SY/T 0530-1993 Determination of oil content in oilfield wastewater - Spectrophotometric method
Some standard content:
Petroleum and Natural Gas Industry Standard of the People's Republic of China SY/T 0530--93
Method for determination of oil content in oilfield wastewater
Spectrophotometry
Published on January 6, 1994
China National Petroleum Corporation
Implementation on June 1, 1994
1 Topic Content and Scope of Application
Petroleum and Natural Gas Industry Standard of the People's Republic of China Method for determination of oil content in oilfield wastewater
Spectrophotometry
SY/T 0530--93
1.1 This standard specifies the terminology, method principle, reagent materials, instrument equipment, preparation work, analysis steps, precision, etc. for the determination of oil content in oilfield wastewater by spectrophotometry. This standard is applicable to the determination of oil content in oilfield produced water with a leakage greater than 1.511/, river water, and oilfield wastewater collected during water treatment.
2 Terms and symbols
Definition: refers to all substances in the water sample that can be dissolved in a specific solvent: including all substances extracted from the acidified water sample by the solvent and not volatilized during the test. Reference oil: The reference oil mentioned in this standard refers to the crude oil with similar oil quality to the water sample to be tested. The oil in the water sample to be tested is extracted by solvent, and the components are obtained after simmering, drying and constant weight at a specified temperature. Absorption coefficient: The slope of the concentration-absorbance standard curve. 3 Principle of the method
The liquid in the sewage is extracted with a solvent, and the depth of the color of the extract has a linear relationship with the oil content within a certain concentration range. The extract is subjected to colorimetry on a spectrophotometer to measure the absorbance (or concentration), and the oil content in the sewage is obtained by calculation. 4 Reagents and materials
a, unleaded solvent gasoline (hereinafter referred to as gasoline): put the commercially available colorless and transparent unleaded 120 gasoline into the lower bottle, add the desiccant (CaCl) for use. If there is color, it can be re-steamed and then put into the lower bottle to add the solvent, b. Anhydrous sodium sulfate: analytical grade, fry at 250~~300℃ for 1h, cool in the dry dew and bottle for use; c1:1 hydrochloric acid: add a certain volume of analytical grade hydrochloric acid to an equal volume of distilled water. 5 Instruments and equipment
a, spectrophotometer: wavelength in the range of 380~7201m, equipped with a glass dish with a pathlength of 5c b. Electric constant temperature water bath: temperature range 37~100, temperature ±1℃, c electric heating cover: volume 10D0mL, maximum temperature 450C! d. A set of distillation cooling equipment: 1000mL distillation flask e. 500mL conical separating funnel;
f. 250mL narrow-necked flask;
g. Short-necked funnel: straight and light 80~120mm
h. Evaporating blood: capacity 80~100mL
Approved by China National Petroleum Corporation on January 6, 1994 and implemented on June 1, 1994
i. Weighing bottle, low type 10~125mL,
sY/T 0530--93
j. Dryer: normal pressure, upper diameter 210mm or 240mm, k, volumetric flask, 50, 100, 150mL
I, stoppered conical flask, 500niL:
m. Pipette: straight tube, 1, 2, 5, 10mLn. Measuring cylinder, 250, 500mL
0. Stoppered graduated colorimetric tube, 50mL.
.6 Preparation before analysis
6.1 Preparation of reference oil
The base oil is prepared by the gasoline extract in the water sample to be tested. Take an appropriate amount of oil-containing water sample (raw water) in a separatory funnel, add a certain amount of gasoline (depending on the oil content in the water sample, generally to dissolve all the oil blocks in the water sample), and add an appropriate amount of 1:1 hydrochloric acid (adjust pH to about 2). Fully shake and continuously remove gas, let it stand for stratification, collect the upper gasoline extract in a conical flask, add an appropriate amount of anhydrous sodium sulfate (until it no longer lumps), add a stopper and place it for more than 2 hours to dehydrate. Then filter the above extract with a quick qualitative filter paper, collect the filtrate in a distillation flask, steam and recover most of the gasoline, transfer the remaining small amount of extract into Yanfa III, evaporate it to dryness in a constant temperature water bath at 80±1°C, transfer it to a weighing bottle while it is hot, and put it in an oven at 80±1°C to dry to constant weight. Get the reference oil. Put it into a small brown wide-mouth bottle, seal the lid and put it in a desiccator, which can be stored for about one year.
6.2 Reference oil preparation solution
Accurately weigh 5000g of reference oil, add a small amount of gasoline to dissolve, transfer to a 50DmL volumetric flask, dilute to the scale, spread evenly, the oil concentration of this solution is 1000mg/L
6.3 Selection of wavelength
The wavelength should be between 410~430mm.
6.4 Instrument calibration
The spectrophotometer should be calibrated with the above-mentioned reference oil preparation solution before use. When the digital display given by the instrument is concentration, it can be calibrated according to the method specified in 6.4.1 of this standard. When the digital display given by the instrument is absorbance, it can be calibrated according to the method specified in 6.4.2 of this standard.
