How to detect the TOC in acidic wastewater？
author: Otis,cily
2023-01-03
How to detect the TOC in acidic wastewater？
Otis 2022/12/29
Some customers reported that the treated acidic wastewater could not meet the discharge data standard, so they specially launched the first phase of case operation to test the TOC content of three types of acidic wastewater from an environmental protection company in Guangdong, China. The customer chose our Optosky TOC2000 total organic carbon analyzer to determine the total organic carbon in the sample by combustion oxidation method.
Strong acid mainly refers to hypermanganese acid, hydrochloric acid (hydrochloric acid), sulfuric acid, nitric acid, perchloric acid, selenic acid, hydrobromic acid, hydroioic acid, chloric acid, including perchloric acid, hydroioic acid, hydrobroic acid, hydrochloric acid (hydrochloric acid), called six big inorganic strong acid, they are volatile and corrosive, plays an important role in the process of industrial production.
At present, an environmental protection company in Huizhou, Guangdong, China provides data support to help the treated acidic wastewater meet the discharge standard, and needs to test the TOC content of the existing three types of acidic wastewater. We choose TOC-2000 total organic carbon analyzer to determine the total organic carbon in the sample by combustion oxidation method. According to the standard "HJ 501-2009 water quality TOC determination of combustion oxidation-non-dispersed infrared absorption method" requirements configuration of organic carbon standard solution.
Experimental part
Instruments and reagents
Decarbon dioxide distilled water
The configuration of the standard solution
Cigh 2.1254g of potassium hydrogen phthalate to 1000 mL into a standard solution with a TOC value of 1000 mg/L.
02
The drawing of the standard curve
The standard series solution with organic carbon concentration of 0.0, 2.0, 5.0, 10.0, 20.0, 40.0, 100.0mg/L is prepared according to the standard, and the standard line is drawn with the injection with different concentrations of the same volume, with the mass of carbon as the abscissa and the integrated area signal as the ordinate:
Square of TC curve: Y= -2288068X2 + 260783X + 9, correlation coefficient R= 0.9999
03
Sample test
The customer provides information that the sulfuric acid content in "Sample 1" and "Sample 2" is about 37% and 86%, "Sample 3" contains about 10% hydrochloric acid, and the COD content of the three samples is very high, so there is a theoretical correlation between COD content and TOC content.
In order to minimize the loss of acid material to the instrument, the sample is first released and based to the COD content of three samples, the TOC content of "sample 1" is between 4000-6000mg / L; the TOC content of "sample 2" is between 50000-80000 mg/L; and the TOC content of "sample 3" is between 500-800 mg/L.
To ensure good test accuracy, the TOC concentration of the sample was released near the middle of the standard curve, using ultrapure water to release "sample 1" 200 times, "sample 2" 2000 times, "sample 3" 20 times, and then the released sample was transferred to the sample bottle.
04
test parameter
Lysis furnace temperature: 800℃
Gas-carrying flow rate: 180 mL/min
Injection volume: 100 μ L
Injection method: automatic sampler
05
Test result
When the acid content in the sample is very high, the sample must be released first to ensure that the acid content in the sample entering the instrument system is 1000 mg/L. If the sample cannot be released to this concentration, it should also be within 5000mg / L, otherwise when the sample is injected into the high temperature reaction tube, it is easy to produce white acid smoke, easy to cause certain damage to the water removal system, flow control system and detection system, and SO42-, Cl-, S2-will also interfere with the test of TOC.
(Note: There are relevant literature data proving that the COD content of aqueous solution samples is generally 2-4 times that of their TOC, and there is a theoretical correlation between the two. Therefore, when the COD content of the sample is known, the TOC content range of the sample can be roughly calculated first, so as to determine the multiple of the sample to be released, so as to get a good test accuracy and accuracy.
