Furfural Degradation Research Articles

Detoxification of furfural in Corynebacterium glutamicum under aerobic and anaerobic conditions.

The toxic fermentation inhibitors in lignocellulosic hydrolysates raise serious problems for the microbial production of fuels and chemicals. Furfural is considered to be one of the most toxic compounds among these inhibitors. Here, we describe the detoxification of furfural in Corynebacterium glutamicum ATCC13032 under both aerobic and anaerobic conditions. Under aerobic culture conditions, furfuryl alcohol and 2-furoic acid were produced as detoxification products of furfural. The ratio of the products varied depending on the initial furfural concentration. Neither furfuryl alcohol nor 2-furoic acid showed any toxic effect on cell growth, and both compounds were determined to be the end products of furfural degradation. Interestingly, unlike under aerobic conditions, most of the furfural was converted to furfuryl alcohol under anaerobic conditions, without affecting the glucose consumption rate. Both the NADH/NAD(+) and NADPH/NADP(+) ratio decreased in the accordance with furfural concentration under both aerobic and anaerobic conditions. These results indicate the presence of a single or multiple endogenous enzymes with broad and high affinity for furfural and co-factors in C. glutamicum ATCC13032.

Kinetic study on homogeneously catalyzed xylose dehydration to furfural in the presence of arabinose and glucose

It is known that lower furfural yields are obtained for the dehydration of biomass resources compared to pure pentoses. In order to study this discrepancy, the dehydration of xylose (0.05 mol L−1) in complex saccharide solutions using homogeneous catalysts is investigated. Firstly, kinetic results are presented for the dehydration of both xylose and arabinose in separate experiments. In the second part, experimental results of the dehydration of xylose in complex saccharide solutions are compared with these kinetic models. It is observed that pentoses disappear similarly in complex saccharide solutions as they do separately. Furfural, however, is degrading faster in more complex saccharide solutions. Both the presence of pentose and hexose degradation products enhances furfural degradation, however, the effect of the latter was larger. These observations partly explain the lower furfural yields observed for the dehydration of actual biomass resources.

ANALYZED AND PROPOSED MECHANISM OF PHOTOCATALYTIC DEGRADATION OF FURFURAL AT TIO2 NANO-PARTICLES BY HPLC-UV AND LC-MASS METHODS

In this work the degradation of furfural in aqueous solution was investigated by means of photo catalysis of TiO2 nanoparticles with 25 nm crystallite sizes and surface area of 50 ± 10 m2 g−1, that was immobilized on a glass support by impregnation and calcination methods. The effects of amount of TiO2, irradiation intensity, and pH on efficiency of TiO2 nanoparticles were studied by HPLC-UV method. The optimum conditions are found as follows: pH = 7, 120 min of irradiation, and 125 W light intensity. In addition, the mechanism of photocatalytic degradation of furfural was studied by LC-Mass technique. According to the LC-MASS data we proposed three steps for furfural degradation including aldehyde group oxidation, photo-oxidation of aromatic ring and ring cleavage. Furfural photocatalytic reaction in 140min led to production of maleic and 2, 3-Dihydroxy-succinic (tartaric) acids as intermediates.

Kinetics of furfural production from pre-hydrolysis liquor (PHL) of a kraft-based hardwood dissolving pulp production process

The kinetics of C-5 sugars (xylose/xylan) conversion to furfural in an industrial pre-hydrolysis liquor (PHL) in both acetic acid (HAc)-catalyzed system and sulfuric acid (H2SO4)-catalyzed system, were determined in a temperature range of 150–190 °C. The main reactions involved during the process included: 1) C-5 sugars consumption for furfural formation and side reactions; 2) furfural degradation. It was found that these reactions followed first order kinetics. A consecutive reaction model (from xylose to furfural, then to degradation products) fitted into the data obtained in the H2SO4-catalyzed system; while a consecutive/parallel model suited for the HAc-catalyzed system due to side reactions, which also consumed C-5 sugars. The activation energy for C-5 sugar disappearance, and the furfural degradation, was 151 kJ mol−1 and 115 kJ mol−1, respectively, in the HAc-catalyzed system.

Kinetics of furfural destruction in a formic acid medium

Kinetics of furfural degradation in a formic acid catalyst was studied, and it was found out that the overall order of the reaction changes with the amount of acid catalyst.

