CN101226154A - An indicator substance that can be used to detect the concentration of formaldehyde gas online - Google Patents

Abstract

The invention relates to an indicator substance applicable to on-site detection of formaldehyde gas concentration. The indicator substance is composed of a main agent, an auxiliary agent, an interface modifier and a carrier, wherein the main agent is a mixture of an acidic hydroxylamine salt and a hydrogen ion concentration indicator. Putting the substance into various designed detectors capable of quantitatively displaying different formaldehyde concentrations can realize on-line detection. The detection method of the detector made of the substance is simple, sensitive and low in cost.

Description

An indicator substance that can be used to detect the concentration of formaldehyde gas online

Technical field:

The invention relates to an indicator substance capable of detecting the concentration of harmful gas, in particular a substance capable of indicating the concentration of formaldehyde in the air.

Background technique:

With the rise of home decoration, the extensive use of decorative materials will inevitably cause indoor air pollution, and the pollution caused by formaldehyde has attracted much attention. When the formaldehyde content in the indoor air is 0.1mg/ ^m3 , there will be peculiar smell and discomfort; at 0.5mg/ ^m3, it can irritate the eyes and cause tears; at 0.6mg/ ^m3 , it will cause throat discomfort or pain; when the concentration is higher It can cause nausea, vomiting, cough, chest tightness, asthma and even emphysema; at 30 mg/m ³ , it can lead to death immediately. For this reason, many countries have all made instructive limit value regulation to the formaldehyde concentration in the air, and the " indoor air quality standard " that our country issued on March 1, 2003 stipulates that the concentration of formaldehyde in the indoor air should not exceed 0.1mg/ m ³ .

Conventional methods for measuring formaldehyde content in the air generally use large-scale instruments at present. Its advantages include high assay sensitivity and accurate quantification. However, the determination steps are complicated, professional personnel are required to operate, and the determination cost is high, so it is not easy to popularize.

In order to meet the needs of online testing, some portable formaldehyde detection instruments have also appeared on the market, such as the PPM400 formaldehyde detector in the UK and the INTERSCAN 4160 formaldehyde detector in the United States. The portable 101-type on-site formaldehyde measuring instrument made by the principle. These instruments are expensive, and the service life of sensitive devices is short, so they are not suitable for simple monitoring.

The Chinese patent discloses several simple designs. Such as patent 02285930.6 (application date 2002.11.12) announced a "disposable formaldehyde in the air colorimetric rapid test package", respectively with acetylacetone or phenol reagent or 4-amino-3-hydrazine-5-mercapto-1 , 2,4-triazolene (AHMT) reagent is used as chromogenic agent, and most of the formaldehyde rapid detection products on the market belong to this type at present, and it exists the problem that color change is not obvious, and is greatly influenced by temperature; patent 200410017701.2 ( Application date 2004.04.15) announced a "rapid determination of formaldehyde in the air test paper", this type of test paper needs to determine the results by visual colorimetry, individual differences are large, resulting in lower accuracy of results; patent 200420084922.7 (application date 2004.07.28 ) announced a "formaldehyde gas detection tube", which uses the reaction of formaldehyde and benzene series to form a brown substance to detect formaldehyde gas, and uses sulfuric acid as a catalyst, which has low sensitivity, and benzene series is easy to sulfonate with sulfuric acid Disadvantages such as affecting identification.

Invention content:

The technical problem to be solved by the present invention is to provide an indicator substance that can be used for on-line detection of formaldehyde gas concentration with accurate quantification, obvious color change and high sensitivity for the common problems in the prior art.

In order to realize the object of the above invention, the formaldehyde gas concentration indicating substance of the present invention is composed of a main agent, an auxiliary agent, an interface modifier and a 90-100 purpose carrier, wherein the main agent is a mixture of an acidic hydroxylamine salt and a hydrogen ion concentration indicator, and the auxiliary agent The agent is a buffer solution composed of a strong base and its salt, and the interface modifier is a metal chloride salt; the ratio of each component in the indicator substance is as follows:

Main agent: auxiliary agent (volume ratio) = 100 ~ 150: 1 ~ 3

Main agent: interface modifier (weight ratio) = 100~150: 1~5

(main agent + auxiliary agent + interface modifier): carrier (volume: weight) = 100～150: 100～120

The main agent is prepared by uniformly mixing 1% acidic hydroxylamine salt solution and 0.1% hydrogen ion concentration indicator ethanol solution according to volume ratio (5-10):100.

The acidic hydroxylamine salt is one of hydroxylamine sulfate or a salt thereof or hydroxylamine hydrochloride or a salt thereof.

The hydrogen ion concentration indicator is one of metaramine yellow, alizarin yellow and methyl yellow.

The buffer solution is a mixture of 0.1mol/L _Na2CO3 and _0.1mol /L _NaHCO3 solution in a ratio of 1 _: 1 or 0.1mol/L _Na2CO3 and 0.1mol/L NaOH in a ratio of 1:1 ratio mix.

