Determination of trace elements in refined brine by HK-8100 single-channel scanning spectrometer

HK-8100

Determination of trace elements in refined brine by single-pass scanning spectrometer

The ionic membrane alkali process is an advanced alkali-making technology. It offers low production costs, reduced energy consumption, and is pollution-free. It produces high concentration and purity of sodium hydroxide, making it the most advanced alkali-making method globally. The quality of refined brine is crucial for this process, as it significantly affects the life of the ion membrane, cell voltage, current efficiency, and product quality.

Impurities such as Ca²⁺, Mg²⁺, Sr²⁺, Fe²⁺, Al³⁺, Ni²⁺, I₂, and SO₄²⁻ are considered first-class impurities. When these ions enter the membrane in ionic form, they deposit on the membrane as metal hydroxides, sulfates, or silicates, potentially clogging its pores. Ba²⁺ may affect the anode activity, while Si⁴⁺, when bonded with Ca²⁺, Sr²⁺, or Al³⁺, can reduce current efficiency. These effects become more pronounced when multiple ions are present together.

Therefore, establishing a rapid, sensitive, and accurate method for determining trace elements in refined brine is essential for the production process of ionic membrane alkali. Inductively coupled plasma optical emission spectrometry (ICP-AES) has become the primary analytical technique due to its low detection limit, wide linear range, and ability to simultaneously determine multiple elements. Computer-controlled single-pass scanning ICP-AES is widely used in elemental quantification due to its flexibility and precision.

Experimental Part:

(1) HK-8100 Inductively Coupled Plasma Emission Spectrometer

(2) High-salt Atomizer

(3) Swirl Atomization Chamber

(4) Nitric Acid: Ultra-pure Grade

(7) Standard Solutions for Ca²⁺, Mg²⁺, Sr²⁺, Fe²⁺, Al³⁺, Ni²⁺, Mn²⁺, and SiO₂

(8) Mixed Standard Solution

Instrument Working Conditions:

Generator Power: 1150 W; Auxiliary Gas Flow: 1.0 L/min; Nebulizer Pressure: 2.07 kPa

Experimental Method: Under optimal working conditions, a series of 100 mL polyethylene volumetric flasks were prepared with 50 mL sample solution. Then, 2 mL nitric acid was added, followed by different volumes of standard solutions (0.2, 0.5, and 1.0 mL for SiOâ‚‚). The volume was adjusted with secondary deionized water. The resulting standard solutions were used for analysis.

Results and Discussion:

For the HK-8100 single-channel scanning spectroscopy instrument, the spectral line with the second highest intensity, minimal interference, low background, and high signal-to-noise ratio was selected as the analytical line. Background correction points were also chosen for each line to eliminate baseline irregularities. The most sensitive ultraviolet line for aluminum at 167.1 nm was used, and argon purging was performed before measurement for 72 hours to ensure accuracy. Further experiments showed that the secondary sensitive line at 396.1 nm also yielded satisfactory results.

Interference and Elimination:

To address spectral interferences from sodium ion generation, blank experiments, group measurements, standard addition methods, and simultaneous background subtraction techniques were employed. This approach effectively compensated for the difficulty in matching large amounts of sodium chloride matrix in brine, enabling accurate trace element determination that is challenging with other analytical methods.

Beijing Huake Yitong Analytical Instrument Co., Ltd. is a professional manufacturer of inductively coupled plasma optical emission spectrometers. As a high-tech enterprise, it integrates research, development, production, sales, and technical services. The HK-8100 and HK-2000 models are based on existing technologies, incorporating the latest international advancements to deliver superior performance.

Key Specifications:

1. Wavelength Range: 180–800 nm (2400 lines/mm) or 180–500 nm (3600 lines/mm)

2. Resolution: ≤ 0.006 nm within 180–500 nm

3. Wavelength Accuracy and Reproducibility: ≤ 0.02 nm and ≤ 0.003 nm, respectively

4. Scanning Step: 0.0004 nm

5. Precision: RSD ≤ 1.5%

6. Stability: RSD ≤ 2.0%

7. Detection Limit: PPb level

8. Element Analysis Range: 72 metal elements and some non-metals like B, P, Si, Se, Te

9. Linear Range: More than one order of magnitude

10. Analysis Speed: Over 20 elements per minute

11. Certification: National Measurement Instrument Type Approval (Class A)