2.2. Chemical composition of charcoal after cavitation
To characterize the properties of the charcoal suspension after cavitation (CHAR-C), the following properties were determined in the material: electrical conductivity – conductometrically, pH – potentiometrically, and the content of N-NH4 and N-NO3 – using ion selective electrodes. The contents of macroelements (P, K, Ca, and Mg) and trace elements (Cu, Fe, Mn, and Zn) were determined after mineralising the sample in a mixture of concentrated HNO3 and HClO4 (3:2). The contents of the studied elements were determined in the obtained solutions by inductively coupled plasma optical emission spectrometry (ICP-OES, Perkin Elmer Optima 7300 DV, Waltham, USA) (Oleszczuk et al. 2007). The material chemical composition is presented in Table 1.