The short version
If you've ever dealt with rusty, iron-heavy well water, this one's for you. A St. Petersburg technical-institute group measured how much dissolved iron(III) shungite can grab - and how much better it gets after a basic heat treatment.
What they found
"модифицированный шунгит адсорбирует по сравнению с гидроантрацитом в 1,4 раз выше и в 2 раза выше, чем природный шунгит"
"modified shungite adsorbs 1.4 times more than hydroanthracite, and 2 times more than natural shungite."
The headline numbers:
- Heat-treated ("modified") shungite reached a maximum iron(III) capacity of 1.11 mmol/g
- That's roughly 7 times hydroanthracite (a coal-based reference sorbent at 0.152 mmol/g) and 2 times plain natural shungite
- The trick: heating to 500 °C nearly doubled the pore volume and more than doubled the surface area, opening up pores in the 80-200 Å range that iron(III) slots into
Worth knowing
It's a concrete, measurable reason the "activate your stones" advice keeps coming up - the same rock works substantially harder once its pores are opened up.
Sources
- Alekseev A.I., Churkina O.S., Golubev P.V. (2016), "Исследование химизма сорбции катионов железа(III) углеродсодержащими соединениями", Известия СПбГТИ(ТУ):
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