JPH0336592B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for efficiently removing fluorine ions from water. More specifically, it concerns a method of removing fluoride ions from water using a waste removal adsorbent and then treating the water with a chelate resin that adsorbs metal ions to a low concentration. . Currently, the methods for removing fluorine ions liberated in water are: first, adding lime or slaked lime to water to precipitate fluorine as calcium fluoride; second, adsorbing it with an anion exchange resin. The third method is to remove fluorine ions by adsorbing metal ions (e.g. iron ions, aluminum ions, etc.) to iminodiacetic acid type chelate resin (Japanese Patent Application Laid-Open No. 50-44649, JP-A No. 51-115058).
A method is known in which fluorine ions are adsorbed and removed using an aminoalkylene phosphate type chelate resin that has adsorbed a fourth metal ion (Japanese Patent Application Laid-Open No. 107287-1987). However, the first method has the disadvantage that fluoride ions cannot be removed to a low concentration because the solubility of calcium fluoride is about 16 mg/. In the second method, the exchange order of the anion exchange resin is OH ^- > SO ₄ ^2- > CrO ₄ ^2- > H ₂ PO ₄ ^- >
Cl ^- ... > F ^- , and has the drawback of very low selectivity for fluorine ions and being susceptible to coexisting salts. In the third method, fluorine ions can be removed to a low concentration, but the total adsorption amount is small and the regeneration cycle time is short, making it extremely impractical. The fourth method is a method previously reported by the present inventors to improve the shortcomings of these conventional methods, and has a good removal limit for fluorine ions and a large total adsorption amount, especially for fluorine ions in water. It is sufficiently effective when the concentration of ions is low, but when the concentration is high, the regeneration frequency increases and the performance of the resin cannot be fully utilized. Therefore, the present inventors conducted intensive studies to solve these drawbacks, and as a result, as a method for removing fluorine ions from water, the first step was to remove fluoride ions using an adsorbent that contains fluoride ions. After cleaning most of the water, we found that by treating it with an aminoalkylene phosphate chelate resin that adsorbed metal ions, we were able to efficiently remove fluoride ions to a low concentration. Inorganic adsorbents for fluorine ions used in the present invention include diatomaceous earth, magnesia, bauxite, zeolite, silica gel, activated alumina, bone char, magnesia-alumina type, titania-silica type, etc. Composite materials include organic adsorbents in which the resin matrix is styrene-divinylbenzene copolymer, phenol-formalin resin, resorcinol-formalin resin, epoxy resin, acrylic resin, vinyl chloride resin, and the functional groups include amino acid groups, iminoacetic acid group, iminodiacetic acid group, iminopropionic acid group,
It has an iminodipropionic acid group, a thiourea group, a diethyldithiocarbamate group, a thiol group, an oxime group, an amidoxime group, an aminoalkylene phosphate group, and its functional groups include iron ions, aluminum ions, lanthanide ions, etc. Tomo1
Examples include resins that have adsorbed seeds, and at least one selected from these can be used. The aminoalkylene phosphate type chelate resin referred to in the present invention is one that has an aminoalkylene phosphate group as a functional group in the resin, and has iron ions, aluminum ions, lanthanide ions, etc. adsorbed thereto. Further, as the resin matrix of the aminoalkylene phosphate type chelate resin used here, styrene-divinylbenzene copolymer, phenol-formalin resin, resorcinol-formalin resin, epoxy resin, acrylic resin, vinyl chloride resin, etc. are used. Methods for removing fluorine ions using these fluoride ion-distributing adsorbents and aminoalkylene phosphate chelate resins can be applied to column methods, batch methods, or a combination of both methods. However, the method is not particularly limited to these methods. The present invention will be explained below with reference to Examples. Example 1 Table as an adsorbent for dissolving fluorine ions
Activated alumina having the physical property values shown in 1, and as a chelate resin, the resin matrix is a styrene-divinylbenzene copolymer and has a phosphomethylamino group (-NH- _CH2 - _{PO3Na2 )} as a functional group. This chelate resin was treated with an aqueous aluminum sulfate solution to prepare an aminomethylene phosphate type chelate resin that adsorbed Al ³⁺ . Two columns, in which 100 ml of activated alumina was packed in a column (inner diameter 40 mmφ) and another column was filled with 100 ml of aminomethylene phosphate chelate resin adsorbed with Al ³⁺ , were connected in series so that water could flow therethrough. Next, as raw water, F ^- : 25 ppm (dissolved as NaF), Ca ²⁺ : 10 ppm (dissolved as CaCl ₂ ), NaCl:
1%, Na ₂ SO ₄ : 1%, pH 6 aqueous solution passing rate
The liquid was passed in a downward flow at SV10 (/Hr). The results of the liquid passage are shown in Figure 1.

