CN101493395B - Method for measuring rhodium content in plating liquid - Google Patents

Abstract

The invention discloses a method for determining content of rhodium in plating solution. The method is characterized by comprising the following steps: (1) first, accurately extracting 1-10ml rhodium sulfate solution to be measured in a 500ml conical flask; (2) adding deionized water for dilution, adding a proper amount of sulphuric acid solution with the ratio of 1:5 (V/V), heating to 50-60 DEG C, slowly adding high-purity zinc powder until the solution is colorless and transparent and the rhodium is completely reduced, then adding a proper amount of the sulphuric acid solution with the ratio of 1:10, and heating to slightly boil to completely dissolve the excess zinc powder until the solution is colorless, clear and transparent; (3) filtering the solution obtained in the step (2) by a constant-weight sand core crucible and washed a plurality of times by hot deionized water; (4) drying the sand core crucible in the step (3) and putting the crucible into a drier for cooling, and weighing the crucible; and (5) performing a computation method of the content of the rhodium: (a formula is shown at the upper right).

Description

Determining content of rhodium in the plating bath

Technical field

The present invention relates to a kind of rhodium electroplate liquid determining content of rhodium that is used for measuring.

Background technology

Because the peculiar property of rhodium makes that the jewelry of handling through rhodanizing has good luster, wearing quality is strong, coating hardness is high, the surface is will never change colour, corrosion stability is good, be not subjected to characteristics such as etchant gas effect such as oxysulfide and oxycarbide in atmosphere.Existing decorative machining is much all just used rhodium plating coating as plating such as electroplating surfaces such as jewellery processing, high-grade Clocks, Watches and Glasses, tie clip, belt hook and engineering such as Electrical and Electronic connector, printed-wiring board (PWB), optical instrument part etc.Reclaiming in the process that reclaims rhodium and Electroplating Production in the liquid all needs rhodium content is measured.

Domestic and international many scholars studied the assay method of rhodium, and wherein majority is a gravimetric method, as national standard " platinum-rhodium alloy chemical analysis method " (GB1485-79) in the mensuration, sodium borohydride of rhodium amount measure rhodium etc. as the reductive agent of rhodium and all belong to gravimetric method.Also have instrument analytical methods such as colourimetry, flame atomic absorption method and inductively coupled plasma emission spectrometry in addition.Various assay methods all have different determination limits, and the accuracy of mensuration and precision are also variant, and most of assay method is all more loaded down with trivial details or not accurate enough.So conventional detection awaits further perfect.

Summary of the invention

The objective of the invention is provides a kind of and can fast, accurately measure rhodium Determination on content method in plating bath in order to overcome the weak point in the existing assay method.

In order to achieve the above object, the present invention adopts following scheme:

Determining content of rhodium in a kind of plating bath is characterized in that:

(1), at first accurately extracts rhodium sulfate solution 1～10ml to be measured in the 500ml conical flask;

(2), after the dilution of adding deionized water, add an amount of 1: 5 (V/V) sulfuric acid solution, be heated to 50～60 ℃, slowly add high-purity zinc powder, up to the solution achromaticity and clarification, till rhodium reduces fully, it is an amount of to add 1: 10 sulfuric acid solution then, be heated to little boiling, excessive zinc powder is dissolved fully, it is transparent that solution is achromaticity and clarification fully;

(3), the core crucible of the solution in (2) with constant weight filtered, and clean for several times with hot deionized water;

(4), with the core crucible in (3) oven dry, weigh after putting into the exsiccator cooling.

(5), the computing method of rhodium content:

Determining content of rhodium in the aforesaid plating bath is characterized in that

(1), accurately extracts rhodium sulfate solution 10ml to be measured in the 500ml conical flask;

(2), add the dilution of 30ml deionized water after, add 1: 5 (V/V) sulfuric acid solution about 20ml, be heated to about 50～60 ℃, slowly add high-purity zinc powder, up to the solution achromaticity and clarification, till rhodium reduces fully.Add 1: 10 sulfuric acid solution 50ml then, be heated to little boiling 15～30 minutes, excessive zinc powder is dissolved fully, it is transparent that solution is achromaticity and clarification fully;

(3), No. 4 core crucibles of the solution in (2) with constant weight are filtered, and clean for several times with hot deionized water;

(4), No. 4 core crucibles in (3) were dried two hours under 120 ℃ condition, putting into the exsiccator cooling weighed after 30 minutes;

(5), the computing method of rhodium content:

Determining content of rhodium in the aforesaid plating bath is characterized in that needing to dry two hours down at 120 ℃ earlier before the core crucible filtration in use step (3), cools off 30 minutes constant weight in exsiccator.

Assay method of the present invention in the rhodium content, should be noted following item in measuring plating bath:

(1), detected solution can not contain gold, silver, platinum, palladium, copper and other can be by the composition of zinc powder reduction.

(2), because the costing an arm and a leg of rhodium, the volume of draw samples should guarantee analysis result accurately under the prerequisite, as far as possible littler, the general rhodium grain weight amount after the final reduction that makes restrains 0.1～0.3.

(3), viscosity is big slightly sometimes for rhodium sulfate solution (rhodanizing liquid), need keep certain emitting the solution time during sampling, otherwise causes analysis result on the low side easily.

