All solutions for leaching experiments and metals content evaluation were prepared with analytical grade reagents and de-ionized water. The acids, standards and salts were purchased from Sigma Aldrich, metal ions were determined by Microwave Plasma Atomic Emission Spectrometery (4100 MP-AES, Agilent Technologies); powder composition was determined by X-ray fluorescence spectrometer (Spectro X-LAB 2000 spectrometer). Calibration was carried out for each analysed metal by analyzing at least 5 concentration level standard solutions. Internal quality control checks were carried
out, including procedural blank evaluation. All experiments were performed at 25°C