2000 spectrophotometer

Attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR): The precursors and the resins were analyzed with a PerkinElmer 2000 spectrophotometer equipped with an attenuated total reflection (ATR) setup. The analysis was made in a range of 400–4000 cm⁻¹.

FTIR spectra measurements were determined using a PerkinElmer 2000 spectrophotometer. Each sample was mixed with crystalline KBr in a 1:10 (sample/KBr) ratio and left for 6 min on the disk for dehydration. A spectrum was measured using wavenumbers in the 400 to 4,000 cm⁻¹ range. X-ray diffraction (XRD) patterns for Fe₃O₄- and PVA@Fe₃O₄-loaded p-CoA and GA were obtained with a Philips PW 1710 X-ray diffractometer using Cu Kα radiation (λ = 1.78987 Å) at the ranges angle (2θ) 12 in the range of 5° to 80°, and the tube was operated at 40 kV and 30 mA. The vibrating sample magnetometer (VSM) was examined with a 0.5 T physical property measurement system (PPMS-9; Quantum Design, USA) at 300 K.

The samples were dispersed in potassium bromide using a mortar and pestle and were pressed to thin and translucent tablets. FT-IR was performed in a PerkinElmer 2000 spectrophotometer (Waltham, MA, USA), and the spectra were recorded from 4000 to 400 cm⁻¹.

The melting points were determined on a Krüss KSP 1N capillary melting point apparatus. Infrared (IR) spectra (ATR-FT or KBr) were recorded on a PerkinElmer 2000 spectrophotometer. ¹H and ¹³C nuclear magnetic resonance (NMRs) spectra were captured on a Varian Mercury (300 MHz) instrument, with CDCl₃ as the solvent and tetramethylsilane (TMS) as the internal standard. Signal assignments were based on two-dimensional NMR spectra (heteronuclear multiple quantum correlation [HMQC] and heteronuclear multiple-bond correlation [HMBC]). High-resolution mass spectra (HRMS) were obtained (in electron impact mode) on a Jeol JSM-GCMateII spectrometer. Analytical thin-layer chromatography was carried out using E. Merck silica gel 60 F254-coated 0.25 plates, visualized by using a long- and short-wavelength UV lamp. Flash column chromatography was conducted over Natland International Co. silica gel (230-400 and 230-400 mesh). All air moisture-sensitive reactions were carried out under N₂ using oven-dried glassware. CH₂Cl₂ and DMF (Sigma-Aldrich) were distilled over CaH₂ (Sigma-Aldrich) prior to use. All other reagents (Sigma-Aldrich) were employed without further purification.

X-ray powder diffraction (XRPD) patterns of the synthesized nanoparticles were collected using a Bruker D2 Phaser diffractometer, controlled by a Diffract. measurement software, operating at 30 kV and 10 mA in Bragg-Brentano reflection geometry with CoKα radiation (λ = 1.7880 Å), using a 2° range 20°–90° and a scanning rate of 2° min^–1. The functionalization, chemical modification of the support and immobilization process of all samples were carried out by FTIR spectroscopy. The spectra were obtained for dried samples (pressed in disk-shaped KBr pellet) in the range 4000–400 cm^–1 using a Perkin Elmer 2000 spectrophotometer. Transmission electron microscopy (TEM) images of biocatalyst were obtained using a Hitachi^® HT7700 TEM system operating at an accelerating voltage of 120 kV. In order to perform the TEM investigation, the nanomaterials were firstly dispersed in ethanol and deposited onto a carbon-coated copper grid sample holder. The magnetic curves were obtained using a vibrating sample magnetometer (VSM) at 300 K. In order to assure the magnetic moments values acquired, the VSM was previously calibrated using a standard reference material (yttrium Iron Garnet Sphere) from the National Institute of Standards and Technology (NIST). For all measurements, the magnetic moment obtained for each applied field was normalized by the mass of NPs.

Samples were dried at 105°C in a furnace for 48 h, and then ground in a laboratory ball mill (Retsch mill model MM200) before analysis. Two milligrams of each dried milled sample was ground with 200 mg KBr (FTIR grade) and homogenized. KBr pellets were compressed under vacuum in a standard device under pressure of 6000 kg cm^-1 for 10 min. Infrared spectra were recorded using an FTIR Perkin-Elmer 2000 spectrophotometer over the 4000 to 400 cm^-1 range at a rate of 0.5 cm s^-1. Fifty scans were collected, averaged for each spectrum, and corrected against ambient air as background, as described by Cuetos et al. [24 (link)]. Digestate samples from semi-continuous experiments and SS feedstock were analyzed. Spectra are represented as the mean values of three replicates for each sample. Digestate samples were obtained at the end of experiments prior to dismantling the semi-continuous reactors. Sewage sludge and commercial LCFAs (palmitic and stearic acids) were also analyzed to facilitate the interpretation of the spectra. Moreover, spectra were vector-normalized for comparison following the procedure proposed by Meissl et al. [25 (link)].