Simultaneous and Rapid Determination of Nickel, Zinc, and Copper in Electroplating Wastewater of Electric Heating Tubes

Simultaneous and Rapid Determination of Nickel, Zinc, and Copper in Electroplating Wastewater of Electric Heating Tubes

Electroplating wastewater usually contains various heavy metals and toxic substances. The monitoring methods for nickel mainly include flame atomic absorption spectrophotometry, dimethylglyoxime spectrophotometry, oscillopolarography, and ICP-AES. The monitoring methods for zinc mainly include atomic absorption spectrophotometry, dithizone spectrophotometry, oscillopolarography, and ICP-AES. The monitoring methods for copper mainly include atomic absorption spectrophotometry Sodium diethyldisulfide spectrophotometry, oscillopolarography, anodic stripping voltammetry, ICP-AES [1,2]. The study on the simultaneous rapid determination of nickel, zinc, and copper in electroplating wastewater is beneficial for environmental supervision and emergency monitoring of electroplating wastewater.

1. Experimental Principles

Nickel, zinc, and copper in water and wastewater combine with l - (2-pyridylazo) -2-naphthol in an ethanol medium to form a red complex. When the second derivative spectrum is measured, three independent inverted peaks appear at 545nm, 557nm, and 595nm, and the distance from the peak to the baseline is proportional to the concentration of nickel, zinc, and copper, respectively. Therefore, the concentration of three metal elements in electroplating wastewater is determined simultaneously.

2. Materials and Methods

2.1 Main instruments and reagents

(1) Dual beam dual wavelength UV visible spectrophotometer (Shimadzu UV-1750 model), which can measure both ordinary and divalent derivative spectra.

(2) Nickel standard solution: Weigh 0.5000g of metallic nickel (purity 99.9%), dissolve it in a small amount of (1+1) nitric acid, dilute it with 1% HNO3 to 500mL, shake well, and transfer it into a plastic bottle. The concentration of this stock solution is 1.00mg of nickel per milliliter. Dilute the nickel standard solution from the above standard stock solution to a concentration of 5.00 per milliliter μ G Nickel.

(3) Zinc standard solution: weigh 0.5000 g of metal zinc particles (99.9% purity), dissolve them in 10 mL (6+1) hydrochloric acid, transfer them into a 500 mL volumetric flask, and dilute them with water to the marking line. The concentration of this stock solution is 1.00mg of zinc per milliliter. Dilute the zinc standard solution from the above standard stock solution to a concentration of 5.00 per milliliter μ G Nickel.

(4) Copper standard solution: Accurately weigh 1.000g of metallic copper (purity 99.9%), place it in a 150mL conical flask, add 20mL of (1+1) nitric acid, heat to dissolve, add 10mL of (1+1) sulfuric acid, and heat until white smoke comes out. After cooling, add water to dissolve and transfer to a 1000mL volumetric flask, dilute with water to the mark, and shake well. The concentration of this stock solution is 1.00 mg of copper per milliliter. Dilute the copper standard solution from the above standard stock solution to a concentration of 5.00 per milliliter μ G Copper.

(5) L - (2-pyridylazo) -2-naphthol solution: Weigh 0.1gl - (2-pyridylazo) -2-naphthol and dissolve it in 100mL of ethanol.

(6) PH 4.8 buffer solution: Weigh 56.0g of NaAc3H2O, add 25.0mL of glacial acetic acid, mix well, and dilute with water to 1L. Use a pH meter to adjust the buffer solution so that its pH value is 4.8.

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