A
Anonymous
Guest
Hello....it is my first topic that I was released here....and my english is not good.
That is the tesing procedure of determination platinum alloy, (Pt-95%, Pd-4%, Rh<1%, Ru<1%, Ir<1%)
Step 1:
Weight and rotate the metal sample to a thin plate ~~~5g
Step2:
Dissolve/ digestion the sample by Aqua Regia
Step 3:
After the metal is dissolved completely in Aqua Regia, dry the acid solution that almost all convert to precipitate form
Step4:
Repeat add few ml conc. HCl and a few drop hydrogen peroxide approx. 5-8 times. Add 2 ml HCl at last step and cool down in room temperature
Step 5:
Add 5g ammonium chloride to precipitate the precious metal. Then filtrate and wash the precipitate and transfer to crucible
Step 6:
Ashing the fitrate in muffler furnace
Step 7:
Weight the ashed fitrate
Step 8:
Dissolve it back to Aqua Regia
Step 9:
Measure the solution by ICP-OES (Au, Ag, Pd, Ir, Rh, Ru, Cu)
Step 10:
Finally, Subtract the sample inital weight from the weight after ashing and ICP measurement
I have some problems and list as following:
1)Why we need add hydrogen peroxide in step4 ,what is the function for adding?? for precipitate the gold in sample solution?? or for break down the gold molecules to nano-dimetion
2)Is it need to add few baic buffer (e.g. pH10) before adding hydrogen peroxide??? for provide a pH swing???
3) Do ammonium chloride salt/solution precipitate all precious metal ??? What function on it????Only Pt or Pd can be precipitate???how about Cu???
Anybody can explain these question
Thx!!!!!!!!!!!!
That is the tesing procedure of determination platinum alloy, (Pt-95%, Pd-4%, Rh<1%, Ru<1%, Ir<1%)
Step 1:
Weight and rotate the metal sample to a thin plate ~~~5g
Step2:
Dissolve/ digestion the sample by Aqua Regia
Step 3:
After the metal is dissolved completely in Aqua Regia, dry the acid solution that almost all convert to precipitate form
Step4:
Repeat add few ml conc. HCl and a few drop hydrogen peroxide approx. 5-8 times. Add 2 ml HCl at last step and cool down in room temperature
Step 5:
Add 5g ammonium chloride to precipitate the precious metal. Then filtrate and wash the precipitate and transfer to crucible
Step 6:
Ashing the fitrate in muffler furnace
Step 7:
Weight the ashed fitrate
Step 8:
Dissolve it back to Aqua Regia
Step 9:
Measure the solution by ICP-OES (Au, Ag, Pd, Ir, Rh, Ru, Cu)
Step 10:
Finally, Subtract the sample inital weight from the weight after ashing and ICP measurement
I have some problems and list as following:
1)Why we need add hydrogen peroxide in step4 ,what is the function for adding?? for precipitate the gold in sample solution?? or for break down the gold molecules to nano-dimetion
2)Is it need to add few baic buffer (e.g. pH10) before adding hydrogen peroxide??? for provide a pH swing???
3) Do ammonium chloride salt/solution precipitate all precious metal ??? What function on it????Only Pt or Pd can be precipitate???how about Cu???
Anybody can explain these question
Thx!!!!!!!!!!!!