[Table] At the exit of the first column, 2 ppm of fluorine ions began to leak around the liquid flow rate of 100/-R, and 15 ppm of fluorine ions leaked at the liquid flow rate of 300/-R. However, at the exit of the second column, the liquid flow rate is
Fluorine ions were below 0.5 ppm up to around 600/-R. Example 2 As an adsorbent for fluoride ions, we used an adsorbent whose resin base was a styrene-divinylbenzene copolymer and had an iminodiacetic acid group as a functional group, and which had lanthanum ions adsorbed on this resin. The adsorbed chelate resin used was one in which the resin matrix was a phenol-formalin resin, the functional group was a phosphomethylamino group, and aluminum ions were adsorbed onto this resin. To 100% of raw water containing 100 ppm of fluorine ions and 5000 ppm of NaCl and having a pH of 6, 3 resins adsorbed with the above-mentioned lanthanum ions for roughness were added, and the mixture was stirred in a container for 5 hours to adsorb and remove fluorine. As a result, the residual concentration of fluorine ions is
It was 2.8 ppm. Next, the treated water obtained by solid-liquid separation was added to 100 ml of the above chelate resin that adsorbed aluminum ions.
The liquid flow rate was SV15 (/Hr),
The liquid was passed in a downward flow. When the fluorine ion concentration of the effluent was measured, it was less than 0.1 ppm. Next, the same treatment as above was repeated 9 times (10 times in total, 1000 times) using the same fresh raw water as above for the adsorbent and chelate resin used above, but in each case, the fluorine ion concentration was
It was 0.1ppm. Example 3 As an adsorbent for dispersing fluorine ions, white bead-like shape, particle size 60-150 mesh, apparent density
0.71 zeolite, and as a chelate resin for post-treatment, an aminoethylene phosphate type chelate resin whose resin base is a styrene-divinylbenzene copolymer, has a phosphoethylamino group as a functional group, and has aluminum ions adsorbed thereto. It was used. Zeolite 12 was added to 100% of raw water containing 260 ppm of fluorine ions and 3,800 ppm of NaCl and having a pH of 6, and the mixture was stirred in a container for 4 hours to adsorb and remove fluorine. As a result, the residual concentration of fluorine ions was 28.2 ppm. Next, the treated water obtained by solid-liquid separation is mixed with chelate resin 100, which has adsorbed aluminum ions, as described above.
ml at a water flow rate of SV15 (/
Hr), the liquid is passed in a downward flow. When the fluorine ion concentration of the effluent was measured, it was 0.5 ppm. Example 4 As an adsorbent for fluoride ions, we used an adsorbent whose resin base was a styrene-divinylbenzene copolymer and had an iminodiacetic acid group as a functional group, and which had lanthanum ions adsorbed on this resin. The adsorbed aminoalkylene phosphate type chelate resin used was one in which the resin base was a phenol-formalin resin, the functional group was a phosphomethylamino group, and aluminum ions were adsorbed onto this resin. Adsorbent 100 that alters the above fluorine ions
ml was packed into a column (first column, inner diameter 40 mmφ), and 100 ml of aminomethylene phosphate type chelate resin adsorbing Al ³⁺ was packed into another column (second column, same inner diameter as the first column). Two columns were connected to allow water to flow in series. Then ^F- as raw water:
85ppm (dissolved as NaF), Ca2 ⁺ : 16ppm ( _CaCl2
), NaCl: 2.5%, Na ₂ SO ₄ : 1%, PH
The aqueous solution of No. 6 was passed in a downward flow at a passing rate of SV10 (/Hr). At the exit of the first column, 4 ppm of fluorine ions begin to leak from around the liquid flow rate of 100/-R, and at liquid flow rates of 300, 400, 500, and 600/-R, fluorine ions leak out to 8 ppm, 10 ppm, 12 ppm, respectively. 15ppm leaked. However, at the exit of the second column, the liquid flow rate is
Fluorine ions were at 0.5 ppm up to around 600/-R. Example 5 Activated alumina having the same properties as those used in Example 1 was used as an adsorbent for fluoride ions, and as a chelate resin, the resin matrix was a styrene-divinylbenzene copolymer and the functional group was a phosphomethylamino group. This resin had aluminum ions adsorbed to it. Activated alumina 20 was added to raw water containing 570 ppm of fluorine ions and 6500 ppm of NaCl and adjusted to pH 6 at 100, followed by stirring in a container for 5 hours to adsorb and remove fluorine. As a result, the residual concentration of fluorine ions was 35.2 ppm. Next, the treated water obtained by solid-liquid separation was added to 100 ml of the above chelate resin that adsorbed aluminum ions.
The liquid flow rate was SV15 (/Hr),
The liquid was passed in a downward flow. When the fluorine ion concentration of the effluent was measured, it was 0.5 ppm. Comparative Examples 1 and 2 100 ml of a chelate resin made of the styrene-divinylbenzene copolymer used in Example 1 as a base, having an aminomethylene phosphate group as a functional group, and having aluminum ions adsorbed thereto was placed in a column (inner diameter 40 mmφ). ), the same raw water used in Examples 1 and 2 was added at a flow rate of SV15/Hr,
Comparative Examples 1 and 2 were obtained by passing the liquid in a downward flow. In Comparative Example 1, 1 ppm of fluorine ions began to leak at a liquid flow rate of 100/-R, and at 400/-R.
15ppm leaked. Comparative example 2 has a liquid flow rate of 100/
-Fluorine ions start leaking at 6 ppm at -R, and 300
/-R leaked 15ppm.

[Brief explanation of the drawing]

Figure 1 shows the liquid passing results of Example 1 at the liquid passing magnification (/
-R) and the outflow fluorine ion concentration (ppm).

Claims (1)

[Claims] 1. In the method of removing fluoride ions from water, first, diatomaceous earth, magnesia, bauxite, zeolite, silica gel, activated alumina, bone char, magnesia-alumina-based or titania-silica-based composites are used as adsorbents to remove fluoride ions. The material and the resin matrix are made of at least one selected from styrene-divinylbenzene copolymer, phenol-formalin resin, resorcinol-formalin resin, epoxy resin, acrylic resin, and vinyl chloride resin, and the functional group is an amino acid group. , an iminoacetic acid group, an iminodiacetic acid group, an iminopropionic acid group, an iminodipropionic acid group, a thiourea group, a diethyldithiocarbamate group, a thiol group, an oxime group, and an amidoxime group, After fluoride ions are added to the functional group using at least one resin selected from the group consisting of resins that have adsorbed at least one of iron ions, aluminum ions, and lanthanide ions, metal ions are then adsorbed. A method for removing fluorine ions in water, the method comprising treating with an aminoalkylene phosphate type chelate resin.