The interface modifier is one of BaCl ₂ ·2H ₂ O, MgCl ₂ ·6H ₂ O, AlCl ₃ ·6H ₂ O and ZnCl ₂ .

The carrier is one of silica gel, quartz sand and ceramics.

Preparation method of indicator substance:

Measure the main agent, auxiliary agent, interface modifier and carrier according to the ratio of the above indicator substances; put the interface modifier into the main agent and auxiliary agent to dissolve and mix, then pour an appropriate amount of carrier, so that it is just moistened by the solution Wet, spread it flat on the bottom of the container, dry it in a vacuum with closed light, and store it in a sealed container.

The principle that the indicator substance can realize online detection of formaldehyde gas concentration is as follows:

Formaldehyde can decompose acidic hydroxylamine salt, and its reaction equation is as follows:

2HCHO+(NH ₂ OH) ₂ ·H ₂ SO ₄ →2H ₂ C＝NOH+H ₂ SO ₄ +2H ₂ O

As we all know, the acid produced above can change the color of the hydrogen ion concentration indicator, the color change is determined by the concentration of the acid, and the concentration of the acid depends on the concentration of formaldehyde, so the indicator substance can realize the function of detecting the concentration of formaldehyde gas .

Among them, the hydrogen ion concentration indicator is easily affected by _CO2 in the air. Adding a buffer solution is to avoid the interference of _CO2 in the air and prevent discoloration before loading the tube.

The function of the interface modifier is to make the discoloration interface obvious, clear and easy to read.

The indicator is adsorbed on the carrier, which acts as a color-changing column.

The method of using the indicator substance to detect formaldehyde gas:

The invention can be put into a transparent tube with one end sealed by a diffusion control film, solidified with a hard object, and then the other end of the transparent tube is sealed, and then combined with a concentration control scale to make a simple badge type detector. When using it, put it in the cabinet, in the drawer, indoors, on the table, etc., it can quickly absorb formaldehyde and produce a color change from yellow to dark pink (using metaamine yellow as an indicator), and the concentration can be compared according to the length of discoloration Read the formaldehyde concentration on the scale.

The optimum detection range of this invention is 0.1 mg/m ³ -100.0 mg/m ³ , and the measurement error is within 10%.

The length of the transparent tube is 30-50 mm, the inner diameter is 2.0-3.0 mm, and the outer diameter is 4.0-6.0 mm. The control diffusion film at both ends of the transparent tube can be a polyester film, the thickness of which is 1mm is the best.

The method of making the above-mentioned concentration control scale: fix the detection time for 8 hours, draw a curve with the formaldehyde concentration versus the length of the discoloration section, and then obtain the calibration curve of the formaldehyde detection component at the detection time. According to the calibration curve, take the concentration corresponding to the integer color change length to make the concentration control scale.

The formaldehyde gas concentration indicating substance of the present invention can be applied to other types of detectors, and is not limited to the aforementioned badge type detectors.

Technical effect of the present invention is:

1. According to the ratio of the main agent in the indicator substance, it can be used to detect different concentrations of formaldehyde gas;

2. The invention does not require power, has high sensitivity, and can be stored for a long time;

3. The color change boundary is clear and the vision is obvious;

4. The invention has low cost, simple preparation process and convenient use.

Detailed ways:

The present invention will be further described below in conjunction with embodiment.

Main agent: 1% hydroxylammonium sulfate (Beijing Chemical Plant) and 0.1% m-ammonium yellow acid indicator (Shanghai Xinsheng Shi Chemical Technology Co., Ltd.), the ratio of the two solutions is (5～10): 100 (volume ratio ).

1% hydroxylamine sulfate solution (solution 1): 1 g of hydroxylamine sulfate was dissolved in 100 ml of distilled water.

Metamine Yellow Indicator (Solution 2): Dissolve 0.1 g of Metamine Yellow Indicator (its color-changing pH range is 1.2 to 2.3) in 100 ml of ethanol.

Auxiliary agent: 0.1mol/L Na ₂ CO ₃ and 0.1mol/L NaHCO ₃ solution in a 1:1 ratio buffer solution, pH value is 8.94;

Carrier: 90-100 mesh silica gel (Shanghai Wusi Chemical Reagent Factory) was fired in a muffle furnace at 400-600°C for 2-4h, and then closed at high temperature.

Interface modifier: MgCl ₂ ·6H ₂ O and ZnCl ₂ (Tianjin Tianda Purification Materials Fine Chemicals).

Example 1

The above-mentioned solution 1 and solution 2 were mixed at a ratio of 1:10 (volume ratio) to obtain 110 mL of the main agent. Add 3.4mL Na ₂ CO ₃ -NaHCO ₃ buffer solution (pH 8.94) according to 3% of the total volume of the mixed solution, and then weigh 3.5g of the interface modifier MgCl ₂ 6H ₂ according to 3% of the total mass of the mixed solution O, the indicator solution must be mixed and put into a brown reagent bottle for later use. Take 0.15mL of the mixed indicator solution, pour 0.11g of silica gel carrier into it, let it soak evenly to saturation, make the indicator substance, air dry naturally, and keep it sealed.

