In situ determination of the syringyl/guaiacyl ratio of residual lignin in pre-bleached eucalypt kraft pulps by analytical pyrolysis

Abstract

Keywords:Py-GC/MS-SIM S/G ratio Residual lignin Oxygen pre-bleached cellulosic pulp a b s t r a c t Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 • C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans-4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans-isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.

Characterization and use of a lignin sample extracted from Eucalyptus grandis sawdust for the removal of methylene blue dye

“…Twenty compounds were identified by GC-MS (Table 4) in the pyrogram of the E. grandis lignin sample (Figure 3). These compounds were mainly phenolic moieties that are characteristic of lignocellulosic materials [54,55]. The ubiquitous palmitic (C 16 ) and stearic (C 18 ) fatty acid methyl esters, which are not specific, were also detected.…”

Characterization and identification of traditional Chinese handmade paper via pyrolysis-gas chromatography-mass spectrometry

“…1, labelled as 12, 14) and syringyl (S) (Fig. 1, labelled as 13, 16) lignin content, which are difficult to delignified (Lima et al 2015). Lignin compounds were not detected in other three kinds of handmade papers, because the lignin content of their raw materials is low.…”

“…1, labelled as 16), which were not found in the other three samples. Those phenolic compounds are the pyrolysis products of lignin (Lima et al 2015). It is known that paper primarily consists of cellulose, hemicellulose, and a small amount of lignin.…”

Bleachability improvement of eucalypt mechanical pulps using hydrogen peroxide in ethanol-water media

“…1379 The structure of residues in spent bleaching liquors of four samples bleached in two alkali dosages (35 and 50 kg NaOH/t o.d.) and two kinds of solvent systems were characterized by Py-GC/MS, which is an efficient tool to characterize the chemical composition of the macromolecular organic compounds (Ibarra et al 2007;Lima et al 2015). Pyrolysis products in Table 3 were classified as benzene and hydrocarbyl benzene (B), phenol and hydrocarbyl phenol (H), guaiacol and hydrocarbyl guaiacol (G), and syringol and hydrocarbyl syringol (S).…”