代えて、フッ素不溶化剤Ｂを使用した以外は、実施例１のフッ素含有汚染水の処理方法Ａと同様の方法で行った。その測定結果を図３に実施例２として示した。また、処理時間２４０分後の懸濁液を０．４５μｍのメンブレンフィルターにて濾過して固相を採取し、乾燥させた構成相をＸＲＤ、粒子表面の形態及び構成相をＳＥＭを用いて調べた。ＳＥＭ写真を図６に、ＸＲＤの結果を図４の符号（１－２）に示した。その結果、処理済のフッ素不溶化剤は、全体がＦＡｐと確認できた。また、フッ素不溶化剤ＡのＤＣＰＤ部分は、その形状を保持したまま、ＦＡｐに転換されたものであった。
<Method B for treating fluorine-containing contaminated water>
The procedure was carried out in the same manner as in Method A for treating fluorine-containing contaminated water in Example 1, except that fluorine-insolubilizing agent B was used instead of fluorine-insolubilizing agent A. The measurement results are shown as Example 2 in FIG. After 240 minutes of treatment, the suspension was filtered through a 0.45 μm membrane filter to collect the solid phase. The SEM photograph is shown in FIG. 6, and the XRD result is shown by reference numerals (1-2) in FIG. As a result, it was confirmed that the treated fluorine-insolubilizing agent was entirely FAp. Also, the DCPD portion of the fluorine-insolubilizing agent A was converted to FAp while retaining its shape.
（比較例１）
（弱酸性溶液Ｂの調製）
室温下、１０００ｍｌの水に、ＣａＣｌ２を０．２７８ｇ（Ｃａ２＋濃度２．５ｍｍｏｌ）及びＫ２ＨＰＯ４・３Ｈ２Ｏを０．２２８ｇ（ＨＰＯ４
２－濃度１．０ｍｍｏｌ）添加してｐＨ４．６に調整した。これにより、沈殿物のない弱酸性溶液Ｂを得た。すなわち、弱酸性溶液Ｂは、実施例１の弱酸性溶液Ａにおいてフッ素化合物の添加を省略したものである。
(Comparative example 1)
(Preparation of weakly acidic solution B)
At room temperature, 0.278 g of CaCl 2 (Ca 2+ concentration 2.5 mmol) and 0.228 g of K 2 HPO 4 .3H 2 O (HPO 4 2- concentration 1.0 mmol) were added to 1000 ml of water to adjust the pH to 4.6. As a result, a weakly acidic solution B without precipitate was obtained. That is, the weakly acidic solution B is obtained by omitting the addition of the fluorine compound in the weakly acidic solution A of Example 1.
（フッ素不溶化剤Ｃの調製）
弱酸性溶液Ａに代えて、弱酸性溶液Ｂとした以外は、実施例１のフッ素不溶化剤Ａの調製と同様の方法で調製し、フッ素不溶化剤Ｃを得た。フッ素不溶化剤ＣのＳＥＭ写真を図７に、ＸＲＤの結果を図４の符号（３－１）に示した。この結果、フッ素不溶化剤Ｃは、ＤＣＰＤの表面にＦＡｐの沈着は当然、確認されないものであった。
(Preparation of fluorine insolubilizer C)
A fluorine-insolubilizing agent C was obtained in the same manner as the fluorine-insolubilizing agent A in Example 1, except that the weakly acidic solution B was used instead of the weakly acidic solution A. An SEM photograph of the fluorine-insolubilizing agent C is shown in FIG. 7, and the XRD result is shown by reference numeral (3-1) in FIG. As a result, the deposition of FAp on the surface of DCPD was of course not confirmed with the fluorine-insolubilizing agent C.
＜フッ素含有汚染水の処理方法Ｃ＞
フッ素不溶化剤Ａに代えて、フッ素不溶化剤Ｃを使用した以外は、実施例１のフッ素含有汚染水の処理方法と同様の方法で行った。その測定結果を図３に比較例１として示した。また、２４０時間処理後の固相の乾燥物のＸＲＤの結果を図４の符号（３－２）に示した。
<Method C for treating fluorine-containing contaminated water>
The fluorine-containing contaminated water was treated in the same manner as in Example 1, except that the fluorine-insolubilizing agent C was used instead of the fluorine-insolubilizing agent A. The measurement results are shown as Comparative Example 1 in FIG. In addition, the result of XRD of the solid-phase dried product after 240 hours of treatment is indicated by symbol (3-2) in FIG.
