2.2.1. Elemental Characterization of Pristine Materials

The elemental composition of ALI, PS9 and G30 was obtained by two Inductively Coupled Plasma techniques: ICP-OES (Optima 8300 ICP–OES Spectrometer, Perkin Elmer, Waltham, MA, USA) and ICP-MS (NexION-300d ICP mass spectrometer, Perkin Elmer), equipped with a triple cone interface and a quadrupole ion deflector using argon for plasma formation. PS9 and G30 were subjected to acid digestion in strong acids (HNO3 and HF at a 3:5 ratio, Sigma-Aldrich, MO, USA) inside a Teflon reactor, placed in a microwave oven (Millestone ETHOS ONE, Sorisole, Italy). Calibration curves for ICP-OES were obtained by means of standards solution of 1000 ppm for each element. For ICP-MS, single-element standard solutions (Merck, Darmstadt, Germany) were prepared after dilution with 10% HNO3. Ultrapurified water (milliQ grade) was used in both techniques.
