Hydrogen production by the hyperthermophilic eubacterium, Thermotoga neapolitana, using cellulose pretreated by ionic liquid (original) (raw)
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Biomass and Bioenergy, 2015
Thermophilic hydrogen fermentation of cellulose was evaluated by a long term continuous experiment and batch experiments. The continuous experiment was conducted under 55 C using a continuously stirred tank reactor (CSTR) at a hydraulic retention time (HRT) of 10 day. A stable hydrogen yield of 15.4 ± 0.23 mol kg À1 of cellulose consumed was maintained for 190 days with acetate and butyrate as the main soluble byproducts. An analysis of the 16S rRNA sequences showed that the hydrogen-producing thermophilic cellulolytic microorganisms (HPTCM) were close to Thermoanaerobacterium thermosaccharolyticum, Clostridium sp. and Enterobacter cloacae. Batch experiment demonstrated that the highest H 2 producing activity was obtained at 55 C and the ultimate hydrogen yield and the metabolic by-products were influenced greatly by temperatures. The effect of temperature variation showed that the activation energy for cellulose and glucose were estimated at 103 and 98.8 kJ mol À1 , respectively.
2019
Biohydrogen attracts many attentions since it has many advantages as source of energy. Biohydrogen from sugarcane bagasse offers many advantages from economic and environmental point of view. This work aimed to study the production of hydrogen from sugarcane bagasse through enzymatic hydrolysis and fermentation using Enterobacter aerogenes. Pretreatment with ionic liquid [DMIM]DMP was carried out prior to hydrolysis. It was found that process with ionic liquid was able to shift the cellulose structure from crystalline cellulose to more amorphous cellulose. Alkaline pretreatment followed by ionic liquid conducted for 20 min at 120oC gave the lowest crystallinity index. This condition also gave the highest total recovery of cellulose and hemicellulose, a condition that is very important for enzymatic hydrolysis to produce as much sugar as possible. Pretreatment condition was also found to give significant effect to the yield and type of monosaccharides produced from the hydrolysis pro...
Biohydrogen from Sugarcane Bagasse Pretreated with Combined Alkaline and Ionic Liquid [DMIM]DMP
Malaysian Journal of Fundamental and Applied Sciences, 2019
Biohydrogen attracts many attentions since it has many advantages as source of energy. Biohydrogen from sugarcane bagasse offers many advantages from economic and environmental point of view. This work aimed to study the production of hydrogen from sugarcane bagasse through enzymatic hydrolysis and fermentation using Enterobacter aerogenes . Pretreatment with ionic liquid [DMIM]DMP was carried out prior to hydrolysis. It was found that process with ionic liquid was able to shift the cellulose structure from crystalline cellulose to more amorphous cellulose. Alkaline pretreatment followed by ionic liquid conducted for 20 min at 120 o C gave the lowest crystallinity index. This condition also gave the highest total recovery of cellulose and hemicellulose, a condition that is very important for enzymatic hydrolysis to produce as much sugar as possible. Pretreatment condition was also found to give significant effect to the yield and type of monosaccharides produced from the hydrolysis ...
ChemSusChem, 2014
This work describes a relatively simple methodology for efficiently deconstructing cellulose into monomeric glucose, which is more easily transformed into a variety of platform molecules for the production of chemicals and fuels. The approach undertaken here first involves the dissolution of cellulose in an ionic liquid (IL), followed by a second reconstruction step aided by an antisolvent. The regenerated cellulose exhibited strong structural and morphological changes, as revealed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. These changes dramatically affect the hydrolytic reactivity of the cellulose with dilute mineral acids. As a consequence, the glucose yield obtained from the deconstructed-reconstructed cellulose was substantially higher than that achieved via hydrolysis of the starting cellulose. Factors that affect the hydrolysis reaction include the type of cellulose substrate, the type of IL used in the pretreatment and the type of acid used in the hydrolysis step. The best results were obtained by treating the cellulose with IL and using phosphotungstic acid (0.067 mol/L) as a catalyst at 413 K. Under these conditions, the conversion of cellulose was almost complete (> 99 %), with a glucose yield of 87 % after only 5 h of reaction.