（比較例２）
＜フッ素含有汚染水の処理方法Ｄ＞
フッ素不溶化剤Ａに代えて、ＤＣＰＤ粉末Ａを使用した以外は、実施例１のフッ素含有汚染水の処理方法と同様の方法で行った。その測定結果を図３に比較例２として示した。汚染水の処理方法Ｄの２４０時間処理後の固相の乾燥物のＸＲＤの結果を図４の符号（４－２）に示した。
(Comparative example 2)
<Method D for treating fluorine-containing contaminated water>
The treatment was carried out in the same manner as the fluorine-containing contaminated water treatment method of Example 1, except that the DCPD powder A was used instead of the fluorine-insolubilizing agent A. The measurement results are shown as Comparative Example 2 in FIG. The results of XRD of the solid-phase dried product after 240 hours of treatment by the contaminated water treatment method D are indicated by reference numeral (4-2) in FIG.
図３の結果から、ＦＡｐ付着ＤＣＰＤ粉体をフッ素不溶化剤とした実施例１では、ＤＣＰＤと汚染物質であるフッ化物イオンの反応遅れ時間が約半分に短縮できた。また、３度の繰り返し浸漬により、ＤＣＰＤ粉体に付着したＦＡｐの付着量を高めた実施例２では、遅れ時間が無視できる程度にまで短縮できた。また、ＤＣＰＤの浸漬に使用する弱酸性溶液のフッ化物イオンの添加を省略した比較例１では、未処理のＤＣＰＤ粉体を使用した比較例２と同等の結果であり、反応開始までの誘導時間（遅れ時間）に改善は見られなかった。 From the results of FIG. 3, in Example 1 in which the FAp-adhered DCPD powder was used as the fluorine insolubilizer, the reaction delay time between DCPD and fluoride ions, which are contaminants, could be shortened by about half. Further, in Example 2, in which the amount of FAp adhering to the DCPD powder was increased by repeated immersion three times, the delay time could be shortened to a negligible level. In addition, in Comparative Example 1 in which the addition of fluoride ions to the weakly acidic solution used for immersing DCPD was omitted, the results were the same as in Comparative Example 2 in which untreated DCPD powder was used, and no improvement was seen in the induction time (delay time) until the start of the reaction.
（フッ素不溶化剤の調製方法における固液比の影響‐１回浸漬処理）
実施例１の（フッ素不溶化剤Ａの調製）において、固液比１/１０、１/２０、１/３０、１/５０（実施例１）の４つの系の、振とう日数１日、３日、７日におけるフッ素不溶化剤についてＩＣＰ分析を行い、Ｃａ/Ｐ値、フッ素不溶化剤中のＦＡｐの質量％を測定した。その結果を表１に示す。
(Influence of solid-liquid ratio in preparation method of fluorine insolubilizer-one immersion treatment)
In Example 1 (preparation of fluorine-insolubilizing agent A), four systems with a solid-liquid ratio of 1/10, 1/20, 1/30, and 1/50 (Example 1) were shaken for 1 day, 3 days, and 7 days. ICP analysis was performed on the fluorine-insolubilizing agent, and the Ca/P value and the mass% of FAp in the fluorine-insolubilizing agent were measured. Table 1 shows the results.