Make the prepared indicator substance into a badge-type detector, put it in the environment to be detected for 8 hours, and determine the concentration of formaldehyde in the room according to the length of the color-changing column in the 8-hour detector against the concentration scale.

The optimal detection range of the detector is 0.1-100 mg/m ³ , and the measurement error is within 10%.

Example 2

Mix solution 1 and solution 2 at a ratio of 1:10 (volume ratio) to obtain 110 mL of the main agent. Add 4.6mL Na ₂ CO ₃ -NaHCO ₃ buffer solution (pH value is 8.94) according to 4% of the total volume of the mixed solution, and then weigh 2.3g of the interface modifier ZnCl ₂ according to 2% of the total mass of the mixed solution to obtain a mixed Put the indicator solution into the reagent bottle for later use. Take 0.15mL of the mixed indicator solution, pour 0.11g of silica gel carrier into it, let it soak evenly to saturation, make the indicator substance, air dry naturally, and keep it sealed.

The prepared indicator substance is made into a badge-type detector, and the best detection range of the detector is 0.1-100 mg/m ³ , and the measurement error is within 10%.

Example 3

Mix solution 1 and solution 2 at a ratio of 7:100 (volume ratio) to obtain 107 mL of the main agent. Add 3.3mL Na ₂ CO ₃ -NaHCO ₃ buffer solution (pH 8.94) according to 3% of the total volume of the mixed solution, and then weigh 3.4g of the interface modifier MgCl ₂ 6H ₂ according to 3% of the total mass of the mixed solution O, the indicator solution must be mixed and put into a brown reagent bottle for later use. Take 0.15mL of the mixed indicator solution, pour 0.11g of silica gel carrier into it, let it soak evenly to saturation, make the indicator substance, air dry naturally, and keep it sealed.

The prepared indicator substance is made into a badge type detector, the best detection range is 0.1-80mg/m ³ , and the measurement error is within 10%.

Example 4

Mix solution 1 and solution 2 at a ratio of 7:100 (volume ratio) to obtain 107 mL of the main agent. Add 4.4mL Na ₂ CO ₃ -NaHCO ₃ buffer solution (pH value is 8.94) according to 4% of the total volume of the mixed solution, and then weigh 2.3g of the interface modifier ZnCl ₂ according to 2% of the total mass of the mixed solution to obtain a mixed Put the indicator solution into a brown reagent bottle for later use. Take 0.15mL of the mixed indicator solution, pour 0.11g of silica gel carrier into it, let it soak evenly to saturation, make the indicator substance, air dry naturally, and keep it sealed.

The prepared indicator substance is made into a badge type detector, the best detection range is 0.1-80mg/m ³ , and the measurement error is within 10%.

Claims (7)

1. the indicator substance that can be used for online detection formaldehyde gas concentration, form by host, auxiliary agent, interface modifier and 90-100 purpose carrier, wherein host is the potpourri of acid hydroxylamine salt and pH indicator, auxiliary agent is the buffer solution that highly basic and salt thereof are formed, and interface modifier is the chlorination metallic salt; Each component by following proportioning is in the indicator substance:

Host: auxiliary agent (volume ratio)=100～150: 1～3

Host: interface modifier (weight ratio)=100～150: 1～5

(host+auxiliary agent+interface modifier): carrier (volume: weight)=100～150: 100～120.

2. according to the described indicator substance that can be used for online detection formaldehyde gas concentration of claim 1, it is characterized in that: described host is to be that 1% acid hydroxylamine salt aqueous solution and concentration are 0.1% pH indicator ethanolic solution by concentration, and be by volume (5～10): 100 ratio mixes and forms.

3. according to the described indicator substance that can be used for online detection formaldehyde gas concentration of claim 2, it is characterized in that: described acid hydroxylamine salt is a kind of in Hydroxylamine sulfate salt or the oxammonium hydrochloride salt.

4. according to claim 1 or 2 described formaldehyde gas concentration indicator substance, it is characterized in that: described pH indicator is a kind of in tropeolin G, alizarin yellow, the methyl yellow.

5. according to claim 1 or 2 described formaldehyde gas concentration indicator substance, it is characterized in that: described buffer solution is the Na of 0.1mol/L ₂CO ₃NaHCO with 0.1mol/L ₃Solution is in 1: 1 ratio mixing or the Na of 0.1mol/L ₂CO ₃Mix in 1: 1 ratio with 0.1mol/L NaOH.

6. according to claim 1 or 2 described formaldehyde gas concentration indicator substance, it is characterized in that: described interface modifier is BaCl ₂2H ₂O, MgCl ₂6H ₂O, AlCl ₃6H ₂O and ZnCl ₂In a kind of.

7. according to claim 1 or 2 described formaldehyde gas concentration indicator substance, it is characterized in that: described carrier is a kind of in silica gel, silica sand, the pottery.