Levulinic Acid Concentration Research Articles

Removal of levulinic acid from aqueous solutions by clay nano-adsorbents: equilibrium, kinetic, and thermodynamic data

In this research, the removal of levulinic acid from aqueous solutions was examined by using clay nano-adsorbents, namely montmorillonite and Cloisite 20A. The batch adsorption experiments were exerted at a different contact time (30–210 min), initial levulinic acid concentrations (20–100 g L−1), adsorbent amounts (0.05–0.25 g), and temperatures (25–45 °C). The equilibrium, kinetic, and thermodynamic data were obtained by using the adsorption capacities of clay nano-adsorbents. It was found that Cloisite 20A exhibited a higher adsorption capacity than montmorillonite. Different adsorption isotherm and kinetic models were utilized to explain the adsorption mechanism and the parameters of these models were determined. Moreover, the thermodynamic analysis was performed to express the adsorption process. For the adsorption of levulinic acid on both clay nano-adsorbents, the adsorption equilibrium data were well represented by the Freundlich isotherm model and the adsorption kinetic data were well characterized by the pseudo-second-order kinetic model for the removal of levulinic acid by two clay nano-adsorbents.

Challenges to Levulinic Acid and Humins Valuation in the Sugarcane Bagasse Biorefinery Concept

Levulinic acid (LA) is currently one of the most promising chemicals derived from biomass. However, its large-scale production is hampered by the challenges in biomass hydrolysis and the poor selectivity due to the formation of humins (HUs). This study addresses these challenges using the biorefinery concept of biomass fractionation. A three-step process (pretreatment, delignification, and acid-catalyzed conversion) was optimized to produce LA from SCB considering the yield (YLA), efficiency (ELA), and concentration of LA (CLA) as functions of temperature, reaction time, acid concentration, and solids loading. By means of a multi-response optimization, values of YLA (20.9 ± 1.25 g/100gISF-D), ELA (37.5 ± 2.24 mol%), and CLA (25.1 ± 1.50 g/L) were obtained at 180 °C, 75 min, 7.0% w/v H2SO4, and 12.0% w/v of solids loading. Six scenarios for production of LA were analyzed in terms of yields of LA, HUs, lignin, and other sugar-derived products considering one-, two-, or three-step processes. The economic analysis indicated that the three-step scenario delivers better economic figures given that other valuable biomass fractions (hemicellulosic sugars and lignin) are better used and contribute to the overall economic performance of the process. The results also demonstrate the burden of HUs in the economics of the process because it was shown that the largest production of LA is also linked to the largest formation of HUs, which does not necessarily yield the best economic results. These findings indicate the importance of added value by-products for the profitable production of LA in biorefineries.

Reactive Extraction of Levulinic Acid using Tri-n-octylamine in 1-Octanol: Equilibria and Effect of pH

Reactive extraction is a sophisticated separation technique used for the recovery of carboxylic acids from fermentation broth. Levulinic acid is a versatile chemical. A right combination of extractant and diluent will provide a high yield. The reactive extraction of levulinic acid from aqueous solution with tri-n-octylamine (TOA) dissolved in 1-octanol was investigated at room temperature. The effect of pH was studied. From the physical and chemical equilibrium experimental results, the distribution coefficient (KD), extraction efficiency (E%), loading ratio (Z), stoichiometric loading factor (ZS) and modified separation factor (Sf) are calculated. It was found that physical extraction provided less yield compared to chemical extraction. A maximum KD was obtained as 5.248 using 40% TOA (0.9059 mol/L) while 83.99 % of the levulinic acid was extracted. By increasing the initial concentration of levulinic acid increased the concentration of levulinic acid in both the organic phase and aqueous phase. As the concentration of TOA increases from 10 to 40 % (0.2264 mol/L to 0.9059 mol/L), the distribution coefficient and extraction efficiency also increase. By increasing the pH from 3 to 7, the distribution coefficient and extraction efficiency were drastically affected.

