Inexpensive Feedstock Research Articles

Electrochemical production of lactic acid from glycerol oxidation catalyzed by AuPt nanoparticles

The production of valuable chemicals from relatively inexpensive feedstocks utilizing electrochemical methods has been attracting widespread attention in recent years since it is highly efficient, decentralized, environmental-friendly and can operate in room temperature and pressure. Currently, the industrial production of lactic acid is mainly based on bio-fermentation, leading to drawbacks including severe conditions, unfriendliness to environment, low efficiency and requirement of expensive equipment, which can potentially overcome by electrochemical methods. Herein, we report for the first time the preparation of lactic acid at room temperature and pressure from the one-pot electro-oxidation of glycerol, a byproduct from biodiesel production. AuPt nanoparticles with different surface compositions were employed in this work to optimize the catalysis performance, and the glycerol oxidation was operated at a series of applied potentials, pH and glycerol concentration. The optimal lactic acid selectivity was 73%, obtained with Au-enriched surface at applied potential of 0.45 V vs. RHE.

Dye-Sensitized Hydrobromic Acid Splitting for Hydrogen Solar Fuel Production.

Hydrobromic acid (HBr) has significant potential as an inexpensive feedstock for hydrogen gas (H2) solar fuel production through HBr splitting. Mesoporous thin films of anatase TiO2 or SnO2/TiO2 core-shell nanoparticles were sensitized to visible light with a new RuII polypyridyl complex that served as a photocatalyst for bromide oxidation. These thin films were tested as photoelectrodes in dye-sensitized photoelectrosynthesis cells. In 1 N HBr (aq), the photocatalyst undergoes excited-state electron injection and light-driven Br- oxidation. The injected electrons induce proton reduction at a Pt electrode. Under 100 mW cm-2 white-light illumination, sustained photocurrents of 1.5 mA cm-2 were measured under an applied bias. Faradaic efficiencies of 71 ± 5% for Br- oxidation and 94 ± 2% for H2 production were measured. A 12 μmol h-1 sustained rate of H2 production was maintained during illumination. The results demonstrate a molecular approach to HBr splitting with a visible light absorbing complex capable of aqueous Br- oxidation and excited-state electron injection.

Fed-batch production of vanillin by Bacillus aryabhattai BA03

Bacillus aryabhattai BA03, a strain isolated in our laboratory, has interesting properties related to the production of natural aromas and flavors. Specifically, we have found that it was able to produce vanillin from ferulic acid (FA). Furthermore, this strain produces high amounts of 4-vinylguaiacol in only 14h, this being the only intermediate metabolite observed in the process. FA is an inexpensive feedstock for the production of natural value-added compounds when extracted from lignocellulosic wastes. In this study, we optimized the operational conditions (temperature, pH and agitation), medium composition and bioconversion technology (batch or fed-batch) to produce vanillin. In a fed-batch process conducted with just one additional supplementation after 24h, the maximal concentration of vanillin (147.1±0.9mg/L) was observed after 216h (QV=0.681mg/Lh; YV/fFA=0.082mg/mg) after degrading 90.3% FA. In view of our data, we postulate that Bacillus aryabhattai BA03 carries out a decarboxylation of ferulic acid as a metabolic pathway.

Fast Pyrolysis of Short Rotation Coppice Poplar: An Investigation in Thermochemical Conversion of a Realistic Feedstock for the Biorefinery

Short rotation coppice (SRC) is a promising plantation system because it provides inexpensive feedstock for biorefineries. This study investigated the conversion of 2-year-old first rotation SRC poplar into bio-oil via fast pyrolysis. The impact of leaf removal was studied by comparing the yields and compositions of bio-oil from no-leaf coppice (NLC) and whole tree coppice (WTC). Leaf removal did not affect the bio-oil yield of SRC poplar samples (∼55%) but lowered the char yield from 19.7% to 13.6% and increased the gas yield from 14.3% to 17.7%. The chemical compositions of bio-oils, char, and noncondensable gases obtained from WTC and NLC were different. Leaf removal changed the elemental composition of the bio-oil. The bio-oil from WTC had higher H (9.1%) and O (64.8%) but lower C (25.3%) than that from NLC. Consequently, leaf removal increased the higher heating value (HHV) of bio-oil by 2.1 MJ/kg (16.0%). On the basis of the results of the current research and our previous study, the energy recovery...

