Uv 3600 double beam spectrometer

X-ray diffraction (XRD, Brucker D8 Advance, Brucker, Germany) analysis were performed to determine the minerals of the raw VS and the leaching residues. The morphology and element distribution of the raw VS and the leaching residues were detected by a field emission-scanning electron microscopy coupled to an energy dispersive spectrometer (FESEM-EDS, SU8020, Hitachi, Japan). Using the Mastersizer 3000 laser particle size analyzer, the PS of the leaching residues was detected. The pore volume and specific surface area of the leaching residues were measured using the ASAP 2460 surface area analyzer. V concentration of the sampled leachate was determined using inductively coupled plasma massspectrometry (ICP-MS, Agilent ICPMS7800, Agilent, USA) analysis. The leachate pH and Eh were determined by pH and Eh meters. The Eh-pH diagram of V-H₂O system at 25 °C was obtained using HSC software based on the basic thermodynamic data. The ultraviolet visible (UV–vis) absorption spectra of the obtained leachates were determined using the UV-3600 double-beam spectrometer (Shimadzu, Japan).

Absorption spectra were collected using a UV-3600 double beam spectrometer (Shimadzu), and fluorescence spectra were collected using Fluoromax fluorescence spectrometer (Jobin Yvon). The solutions were degassed in a long-necked quartz cuvette using three freeze–thaw cycles and then mounted in a liquid nitrogen cryostat (Janis Research) for the measurements at low temperatures. Time-resolved photoluminescence spectra (including Ph) decays were measured using either a time-correlated single photon counting set-up (TCSPC, Horiba Deltaflex) with a range of nanoLED (357 nm) and laser diode (405 nm) excitation sources, or a nanosecond gated spectrograph-coupled iCCD (Stanford, 4Picos) and a high energy pulsed Nd:YAG laser emitting at 355 nm (SL312, EKSPLA); the pulse duration was approximately 150 ps and the energy of per pulse was chosen around 100 μJ. Emission was focused onto a spectrograph and detected on a sensitive gated iCCD camera (Stanford Computer Optics) having sub-nanosecond resolution. The quantum yields were determined using a Hamamatsu Photonics Absolute Quantum Yield Measurement System model c9920-02G. For powder measurements, a cylindrical quartz cuvette was used.