Reactive extraction of levulinic acid using tri-n-octylamine in 1-hexanol

Reactive extraction of levulinic acid using trin- octylamine (TOA) in 1-hexanol was investigated by physical and chemical extractions from aqueous solution at room temperature. Using the equilibrium data, the distribution coefficient (KD), extraction efficiency (E%), loading ratio (Z), stoichiometric loading factor (ZS) and modified separation factor (Sf) are evaluated. It was observed that chemical extraction provided a better yield than physical extraction. A maximum KD was obtained as 10.715 using 40% TOA (0.9059 mol/L) while 91.46% of the levulinic acid was extracted. By increasing the initial concentration of levulinic acid resulted in a decrease of KD and E%. The KD and E% increased by increasing the TOA concentration from 10 to 40% (0.2264 mol/L to 0.9059 mol/L).

Microwave-Assisted One-Step Conversion of Wood Wastes into Levulinic Acid

This study aimed to evaluate the use of softwood and hardwood waste for the production of levulinic acid by one-stage conversion using microwave radiation combined with acid catalysis. The analysis demonstrated that the type and concentration of the acid used, the concentration of biomass in the reaction mixture and pressure value had the greatest impact on the yield of levulinic acid. The highest efficiency of carbohydrate conversion to levulinic acid, regardless of the type of raw material, was achieved using a pressure of 225 PSI and sulfuric acid as a catalyst. Maximum yield from biomass, ca. 16.5% for cherry wood chips and ca. 25% for pine chips, was obtained using sulfuric acid at a concentration of 1% v/v and 2% v/v, respectively, for the following process parameters: Exposure time 20 min, biomass concentration 3.3%, and the pressure of 225 PSI. The ratio of actual yield to theoretical yield was high: 64.7% ± 4.5% for pine chips and 43.4% ± 1.0% for cherry wood chips. High efficiency of the presented method of biomass conversion to levulinic acid indicates the possibility of its use for waste management in the wood processing industry. High concentration of levulinic acid in the post-reaction mixture allows for cost-effective extraction and purification of the compound.

A kinetic study on the hydrolysis of corncob residues to levulinic acid in the FeCl3–NaCl system

Levulinic acid (LA) production from corncob acid hydrolysis residues (CAHR) using FeCl3 as Lewis acid catalyst in green solutions of salt was investigated. The reaction kinetic relationships were determined in the temperature range of 160–180 °C, with FeCl3 concentrations of 0.12–0.36 M, and a reaction time of 0–60 min. The maximum LA concentration of 59.0 mol% (24.5 g/L) was achieved at 170 °C in a 30% NaCl solution containing 0.24 M FeCl3. A pseudo first-order kinetic model was proposed to describe the cellulose deconstruction to LA. The model agreed perfectly with the evolution in the concentrations of the major compounds such as glucose, 5-hydroxymethylfurfural and LA during the CAHR hydrolysis. The kinetic model developed for CAHR was in good agreement with that previously developed for other lignocellulosic systems. Based on our kinetic model and reaction system, the LA yield is increased at the lower end of the temperature range with the higher acid concentrations. The results indicated that the concentrated seawater after desalination could be a green solvent in the biorefinery.

Investigating how biomass hydrolysis derivatives inhibit H2 production by an isolated Clostridium beijerinckii

This study evaluates how fermentation inhibitors derived from biomass, namely 5-hydroxymethylfurfural (HMF), levulinic acid (LA), and formic acid (FA), affect H2 production by a Clostridium beijerinckii strain. The specific fermentative H2 production rate (μH2), bacterial cell growth rate (μ), and substrate (glucose) consumption rate (μS) during fermentation helped to estimate which HMF, LA, and FA concentrations inhibited 50% of the rates (IC50). IC50 for μ was 2.4, 2.7, and 1.4 g/L for HMF, LA, and FA, respectively. HMF inhibited H2 production the most potently and favored the lactate and ethanol pathways. Butyric acid was the only metabolite to be detected in the presence of LA or FA, which attested that these inhibitors completely inhibited the acetate pathway. The glucose consumption rate was the least affected by the inhibitors, and FA was more potent than HMF and LA. This information should be useful for more appropriate biomass feedstock application in fermentative H2 production.

