Cpc 411

Changes in TBBPA concentration were determined by high performance liquid chromatography (HPLC, Shimadzu, Kyoto, Japan) equipped with a UV detector (SPD-10 AV) and a C18 column (Knauer 250 mm × 4.6 mm with precolumn, Eurospher II, 100-5 C18 H). Analysis conditions: mobile phase—70% acetonitrile and 30% water, flow rate: 1.0 cm³ min⁻¹, injection volume: 20 × 10⁻³ cm³, absorbance detection: 310 nm. For calibration, nine standardised TBBPA solutions with concentration levels ranging from 2.0 × 10⁻⁵ to 1 × 10⁻⁶ mol dm⁻³ were used.
The concentration of bromide ions was assessed using a potentiometric technique using a bromide-ion-selective electrode (EBr-01, Hydromet, Gliwice, Poland) with a silver chloride reference electrode (RL-100, Hydromet, Gliwice, Poland) and a multimeter (CPC 411, Elmetron, Zabrze, Poland). For the quantification of the bromide ions, seven standardised bromide solutions with concentration levels ranging from 10⁻⁵ to 10⁻² mol·dm⁻³ were used.

The materials used and generated in the study (process residues), with some exceptions, were analyzed for total solids (TS), volatile solids (VS), ash content (AC), pH, electrical conductivity (EC), elemental contents (C, H, N, S, O), and trace elements content (Fe, Co, Mo, Se, W, Cu, Zn, Mn). The TS, VS, and AC were determined using a laboratory dryer (WAMED, model KBC-65W, Warsaw, Poland) and muffle furnace (SNOL, model 8.1/1100, Utena, Lithuania) according to the PN-EN 14346:2011 and 15169:2011 standards [31 ,32 ]. The pH and EC were measured using a ph/EC meter (Elmetron, model CPC-411, Zabrze, Poland). For the dry materials, the pH and EC measurements were made in material-to-distilled water solutions of 1:10 by mass, while for the liquid materials, direct measurement was made. The elemental content was determined using an elemental analyzer (PerkinElmer, 2400 CHNS/O Series II, Waltham, MA, USA). The trace element content was determined using an inductively coupled plasma atomic emission spectrometry (Thermo Scientific, model 7400, Waltham, MA, USA) according to the PN-EN ISO 118852009 standard [33 ].

The PZC of catalysts was measured according to Kocharova and co-workers [41 (link)]. For the determination of pH_PZC, eleven vials were filled with 0.1 mol·L⁻¹ NaCl solution. The pH of each vial was adjusted with NaOH and HCl solutions to pH 2–12. Next, 10 mg of catalyst was dispersed in each vial. The solution was constantly agitated at 240 rpm for 3 h at ambient temperature to reach equilibrium. The equilibrium pH value was measured with a multimeter (CPC 411, Elmetron, Poland) and the values were plotted against the initial pH values for both series. The PZC value was then obtained from the point at which the curve showing final pH vs initial pH intersected the y = x line on the graph. The morphology of the catalysts was observed with a field-emission scanning electron microscope (Zeiss Ultra 55, Oberkochen, Germany). The crystalline phases were analyzed with a Cu Kα powder diffractometer (D8 Advance, Bruker, Ettlingen, Germany) operating at 40 kV and 36 mA (λ = 0.154056 nm). The optical characterization of the catalysts was performed by using a spectrophotometer (Cary Series UV-Vis-NIR, Agilent Technologies) in the wavelength range of 190–800 nm.