Separation of high‐purity syringol and acetosyringone from rice straw‐derived bio‐oil by combining the basification‐acidification process and column chromatography

Abstract

Numerous technologies have been used to reclaim valuable chemicals from bio-oil. In this study, a combination of the basification-acidification process and column chromatography was employed for the separation of high-purity syringol and acetosyringone from rice straw-derived bio-oil. The optimal conditions for the basification-acidification process and the possible precipitation mechanism of the basification were explored. The results showed the following as the optimal conditions for the basification process: mass ratio of calcium hydroxide (Ca(OH) ) to bio-oil, 2.0; reaction temperature, 70°C; and reaction time, 30 min. The results also showed that 1.6 mol of hydrochloric acid (HCl) per gram of bio-oil was optimal for the acidification. The precipitation was found to proceed via a possible mechanism involving the reaction of the phenolic compounds in the bio-oil with Ca(OH) to produce a precipitate. After further separation by column chromatography, purities of 91.4 and 96.2% (from gas chromatography-mass spectrometry) were obtained for syringol and acetosyringone, respectively. Their recoveries for the whole process were 73.0 and 39.3%, respectively.

Improving fast pyrolysis of lignin using three additives with different modes of action

“…However, the results of the studies by Zhou et al 52 and Li et al 54 cannot exclude the formation of a cross-linked structure, like lignin-O-Ca-O-ϕlignin. Instead, the FT-IR spectra of lignin-calcium hydroxide recorded by Zhou et al 52 and Li et al 54 and the FT-IR spectra for various pure (methoxy)phenols precipitated with calcium hydroxide recorded by Schlosberg and Scouten 56 and Hao et al 74 seem to support the hypothesis that two lignin-phenolic moieties react with calcium hydroxide and thus induce cross-linking.…”

“…52,56 This peak was, however, not observed in the FT-IR spectra for lignin to which calcium hydroxide was added. 52,54 The addition of calcium hydroxide to pure methoxyphenols (guaiacol, syringol, 4-ethylguaiacol, and acetosyringone), phenol, and 4-ethylphenol by Hao et al 74 led to a precipitate in case of the methoxyphenols, but not for phenol and 4-ethylphenol. Those precipitates also lacked a characteristic peak for OH at ν = 3640 cm −1 , which would be apparent if half salts would have been formed.…”

Syringol Isolated From Eleusine Coracana (L.) Gaertn Bran Suppresses Inflammatory Response Through the Down-Regulation of cPLA2, COX-2, IκBα, p38 and MPO Signaling in sPLA2 Induced Mice Paw Edema.

“…They are major constituents of wood smoke condensate and identified as having a woody/herby flavor and smoky odor (Maga 1987). Syringol is also been isolated from rice straw derived bio-oil (Hao, Chen et al 2016). Apart from being a constituent of wood smoke, syringol is shown to exhibit different bio-functions.…”

An overview of recent development in bio-oil upgrading and separation techniques

“…The eluents used in bio-oil separation are hexane, toluene, benzene, pentane, ethyl acetate, and methanol [72][73][74]. However, Hao et al [75] reported that the valuable chemical compound like syringol and acetosyringone can be effectively separated from column chromatography.…”