Axial dispersion and CFD models for the extraction of levulinic acid from dilute aqueous solution in a Kühni column with 2-methyltetrahydrofuran solvent

1D axial dispersion and 3D CFD models for the extraction of levulinic acid from dilute aqueous solution by applying 2-methyltetrahydrofuran as a solvent are presented. The models are validated by comparison with the measured levulinic acid concentration profile data obtained in a bench-scale Kühni column. The 1D model contains NRTL parameters for the system levulinic acid-water-2MTHF. Correlations for drop size and hold-up for Kühni columns were taken from literature. The values for overall mass transfer coefficient ranged from 1.4E-5 to 2.2E-5 ms−1, and increased as a function of the rotor speed. The fitting of the column performance resulted in a very good prediction of the solute concentration profiles in the extraction column, and the average absolute value of relative error for the 1D model was 23%. CFD model visualized the column performance at the column height of 150.5–160 cm giving valuable information on back mixing, phase velocities, dispersed phase volume fraction, and mass transfer. Dispersed phase volume fraction and mass transfer contours revealed, that the mass transfer rate (app. 0.25 g L−1s−1) is at its highest just below the rotor, and that there are blind spots in the compartments close to the extractor and just above each down comer. Values for the dispersed phase volume fraction are highest in the same area where the mass transfer reaches the highest values. The highest slip velocity values (app. 0.03 m−1) are located in the tip of each compartment partition plates.General correlations, such as hold-up and drop size correlations, can successfully be applied in levulinic acid-water-2MTHF system reported in this work. The 1D axial dispersion model proved to be valuable tool for scale-up purposes, and CFD model, despite the long time needed for each simulation, gave useful information for the design purposes.

Continuous Flow Synthesis of High Valuable N-Heterocycles via Catalytic Conversion of Levulinic Acid.

Graphitic carbon nitride (g-C3N4) was successfully functionalized with a low platinum loading to give rise to an effective and stable catalytic material. The synthesized g-C3N4/Pt was fully characterized by XRD, N2 physisorption, XPS, SEM-Mapping, and TEM techniques. Remarkably, XPS analysis revealed that Pt was in a dominant metallic state. In addition, XPS together with XRD and N2 physisorption measurements indicated that the g-C3N4 preserves its native structure after the platinum deposition process. g-C3N4/Pt was applied to the catalytic conversion of levulinic acid to N-heterocycles under continuous flow conditions. Reaction parameters (temperature, pressure, and concentration of levulinic acid) were studied using 3 levels for each parameter, and the best conditions were employed for the analysis of the catalyst's stability. The catalytic system displayed high selectivity to 1-ethyl-5-methylpyrrolidin-2-one and outstanding stability after 3 h of reaction.

Production of levulinic acid from corn cob residue in a fed-batch acid hydrolysis process

Abstract Levulinic acid (LA) is an important platform chemical, the production of which by using biomass resources such as corncob is of great significance to the sustainable development. Traditional hydrolysis processes yield low concentrations of levulinic acid with large amounts of acid being consumed. In this paper, a new fed-batch process for hydrolyzing corncob residues with sulfuric acid being utilized as the catalysis to produce levulinic acid at high concentrations is proposed. The mass concentration of the levulinic acid increased with growing the times of feeding and a 107.93 g/L of the levulinic acid can be reached at the 7th hydrolysis. However, the yield of levulinic acid reduces gradually during the fed-batch process. To explore the phenomenon, the reaction mechanism of cellulose acid hydrolysis was experimentally studied. It can be deduced that the reduction of the levulinic acid yield was caused by the polymerization of the soluble humin analogues and the 5-hydroxymethyl furfural (5-HMF) as well as the glucose.

Effects of transition metals on hydrothermal liquefaction of empty fruit bunches (EFB) for conversion to biofuel and valuable chemicals