Bioresource technology, 2016
A series of standardized activity experiments were performed to characterize three different temperature ranges of hydrogen fermentation from different carbon sources. 16S rRNA sequences analysis showed that the bacteria were close to Enterobacter genus in the mesophilic mixed culture (MMC) and Thermoanaerobacterium genus in the thermophilic and hyper-thermophilic mixed cultures (TMC and HMC). The MMC was able to utilize the glucose and cellulose to produce methane gas within a temperature range between 25 and 45 °C and hydrogen gas from 35 to 60°C. While, the TMC and HMC produced only hydrogen gas at all temperature ranges and the highest activity of 521.4mlH2/gVSSd was obtained by TMC. The thermodynamic analysis showed that more energy is consumed by hydrogen production from cellulose than from glucose. The experimental results could help to improve the economic feasibility of cellulosic biomass energy using three-phase technology to produce hythane.
Green Chemistry, 2010
New strategies are needed to efficiently convert non-food biomass to glucose as a platform chemical. One promising approach is to use ionic liquids to first dissolve lignocellulose. Yet, in the presence of such solvents, the enzymes that catalyze cellulose hydrolysis become compromised in their activity. However, this decreased cellulase activity has not been examined in detail. Thus, the aim of this study was to investigate how the ionic liquid precisely affects cellulase activity and stability with regard to different cellulose substrates. Hereby, four ionic liquids were screened to identify which one best minimized the loss of enzyme activity. Then, this best ionic liquid was tested on one insoluble and two soluble cellulose substrates. Subsequently, the relevant parameters of solution viscosity and ionic strength were evaluated with respect to enzyme activity and stability. Finally the residual ionic liquid concentration from the precipitation of a-cellulose was varied. The best ionic liquid was found to be 1,3-dimethylimidazolium dimethylphosphate with the highest retained activity of 30% on the a-cellulose substrate in the presence of 10% (v/v) ionic liquid. Most importantly, an increase in viscosity and ionic strength contributed to the decrease in enzyme activity which nonetheless retained their stability. The hydrolysis of precipitated a-cellulose from ionic liquid showed significant higher reaction rates but reduced sugar yields when residual ionic liquid was present. None the less, it should be possible to effectively produce glucose from precipitated cellulose without needing to wash off all residual ionic liquid when optimized cellulase mixtures are used.
Effect of temperature on continuous hydrogen production of cellulose
International Journal of Hydrogen Energy, 2012
The effect of temperature on the hydrogen fermentation of cellulose was evaluated by a continuous experiment using a mixed culture without pretreatment. The experiments were conducted at three different temperatures, which were mesophilic [37 AE 2 C], thermophilic [55 AE 2 C] and hyper-thermophilic [80 AE 2 C], with an influent concentration of cellulose of 5 g/l and a hydraulic retention time [HRT] of 10 days. A stable hydrogen production was observed at each condition. At 37 AE 2 C, the maximum hydrogen yield was 0.6 mmol H 2 /g cellulose. However, at 55 AE 2 C and 80 AE 2 C, the maximum hydrogen yields were 15.2 and 19.02 mmol H 2 /g cellulose, respectively. While 26% of the biogas was methane under the mesophilic temperature, no methane gas was detected under both the thermophilic and hyper-thermophilic temperatures. The results show that operational temperature is a key to sustainable bio-hydrogen production and that the thermophilic and hyper-thermophilic conditions produced better results than mesophilic condition.
International Journal of Hydrogen Energy, 2013
A continuous stirred tank reactor was used for the dark hydrogen fermentation of cellulose by mixed microflora at hyper-thermophilic temperature (70 AE 1 C) for 240 days. A total of twenty six batch experiments were conducted to investigate the effect of temperature on the activity of cellulosic-hydrogen producing bacteria. The results show that the system reached a steady state condition after 90 days. A stable hydrogen yield of 7.07 AE 0.23 mmol H 2 /g cellulose was maintained for 150 days with acetate, butyrate, ethanol and propionate as main soluble byproducts. Analysis of 16S rRNA sequences showed that the cellulolytic bacteria were close to Thermoanaerobacterium genus. The cellulosic-hydrogen producing bacteria were able to utilize the cellulose or glucose within a wide range of fermentation temperatures (45e80 C) to produce hydrogen. The activation energy for cellulose and glucose were estimated at 133.2 and 117.7 kJ/mol, respectively.