Metal accumulation by sunflower (Helianthus annuus L.) and the efficacy of its biomass in enzymatic saccharification

Accumulation of metal contaminants in soil as a result of various industrial and anthropogenic activities has reduced soil fertility significantly. Phytoextraction of metal contaminants can improve soil fertility and provide inexpensive feedstock for biorefineries. We investigated the hyperaccumulation capacity of sunflower (Helianthus annuus) biomass by cultivating these plants in various concentrations of metal contaminants. Sunflowers were grown in soils contaminated with various levels of heavy metals (10–2,000 mg/kg dry soil). The degree of metal uptake by different parts of the biomass and the residual concentration in the soil were estimated through inductively coupled plasma mass spectrometry. An almost 2.5-fold hyperaccumulation of Zn2+ was observed in the leaf and flower biomass compared with the concentration in the soil. For the subsequent saccharification of biomass with hyperaccumulated contaminants, a fungal lignocellulosic consortium was used. The fungal consortium cocktail retained more than 95% filter paper activity with 100 mM Ni2+ ions even after 36 h. The highest saccharification yield (SY, 87.4%) was observed with Ni2+ as the contaminant (10 mg/kg dry wt), whereas Pb2+ (251.9 mg/kg dry wt) was the strongest inhibitor of biomass hydrolysis, resulting in only a 30% SY. Importantly, the enzyme cocktail produced by the fungal consortium resulted in almost the same SY (%) as that obtained from a combination of commercial cellulase and β-glucosidase. Significant sugar conversion (61.7%) from H. annuus biomass hydrolysate occurred, resulting in the production of 11.4 g/L of bioethanol. This is the first study to assess the suitability of phytoremediated sunflower biomass for bioethanol production.

Production of ethanol from steam exploded triticale straw in a simultaneous saccharification and fermentation process

Abstract The cost-effective production of bioethanol requires an inexpensive feedstock that is easily hydrolysed by minimal amounts of cellulase enzymes and efficiently converted to ethanol. Steam-exploded triticale straw was investigated for ethanol production using selected commercial cellulases, with Spezyme® CP outperforming the other enzymes in terms of glucose release. Varying enzyme dosages (5, 10 and 15 FPU Spezyme® CP/g cellulose) and different solids loadings (5, 10 and 15% w/v) were evaluated in simultaneous saccarification and fermentation (SSF) experiments with Saccharomyces cerevisiae Ethanol Red® as fermenting yeast. A 15% (w/v) solids loading with 15 FPU Spezyme® CP/g cellulose produced 29.6 g/l ethanol (81.3% ethanol yield). When the high-gravity SSF was repeated in a 1-l bioreactor using 15% solids and 15 FPU Spezyme® CP/g cellulose, an ethanol concentration of 29.31 g/l (84.7% ethanol yield) was achieved after 144 h without additional β-glucosidase. Similar results have been observed by other researchers, but with higher enzyme dosages or the addition of β‐glucosidase or xylanase. This study demonstrates that triticale straw is a potential feedstock for the production of lignocellulosic bio-ethanol, and further optimisation of the SSF conditions could result in a commercially viable process for the production of bio-ethanol.

Kinetic Simulations of H2 Production from H2S Pyrolysis in Sulfur Recovery Units Using a Detailed Reaction Mechanism

Acid gas (H2S and CO2) is produced in large volumes worldwide from the desulfurization of hydrocarbon fuels and is utilized in sulfur recovery units (SRUs) to produce sulfur. However, the hydrogen content of acid gas is wasted as low-grade steam, which highlights the need for the efficient utilization of this resource. The production of H2 from acid gas is desired, as it is an inexpensive feedstock. In this work, a kinetic study is conducted on H2 production from acid gas in an industrial SRU to utilize its built-in inertia, while saving on the capital cost and enhancing the processing capacity of the SRU. The thermal energy generated during the combustion of acid gas in the reaction furnace (RF) is used for acid gas pyrolysis in the waste heat boiler (WHB) of the SRU. While this technique has been investigated previously, its realization at the industrial scale is hindered by low H2 yield. This paper presents suitable means of enhancing H2 production via operational modifications in RF and WHB. A detaile...

