UPSC Combined Geo-Scientist, Mains · 2019 · Mains Paper III
Q3(e). Heavy-metal adsorption on hydrous oxides
Question
How can adsorption of Zn, Cd and Mn hydroxides on hydrous Fe(III)/Al oxides be minimised?
Answer in brief
Precipitate at controlled low enough pH, suppress local hydroxide excess and reprecipitate the hydrous oxides when necessary.
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CoversHeavy-metal adsorption on hydrous oxidesPrecipitation separations
All parts of Question 3
- 3(a) Potentiometric fluoride measurement10 marks
- 3(b) Isoelectric and isoionic points5 marks
- 3(c) Identifying and balancing redox5 marks
- 3(d) Errors from coprecipitation5 marks
- 3(e) Heavy-metal adsorption on hydrous oxides5 marks