Method for measuring lead content in casting lead brass lead washing bath solution

A determination method and technology of lead content, applied in chemical analysis by titration method, preparation of test samples, etc., can solve problems such as inapplicable determination of trace lead content, increase of experimental error, and residual ions on the cup wall, etc., to achieve Ease of access, low cost, and ease of operation

Pending Publication Date: 2022-05-13
JOMOO KITCHEN & BATHROOM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The mensuration of lead content adopts EDTA titration method more at present, discloses a kind of mensuration method of lead content in gold concentrate, lead concentrate as CN105842390A, and CN108444929A discloses a kind of mensuration method of lead content in polymetallic ore, and these patents have following limitation : the one, only applicable to the situation (percentage level) that this kind of lead content is higher in ore, is not suitable for the mensuration of trace lead content; The 2nd, add dilute sulfuric acid and sulfate to make lead ion precipitate, yet lead sulfate precipitates at room temperature The solubility product Ksp is too large (about 2.8*10 -8 ), when the lead content is at the ppm level (parts per million level), even if a large amount of sulfate radicals are added, it is difficult to completely precipitate the lead ions, and it is easy to dissolve the free lead ions when washing the precipitate, which is difficult to recycle, so that the titration result is too small The third is that the sample needs to be evaporated and concentrated to increase the concentration of lead ions. In addition to time-consuming, heating and boiling can easily cause residual ions on the cup wall and increase the experimental error.

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  • Method for measuring lead content in casting lead brass lead washing bath solution
  • Method for measuring lead content in casting lead brass lead washing bath solution
  • Method for measuring lead content in casting lead brass lead washing bath solution

Examples

Experimental program
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Effect test

Embodiment 1

[0046] A method for determining the content of lead in the lead-washing bath of a lead-cast brass faucet, the specific operation steps are as follows:

[0047] Step 1: Measure 100mL of the lead washing bath solution sample and place it in a 250mL beaker, add 8g of solid sodium sulfide nonahydrate, stir to dissolve it, and let it stand for at least 30min. Adding an appropriate amount of sodium sulfide nonahydrate can completely precipitate zinc, copper, and lead ions, and the aluminum ions will not precipitate and can be removed by filtration; however, the aqueous solution of sodium sulfide nonahydrate is strongly alkaline, and if excessive sodium sulfide nonahydrate is added, it is easy to make the pH The increase will lead to the precipitation of aluminum ions, so the ratio of the volume of the lead washing bath to the solid sodium sulfide nonahydrate is 100mL: 6 ~ 10g.

[0048] Step 2: Filter with slow quantitative filter paper, wash the cup wall and the precipitate with dei...

Embodiment 2

[0065] To analyze the lead standard solution BWG083780-100 (the lead concentration is the standard value: 100 μg / mL), the specific operation steps are as follows:

[0066] Step 1: Measure 100mL of lead standard solution and place it in a 250mL beaker, add 10g of solid sodium sulfide nonahydrate, stir to dissolve it, and let stand for at least 30min.

[0067] Step 2: Filter with slow quantitative filter paper, wash the cup wall and the precipitate with deionized water 5 times each, and transfer the precipitate and filter paper to a new 250 mL beaker.

[0068] Step 3: Add 60mL (1+4) dilute hydrochloric acid into a new beaker, stir, no precipitate dissolves, filter with slow quantitative filter paper, wash the beaker wall and the precipitate with (1+9) dilute hydrochloric acid 5 times each, and separate the precipitate and The filter paper was transferred to a new 250 mL beaker.

[0069] Step 4: Add 50mL (1+3) dilute nitric acid into a new beaker, cover with a watch glass, heat ...

Embodiment 3

[0083] The cast lead brass faucet washing lead bath solution of embodiment 1 is added the standard sample of embodiment 2 to analyze (lead standard solution BWG083780-100, lead concentration standard value is 100 μ g / mL), concrete operation steps are as follows:

[0084] Step 1: Take 50mL lead washing bath sample and 50mL lead standard solution respectively and place them in a 250mL beaker, add 10g solid sodium sulfide nonahydrate, stir to dissolve, and let stand for at least 30min.

[0085] Step 2: Filter with slow quantitative filter paper, wash the cup wall and the precipitate with deionized water 5 times each, and transfer the precipitate and filter paper to a new 250 mL beaker.

[0086] Step 3: Add 50mL (1+4) dilute hydrochloric acid into a new beaker, stir until the white precipitate dissolves, filter with slow quantitative filter paper, wash the beaker wall and the precipitate with (1+9) dilute hydrochloric acid 5 times each, separate the precipitate and The filter pape...

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Abstract

The invention relates to a method for measuring the content of lead in a casting lead brass lead washing bath solution, which comprises the following steps of: sequentially filtering and removing aluminum ions, zinc ions and copper ions by adopting a method of precipitating and then dissolving aiming at main interference factors of copper ions, zinc ions and aluminum ions; and finally, completely converting the residual lead sulfide precipitate into lead sulfate precipitate, adjusting the pH value, dissolving the lead sulfate precipitate, adding xylenol orange as an indicator, adding a phenanthroline aqueous solution to shield residual copper, zinc and aluminum ions, and titrating the lead ion concentration by using an EDTA standard solution. The method is suitable for measuring the concentration of trace lead ions (ppm level) in the lead washing bath solution, can achieve the effect of removing interference ions such as copper, zinc, aluminum and the like to the greatest extent while hardly losing the lead ions, and is simple in process, convenient to operate, obvious in phenomenon, easy to judge and high in accuracy.

Description

technical field [0001] The invention relates to the technical field of a method for measuring lead content in liquid, in particular to a method for measuring lead content in a lead-washing bath for cast lead brass. Background technique [0002] There are strict requirements on the lead content of brass products in the fields of kitchen and bathroom. For example, the commonly used material for faucets is lead brass HPb59-1 for casting, which contains 0.8% to 1.9% lead. In order to meet the requirements of GB 18145-2014 The statistical value of lead precipitation (Q) should be less than 5μg / L, and it is usually subjected to lead washing treatment, that is, the faucet is soaked in the lead washing tank for tens of minutes to dissolve and separate the lead complexes, thereby reducing Lead content in faucet cavities and exterior surfaces. At the same time, during the lead washing process, other metal ions (mainly copper, zinc, aluminum ions) in the faucet will also be partially ...

Claims

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Application Information

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IPC IPC(8): G01N31/16G01N1/28G01N1/34G01N1/38G01N1/44
CPCG01N31/16G01N1/28G01N1/34G01N1/38G01N1/44
Inventor 林孝发林孝山姚劲毅周年润汪火良
Owner JOMOO KITCHEN & BATHROOM
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