Simultaneous Saccharification and Fermentation of Sugar Beet Pulp with Mixed Bacterial Cultures for Lactic Acid and Propylene Glycol Production.

Research into fermentative production of lactic acid from agricultural by-products has recently concentrated on the direct conversion of biomass, whereby pure sugars are replaced with inexpensive feedstock in the process of lactic acid production. In our studies, for the first time, the source of carbon used is sugar beet pulp, generated as a by-product of industrial sugar production. In this paper, we focus on the simultaneous saccharification of lignocellulosic biomass and fermentation of lactic acid, using mixed cultures with complementary assimilation profiles. Lactic acid is one of the primary platform chemicals, and can be used to synthesize a wide variety of useful products, including green propylene glycol. A series of controlled batch fermentations was conducted under various conditions, including pretreatment with enzymatic hydrolysis. Inoculation was performed in two sequential stages, to avoid carbon catabolite repression. Biologically-synthesized lactic acid was catalytically reduced to propylene glycol over 5% Ru/C. The highest lactic acid yield was obtained with mixed cultures. The yield of propylene glycol from the biological lactic acid was similar to that obtained with a water solution of pure lactic acid. Our results show that simultaneous saccharification and fermentation enables generation of lactic acid, suitable for further chemical transformations, from agricultural residues.

Thermochemical Transformations of Plant Materials

Cherry pits and hazelnut shells were investigated as inexpensive alternative feedstocks for producing carbon absorbents via thermolysis and carbonization. It was found that the absorption properties of the obtained products depended on the chemical composition of the plant materials and the thermolysis and carbonization conditions.

Catalytic Synthesis of Organophosphorus Compounds from Inorganic Derivatives of Low Valence Phosphorus

<p>A variety of new reactions of inorganic compounds of elemental and low valence phosphorus (phosphine, white phosphorus, sodium hypophosphite) with various organic substrates (alcohols, olefins, quinones) catalysed by different transition metal (Pd<sup>II</sup>, Hg<sup>II</sup>, Pt<sup>II</sup>, Pt<sup>IV</sup>, Ag<sup>I</sup>, Fe<sup>III</sup>, Cu<sup>II</sup>) salts leading to the formation of valuable organophosphorus derivatives (trialkylphosphates, dialkylphosphites, trialkylphoshinoxides, phosphonium salts) are reviewed. The principal features of the oxidative phosphorylation reactions which are of great practical importance are described. The mechanisms of the catalytic oxidative P-O and P-C coupling of phosphine, white phosphorus and hypophosphite with alcohols, olefins and quinones are considered. It has been shown that this catalytic protocol allows to provide a highly selective conversion of relatively inexpensive feedstocks to desirable higher added-value products.</p>

Integrated bioprocess for conversion of gaseous substrates to liquids

In the quest for inexpensive feedstocks for the cost-effective production of liquid fuels, we have examined gaseous substrates that could be made available at low cost and sufficiently large scale for industrial fuel production. Here we introduce a new bioconversion scheme that effectively converts syngas, generated from gasification of coal, natural gas, or biomass, into lipids that can be used for biodiesel production. We present an integrated conversion method comprising a two-stage system. In the first stage, an anaerobic bioreactor converts mixtures of gases of CO2 and CO or H2 to acetic acid, using the anaerobic acetogen Moorella thermoacetica The acetic acid product is fed as a substrate to a second bioreactor, where it is converted aerobically into lipids by an engineered oleaginous yeast, Yarrowia lipolytica We first describe the process carried out in each reactor and then present an integrated system that produces microbial oil, using synthesis gas as input. The integrated continuous bench-scale reactor system produced 18 g/L of C16-C18 triacylglycerides directly from synthesis gas, with an overall productivity of 0.19 g⋅L(-1)⋅h(-1) and a lipid content of 36%. Although suboptimal relative to the performance of the individual reactor components, the presented integrated system demonstrates the feasibility of substantial net fixation of carbon dioxide and conversion of gaseous feedstocks to lipids for biodiesel production. The system can be further optimized to approach the performance of its individual units so that it can be used for the economical conversion of waste gases from steel mills to valuable liquid fuels for transportation.

