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Other Feedstocks—Coal, Oil Shale, and Biomass
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
The first step in refining benzole is steam distillation is employed to remove compounds boiling below benzene. Low-boiling naphtha and high-boiling naphtha are the mixtures obtained when the 150°C–200°C (300°F–390°F) fraction, after removal of tar acids and tar bases, is fractionated. These naphtha fractions are used as solvents. To obtain pure products, the benzole can be distilled to yield a fraction containing benzene, toluene, and xylene(s). Benzene is used in the manufacture of numerous products including nylon, gammexane, polystyrene, phenol, nitrobenzene, and aniline. On the other hand, toluene is a starting material in the preparation of saccharin, trinitrotoluene, and polyurethane foams. The xylenes present in the low-boiling oil are not always separated into the individual pure isomers since xylene mixtures can be marketed as specialty solvents. Higher-boiling fractions of the distillate from the tar contain pyridine bases, naphtha, and coumarone resins. Other tar bases occur in the higher-boiling range and these are mainly quinoline, isoquinoline, and quinaldine.
New analytical methods for the determination of sulfur species with microextraction techniques: a review
Published in Journal of Sulfur Chemistry, 2022
Arina Skok, Yaroslav Bazel, Andriy Vishnikin
According to our knowledge, in the last decade only two microextraction methods were proposed for SDS determination. The first is based on the ion association complex formation between sodium dodecyl sulfate ion and the cationic form of quinaldine red [53], extraction with 100 µL of a 4:1 mixture of carbon tetrachloride and dichloroethane and measuring the absorbance. The detection limit of the method is calculated as 0.04 mg L−1, and a selectivity study showed no significant interference of other ions that may be present in water samples. The accuracy of the method was successfully tested on rinse water from a washing machine. In the secone method, the reaction of sodium dodecyl sulfate with methylene blue was used for anionic surfactants and SDS determination in a continuous sample drop flow-based microextraction [54]. The method is based on the continuous flow of sample through the layer of extraction solvent (90 µL of chloroform) using a peristaltic pump. A high enrichment factor was achieved that allowed high sensitivity (LOD = 8.2 µg L−1) to be achieved. However, this parameter strongly depends not only on the nature of solvent and analyte, but also on the transfer rate of analyte through the border phase. The method was applied to the analysis of shampoo, hand washing liquid and liquid laundry detergent.