Hydrothermal liquefaction(HTL) of empty fruit bunches(EFB) was performed with an autoclave reactor at various temperatures (240, 270, 300, and 330 °C) in the presence of transition metal chlorides(ZnCl2, CuCl2, and NiCl2) under high pressure(∼22 MPa) and N2 atmosphere. Main HTL products including hydrochar, gas, water-soluble fraction (WSF), and crude-like HTL oil were investigated. The yield of HTL oil gradually increased with increasing temperature, and the highest oil yield of 22.8 wt% was obtained at 300 °C. When transition metal chlorides (2.5–10.0% (w/w sample)) were added to the reaction, mass distributions of the four fractions were clearly modified based on the type of transition metal chloride as well as their concentration. In general, the yield of HTL oil decreased with an increase in transition metal concentration up to 10.0%, the water content increased and the chemical compounds decreased with an increase in the amount of metal. γ-Valerolactone (GVL) and levulinic acid (LA) were detected in the catalytic HTL oil, due to the presence of transition metal ion and high acidity. Unlike other metal chlorides, the presence of CuCl2 resulted in relatively low GVL and high LA concentration, which may inactivate the route from LA to GVL under acidic hydrothermal conditions.

Tolerance and metabolic response of Pseudomonas taiwanensis VLB120 towards biomass hydrolysate-derived inhibitors

BackgroundBio-conversion of lignocellulosic biomass to high-value products offers numerous benefits; however, its development is hampered by chemical inhibitors generated during the pretreatment process. A better understanding of how microbes naturally respond to those inhibitors is valuable in the process of designing microorganisms with improved tolerance. Pseudomonas taiwanensis VLB120 is a natively tolerant strain that utilizes a wide range of carbon sources including pentose and hexose sugars. To this end, we investigated the tolerance and metabolic response of P. taiwanensis VLB120 towards biomass hydrolysate-derived inhibitors including organic acids (acetic acid, formic acid, and levulinic acid), furans (furfural, 5-hydroxymethylfurfural), and phenols (vanillin).ResultsThe inhibitory effect of the tested compounds varied with respect to lag phase, specific growth rate, and biomass yield compared to the control cultures grown under the same conditions without addition of inhibitors. However, P. taiwanensis was able to oxidize vanillin and furfural to vanillic acid and 2-furoic acid, respectively. Vanillic acid was further metabolized, whereas 2-furoic acid was secreted outside the cells and remained in the fermentation broth without further conversion. Acetic acid and formic acid were completely consumed from the fermentation broth, while concentration of levulinic acid remained constant throughout the fermentation process. Analysis of free intracellular metabolites revealed varying levels when P. taiwanensis VLB120 was exposed to inhibitory compounds. This resulted in increased levels of ATP to export inhibitors from the cell and NADPH/NADP ratio that provides reducing power to deal with the oxidative stress caused by the inhibitors. Thus, adequate supply of these metabolites is essential for the survival and reproduction of P. taiwanensis in the presence of biomass-derived inhibitors.ConclusionsIn this study, the tolerance and metabolic response of P. taiwanensis VLB120 to biomass hydrolysate-derived inhibitors was investigated. P. taiwanensis VLB120 showed high tolerance towards biomass hydrolysate-derived inhibitors compared to most wild-type microbes reported in the literature. It adopts different resistance mechanisms, including detoxification, efflux, and repair, which require additional energy and resources. Thus, targeting redox and energy metabolism in strain engineering may be a successful strategy to overcome inhibition during biomass hydrolysate conversion and lead to development of more robust strains.

Proximate composition and the production of fermentable sugars, levulinic acid, and HMF from Gracilaria fisheri and Gracilaria tenuistipitata cultivated in earthen ponds

The red seaweeds are generally known to have a high content of polysaccharides and low content of lignin. They can be used as a bioethanol feedstock and to produce biochemicals. This study was conducted to examine the pretreatment conditions to improve the production of fermentable sugars and by-products from Gracilaria fisheri and Gracilaria. tenuistipitata. The algal materials were gathered from earthen pond cultivation. The pretreatment was conducted at different concentrations of H2SO4 (0.2–1 M) and time (30–150 min) at 95 °C. The proximate composition and contents of glucose, galactose, levulinic acid, and 5-hydroxymethylfurfural (5-HMF) were analyzed. Our results showed high carbohydrate content of 63.01 ± 0.47 g carbohydrate (100 g TS)−1 for G. fisheri and 59.07 ± 0.43 g carbohydrate (100 g TS)−1 for G. tenuistipitata. The optimal pretreatment with 1 M of H2SO4 at 95 °C for 150 min resulted in high concentrations of sugars in G. fisheri (7.86 g L−1 glucose, 8.37 g L−1 galactose) compared to G. tenuistipitata (3.15 g L−1 glucose, 5.75 g L−1 galactose). The pretreatment of the algae resulted in concentrations of 5-HMF for G. fisheri and G. tenuistipitata of 1.55 and 1.42 g L−1, respectively. The levulinic acid concentration was 3.66 g L−1 for G. fisheri and 6.12 g L−1 for G. tenuistipitata. Gracilaria fisheri was more susceptible to the sulfuric acid hydrolysis compared to G. tenuistipitata. Our study revealed that the acid hydrolysis of G. fisheri and G. tenuistipitata can improve the yield of sugars to produce bioethanol feedstocks.

