Asap 2020 volumetric adsorption analyzer

N₂ adsorption–desorption measurements were conducted using an ASAP 2020 volumetric adsorption analyzer (Micromeritics, Norcross, GA, USA). The specific surface areas were measured using the standard Brunauer-Emmett-Teller (BET) method. The surface morphology of the samples was characterized via a scanning electron microscope (SEM, ZEISS SUPRA 55, Jena, Germany). The composition and chemical oxidation state of the elements were determined by X-ray photoelectron spectroscopy (XPS, ESCALAB 250Xi, ThermoFisher Scientific, Waltham, MA, USA). Fourier-transform infrared spectroscopy (FTIR, VERTEX 70, Bruker, Karlsruhe, Germany) was used for the characterization of CuFe₂O₄ before and after the reaction. The pH values were measured via a pH meter (Starter-3100, Ohaus, Parsippany-Troy Hills, NJ, USA). The PAA concentration was measured according to the N, N-diethyl-p-phenylenediamine (DPD) colorimetric method [57 (link)]. The Rhodamine B concentration was measured via a UV-Vis spectrophotometer (Agilent, Santa Clara, CA, USA) at 553 nm.

Scanning electron microscopy (SEM, JSM-6701F, operating at 10 kV) and transmission electron microscopy (TEM, JEOL-2010, operating at 200 kV) were carried out to characterize morphologies and structures of the samples. Powder X-ray diffraction (XRD) measurements were performed on a RIGAK X-ray diffractometer (D/MAX2550 VB/PC, Japan) using a Cu Kα radiation (1.5418 Å) at a voltage of 40 kV. Raman spectra were measured on a Tri Vista^TM 555CRS Raman spectrometer at 532 nm of excitation. X-ray photoelectron spectroscopy (XPS) measurements were operated with an ESCLAB 250 spectrometer using X-ray source of Al Kα (1486.6 eV photons). The specific surface area determination and pore size distribution analysis were carried out by the Brunauer-Emmett-Teller (BET) method and density functional theory (DFT) pore model, respectively, using an ASAP2020 volumetric adsorption analyzer (Micromeritics) at 77 K.

The surface morphologies of all samples were studied by scanning electron microscopy (SEM). Prior to SEM observation, the samples were coated with spray-gold under high-vacuum conditions. The composition of BC and the BC/EVMT composite were analyzed using a PHI 5000 VersaProbe spectrometer (ULVAC-PHI, Chigasaki, Japan). FTIR spectra were reflected using a Thermo Scientific Nicolet iS5 spectrometer (Spectral range: 500 cm⁻¹ to 4000 cm⁻¹, resolution: 2 cm⁻¹). The thermogravimetric analysis (TGA) was performed on a TA instrument (model no 300, EXSTAR, Fukuoka, Japan) with temperature ranging from 50 °C to 800 °C, a heating rate of 10 °C min⁻¹, and under a nitrogen atmosphere. X-ray diffractometry (XRD) patterns were obtained using a Bruker AXS D8 advanced diffractometer with Cu Kα radiation (λ = 1.5418 Å) at 30 kV and 15 mA, with a scanning rate of 5° min⁻¹ and a 2θ angle ranging from 5° to 70°. XPS analyses were carried out using X-ray photoelectron spectroscopy (ESCALAB 250Xi, Thermo Scientific Escalab, Waltham, MA, USA). The Brunauer–Emmett–Teller (BET) surface area and pore size were obtained by the N₂ adsorption–desorption isotherm at 77 k with a Micromeritics ASAP 2020 volumetric adsorption analyzer.

The samples were characterized by different analytical techniques. Simultaneous TG/DSC analysis was performed on a NETZSCH STA 449 C Jupiter system. Optical image was captured on a Nikon Microphot-FXA microscope. SEM observations were made on a JEOL JSM-6700F field-emission SEM. TEM images, SAED pattern, EELS, and EDS were obtained on a JEOL JEM-2100F STEM (200 kV, field-emission gun) system equipped with an Oxford INCA x-sight EDS and an ENFINA 1000 EELS. XPS spectra were acquired on a Thermo Scientific Escalab 250Xi spectrometer. XRD measurement was conducted using a Rigaku SmartLab Intelligent X-ray diffraction system with filtered Cu K_α radiation (λ = 1.5406 Å, operating at 45 kV and 200 mA). Raman measurement was taken using a Horiba Jobin Yvon LabRAM HR system with a laser wavelength of 488 nm. The nitrogen adsorption and desorption isotherms were obtained at 77 K with a Micromeritics ASAP 2020 volumetric adsorption analyzer.