Integrated enzyme production lowers the cost of cellulosic ethanol

AbstractPrevious studies of cellulosic‐ethanol production have shown that the cost of producing cellulase is surprisingly significant, and that reducing this cost is key to making cellulosic‐ethanol economically viable. This study confirms that finding, and compares the costs of the three approaches for producing cellulase: off‐site, on‐site, and integrated. It finds that the integrated method is the lowest cost, primarily because it substitutes an inexpensive feedstock, biomass, for a relatively expensive one, glucose. This substitution also makes the ethanol a 100% second‐generation biofuel, i.e., it uses no ‘food for fuel’. This study also compares the activity of cellulase produced by the integrated method versus that produced by the off‐site method. Laboratory trials of the two show the ‘integrated’ cellulase to be better or equal to commercially available ‘off‐site’ cellulase in converting cellulose to sugar. © 2016 The Authors. Biofuels, Bioproducts, Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd.

Dairy Manure as a Potential Feedstock for Cost-Effective Cellulosic Bioethanol

This study investigated sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) pretreatment and subsequent enzymatic digestibility of undigested dairy manure to preliminarily assess its potential use as an inexpensive feedstock for cellulosic bioethanol production. The sulfite pretreatment was carried out in a factorial analysis using 163 to 197 °C for 3 to 37 min with 0.8% to 4.2% sulfuric acid combined with 2.6% to 9.4% sodium sulfite. These treatments were compared with other standard pretreatments of dilute acid, and hot and cold alkali pretreatments. This comparative study showed that the sulfite pretreatment, through its combined effects of hemicellulose and lignin removal and lignin sulfonation, is more effective than the diluted acid and alkali pretreatments to improve the enzymatic digestibility of dairy manure.

Experimental assessment of performance and emissions maps for biodiesel fueled compression ignition engine

Attempts to use many types of biofuel have been tried throughout the past. Waste cooking oils (WCO) represent attractive alternatives to edible fat and oils for the production of biodiesel fuel from different points of view: they are inexpensive feedstock for biodiesel production. At the same time, using this kind of feedstock eliminates food versus fuel competition. Finally, Their use supposes an environmentally friendly approach.Internal combustion engines operate correctly on a wide range of speeds and loads. However, only few studies on biodiesel fueled engines are undertaken for performance mapping. In the present study, the effects of entire operational range of speed/load on engine performance and emission levels of an engine are investigated when neat WCO biodiesel (B100) and its blends (B25) and (B50) are used. The obtained results are compared to those of conventional diesel (B0).The suitability of WCO biodiesel has been established by many researchers. However their results report a wide disparity on emission levels. Combustion characteristics, performance and emission maps will be performed to give appropriate indications explaining the divergence reported in literature. The map indicates that B50 and B25 exhibit similar trends of BSFC to diesel fuel, across the speed variation albeit with difference in response levels. Contrariwise B100 shows an inverse behavior with speed increase. Results show also that Unburned Hydro-Carbons (UHC) emissions are highly correlated with engine speed. However, CO and PM emissions are extremely correlated with load and they are less sensitive to engine speed. NOx emissions are generally higher with biodiesel except some extreme zones of the map.

Design and optimization of the levulinic acid recovery process from lignocellulosic biomass

Levulinic acid (LA), which is one of the top twelve value-added chemicals from biomass feedstock, has been recognized in a large number of applications. Nevertheless, its capability on an industrial scale has been limited by the high-cost of the raw materials and the lack of detailed process design. This paper reports the simulation, detailed design and optimization of an industrial process recovering LA from biomass, a renewable and inexpensive feedstock. The aqueous feed mixture from the acidic hydrolysis of biomass was fed to the separation process to recover LA as the main product, along with furfural and formic acid as valuable byproducts. Furfural was then used as an extracting solvent, resulting a significant decrease in total cost. Detailed analysis was conducted to assess the feasibility of the separation method. The purification process was intensified by applying an innovative top dividing wall column with a decanter configuration (TDWC-D). The response surface methodology (RSM), which allows the interactions between variables to be identified and quantified, was used to optimize the TDWC-D structure. The predictions by the RSM showed satisfactory agreement with the rigorous simulation results. The results showed that the innovative TDWC-D configuration could save up 16.4% and 20.6% of the overall energy requirements and total annual cost, respectively, compared to the conventional sequence.

