Fast spectroscopic monitoring of inhibitors in the 2G ethanol process

Abstract

One of the main challenges of second generation (2G) ethanol production is the high quantities of phenolic compounds and furan derivatives generated in the pretreatment of the lignocellulosic biomass, which inhibit the enzymatic hydrolysis and fermentation steps. Fast monitoring of these inhibitory compounds could provide better control of the pretreatment, hydrolysis, and fermentation processes by enabling the implementation of strategic process control actions. We investigated the feasibility of monitoring these inhibitory compounds by ultraviolet-visible (UV-Vis) spectroscopy associated with partial least squares (PLS) regression. Hydroxymethylfurfural, furfural, vanillin, and ferulic and p-coumaric acids generated during different severities of liquid hot water pretreatment of sugarcane bagasse were quantified with highly accuracy. In cross-validation (leave-one-out), the PLS-UV-Vis method presented root mean square error of prediction (RMSECV) of around only 5.0%. The results demonstrated that the monitoring performance achieved with PLS-UV-Vis could support future studies of optimization and control protocols for application in industrial processes.

Benchmarking real-time monitoring strategies for ethanol production from lignocellulosic biomass

“…glucose or ethanol) and because the light scattering caused by the suspended solid particles dominates the absorption process [35,52]. However, in the context of cellulose to ethanol fermentation, the technique gains special relevance because many of the inhibitors present in lignocellulosic hydrolysate including furfural, HMF or acetic acid absorb in this region [53]. Pinto et al [53] used at-line UV-Vis spectroscopy to quantify the concentration of furfural and HMF from filtered samples, attaining a high sensitivity and low prediction errors (RMSEP of 0.375 g/L and 0.041 g/L for furfural and HMF respectively).…”

“…However, in the context of cellulose to ethanol fermentation, the technique gains special relevance because many of the inhibitors present in lignocellulosic hydrolysate including furfural, HMF or acetic acid absorb in this region [53]. Pinto et al [53] used at-line UV-Vis spectroscopy to quantify the concentration of furfural and HMF from filtered samples, attaining a high sensitivity and low prediction errors (RMSEP of 0.375 g/L and 0.041 g/L for furfural and HMF respectively). UV-Vis is a useful method to quickly detect inhibitory compounds and lactic acid (useful to detect contaminations), in an inexpensive manner.…”

Application of green analytical chemistry to a green chemistry process: Magnetic resonance and Raman spectroscopic process monitoring of continuous ethanolic fermentation

“…It is advantageous to apply PLS2 when the target variables are interdependent or correlated with each other, as is often the case with chemical reactions, and when the correlated y variables possess different error ranges. The dimensions of the analyzers should follow an ecological and economical point of view (Pinto, Pereira, Ribeiro, & Farinas, ; Pinto, Ribeiro, & Farinas, ). Compact spectrometers, that is, small‐dimension analyzers, are flexible, robust and today available for a wide range of applications (Blümich, ; Blümich & Singh, ; Danieli et al, ; Kern et al, ; Killner, Garro Linck, Danieli, Rohwedder, & Blümich, ; Kreyenschulte, Paciok, Regestein, Blümich, & Büchs, ; Meyer, Kern, Zientek, Guthausen, & Maiwald, ; Singh, Danieli, & Blümich, ).…”

“…It is advantageous to apply PLS2 when the target variables are interdependent or correlated with each other, as is often the case with chemical reactions, and when the correlated y variables possess different error ranges. The dimensions of the analyzers should follow an ecological and economical point of view (Pinto, Pereira, Ribeiro, & Farinas, 2016;Pinto, Ribeiro, & Farinas, 2018).…”

Pre-treatment of steam explosion, chemical and morphological characterization of sugarcane bagasse used for 2G Ethanol production

“…O que justifica a perda do rendimento etanólico em fermentações com altas taxas dos subprodutos formados durante o pré-tratamento da biomassa. Sob essa perspectiva, Pinto e cols 29. afirmam que os principais desafios da produção de etanol 2G sejam as altas concentrações de compostos fenólicos e derivados de furano gerados no pré-tratamento da biomassa lignocelulósica, os quais agem suprimindo a eficiência da hidrólise enzimática e fermentação.…”