Measurement for Pollution Control in Domestic Waste

Detection Target

Measurement for Pollution Control in Domestic Waste

Sample Testing

1. HKL-22036 ICP for Determination of metal elements in domestic waste

   1) Principle

   The sample is introduced into the sampling system via a carrier gas for nebulization, entering the plasma flame in the form of an aerosol. Under high temperature and an inert atmosphere, it undergoes thorough evaporation, atomization, ionization, and excitation, emitting characteristic spectral lines of the contained elements. Qualitative analysis of specific elements is performed based on the presence or absence of these characteristic spectral lines, while quantitative analysis of specific elements in the sample is conducted based on the intensity of the characteristic spectral lines.

   2) Preparation of Standard Solutions

   Pipette 5 ml each of Zn, Pb, Cd, Ni, Cr, Cu, Be, Ba (As, Hg, Se) standard solutions (1000 mg/L) into a 100 ml volumetric flask. Dilute to the mark with deionized water to obtain standard stock solutions (50 mg/L) for Zn, Pb, Cd, Ni, Cr, Cu, Be, Ba (As, Hg, Se).

   Pipette 0, 0.5, 1, 2, 5, and 10 ml aliquots of the standard stock solution into six separate 100 ml volumetric flasks. Add 3 ml of nitric acid solution to each flask, then dilute to the mark with deionized water to prepare working standard solutions with concentrations of 0 mg/L, 0.25 mg/L, 0.5 mg/L, 1.0 mg/L, 2.5 mg/L, and 5.0 mg/L for Zn, Pb, Cd, Ni, Cr, Cu, Be, Ba (As, Hg, Se).

   3) Test Results

1. HKL-AFS for Determination of As, Hg, and Se in Domestic Waste

   1) Principle

   The acidic solution containing the target analyte in the liquid sample is converted to a specific valence state under the action of a prereductant. The reducing agent KBH₄ then reacts to generate hydride and hydrogen gas. Driven by the carrier gas, the hydride and hydrogen are transported into the atomizer for atomization, where specific matrix atoms are excited by the absorption of a beam of electromagnetic radiation. The excited species then relax to the ground state, giving up their excess energy as photons. Intensity of the photons is measured.

   2) Preparation of Test Solutions

   Arsenic (As)

   (1) Preparation of Arsenic Standard Solutions

   ① 10% Thiourea + 10% Ascorbic Acid Mixed Solution: Weigh 10 g thiourea and 10 g ascorbic acid in a beaker, add 100 ml water, and mix well to prepare 100 ml of the mixed solution.

   ② 10 mg/L Arsenic Stock Standard Solution: Pipette 1 ml from a 1000 mg/L arsenic standard solution and dilute to 100 ml in a volumetric flask.

   ③ 100 μg/L Arsenic Stock Standard Solution: Pipette 1 ml from the 10 mg/L arsenic standard solution and dilute to 100 ml in a volumetric flask.

   ④ 1 μg/L Arsenic Standard Solution: Pipette 1 ml from the 100 μg/L arsenic standard solution, add 5 ml concentrated hydrochloric acid, 10 ml of the 10% thiourea + 10% ascorbic acid mixed solution, and dilute to 100 ml in a volumetric flask.

   ⑤ 2 μg/L Arsenic Standard Solution: Pipette 2 ml from the 100 μg/L arsenic standard solution, add 5 ml concentrated hydrochloric acid, 10 ml of the 10% thiourea + 10% ascorbic acid mixed solution, and dilute to 100 ml in a volumetric flask.

   ⑥ 4 μg/L Arsenic Standard Solution: Pipette 4 ml from the 100 μg/L arsenic standard solution, add 5 ml concentrated hydrochloric acid, 10 ml of the 10% thiourea + 10% ascorbic acid mixed solution, and dilute to 100 ml in a volumetric flask.

   ⑦ 8 μg/L Arsenic Standard Solution: Pipette 8 ml from the 100 μg/L arsenic standard solution, add 5 ml concentrated hydrochloric acid, 10 ml of the 10% thiourea + 10% ascorbic acid mixed solution, and dilute to 100 ml in a volumetric flask.

   ⑧ 10 μg/L Arsenic Standard Solution: Pipette 10 ml from the 100 μg/L arsenic standard solution, add 5 ml concentrated hydrochloric acid, 10 ml of the 10% thiourea + 10% ascorbic acid mixed solution, and dilute to 100 ml in a volumetric flask.

   ⑨ Arsenic Standard Blank: Add 5 ml concentrated hydrochloric acid and 10 ml of the 10% thiourea + 10% ascorbic acid mixed solution, then dilute to 100 ml in a volumetric flask.

   (2) Carrier Solution

   5% Hydrochloric Acid (v/v): Measure 25 ml of concentrated hydrochloric acid and dilute to 500 ml with deionized water.

