The leaching takes place on a laboratory scale using a glass container made of borosilicate glass with a filling volume of 100 mL of suspension, see Figure . First, a mixture of deionized water and the particles with a mass fraction between 5 and 15 % w/w is prepared. The sample is then taken without acid, which corresponds to the leaching value at 0 h. The value of ion concentration without acid determines the solubility of the particles in water. Acid is then added with continuous stirring using a propeller stirrer.