Ionic liquids as bulk liquid membranes on levulinic acid removal: A design study

Ionic liquids are considered as green solvents because of their remarkable properties. In view of this, imidazolium-based ionic liquids were used as a bulk liquid membrane (BILM) for levulinic acid removal. Four different hydrophobic ionic liquids, 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][Tf2N], 1-Butyl-3-methylimidazolium hexafluoro phosphate [BMIM][PF6], 1-Hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [HMIM][Tf2N], 1-Hexyl-3-methylimidazolium hexafluorophosphate [HMIM][PF6], were used in the membrane phase. Tributyl phosphate was used as a carrier (0–2 mol/L) in the membrane, and NaOH solutions (0–4 N) were used as stripping phase respectively. Various parameters such as initial levulinic acid concentration in the feed, carrier concentration and ionic liquid type in the membrane, and NaOH concentration in the stripping phase were examined by using D-optimal design. D-optimal design based on the Response Surface Methodology (RSM) is a design method that provides the relationship between independent and dependent factors with a minimum number of experiments. Levulinic acid was successfully transported through BILM using imidazolium-based ionic liquids. Extraction and stripping removal efficiencies were selected as dependent variables and calculated from the experimental results. The experimental results were analyzed by analysis of variance (ANOVA). According to ANOVA, the second order model equations were obtained for dependent variables and have been the good fit with the experimental results. The optimal conditions for BILM process were performed to obtain the higher removal efficiencies. The highest extraction and stripping efficiencies have obtained in case of higher concentration values of TBP and NaOH. Additionally, the molar fluxes at extraction and stripping interfaces were calculated from experimental data. As a result, this design study showed that ionic liquids as bulk liquid membranes can be used on levulinic acid removal.

A novel approach to biphasic strategy for intensification of the hydrothermal process to give levulinic acid: Use of an organic non-solvent

Levulinic acid is a platform chemical obtained from acid-catalyzed hydrothermal conversion of cellulose-rich biomass. The low amounts of solid biomass which can be handled in the reactor limit the levulinic acid concentration in the aqueous stream, making the economic viability of the aqueous phase process unsuitable for large scale applications. Now a novel approach to biphasic process has been proposed, where a mineral oil has been used as non-solvent for levulinic acid, thus concentrating it in the water phase, reducing the water volume to be processed downstream but at the same time maintaining enough liquid phase to sustain the slurry processability. The work has studied: i) the optimization of the biphasic hydrolysis of corn grain to levulinic acid; ii) the characterization of the recovered oil; iii) the evaluation of the energetic properties of the recovered hydrochar for its exploitation, thus smartly closing the biorefinery cycle.

Conversion of Levulinic Acid from Various Herbaceous Biomass Species Using Hydrochloric Acid and Effects of Particle Size and Delignification

Acid catalyzed hydrothermal conversion of levulinic acid (LA) from various herbaceous materials including rice straw (RS), corn stover (CS), sweet sorghum bagasse (SSB), and Miscanthus (MS) was evaluated. With 1 M HCl, 150 °C, 5 h, 20 g/L solid loading, the yields of LA from untreated RS, CS, SSB and MS based on the glucan content were 60.2, 75.1, 78.5 and 61.7 wt %, respectively. It was also found that the particle size had no significant effect on LA conversion yield with >3 h reaction time. With delignification using simulated green liquor (Na2CO3-Na2S, 20 wt % total titratable alkali (TTA), 40 wt % sulfidity) at 200 °C for 15 min, lignin removal was in the range of 64.8–91.2 wt %. Removal of both lignin and xylan during delignification increased the glucan contents from 33.0–44.3 of untreated biomass to 61.7–68.4 wt % of treated biomass. Delignified biomass resulted in much lower conversion yield (50.4–56.0 wt %) compared to 60.2–78.5 wt % of untreated biomass. Nonetheless, the concentration of LA in the product was enhanced by a factor of ~1.5 with delignification.