Methanesulfonic acid-catalyzed conversion of glucose and xylose mixtures to levulinic acid and furfural

Methanesulfonic acid (MSA) was compared with sulfuric acid for the conversion of glucose and xylose mixtures to produce levulinic acid and furfural. The interactions of glucose and xylose, the predominant sugars found in biomass, were found to influence product yields with furfural degradation reactions enhanced under higher reactant loadings. Fast heating rates allowed maximal yields (>60mol%) of levulinic acid and furfural to be achieved under short reaction times. Under the range of conditions examined, sulfuric acid produced a slight increase in levulinic acid yield by 6% (P=0.02), although there was no significant difference (P=0.11) between MSA and sulfuric acid in levulinic acid formed from glucose alone. The amount and type of the solid residue is similar between MSA and sulfuric acid. As such, MSA is a suitable alternative because its use minimizes corrosion and disposal issues associated with mineral acid catalysts. The heating value of the residue was 22MJ/kg implying that it is a suitable source of fuel. On the basis of these results, a two-stage processing strategy is proposed to target high levulinic acid and furfural yields, and other chemical products (e.g. lactic acid, xylitol, acetic acid and formic acid). This will result in full utilization of bagasse components.

Degradation and mineralization of furfural in aqueous solutions using heterogeneous catalytic ozonation

The main aim of this experiment was to study the degradation of furfural in wastewater using catalytic ozonation process with granular activated carbon as a catalyst. Influences of the following parameters were investigated on furfural degradation; initial furfural concentration, solution pH, GAC dosage, and reaction time. In order to gain an understanding of the mechanism, involved these experiments were done in the presence of some radical scavengers. A significant synergistic effect between ozone and activated carbon was obtained in the oxidation and mineralization of furfural compared to single ozonation and adsorption on GAC processes, thus verifying the positive effect of coupling ozonation and GAC to degrade toxic compounds such as furfural. Furthermore, this study demonstrated that the efficiency of furfural removal increased with a decreasing size of AC particles due to an increased surface area. Measurements of COD in SOP and COP showed that more degradation and mineralization of furfural occurred in COP (80.2%) compared to single ozonation process (42.4%). Desorption studies were performed and they showed that percentages for recovery of furfural from GAC used in COP and single adsorption processes were 3.5 and 85.4, respectively.

Furfural degradation in a dilute acidic and saline solution in the presence of glucose

A kinetic study has been performed on the degradation of furfural in a dilute acidic and saline solution with and without the presence of glucose. Experiments have been performed in a stirred batch reactor. The degradation of furfural alone was accurately predicted both using a first- and a second-order kinetic model. It was shown that furfural is degrading significantly faster when glucose is present in the reaction mixture. In the series with glucose present distinct second-order reaction kinetics were observed. From experiments with varying concentrations of glucose it turned out that an additional (second-order) reaction had to be added to the reaction mechanism in order to satisfactorily predict the experimental data. This additional reaction incorporated the initial glucose concentration as a constant in the Arrhenius expression for the reaction rate constant. Furthermore, it has been argued that this second-order reaction could well be a Diels–Alder reaction.

Conversion of Hemicellulose into Furfural Using Solid Acid Catalysts in γ‐Valerolactone

Hold the water: The hemicellulose fraction of lignocellulose can be converted into furfural in high yields (80 %) using solid acid catalysts (H-mordenite) in a monophasic system with γ-valerolactone (GVL) as the solvent. Furfural degradation reactions are decreased significantly when the water concentration in GVL is minimized, thus resulting in high furfural yields.

Screening of steam explosion conditions for glucose production from non-impregnated wheat straw

Abstract The conversion of wheat straw to fermentable sugar for bioethanol production typically involves a thermal pretreatment step, followed by enzymatic hydrolysis. In this study we have investigated the effect of steam explosion parameters on wheat straw digestibility using a newly designed steam explosion unit and a process without acid impregnation. The wheat straw was steam pretreated using 18 different conditions in the temperature range of 170–220 °C and the resulting material was used directly (i.e. without washing) for enzymatic hydrolysis and fermentation in either a separate hydrolysis and fermentation (SHF)-type or a simultaneous saccharification and fermentation (SSF)-type set-up. Maximum glucose yields upon enzymatic hydrolysis were obtained after pretreatment at 210 °C for 10 min and yields were similar at harsher conditions. Xylose yields increased with temperature and residence time up to 190 °C, but decreased at harsher pretreatment conditions since these led to xylan degradation and concomitant production of furfural. In an SHF-type set-up ethanol formation did not follow enzymatic glucose release and was inversely correlated with furfural levels. An SFF-type set-up displayed a straightforward correlation between the expected amount of released glucose and the ethanol yields. The highest saccharification yields corresponded to about 90% of the cellulose in the substrate. Overall, this study shows that steam explosion without an acid catalyst is a good pretreatment method for saccharification of wheat straw. Optimal steam explosion conditions need to be a compromise between sugar accessibility and sugar degradation.

