Following the classic ADOR protocol,30 (link) 0.1 g of calcined IWR sample was treated with 10 ml 0.1 M or 12 M HCl (Sigma-Aldrich) at room temperature for 6 h. Solid products were recovered by centrifugation or filtration, washed thoroughly with methanol (99.98%, Lachner) and acetone (99.99%, Lachner), and dried at 60 °C. The obtained solids were calcined at 450 °C for 2 h with a temperature ramp of 1 °C min−1.
The IWR samples were also subjected to vapour-phase-transport (VPT) treatment according to the procedure reported in ref. 12 (link) For that, 0.1 g of calcined IWR sample was placed on the polytetrafluoroethylene (PTFE) membrane over 10 ml of 12 M hydrochloric acid solution at 25 °C for τ = 16 h.
The IWR samples were also subjected to vapour-phase-transport (VPT) treatment according to the procedure reported in ref. 12 (link) For that, 0.1 g of calcined IWR sample was placed on the polytetrafluoroethylene (PTFE) membrane over 10 ml of 12 M hydrochloric acid solution at 25 °C for τ = 16 h.
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