（参考例２）
（フッ素不溶化剤の調製方法における固液比の影響‐繰り返し浸漬処理）
＜フッ素不溶化剤Ｂの調製＞の繰り返し浸漬３回に代えて、１回、２回、４回とした以外は、実施例２と同様に、フッ素不溶化剤Ｂの調製を行い、得られた固相乾燥物についてＩＣＰ分析を行い、Ｃａ/Ｐ値、フッ素不溶化剤中のＦＡｐの質量％を測定した。その結果を表２に示す。
(Reference example 2)
(Influence of solid-liquid ratio in preparation method of fluorine insolubilizer-repeated immersion treatment)
<Preparation of fluorine-insolubilizing agent B> Repeated immersion was repeated 1 time, 2 times, and 4 times instead of 3 times.The fluorine-insolubilizing agent B was prepared in the same manner as in Example 2, and the obtained solid-phase dried product was subjected to ICP analysis, and the Ca/P value and the mass% of FAp in the fluorine-insolubilizing agent were measured. Table 2 shows the results.
表１から、１回浸漬処理の場合、振とう日数が増えるほど、また、固液比が小さいほど、ＦＡｐの沈着量は多くなることが判る。また、表２から、繰り返し処理の場合、繰り返し処理数が多いほどＦＡｐの沈着量は多くなることが判る。 From Table 1, it can be seen that in the case of one-time immersion treatment, the more the number of shaking days and the lower the solid-liquid ratio, the greater the deposition amount of FAp. Further, from Table 2, it can be seen that in the case of repeated treatment, the more the number of repeated treatments, the greater the deposition amount of FAp.
本発明によれば、ＤＣＰＤと汚染物であるフッ化物イオンとの反応に見られる遅れ時間が改善でき、ＤＣＰＤの高い活性化が可能となった。また、より単純な組成の溶液を使用できるため、施工現場においてＤＣＰＤの処理が可能となる。従来、ＤＣＰＤとフッ化物イオンとの反応に見られる遅れ時間を改善する方法として、ＤＣＰＤの表面にリン酸カルシウムの前駆体を形成する方法が知られているが、本発明のように、ＤＣＰＤの表面に、原位置において固定化されるＦＡｐを、予め沈着させるという発想はこれまでになく、これによる活性効果も大きく、フッ素汚染処理に大きな貢献をもたらすものである。 According to the present invention, the delay time observed in the reaction between DCPD and fluoride ions, which are contaminants, can be improved, and DCPD can be highly activated. Also, since a solution with a simpler composition can be used, DCPD can be treated at the construction site. Conventionally, as a method of improving the lag time observed in the reaction between DCPD and fluoride ions, a method of forming a precursor of calcium phosphate on the surface of DCPD is known. However, unlike the present invention, the idea of pre-depositing FAp, which is immobilized in situ, on the surface of DCPD has never been done before, and the activation effect due to this is great, making a great contribution to fluorine contamination treatment.
Claims (8)
Ｃａ２＋イオン２．０～５．０ｍｍｏｌ/ｌのＣａＣｌ ２ 、ＨＰＯ４ ２－イオン０．５～２．０ｍｍｏｌ/ｌのＫ ２ ＨＰＯ ４ 及びＦ－イオン１．０～３．０ｍｍｏｌ/ｌのＮａＦを添加し、更に塩酸を添加することでｐＨ２．５～６．５に調整された弱酸性溶液に、該第２工程で得られた固相を浸漬させ、リン酸水素カルシウム二水和物の表面に、更にフッ素アパタイトを沈着させる浸漬繰り返し工程と、を有する請求項３～５のいずれか１項に記載のフッ素不溶化剤の製造方法。 a second step of solid-liquid separation of the solid-liquid phase obtained in the first step to take out a solid phase of calcium hydrogen phosphate dihydrate on which fluoroapatite is deposited;
The solid phase obtained in the second step is immersed in a weakly acidic solution adjusted to pH 2.5 to 6.5 by adding Ca 2+ ions of 2.0 to 5.0 mmol/l, HPO 4 2- ions of 0.5 to 2.0 mmol/l, K 2 HPO 4 of 0.5 to 2.0 mmol/l, and NaF of F − ions of 1.0 to 3.0 mmol/l, and further adding hydrochloric acid. 6. The method for producing a fluorine insolubilizer according to any one of claims 3 to 5 , further comprising a repeated immersion step for depositing fluoroapatite.
3. A method for treating contaminated water, comprising adding the fluorine-insolubilizing agent according to claim 1 or 2 to contaminated water contaminated with fluoride ions.
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