Microbial degradation of furanic compounds: biochemistry, genetics, and impact

Microbial metabolism of furanic compounds, especially furfural and 5-hydroxymethylfurfural (HMF), is rapidly gaining interest in the scientific community. This interest can largely be attributed to the occurrence of toxic furanic aldehydes in lignocellulosic hydrolysates. However, these compounds are also widespread in nature and in human processed foods, and are produced in industry. Although several microorganisms are known to degrade furanic compounds, the variety of species is limited mostly to Gram-negative aerobic bacteria, with a few notable exceptions. Furanic aldehydes are highly toxic to microorganisms, which have evolved a wide variety of defense mechanisms, such as the oxidation and/or reduction to the furanic alcohol and acid forms. These oxidation/reduction reactions constitute the initial steps of the biological pathways for furfural and HMF degradation. Furfural degradation proceeds via 2-furoic acid, which is metabolized to the primary intermediate 2-oxoglutarate. HMF is converted, via 2,5-furandicarboxylic acid, into 2-furoic acid. The enzymes in these HMF/furfural degradation pathways are encoded by eight hmf genes, organized in two distinct clusters in Cupriavidus basilensis HMF14. The organization of the five genes of the furfural degradation cluster is highly conserved among microorganisms capable of degrading furfural, while the three genes constituting the initial HMF degradation route are organized in a highly diverse manner. The genetic and biochemical characterization of the microbial metabolism of furanic compounds holds great promises for industrial applications such as the biodetoxifcation of lignocellulosic hydrolysates and the production of value-added compounds such as 2,5-furandicarboxylic acid.

Identification and characterization of the furfural and 5-(hydroxymethyl)furfural degradation pathways of Cupriavidus basilensis HMF14

The toxic fermentation inhibitors in lignocellulosic hydrolysates pose significant problems for the production of second-generation biofuels and biochemicals. Among these inhibitors, 5-(hydroxymethyl)furfural (HMF) and furfural are specifically notorious. In this study, we describe the complete molecular identification and characterization of the pathway by which Cupriavidus basilensis HMF14 metabolizes HMF and furfural. The identification of this pathway enabled the construction of an HMF and furfural-metabolizing Pseudomonas putida. The genetic information obtained furthermore enabled us to predict the HMF and furfural degrading capabilities of sequenced bacterial species that had not previously been connected to furanic aldehyde metabolism. These results pave the way for in situ detoxification of lignocellulosic hydrolysates, which is a major step toward improved efficiency of utilization of lignocellulosic feedstock.

Identification and characterization of fermentation inhibitors formed during hydrothermal treatment and following SSF of wheat straw

A pilot plant for hydrothermal treatment of wheat straw was compared in reactor systems of two steps (first, 80 degrees C; second, 190-205 degrees C) and of three steps (first, 80 degrees C; second, 170-180 degrees C; third, 195 degrees C). Fermentation (SSF) with Sacharomyces cerevisiae of the pretreated fibers and hydrolysate from the two-step system gave higher ethanol yield (64-75%) than that obtained from the three-step system (61-65%), due to higher enzymatic cellulose convertibility. At the optimal conditions (two steps, 195 degrees C for 6 min), 69% of available C6-sugar could be fermented into ethanol with a high hemicellulose recovery (65%). The concentration of furfural obtained during the pretreatment process increased versus temperature from 50 mg/l at 190 degrees C to 1,200 mg/l at 205 degrees C as a result of xylose degradation. S. cerevisiae detoxified the hydrolysates by degradation of several toxic compounds such as 90-99% furfural and 80-100% phenolic aldehydes, which extended the lag phase to 5 h. Acetic acid concentration increased by 0.2-1 g/l during enzymatic hydrolysis and 0-3.4 g/l during fermentation due to hydrolysis of acetyl groups and minor xylose degradation. Formic acid concentration increased by 0.5-1.5 g/l probably due to degradation of furfural. Phenolic aldehydes were oxidized to the corresponding acids during fermentation reducing the inhibition level.

Photocatalytic degradation of furfural by titania nanoparticles in a floating-bed photoreactor

Abstract In this research, an attempt was made to investigate the potential of nanophotocatalysts for treatment of hazardous wastewater streams. Titanium dioxide nanoparticles (as photocatalyst) were immobilized on a porous and low-density support called “perlite” using a very simple and inexpensive method. TiO 2 -coated perlite granules were used in a “Floating-bed photoreactor” to study the photocatalytic purification process of a typical wastewater polluted by furfural. The effects of initial concentration, catalyst mass/solution volume ratio, oxidant molar flow, residence time, and light intensity on process removal efficiency, and kinetics of the reactions were studied. SEM analyses showed a properly uniform distribution of titanium dioxide nanoparticles on perlite granules. HPLC analyses of the photocatalytic treatment experiments of water streams synthetically polluted with furfural showed a fairly good performance for the immobilized catalyst. A furfural concentration reduction of more than 95% was observed within 120 min. Kinetics of the reaction, strongly depends on pollutant concentration in the solution and mass diffusion phenomenon seems to be the controlling step.

