JPH0562949B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for quantifying ammonia in a solution. The method for quantifying ammonia in solution is used as a monitor of the sewage treatment process.
Alternatively, it can be used to monitor water quality of rivers, lakes, seawater, etc.

(Prior Art) Generally, the indophenol colorimetric method and the ammonia-selective electrode method are used to quantify ammonia in sample water.

(Problems to be Solved by the Invention) The indophenol colorimetric method is subject to interference from suspended matter and colored matter in water, so quantitative values are not very accurate. Furthermore, the ammonia-selective electrode method requires time to respond and is susceptible to the ammonia concentration in the previous sample water. Furthermore, if the membrane is used for a long time, deposits will form on the surface of the membrane, making it impossible to obtain stable response values.

The present invention enables continuous measurement of ammonia in sample water without interference from suspended objects or colored substances in water, and is almost unaffected by ammonia in previous sample water.
The purpose is to provide a method for stable measurement since there is almost no deposit on the surface of the membrane.

(Means for Solving the Problems) The present invention uses a membrane separator in which two channels are in contact with each other via a microporous organic or inorganic polymer membrane that does not react with ammonia. Reaction solution A containing at least one metal that is alkaline and becomes a hydroxide, reaction solution B containing at least one hydroxide of an alkali metal or alkaline earth metal, and a sample in one flow path of the membrane separator. Ammonia in the sample solution is determined by flowing a mixed solution with the sample solution, flowing a carrier liquid into the other channel, and quantitatively measuring ammonia that has permeated into the carrier liquid.

(Function) Ammonia in natural water is dissolved in water in the form of ammonium ions, so it cannot pass through microporous polymer membranes. However, by adding an alkali metal or alkaline earth metal hydroxide, the sample water becomes alkaline and ammonium ions are converted to ammonia. This ammonia can pass through the microporous polymer membrane as a gas. Ammonia can be measured by reacting the transmitted ammonia with a carrier liquid and detecting the amount of the reaction using a spectrophotometric detector, an electrochemical detector, or the like. Since the carrier liquid contains hypohalite ions and halogens as substances that react with ammonia, ammonia reacts with these substances and turns into chloramines. The first method of measuring the amount of transmitted ammonia using a spectrophotometric detector is to measure the characteristic ultraviolet absorption of the produced chloramine. Chloramine has a characteristic absorption at 243nm, so the measurement wavelength of the spectrophotometer is set to 243nm.
By setting the value to m, the detected light intensity can be measured as the amount of ammonia. A second method for measuring the amount of transmitted ammonia with a spectrophotometric detector is to measure the characteristic absorption of reactants such as hypohalite ions and halogens in the carrier liquid. Hypohalite ions and halogens have characteristic absorption at 290 nm,
By setting the spectrophotometric detector to 290 nm, the decrease in detection intensity by the detector can be measured as the amount of ammonia.

In the case of an electrochemical detector, the amount of chloramine converted from ammonia can be measured by setting the measurement potential to the redox potential of chloramine converted from ammonia. The reaction solution A containing ferric ions is added to the sample water in order to maintain a constant ammonia permeability through the microporous polymer membrane and obtain a stable response. A mixed solution of reaction solution A, reaction solution B, and sample solution is flowed into one of the two flow channels that are in contact with each other via a microporous polymer membrane, and a carrier liquid is flowed into the other flow channel to start measurement. Then, the ammonia detection output decreases at first, and then stabilizes. In this stable state, it is thought that the attachment and desorption of the precipitate to the microporous polymer membrane are in equilibrium in the flow path on the sample solution side. When this reaction solution A is not added to the flow path on the sample solution side, the ammonia detection output is difficult to stabilize.

(Example) FIG. 1 represents an example of the present invention. Reference numeral 1 denotes a transmission section, which consists of a double tube consisting of an outer Teflon (trade name of polytetrafluoroethylene, manufactured by Du Pont) tube 2 and an inner microporous Teflon tube 3. As the inner microporous Teflon tube 3, for example, Japan Gore-Tex's TB series (70% porosity, maximum pore diameter) can be used.
3.5 μm) etc. can be used. for example
TBOO1 has an inner diameter of 1 mm and an outer diameter of 1.8 mm. Since the length of the microporous Teflon tube 3 affects the sensitivity, it is used at an appropriate length. For example, its length is 50cm.

A sample solution is sent by pump 4, mixed with reaction solution A sent from pump 5 at three-way joint 6, and then mixed with reaction solution B sent from pump 7 at three-way joint 8 to pass through the permeation section. It is sent to the Teflon tube 2 outside of 1.

A carrier liquid is flowed inside the microporous Teflon tube 3 by a pump 9. Add hypochlorite ions or chlorine to the carrier liquid. The inner microporous Teflon tube 3 is connected to an ultraviolet spectrophotometer 10. The ultraviolet spectrophotometer 10 measures the absorbance of hypochlorite ions or chlorine on the ammonia that has passed through the carrier liquid, and outputs the signal to a recorder.

The mixing order of reaction solutions A and B may be reversed.

Alternatively, a solution in which reaction solutions A and B are mixed in advance may be mixed with the sample solution.

Furthermore, the carrier liquid coats the outside of the microporous Teflon tube 3, while the sample solution and reaction solution (A and B)
A mixed solution of may be allowed to flow inside it. In this case, the detector 10 needs to be connected to the drain 11 side. Detector 10 may be an electrochemical detector.