Efficient production of free fatty acids from soybean meal carbohydrates.

Conversion of biomass feedstock to chemicals and fuels has attracted increasing attention recently. Soybean meal, containing significant quantities of carbohydrates, is an inexpensive renewable feedstock. Glucose, galactose, and fructose can be obtained by enzymatic hydrolysis of soluble carbohydrates of soybean meal. Free fatty acids (FFAs) are valuable molecules that can be used as precursors for the production of fuels and other value-added chemicals. In this study, free fatty acids were produced by mutant Escherichia coli strains with plasmid pXZ18Z (carrying acyl-ACP thioesterase (TE) and (3R)-hydroxyacyl-ACP dehydratase) using individual sugars, sugar mixtures, and enzymatic hydrolyzed soybean meal extract. For individual sugar fermentations, strain ML211 (MG1655 fadD(-) fabR(-) )/pXZ18Z showed the best performance, which produced 4.22, 3.79, 3.49 g/L free fatty acids on glucose, fructose, and galactose, respectively. While the strain ML211/pXZ18Z performed the best with individual sugars, however, for sugar mixture fermentation, the triple mutant strain XZK211 (MG1655 fadD(-) fabR(-) ptsG(-) )/pXZ18Z with an additional deletion of ptsG encoding the glucose-specific transporter, functioned the best due to relieved catabolite repression. This strain produced approximately 3.18 g/L of fatty acids with a yield of 0.22 g fatty acids/g total sugar. Maximum free fatty acids production of 2.78 g/L with a high yield of 0.21 g/g was achieved using soybean meal extract hydrolysate. The results suggested that soybean meal carbohydrates after enzymatic treatment could serve as an inexpensive feedstock for the efficient production of free fatty acids.

Low-Cost Synthetic Routes for Fabricating Tandem/Multi-Junction Photoelectrochemical Devices

Using sunlight to convert widely available and inexpensive feed stocks such as water, CO2, and industrial wastes (including halogenides) reliably to fuels and value added chemicals, efficiently and cost-effectively, has been, and continues to be a major goal. Most such reactions require a minimum of 1eV or more photon energies. For example, the minimum free energy required to split water reversibly is 1.23 eV. However, kinetic limitations and other sources of inefficiencies (for example, water oxidation on photoanodes is kinetically sluggish, and CO2 reduction at photocathodes needs high overpotentials) make the practical energy needed to carry such reactions even considerably higher. A single-junction photosynthetic device would therefore need to base on a semiconductor with a band gap (Eg) > 2.5 eV for it to carry out water splitting or CO2 reduction, precluding the exploitation of a substantial portion of the solar spectrum. Using tandem/multi-junction photovoltaic architectures is an attractive strategy to overcome these limitations. Such strategies have been estimated to be capable of achieving ~18% solar-to-hydrogen conversion efficiencies. John Turner and his colleagues [1] demonstrated a solar-to-H2 conversion efficiency of 12.4% using multi-junction III-V semiconductors in 1990’s. However, the high cost and complexity associated with device fabrication using Si and III-V semiconductors to produce triple junction devices have impeded commercialization. Here, we report a novel and low-cost wet chemical synthesis route to fabricate a tandem junction PEC device through direct deposition of inexpensive and efficient metal oxide/sulfide based photoanodes on single junction Si solar cells which act as photocathodes. The above structures were able to generate sufficiently high cell voltages to drive valuable, and, at times, challenging photoelectrochemical processes sustainably. Reference: Khaselev, O. & Turner, J. A monolithic photovoltaic-photoelectrochemical device for hydrogen production via water splitting. Science (New York, N.Y.) 280, 425–7 (1998).

