Cpi 505

The laboratory shaker type 358A (Elpin+, Lubawa, Poland) at amplitude 7 and the stirring rate 180 rpm was used for kinetic and adsorptive studies. After the V(V) adsorption the phases were separated by means of filtration and the pH was measured using a pH meter CPI-505 with a glass-electrode (Elmetron, Zabrze, Poland). The concentration of V(V) in the solution was determined by means of the graphite furnace atomic absorption spectroscopy (GF-AAS) and the Varian AA240Z (Varian Inc., Melbourne, Australia) spectrometer with the graphite tube furnace GTA120 and the four-step time-temperature program (wavelength 318.5 nm, slit width 0.2 nm, lamp current 10 mA).

The NH₄⁺ adsorption capacity (q) and removal efficiency (E) of mineral were calculated using the equations:
and

respectively, where: q (adsorption capacity at time t) is the total amount of adsorbed NH₄⁺ ions per unit of weight of mineral at time t (mgN/g_z); C₀,C_t, C_e are the initial, time t, and equilibrium concentrations of NH₄⁺ in solution (mg N/L); V is the initial volume of treated effluent (L); m is the adsorbent mass (g).
The content of ammonium ions in the wastewater was determined using the ammonium ion-selective electrode (DETEKTOR, Raszyn, Poland) with the silver-chloride reference electrode (DETEKTOR, Raszyn, Poland) and the ionometer (ELMETRON CPI-505, Zabrze, Poland). To control the values obtained by means of using the ammonium ion-selective electrode, the spectrophotometric Hach-Lange cuvette tests (LCK 302) (HACH LANGE Ltd., Wrocław, Poland) [30 ] have been used, and the initial and final concentration has been measured in the course of the experiments.
The chemical oxygen demand (COD) was determined spectrophotometrically using the HACH-Lange cuvette tests (LCK 514) (HACH LANGE Ltd., Wrocław, Poland) [30 ] at the beginning and end of each experiment, when the sorbent activation with NaCl has been studied to verify the possibility of COD removal.

The samples were shaken using a laboratory shaker type 357 of constant vibration speed (180 rpm) (Elpin Plus, Lubawa, Poland). The pH was measured using a pH meter, CPI-505, with a glass electrode (Elmetron, Zabrze, Poland). The concentrations of Cu(II), Zn(II), Mn(II) and Fe(III) complexes with EDDS in the filtrate were determined using the spectrometer ICP-OES of 720 ES type (Varian Inc., Palo Alto, CA, USA). The sample introduction system was equipped with a glass Conikal^® nebulizer, cyclonic double pass spray chamber and three-channel peristaltic pump. The optimal operating parameters used for determination of the studied elements by the ICP-OES technique are as follows: power, 1200 W; plasma argon gas flow rate, 15 dm³/min; auxiliary argon gas flow rate, 2.25 dm³/min; nebulizer argon gas flow rate, 0.2 dm³/min; pump rate, 12 rpm; analytical wavelengths: 327.395 nm for Cu, 213.857 nm for Zn, 257.610 nm for Mn and 259.940 nm for Fe. Scanning electron microscopy images were obtained using the Quanta 3D FEG microscope with the EDS/EBSD system (FEI). Fourier transform infrared spectra of hydrogels were recorded by the attenuated total reflectance technique (FTIR-ATR), and measurements were made using a FTIR Carry 630 spectrometer (Agilent Technologies, Santa Clara, CA, USA).