6.4.1 Calibration method when the digital display is concentration 6.4.1.1 According to the requirements of the water sample to be tested, prepare blank solution, higher concentration standard solution and lower concentration standard solution in advance. 6.4.1.2 Place the cuvettes containing the three solutions described in 6.4.1.1 into the cuvette tank, push the blank solution into the optical path, adjust the reading device to zero, push the standard solution with a higher concentration into the optical path, use the concentration scale knob to adjust the reading device to the concentration value of the standard solution, and then push the standard solution with a lower concentration into the optical path. The value displayed on the reading device should be the concentration value of the standard solution. Otherwise, repeat the above adjustment until the readings on the digital display are consistent with the concentrations of the blank solution, the higher concentration standard solution, and the lower concentration standard solution, and then the water sample can be measured. 6.4.2 Calibration film method when the reading is absorbance 6.4.2.1 Drawing of standard curve
Take 10 50mL stoppered colorimetric tubes, add 0.00, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00mL of reference oil solution respectively with pipette, dilute to scale with gasoline, the concentration of this standard series is 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100mg/L respectively, measure its absorbance on the spectrophotometer, and then draw the concentration (mg/L)-absorbance standard curve with concentration (mg/L) as the horizontal axis and absorbance as the vertical axis. E.4.2.2 Determination of absorbance coefficient K value
This standard recommends two methods, and you can choose one according to the actual situation. Curve value method: First, draw the C-E standard curve according to the method in 6.4.2.1. When the curve passes through the origin and there are more than 7 points on the curve 2
$Y/T 0530-93
, the curve is considered to be usable. Take the E and C values in the middle of the curve and use formula (1) to calculate the K value. K
b. Least square method: Draw the C-E standard curve according to the method in 6.4.2.1. When there are more than 7 points on the curve and the value is above 0.99, use formula (2) to calculate the K value.
ZCEI+(C)(ZE)
In the formula, K~—absorption coefficient, L/mgs
Ecr+(Ec)?
Cr——concentration of the reference oil sample, mg/Ls
Ei——absorbance
M—number of points taken during the measurement.
7 Analysis steps
7.1 Take samples with a 250mL narrow-necked bottle. The sampling bottle should be cleaned and dried in advance. Open the sampling valve before sampling. Wait for the water to flow at a rate of 5-6L/min for 3 minutes before sampling. Do not rinse the sampling bottle with water when sampling, and analyze all the water samples. 7.2 Water sample analysis,
7.2.1 Carefully transfer the water sample that has been measured by the volumetric tube into a 500mL separatory funnel, add 1:1 hydrochloric acid to adjust the pH to about 2 (if it has been acidified during sampling, no acid is needed). After washing the sampling bottle and the volumetric tube with a certain amount of gasoline, transfer the solution into the separatory funnel, fully shake it, and continuously release the gas. After the oil in the water sample is completely dissolved, put the separatory funnel back into the funnel stand to allow it to stand and separate. Pour the water layer into the sampling bottle, and transfer the extract into a stoppered graduated colorimetric tube. 7.2.2 Transfer the water sample to the separatory funnel again and repeat the operation in 7.2.1 until the extracted water sample is colorless (extraction should be performed 2 to 3 times). Record the total volume of the extract (V.). If the color of the extract is dark, use a pipette to accurately transfer an appropriate amount of the extract. Then dilute it several times with gasoline.
7.2.3 Place the extract of the water sample to be tested into a glass colorimetric tube and measure its absorbance E (or concentration C.) on a spectrophotometer using light with a wavelength of 410 to 430 mm and gasoline as a blank solution. 7.2.4 Calculation formula for oil content:
Formula: C. - Oil content of the water sample to be tested, mg/LE - Absorbance of the water sample to be tested
V. - —- Total volume of the extract, mL
Vw — Volume of the water sample to be tested, mL#
K — Absorption coefficient, L/mg
Reason — Dilution multiple.
When the reading given by the instrument is concentration C, the oil content can be calculated using formula (4). c
cav.
Where C'. Concentration read from the instrument, mg/L. 7.2.5 The volume of the water sample, the gasoline plate, and the dilution multiple of the extract should be determined according to the oil content of the water sample. When using a spectrophotometer that reads absorbance, the absorbance should be between 0.10 and 0.80. When using a spectrophotometer that reads concentration, the concentration should be between 10% and 90% of the maximum range. bzxZ.net
8 Precision
SY/T 0530—93
Judge the reliability of the test results (95% confidence level) according to the following provisions. 8.1 Reproducibility
The same operator, in the same laboratory, uses the same instrument to repeat the measurement of the same sample in a continuous period of time according to the steps specified in the method. The difference in the results should not exceed the values in the following table. B.2 Reproducibility
Different operators, in different laboratories, use the same type of instrument to repeat the measurement of the same sample according to the steps specified in the method. The difference in the results should not exceed the values in the following table.
Oil content range in sewage
9Report
10Above
The extract of the same water sample is measured twice, and the arithmetic mean of the two results is taken as the measurement result of the water sample. Additional remarks:
This standard is proposed by the Technical Supervision Bureau of China National Petroleum Corporation. This standard is under the jurisdiction of the Planning and Design Institute of China National Petroleum Corporation. This standard is drafted by the Oilfield Construction Design Institute of Daqing Petroleum Administration. The main drafters of this standard are Feng Xiaomin and Zhang Tanzhen.
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