   (3) Preparation of Reducing Agent

   0.5% Potassium Hydroxide + 2% Potassium

   Borohydride Solution: Dissolve 2.5 g potassium hydroxide (KOH) in deionized water. After complete dissolution, add 10 g potassium borohydride (KBH₄) to the solution. Dilute to 500 ml with deionized water and mix thoroughly. (Prepare fresh before use; avoid overnight storage. The preparation sequence must not be reversed.)

   (4) Sample Preparation

   ① Sample Blank: Pipette 5 ml of microwave-digested blank sample into a 50 ml volumetric flask. Add 2.5 ml concentrated hydrochloric acid and 5 ml of the 10% thiourea + 10% ascorbic acid mixed solution. Dilute to the mark with deionized water.

   ② Test Sample Solution: Pipette 5 ml of microwave-digested test sample into a 50 ml volumetric flask. Add 2.5 ml concentrated hydrochloric acid and 5 ml of the 10% thiourea + 10% ascorbic acid mixed solution. Dilute to the mark with deionized water.

   Mercury (Hg) — preheating time for mercury: 30 minutes

   (1) Preparation of Hg Standard Solutions

   ① The preparation method was consistent with that of the mercury standard solution.

   ② Selenium standard blank: Add 10 mL of concentrated hydrochloric acid and dilute to volume in a 100 mL volumetric flask.

   (2) Carrier Solution

   2% Nitric Acid (v/v): Measure 10 ml concentrated nitric acid and dilute to 500 ml with deionized water.

   (3) Preparation of Reducing Agent (Cold Vapor Mercury)

   0.5% Potassium Hydroxide (KOH) + 0.01% Potassium Borohydride (KBH₄)

   Dissolve 2.5 g KOH in deionized water (ensure complete dissolution). Add 0.05 g KBH₄ to the KOH solution. Dilute to 500 ml with deionized water and mix thoroughly.( Prepare fresh before use, avoid overnight storage. Critical: The preparation sequence must not be reversed.)

   (4) Sample Preparation

   ① Sample Blank: Pipette 5 ml of microwave-digested blank sample into a 50 ml volumetric flask. Add 1 ml concentrated nitric acid and 0.5 ml 10% potassium dichromate solution. Dilute to the mark with deionized water.

   ② Test Sample Solution: Pipette 5 ml of microwave-digested sample into a 50 ml volumetric flask. Add 1 ml concentrated nitric acid and 0.5 ml 10% potassium dichromate solution. Dilute to the mark with deionized water.

   Selenium (Se)

   (1) Preparation of Selenium Standard Solutions

   ① The preparation method was consistent with that of the mercury standard solution.

   ② Selenium Standard Blank: Add 10 ml concentrated hydrochloric acid and dilute to 100 ml in a volumetric flask.

   (2) Carrier Solution 5% Hydrochloric Acid (v/v): Measure 50 ml concentrated hydrochloric acid and dilute to 500 ml with deionized water.

   (3) Preparation of Reducing Agent

   0.5% Potassium Hydroxide + 1.5% Potassium Borohydride Solution

   Dissolve 2.5 g potassium hydroxide (KOH) in deionized water. After complete dissolution, add 7.5 g potassium borohydride (KBH₄) to the solution. Dilute to 500 ml with deionized water and mix thoroughly. (Note: Prepare fresh before use; avoid overnight storage. The preparation sequence must not be reversed.)

   (4) Sample Preparation

   Sample Blank: Pipette 5 ml of microwave-digested blank sample into a 50 ml volumetric flask. Add 5 ml concentrated hydrochloric acid and dilute to the mark with deionized water.

   Test Sample Solution: Pipette 5 ml of microwave-digested test sample into a 50 ml volumetric flask. Add 5 ml concentrated hydrochloric acid and dilute to the mark with deionized water.

   3) Test Results

1. HKL-7196A UV-Vis for Determination of Hexavalent Chromium in Domestic Waste

   1) Principle

   In acidic solution, hexavalent chromium reacts with diphenylcarbazide to form a red-colored complex, which is then determined spectrophotometrically at the maximum absorption wavelength of 540 nm.

   2) Preparation of Standard Solutions

   ReagentPreparation for Hexavalent Chromium (Diphenylcarbazide Spectrophotometric Method)

   (1) 5% + 5% Sulfuric-Phosphoric Mixed Acid: 25 ml sulfuric acid + 25 ml phosphoric acid + 450 ml water.

   (2) 0.05% Color Developing Reagent: Dissolve 0.25 g diphenylcarbazide in 25 ml acetone, then dilute to 500 ml in a volumetric flask with water.

   (3) Hexavalent Chromium Standard Solutions: 0 mg/L, 0.5 mg/L, and 1.0 mg/L. Cr(VI) Standard Solutions: Accurately pipette 0.025 ml and 0.05 ml of chromium standard solution into separate 50 ml volumetric flasks, then dilute to the mark with deionized water.

   3) Sample Testing Procedure

   Take 10 ml of the leachate sample, and then add 1 ml of sulfuric acid-phosphoric acid mixed solution. Add 1 ml of color-developing reagent.

   4) Test Results