Aqueous phase hydrogenation of levulinic acid to γ-valerolactone on supported Ru catalysts prepared by microwave-assisted thermolytic method

γ-Valerolactone (GVL), as a sustainable platform chemical, were produced through an aqueous phase hydrogenation of biomass-derived levulinic acid (LA) in the presence of supported ruthenium catalysts, in which the catalysts were prepared by solvent-free microwave-assisted thermolytic method. The effects of catalyst support, reaction media, pressure, temperature and LA initial concentration were investigated to obtain the optimum conditions for high γ-valerolactone yield. 5% Ru/AC catalyst exhibits a more superior catalytic performance compared with Ru/CNT, Ru/FCNT, Ru/γ-Al2O3-MW and Ru/γ-Al2O3-IM at 100°C and 2.0 MPa of 0.10 g/mL LA concentration in water solution. This superior performance is attributed to the higher dispersion of metallic Ru over coconut shell activated carbon. GVL can be produced with a good yield of > 99% under optimum conditions, and has the potential to provide a green, renewable platform for biotransformation.

Concentrated Levulinic Acid Production from Sugar Cane Molasses

Levulinic acid (LA) is generally produced from biomass through acid hydrolysis and has been recognized as one of the top platform chemicals. In this study, concentrated LA was produced from sugar cane molasses through a superimposed reaction, in which the LA solution generated from hexose hydrolysis was further used as solvent for hydrolysis of sugar cane molasses to produce concentrated LA. After the third and fifth superimposed reactions, LA solutions with concentrations of 148 and 180 g/L were obtained, with average yields of 30.5 and 23.9%, respectively. The LA yield, however, is comparably low as a result of the increase of the LA concentration, and the superimposed reaction conditions promote the formation of aqueous and solid byproducts.

Effect of Hydrochloric Acid Concentration on the Conversion of Sugarcane Bagasse to Levulinic Acid

Levulinic acid is a new green platform chemical used to the synthesis of a variety of materials for numerous applications such as fuel additives, polymers and resins. It can be produced using renewable resources such as biomass like sugarcane bagasse which are cheap and widely available as waste in Indonesia. In this study, sugarcane bagasse was hydrolyzed using hydrochloric acid with a solid liquid ratio 1:10. The effects of hydrochloric acid concentration at temperature of 180 °C and reaction time of 30 min were studied. The presence of levulinic acid in product of hydrolysis was measured with gas chromatography (GC). It was found that the highest concentration of levulinic acid was obtained at 1 M hydrochloric acid in 25.56 yield%.

Burkholderia sacchari DSM 17165: A source of compositionally-tunable block-copolymeric short-chain poly(hydroxyalkanoates) from xylose and levulinic acid

Burkholderia sacchari was used to produce poly-3-hydroxybutyrate-co-3-hydroxyvalerate block copolymers from xylose and levulinic acid. Levulinic acid was the preferred substrate resulting in 3-hydroxyvalerate (3HV) contents as high as 95 mol% at 24 h. The 3HB:3HV ratios were controlled by the initial levulinic acid media concentration and fermentation length. Higher levulinic acid concentrations and longer durations, resulted in polymers with two glass transition temperatures, each approximating those associated with poly-3HB and poly-3HV. 13C NMR confirmed the presence of high concentrations of 3HB-3HB and 3HV-3HV homopolymeric dyads, while mass spectrometry of the partial hydrolysis products did not conform to Bernoullian statistics for randomness, confirming block sequences. MS/MS analysis of specific oligomers showed the mass-loss of 86 amu (a 3HB unit) and 100 amu (a 3HV unit) attesting to some randomness within the polymers. This study verifies the potential for producing Poly-3HB-block-3HV copolymers from inexpensive biorenewable feedstocks without sequential addition of carbon sources.