Otis 2022/12/29
Some customers reported that the treated acidic wastewater could not meet the discharge data standard, so they specially launched the first phase of case operation to test the TOC content of three types of acidic wastewater from an environmental protection company in Guangdong, China. The customer chose our Optosky TOC2000 total organic carbon analyzer to determine the total organic carbon in the sample by combustion oxidation method.
Strong acid mainly refers to hypermanganese acid, hydrochloric acid (hydrochloric acid), sulfuric acid, nitric acid, perchloric acid, selenic acid, hydrobromic acid, hydroioic acid, chloric acid, including perchloric acid, hydroioic acid, hydrobroic acid, hydrochloric acid (hydrochloric acid), called six big inorganic strong acid, they are volatile and corrosive, plays an important role in the process of industrial production.
At present, an environmental protection company in Huizhou, Guangdong, China provides data support to help the treated acidic wastewater meet the discharge standard, and needs to test the TOC content of the existing three types of acidic wastewater. We choose TOC-2000 total organic carbon analyzer to determine the total organic carbon in the sample by combustion oxidation method. According to the standard "HJ 501-2009 water quality TOC determination of combustion oxidation-non-dispersed infrared absorption method" requirements configuration of organic carbon standard solution.
Experimental part
Instruments and reagents
[Reagent]
Potassium hydrogen phthalate (reference reagent)Decarbon dioxide distilled water
[Selectionof instruments]
TOC-2000 total organic carbon analyzer
Empirical method
01The configuration of the standard solution
Cigh 2.1254g of potassium hydrogen phthalate to 1000 mL into a standard solution with a TOC value of 1000 mg/L.
02
The drawing of the standard curve
The standard series solution with organic carbon concentration of 0.0, 2.0, 5.0, 10.0, 20.0, 40.0, 100.0mg/L is prepared according to the standard, and the standard line is drawn with the injection with different concentrations of the same volume, with the mass of carbon as the abscissa and the integrated area signal as the ordinate:
Square of TC curve: Y= -2288068X2 + 260783X + 9, correlation coefficient R= 0.9999
03
Sample test
The customer provides information that the sulfuric acid content in "Sample 1" and "Sample 2" is about 37% and 86%, "Sample 3" contains about 10% hydrochloric acid, and the COD content of the three samples is very high, so there is a theoretical correlation between COD content and TOC content.
In order to minimize the loss of acid material to the instrument, the sample is first released and based to the COD content of three samples, the TOC content of "sample 1" is between 4000-6000mg / L; the TOC content of "sample 2" is between 50000-80000 mg/L; and the TOC content of "sample 3" is between 500-800 mg/L.
To ensure good test accuracy, the TOC concentration of the sample was released near the middle of the standard curve, using ultrapure water to release "sample 1" 200 times, "sample 2" 2000 times, "sample 3" 20 times, and then the released sample was transferred to the sample bottle.
04
test parameter
Lysis furnace temperature: 800℃
Gas-carrying flow rate: 180 mL/min
Injection volume: 100 μ L
Injection method: automatic sampler
05
| Sample name | TOC（mg/L ） | RSD （%） |
| Sample 1 (waste acid 1) | 30.10 | 0.89 |
| Sample 2 (waste acid 2) | 30.94 | 0.55 |
| Sample 3 (containing iron waste hydrochloride 3) | 30.17 | 1.99 |
Results and discussion
When the acid content in the sample is very high, the sample must be released first to ensure that the acid content in the sample entering the instrument system is 1000 mg/L. If the sample cannot be released to this concentration, it should also be within 5000mg / L, otherwise when the sample is injected into the high temperature reaction tube, it is easy to produce white acid smoke, easy to cause certain damage to the water removal system, flow control system and detection system, and SO42-, Cl-, S2-will also interfere with the test of TOC.
(Note: There are relevant literature data proving that the COD content of aqueous solution samples is generally 2-4 times that of their TOC, and there is a theoretical correlation between the two. Therefore, when the COD content of the sample is known, the TOC content range of the sample can be roughly calculated first, so as to determine the multiple of the sample to be released, so as to get a good test accuracy and accuracy.
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