A coloring agent that develops color when oxidized by a reactive substance such as hypohalite ion or halogen is added to the carrier liquid, and the amount of ammonia that has permeated into the carrier liquid is measured quantitatively by measuring the light absorption of the coloring agent. You can also do it. For example, as shown in FIG. 2, a reaction solution C containing a color forming agent that is oxidized by hypochlorite ions and chlorine is added to the carrier liquid exiting the microporous Teflon tube 3 at the pump 12.
The liquid mixture is sent to the detector 10 to be mixed at the three-way joint 13, and the change in the absorption of the coloring agent is measured. In this case, the amount of light absorbed by the coloring agent is proportional to the remaining amount of hypochlorite ions and chlorine in the carrier liquid, and the remaining amount of hypochlorite ions and chlorine corresponds to the amount of ammonia that has permeated into the carrier liquid. decreases. Therefore, the amount of ammonia can be measured by determining the amount of decrease in the amount of light absorption by the color former while the sample solution is flowing, based on the amount of light absorption by the color former before the sample solution is flowed. As a coloring agent, N, N
-diethyl-p-phenylenediamine and o-toluidine can be used. In this case, a visible spectrophotometer can be used as the detector 10.

As the detector, in addition to those exemplified above, for example, a fluorescence detector, a chemiluminescence detector, etc. can be used. When using a fluorescence detector, a nicotinamide or o-phthalaldehyde solution may be added to the carrier liquid, and when using a chemiluminescence detector, a luminol solution may be added to the carrier liquid.

FIG. 3 shows a transmission section 14 in still another embodiment.
shows. A plurality of microporous hollow fibers 15 are bundled, a mixed solution of a sample solution and a reaction solution (A and B) flows inside the hollow fibers 15, and a carrier liquid flows outside the hollow fibers 15. In this case, the carrier liquid may be flowed inside the holographic fiber 15, and the mixed solution may be flowed outside. The material for the microporous hollow fiber 15 is preferably Teflon or cellulose acetate.

FIG. 4 shows a transparent part 16 in still another embodiment.
represents. A plate-shaped microporous polymer membrane 17 is sandwiched between the upper chamber and the lower chamber. Sample solution and reaction solution (A
The mixed solution of and B) is introduced into the upper chamber, and the carrier liquid is flowed into the lower chamber. In this case, the upper and lower chambers may be reversed.

FIG. 5 shows the calibration relationship between the ammonia concentration in the sample solution and the signal obtained when an ultraviolet spectrophotometer is used as a detector. The measurement wavelength was set to 290 nm. The carrier liquid contains a solution containing hypochlorite ions, and the reaction solution A contains 100 ppm.
A 2M sodium hydroxide solution was used as the ferric iron solution and reaction solution B, respectively. Ammonia concentration 0.5−
A good linear relationship was observed between 10Nppm and the signal.

FIG. 6 shows an example in which an amperometric detector, which is a type of electroanalytical detector, is used as a detector. The set potential is −0.05V (vs.
AgCl/Ag electrode) potential is applied. In this case as well, a good linear relationship was observed between the ammonia concentration of 0.2-7 Nppm and the signal.

Figure 7 shows the cases in which reaction solution A (here, 100 ppm ferric iron solution was used) was added, and when 1.0 Nppm ammonia was flowed as the sample solution without addition.
The time course of the signals obtained over one day is shown. Without the addition of reaction solution A, the signal was low and gradually decreased and was not stable. On the other hand, when reaction solution A was added, the signal was high and stable.

(Effects of the Invention) In the present invention, ammonia in the sample solution is continuously and stably quantified by reacting the sample solution with reaction solutions A and B and allowing the ammonia after the reaction to permeate through a microporous polymer membrane. I was able to do that.

Based on FIG. 6, if S/N=3 is set as the lower limit of quantification, ammonia in a solution of 0.02 ppm or more can be selectively quantified by the method of the present invention.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views showing embodiments of the present invention, FIG. 3 is a schematic cross-sectional view showing a transmitting part in yet another embodiment, and FIG. 4 is a schematic cross-sectional view showing a transmitting part in yet another embodiment. Figure 5 is a schematic perspective view showing the calibration relationship when using an ultraviolet spectrophotometer, Figure 6 is a diagram showing the calibration relationship when using an amperometry detector, and Figure 7 is a diagram showing the calibration relationship when using reaction solution A. FIG. 3 is a diagram showing changes over time in signals obtained with and without addition. 1, 14, 16... Transmissive part, 3, 15, 10...
... Microporous Teflon tube, 17... Microporous Teflon membrane, 2... Teflon tube, 10... Ultraviolet spectrophotometer.

Claims (1)

[Claims] 1. A reaction solution containing ferric ions in one flow path of a membrane separator in which two flow paths are in contact with each other through a microporous organic or inorganic polymer membrane that does not react with ammonia. A mixed solution of reaction solution B containing at least one hydroxide of an alkali metal or alkaline earth metal and a sample solution is flowed, and a carrier liquid to which a substance that reacts with ammonia is added is flowed into the other channel, A quantitative method in which the amount of ammonia in a sample solution is determined by measuring the amount of reaction products from ammonia that have permeated into a carrier liquid or the amount of the substance that reacts with ammonia. 2. The quantitative method according to claim 1, wherein the substance that reacts with ammonia is a hypohalite ion, a halogen, or o-phthalaldehyde. 3. A coloring agent that is oxidized and colored by the substance that reacts with ammonia is added to the carrier liquid downstream of the membrane separator, and the quantitative measurement of ammonia that has permeated into the carrier liquid is measured by the light absorption of the coloring agent. The quantitative method according to claim 1, which is carried out by.