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    Home > Chemicals Industry > Chemical Technology > Determination of the corrosivity of solid waste by glass electrode method

    Determination of the corrosivity of solid waste by glass electrode method

    • Last Update: 2022-02-28
    • Source: Internet
    • Author: User
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    In the identification of hazardous waste, corrosive identification is the primary link


    1.


    This method is suitable for the determination of the pH of solid and semi-solid leaching liquids and high-quality liquids


    Second, the principle of the method

    A glass electrode is used as an indicator electrode, and a saturated calomel electrode is used as a reference electrode to form a battery


    3.


    (1) Deionized water


    (2) Use a commercially available certified pH standard buffer solution


    Four, instruments and equipment

    (1) Mixing container: a high-pressure polyethylene bottle with a sealing plug with a volume of 2L


    (2) Oscillator: Reciprocating horizontal oscillator


    (3) Filtration device: a complete set of commercially available filters, the pore size of the fiber membrane is 0.


    (4) pH meter: various types of composite pH meters or ion activity meters, with an accuracy of ±0.


    Five, pre-treatment

    (1) Weigh 100g of the sample (calculated on a dry basis), place it in a mixing container for leaching, and add 1L of water (including the moisture content of the sample)


    (2) The mixing container for leaching was vertically fixed on the shaker, the oscillation frequency was adjusted to 110±10 times/min, the amplitude was 40mm, and the mixture was shaken at room temperature for 8 hours and left to stand for 16 hours


    (3) Separate the solid and liquid phases through a filtration device, and measure the pH of the filtrate immediately after filtration


    (4) If the content of dry solids in the solid waste is less than 0.


    Six, analysis and testing

    (1) Place the sample and the standard calibration solution at room temperature to equilibrate and reach the same temperature, and record the measured temperature


    (2) Calibrate the pH meter with a standard buffer solution with a pH difference of no more than 2 from the test solution
    .
    After positioning with the first standard solution, take out the electrode, rinse thoroughly, and absorb water with filter paper
    .
    Then immerse in the second standard solution for verification, and its value should be within the allowable error range of the standard
    .
    Otherwise, check whether there is a problem with the instrument, electrode or standard solution
    .
    The sample can be measured only when there is no problem in the check
    .

    (3) Pour the sample leaching filtrate into a clean beaker, the liquid level should be higher than the sensitive element of the electrode, put in a stir bar, insert the clean electrode into the beaker, stir or shake at a gentle and fixed rate to make it even , And record its pH after the reading is stable
    .
    The measurement should be repeated 2 to 3 times until the pH change is less than 0.
    1
    .

    (4) If the pH of fluids or semi-solid fluids (such as thin mud, grout, etc.
    ) is measured on site, the electrode can be directly inserted into the sample with appropriate depth and movable, and enough samples should pass through the electrode's sensitive components
    .

    Seven, calculation and presentation of results

    (1) When measuring pH with a composite pH electrode, the pH can be read directly without calculation
    .

    (2) At least 3 parallel tests should be conducted for each sample, the standard deviation of the results shall not exceed ±0.
    15, and the arithmetic mean value shall be used to report the test results
    .

    8.
    Quality Assurance and Quality Control

    At least 3 parallel tests should be conducted for each sample, and the standard deviation of the results should not exceed ±0.
    15
    .

    Nine, matters needing attention

    (1) When the pH of the waste leaching solution is greater than 10, the anorexia effect will interfere with the measurement.
    It is advisable to use a low anomaly electrode or use a standard buffer solution similar to the pH of the leaching solution to calibrate the instrument
    .

    (2) Before calibrating the instrument, use a wide range of pH test paper (pH 0 to 14) to preliminarily determine the pH of the test solution, and then select a similar standard buffer solution for calibration
    .

    (3) When the surface of the electrode is contaminated by oily or particulate matter, it will affect the measurement of the electrode, and it should be cleaned with detergent
    .
    Or use hydrochloric acid (1+1) solution to remove the residue, and then rinse with distilled water
    .

    (4) Temperature affects the accurate determination of pH, because the potential output of the electrode is different at different temperatures, and temperature changes will also affect the pH of the sample
    .
    Therefore, temperature compensation must be performed
    .
    The thermometer and the electrode should be inserted into the solution to be measured at the same time, and the temperature at the time of measurement should be reported at the same time when reporting the measured pH
    .

    (5) After the sample is leached, if the upper liquid contains more particles and the filtration efficiency is slow, the upper liquid can be centrifuged and then filtered
    .

    (6) Since solid waste samples often have a strong pungent odor, they may irritate the eyes and respiratory tract during the experiment, so safety protection measures for experimenters should be taken
    .

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