Biomediated production of structurally diverse poly(hydroxyalkanoates) from surplus streams of the animal processing industry

For commercial success, enhanced poly(hydroxyalkanoate) (PHA) production must address both material performance and economic aspects. Conventional PHA production consumes expensive feedstocks dedicated to nutrition. Switching to carbon-rich (agro)industrial side-streams alleviates industrial disposal problems, preserves food resources, and can be economically superior. Processes developed in the recently performed EU-FP7 project ANIMPOL resort to lipid-rich surplus streams from slaughterhouses and the ren- dering industry; these materials undergo chemical transformation to crude glycerol phase (CGP) and bio- diesel. The saturated biodiesel share (SFAE) counteracts its applicability as a biofuel but, in addition to CGP, can be converted biotechnologically to PHAs. Depending on the applied microbial production strain and the selected carbon source (SFAE or CGP), thermoplastic short chain length PHA (scl-PHA), as well as elastome- ric to latex-like medium chain length PHA (mcl-PHA), can be produced from these inexpensive feed stocks. The article illustrates the biotechnological conversion of animal-based CGP and SFAE towards poly(3-hyd- roxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), respectively, by Cupriavi- dus necator strain DSM 545. SFAE conversion towards mcl-PHAs consisting of various saturated and unsatu- rated building blocks by two pseudomonades, Ps. citronellolis DSM 50332 and Ps. chlororaphis DSM 50083, are also shown. Together with the kinetics of the bioprocesses, the results from the characterization of isolated samples of these structurally diverse biopolyesters are compared; data demonstrate the high versatility of biopolymer properties making them applicable in various fields of the plastic market. In addition to the need for inexpensive carbon feed stocks, the article points to further hot spots of the PHA-production chain that must be considered in order to lower the overall PHA production costs, and to enhance product quality. The benefits arising from multistage continuous cultivation production set-ups, namely high-throughput pro- duction of PHA of predefined composition and constant quality, are especially discussed. Finally, contempo- rary approaches towards environmentally and ecologically sustainable PHA recovery from biomass are summarized.

Efficient free fatty acid production in engineered Escherichia coli strains using soybean oligosaccharides as feedstock.

To be competitive with current petrochemicals, microbial synthesis of free fatty acids can be made to rely on a variety of renewable resources rather than on food carbon sources, which increase its attraction for governments and companies. Industrial waste soybean meal is an inexpensive feedstock, which contains soluble sugars such as stachyose, raffinose, sucrose, glucose, galactose, and fructose. Free fatty acids were produced in this report by introducing an acyl-ACP carrier protein thioesterase and (3R)-hydroxyacyl-ACP dehydratase into E. coli. Plasmid pRU600 bearing genes involved in raffinose and sucrose metabolism was also transformed into engineered E. coli strains, which allowed more efficient utilization of these two kinds of specific oligosaccharide present in the soybean meal extract. Strain ML103 (pRU600, pXZ18Z) produced ~1.60 and 2.66 g/L of free fatty acids on sucrose and raffinose, respectively. A higher level of 2.92 g/L fatty acids was obtained on sugar mixture. The fatty acid production using hydrolysate obtained from acid or enzyme based hydrolysis was evaluated. Engineered strains just produced ~0.21 g/L of free fatty acids with soybean meal acid hydrolysate. However, a fatty acid production of 2.61 g/L with a high yield of 0.19 g/g total sugar was observed on an enzymatic hydrolysate. The results suggest that complex mixtures of oligosaccharides derived from soybean meal can serve as viable feedstock to produce free fatty acids. Enzymatic hydrolysis acts as a much more efficient treatment than acid hydrolysis to facilitate the transformation of industrial waste from soybean processing to high value added chemicals.

Adding value to wastewater by resource recovery and reformulation as growth media: current prospects and potential

Wastewater, despite being a serious environmental constraint, has been identified as a source of valuable commodities including phosphate, ammonia, metal ions and volatile fatty acids. Using low-cost physical pre-treatments, filtration technology gives the opportunity of recovering materials in purified concentrated liquid form and purified water. Filtration also allows manipulation of the nutrient content in the effluents enabling the formulation of a series of streams enriched with important chemical components, enabling their reformulation into balanced nutrient media for microbial growth and the production of biofuels, acids and other chemicals such as lipids and enzymes. This approach benefits industry through the use of a relatively abundant inexpensive feedstock able to be recycled to produce high value chemicals while reducing the carbon footprint of the fermentation and reducing waste disposal. Examples of potential schemes of nutrient formulation and their application are presented.