(4), with after the zinc powder reduction, solution must be that complete achromaticity and clarification is transparent.If solution still has yellow, will continue to add zinc powder reduction till the water white transparency.Thoroughly dissolving is clean with excessive zinc powder to add sulfuric acid at last.

In sum, advantage of the present invention: detection method of the present invention does not need to adopt special analytical instrument and does not need to adopt the chemicals of severe toxicity, and processing ease is fast and convenient, and can accurately measure the content of rhodium in plating bath.

Embodiment

The invention will be further described below in conjunction with embodiment:

Determining content of rhodium in a kind of plating bath of the present invention may further comprise the steps:

(1), at first accurately extracts rhodium sulfate solution 1～10ml to be measured in the 500ml conical flask;

(2), after the dilution of adding deionized water, add an amount of 1: 5 (V/V) sulfuric acid solution, be heated to 50～60 ℃, slowly add high-purity zinc powder, up to the solution achromaticity and clarification, till rhodium reduces fully, it is an amount of to add 1: 10 sulfuric acid solution then, be heated to little boiling, excessive zinc powder is dissolved fully, it is transparent that solution is achromaticity and clarification fully;

(3), the core crucible of the solution in (2) with constant weight filtered, and clean for several times with hot deionized water;

(4), with the core crucible in (3) oven dry, weigh after putting into the exsiccator cooling.

(5), the computing method of rhodium content:

Embodiment 1

(1), accurately extracts rhodium sulfate solution 1ml to be measured in the 500ml conical flask;

(2), add the dilution of 30ml deionized water after, add 1: 5 (V/V) sulfuric acid solution about 20ml, be heated to about 50～60 ℃, slowly add high-purity zinc powder, up to the solution achromaticity and clarification, till rhodium reduces fully.Add 1: 10 sulfuric acid solution 50ml then, be heated to little boiling 15～30 minutes, excessive zinc powder is dissolved fully, it is transparent that solution is achromaticity and clarification fully;

(3), No. 4 core crucibles of the solution in (2) with constant weight are filtered, clean for several times with solution and with hot deionized water, wherein No. 4 core earthenwares oven dry two hours under 120 ℃ condition earlier, cooling is 30 minutes in exsiccator, reaches constant weight;

(4), No. 4 core crucibles in (3) were dried two hours under 120 ℃ condition, putting into the exsiccator cooling weighed after 30 minutes.

Write down the above-mentioned data of weighing, and adopt following computing formula to calculate:

Embodiment 2

(1), accurately extracts rhodium sulfate solution 10ml to be measured in the 500ml conical flask;

(2), add the dilution of 30ml deionized water after, add 1: 5 (V/V) sulfuric acid solution about 20ml, be heated to about 50～60 ℃, slowly add high-purity zinc powder, up to the solution achromaticity and clarification, till rhodium reduces fully.Add 1: 10 sulfuric acid solution 50ml then, be heated to little boiling 15～30 minutes, excessive zinc powder is dissolved fully, it is transparent that solution is achromaticity and clarification fully;

(3), No. 4 core crucibles of the solution in (2) with constant weight are filtered, clean for several times with solution and with hot deionized water, wherein No. 4 core earthenwares oven dry two hours under 120 ℃ condition earlier, cooling is 30 minutes in exsiccator, reaches constant weight;

(4), No. 4 core crucibles in (3) were dried two hours under 120 ℃ condition, putting into the exsiccator cooling weighed after 30 minutes.

Write down the above-mentioned data of weighing, and adopt following computing formula to calculate:

Claims (3)

1. determining content of rhodium in the plating bath is characterized in that may further comprise the steps:

(1), at first accurately extracts rhodium sulfate solution 1～10ml to be measured in the 500ml conical flask;

(2), after the dilution of adding deionized water, add an amount of 1: 5 (V/V) sulfuric acid solution, be heated to 50～60 ℃, slowly add high-purity zinc powder, up to the solution achromaticity and clarification, till rhodium reduces fully, it is an amount of to add 1: 10 sulfuric acid solution then, be heated to little boiling, excessive zinc powder is dissolved fully, it is transparent that solution is achromaticity and clarification fully;

(3), the core crucible of the solution in (2) with constant weight filtered, and clean for several times with hot deionized water;

(4), with the core crucible in (3) oven dry, weigh after putting into the exsiccator cooling;

(5), the computing method of rhodium content:

2. determining content of rhodium in the plating bath according to claim 1 is characterized in that

(1), accurately extracts rhodium sulfate solution 10ml to be measured in the 500ml conical flask;

(2), after the dilution of adding 30ml deionized water, add 1: 5 (V/V) sulfuric acid solution about 20ml, be heated to 50～60 ℃, slowly add high-purity zinc powder, up to the solution achromaticity and clarification, till rhodium reduces fully, add 1: 10 sulfuric acid solution 50ml then, be heated to little boiling 15～30 minutes, excessive zinc powder is dissolved fully, it is transparent that solution is achromaticity and clarification fully;

(3), No. 4 core crucibles of the solution in (2) with constant weight are filtered, and clean for several times with hot deionized water;

(4), No. 4 core crucibles in (3) were dried two hours under 120 ℃ condition, putting into the exsiccator cooling weighed after 30 minutes;

(5), the computing method of rhodium content:

3. determining content of rhodium in the plating bath according to claim 1 and 2 is characterized in that needing to dry two hours down at 120 ℃ earlier before the core crucible filtration in use step (3), cools off 30 minutes constant weight in exsiccator.