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Ultraviolet and Visible Spectrophotometry
Published in Thomas J. Bruno, Paris D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, 2020
Thomas J. Bruno, Paris D.N. Svoronos
Many of these determinations require the use of UV-Vis spectrometry (spectrophotometry) or the simpler colorimetric methods. For this reason, we have placed this table in this chapter rather than Chapter 13, but we realize there is overlap. For brevity, when a determination calls for a spectrophotometric measurement at a particular wavelength, for example at 500 nm, we denote this as: “spec λ = 500 nm.” No wavelength is specified if it is variable, for example, if there is a variation with pH; here we simply indicate: “spec determination.” When a determination calls for spectrofluorometric determination, the excitation and emission wavelengths are provided; thus, specf λex = 303.5 nm and λem = 353 nm. Note that often, surfactants (such as cetyltrimethylammonium bromide, abbreviated CTAB) are used in the test. We provide in Chapter 14 a table of the common surfactants and their properties. When relevant, we provide an approximate limit of detection (LOD), and when the uncertainty can vary, this is expressed as a relative standard deviation (RSD). Some of the procedures listed here require the use of hazardous chemicals (carcinogens such as benzene, strong acids such as HF). Appropriate precautions must always be observed.
Analytical Chemistry
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
In this table of organic reagents used for determination of inorganic elements and compounds we present the major tests, reagents, and some guidance as to the expected result or method of observation. The abbreviations used here are defined in the abbreviations table in this section. In addition, for brevity, when a determination calls for a spectrophotometric measurement at a particular wavelength, for example at 500 nm, we denote this as: "spec = 500 nm." No wavelength is specified if it is variable, for example, with pH; here we indicate: "spec determination." When a determination calls for spectrofluorimetric determination, the excitation and emission wavelengths are provided, thus: specf ex = 303.5 nm, em = 353 nm. Note that a common surfactant used in many of these tests is cetyltrimethylammonium bromide, abbreviated (CTAB). Information and data on this and other surfactants commonly used in chemical analysis are provided in Section 6. When relevant, we provide an approximate limit of detection (LOD), and when the uncertainty can vary, this is expressed as a relative standard deviation (RSD). Some of the procedures listed here require the use of hazardous chemicals (carcinogens such as benzene, strong acids such as HF). Appropriate precautions must be observed. While a great deal of the information presented here is from the recent literature, the reader is referred to several excellent reviews and monographs for additional information (Refs. 1-10). I. Cations
Surfactants versus surface functionalization to improve the stability of graphene nanofluids
Published in Journal of Dispersion Science and Technology, 2022
Camilo Zapata-Hernandez, Geraldine Durango-Giraldo, Diana López, Robison Buitrago-Sierra, Karen Cacua
All the chemicals were reagent-grade and used without any further purification. Graphene nanolayers (thickness, 6–8 nm; average particle diameter, 15 µm; from SSNano) were used in the preparation of the nanofluids; their main characteristics are shown in Table 1. Anionic sodium dodecylbenzenesulfonate (SDBS, Sigma-Aldrich) and cationic cetyltrimethylammonium bromide (CTAB, ≥98% Sigma-Aldrich), at critical micelle concentration, were used for the electrostatic stabilization. These samples were labeled G-SDBS and G-CTAB, respectively. High-purity graphite rods (3 × 305 mm, 99.9%, SPI supplies), sulfuric acid (H2SO4, 96%, Fisher Scientific), and sodium sulfate (Na2SO4, 99%, Chemi) were employed in the graphene oxide synthesis. Paper filter (ADVANTEC) All the dispersions (0.1 wt%) were prepared by the two-step method using deionized water as base fluid. The nanomaterials were dispersed using a probe (QSonica, Q500) operated at 20 kHz, 30% amplitude, and 20 minutes of sonication. Additionally, pulses (1 second on and 2 seconds off) were programmed to control nanofluid heating. Furthermore, to dissipate the heat produced during the ultrasonication, the nanofluid container was immersed in a larger container filled with refrigerated water.
Solubilisation of fruits and vegetable dregs through surfactant mediated sonic disintegration: impact on biomethane potential and energy ratio
Published in Environmental Technology, 2021
M. Shanthi, J. Rajesh Banu, P. Sivashanmugam
FVD consisting of cabbage leaves, rotten beans, cassava, pineapple peel, water melon peel, pomegranate peel were received from fruit Juice shop, NIT Tiruchirappalli and vegetable market, Thiruverumbur, Tiruchirappalli, India. Substrate (FVD) was prepared as per method reported by Kavitha et al. [19] and stored at 4°C for further use. Raw waste (FVD) characterisation was as follows: total solids (TS) g/L – 35 ± 0.3; total chemical oxygen demand (TCOD) g/L – 29 ± 0.3; soluble COD (SCOD) g/L – 0.85 ± 0.05; suspended solids (SS) g/L – 23 ± 0.2; cellulose (% of TS) – 25; lignin (% of TS) – 16.7%. Surfactant (CTAB) was supplied as cetyltrimethylammonium bromide by Merck, India. The chemicals and reagents used for this study are of analytical grade supplied by Merck Specialities Pvt. Ltd (Mumbai, India).
Polar anchoring energy and tilt angle measured by magneto-optical technique in nematic doped with ionic surfactant
Published in Liquid Crystals, 2020
Alexander M. Parshin, Vitaly S. Sutormin, Victor Ya. Zyryanov, Vasily F. Shabanov
The experiment was carried out with sandwich-like cells. These cells consisted of two glass substrates covered by the polymer films of polyvinyl alcohol (PVA) which specify the planar surface anchoring for LC. Spin coater HO-TH-05 (HOLMARC) was used to form the polymer films on the substrates by spin coating. Then the polymer films were uniaxially rubbed by Rubbing machine HO-IAD-BTR-01 (HOLMARC) to assign the uniform director orientation on the PVA films. The substrates were assembled into cells so that the rubbing directions of the polymer films at the top and bottom surfaces were antiparallel. The cell gap thickness d was set using teflon films and measured by means of the interference technique with the spectrometer HR4000CG-UV-NIR. One pair of cells had the gap thicknesses d1 = 13.6 μm and d2 = 13.9 μm (thick samples) while the other samples had d3 = 5.0 μm and d4 = 4.8 μm (thin samples). The cells with d1 and d3 were filled with undoped nematic 4-pentyl-4′-cyanobiphenyl (5CB), the samples with d2 and d4 were filled with 5CB containing 0.78 wt. % of ionic surfactant cetyltrimethylammonium bromide (CTAB).