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Chromatography
Published in Pau Loke Show, Chien Wei Ooi, Tau Chuan Ling, Bioprocess Engineering, 2019
Kirupa Sankar Muthuvelu, Senthil Kumar Arumugasamy
Based on chromatographic bed shape, chromatography is generally classified into column chromatography and planar chromatography. Basically, chromatography is classified into gas, liquid, and supercritical fluid chromatography (Figure 6.1). Liquid chromatography can be classified further based on properties such as size, charge, and affinity. To identify and characterize the resulting product, several identification methods such as Fourier transform infrared spectroscopy (FT-IR) for identifying functional groups, mass spectrometry (MS) for determining molecular weight, and nuclear magnetic resonance (NMR) spectroscopy for predicting the molecular structure, and so on, are employed. Data from all the methods are put together to predict the formed product.
A critical review of separation technologies in lignocellulosic biomass conversion to liquid transportation fuels production processes
Published in Chemical Engineering Communications, 2022
Paola Ibarra-Gonzalez, Lars Porskjaer Christensen, Ben-Guang Rong
In column chromatography, the substances are separated based on their different adsorption capabilities on a stationary phase. Regularly, as the stationary phase, silica gel is employed, and depending on the polarity of the components in the mixture, an eluent is selected (Wang 2013). Li et al. (2005) performed the separation of bio-oil from fast pyrolysis via liquid chromatography. For its separation, a silica gel column was employed, in which the bio-oil was washed down using different solvents like cyclohexane, benzene and methanol. The fractions obtained from the separation were analyzed by GC-MS. The results showed that aromatics with up to four rings predominated in the first fraction, one ring aromatics in the second fraction and polar compounds were found in the third fraction. Moreover, it was found that chemicals like phenol and naphthalene and methyl-naphthalene are produced from lignin and cellulose, respectively (Li et al. 2005).
Role of asphalt binder compositions in the thermoreversible aging Process
Published in International Journal of Pavement Engineering, 2022
Haibo Ding, Azuo Nili, Ali Rahman, Chuanqi Yan, Yanjun Qiu, David Connolly
As asphalt binder is a mixture of various hydrocarbons and their non-metallic (oxygen, sulfur, nitrogen) derivatives, it is difficult to divide it into several single compounds. For the convenience of analysis, it is usually divided into several components according to the polarity of asphalt to the solvent (Helm 1969). Column chromatography is a common method for the purification and separation of organic or inorganic substances. Usually, the substance to be separated is uniformly added to the glass column containing the stationary phase, and then an appropriate eluent is added for washing. Owing to the different speeds of each component moving with the mobile phase in the column, the components are separated by quantitatively collecting the eluent in sections. Finally, the elution solvent is removed by a rotary evaporator to obtain the asphalt components. To be specific, the asphalt binder is separated into four fractions according to the ASTM D4124 method. The four fractions are defined as iso-octane insoluble asphaltenes, naphthene aromatics, polar aromatics, and saturates. In this study, each separation experiment was performed in duplicate in order to allow repeatability. To characterize the dispersion in the polarity of the constituent molecules of a selected asphalt binder, the Gaestel index was used: where Gaestel index (GI) is an empirical parameter characteristic of the degree of dispersion in polarity of an asphalt binder; A is asphaltenes content; SAT is saturates content; PA is polar aromatics content; and NA is naphthene aromatics content.