Comparison of furfural degradation by different photooxidation methods

Abstract In this paper, the degradation of C5H4O2 “Furfural” in aqueous solution by photooxidation technology using UV, UV/H2O2, UV/H2O2/O2, UV/H2O2/Fe2+, UV/O2/Fe2+, O3, UV/O3 process and also oxidation by sodium hypochlorite was investigated in a lab-scale batch photo-reactor. To evaluate the performance of different processes, the efficiency of furfural degradation was studied by measuring the total organic carbon (TOC) throughout the experimentation. Results show that compare to other reactions studied in this research, the UV/H2O2 is a simple and effective process for furfural degradation and presence of Fe2+ ions (UV/H2O2/Fe2+) enhanced removal of furfural in solution. The influence of experimental parameters such as hydrogen peroxide dosage, pH, temperature and UV input power on furfural degradation was investigated. The rate of TOC removal was positively affected by UV source intensity. Results indicated that the efficiency of UV/H2O2 system improves by increasing the solution temperature. Increasing the temperature of the reactor reduces the concentration of dissolved oxygen but has no significant effect on the rate of furfural degradation. The effect of solution pH is also studied and concluded that pH values near neutrality improves reaction speed.

Methanogenesis from furfural by defined mixed cultures.

Methanogenesis from furfural by defined mixed cultures was studied. Under sulfate-reducing conditions, a Desulfovibrio strain was used as the furfural-degrading species producing acetic acid. This sulfate-reducing bacterium (SRB) Desulfovibrio strain B is an incomplete oxidizer, unable to carry out the terminal oxidation of organic substrates, leaving acetic acid as the end product. Introduction of acetate-utilizing methanogenic archaeon Methanosarcina barkeri 227 converted acetic acid to methane. This well-defined mixed consortium used furfural as its sole source of carbon and converted it to methane and CO(2). In the mixed culture, when a methanogen inhibitor was used in the culture medium, furfural was converted to acetic acid by the Desulfovibrio strain B, but acetic acid did not undergo further metabolism. On the other hand, when the growth of Desulfovibrio in the consortium was suppressed with a specific SRB inhibitor, namely molybdate, furfural was not degraded. Thus, the metabolic activities of both Desulfovibrio strain B and M. barkeri 227 were essential for the complete degradation of furfural.

Composition of the water-soluble products from the thermocatalytic activation of aspen wood

The compositions of the water-soluble substances formed on the thermocatalytic activation of aspen wood under the conditions of explosive autohydrolysis at temperatures of 187, 220, and 240δC and, correspondingly, saturated steam pressures of 1.2, 2.4, and 3.4 MPa have been studied. The water-soluble compounds are formed as the result of hydrolysis reactions of the components of the wood catalyzed by organic acids produced in the decomposition of hemicelluloses. It has been established that the main water-soluble compounds are true sugars, low-molecular-mass lignin, acetic acid, furfural, and sugar degradation products. Methanol, isopropanol, propionic acid, and hydroxymethylfurfural are present in minor amounts. Raising the temperature of the autohydrolysis of wood intensifies the degradation of sugars and increases the degree of their depolymerization to form water-soluble low-molecular-mass fragments.

Isolation and characterization of a furfural degrading sulfate-reducing bacterium from an anaerobic digester

A sulfate-reducing bacterium (SRB) was isolated from a continuous anaerobic digester, which converted the furfural-containing wastewater to methane and CO2. This SRB isolate could use furfural, furfuryl alcohol, and 2-furoic acid as sole source of carbon and energy in a defined mineral sulfate medium. Acetic acid was the major end product of furfural degradation. This organism also used wide varieties of other carbon sources, including ethanol, pyruvate, lactate, succinate, propanol, formate, and malate. The SRB isolate contained the electron carrier desulfoviridin. It used SO4, NO3, and thiosulfate as electron acceptors. This isolate used ammonium chloride, nitrate and glutamate as nitrogen source. The characteristics of the SRB isolate were closely similar toDesulfovibrio sp.

Growth of a Strictly Anaerobic Bacterium on Furfural (2-Furaldehyde)

A strictly anaerobic bacterium was isolated from a continuous fermentor culture which converted the organic constituents of sulfite evaporator condensate to methane and carbon dioxide. Furfural is one of the major components of this condensate. This furfural isolate could degrade furfural as the sole source of carbon and energy in a defined mineral-vitamin-sulfate medium. Acetic acid was the major fermentation product. This organism could also use ethanol, lactate, pyruvate, or fumarate and contained cytochrome c(3) and desulfoviridin. Except for furfural degradation, the characteristics of the furfural isolate were remarkably similar to those of the sulfate reducer Desulfovibrio gigas. The furfural isolate has been tentatively identified as Desulfovibrio sp. strain F-1.