Alkaline Steam Research Articles

Two-stage sulfite steam pre-treatment achieves extraordinary bioethanol titer from simultaneously saccharification and fermentation of softwood whole slurries

Softwood biomass, which contains rich portion of readily fermentable sugars, is a type of abundant biomass in Canada and Nordic countries. However, its recalcitrant structure has severely limited its utilization in bioconversion. Sulfite treatment during steam pre-treatment to simultaneously enhance ease of hydrolysis and fermentation of softwood biomass has turned to be an attractive strategy to unlock the possibility of converting softwood to bioethanol. Our previous work showed applying one-stage sulfite treatment during the steam pre-treatment under neutral/alkaline conditions could maximize the sulfonation/delignification and hemicellulose sugar retention, while the use of acidic conditions could enhance the homogenous substrates size reduction. To take the advantages of both the neutral/alkaline and acidic conditions, we developed two-stage sulfite steam pre-treatment to maximize the sugar and ethanol production by utilizing Na2SO3 in the first alkaline steam pre-treatment stage and SO2 in a second acidic steam pre-treatment stage. The resulting substrates showed high sulfonation/delignification extent, nearly 100 % sugar recovery, homogeneous substrates size reduction and sufficient detoxification. Without extra hydrolysate detoxification and concentration, 160 g/L fermentable sugars were obtained from the hydrolysis of two-stage sulfite steam pretreated softwood whole slurry at 25% solid loading. And 80 g/L ethanol was generated by directly fermenting these sugars in the whole slurry hydrolysate without additional detoxification or concentration processes. This work significantly contributed to the development of the industrial relevant bioethanol production from softwood biomass.

Production of lignin-containing cellulose nanofibrils by the combination of different mechanical processes

Due to its interesting properties, attention has been oriented to the production of cellulose nanofibrils. However, the cellulose isolation requires the combination of several steps which are generally very energy consuming. This is one of the main limitations for the use and industrialization of such materials. Trying to participate in the resolution of this probleme, lignin-containing cellulose nanofibrils are produced for the first time from Posidonia oceanica waste. Fibers are alkali-extracted by a conventional soda cooking in autoclave or by alkaline steam explosion. As conventional refining of unbleached fibers is difficult, a comparative study is carried out to test alternative processes for fiber fibrillation (twin-screw extrusion (1 pass) or steam explosion (during 3 times)). Actually, these two processes are known to be environmentally friendly and low energy consuming. For microfibrillation, an ultra-fine friction grinder is used to prepare lignin-containing cellulose nanofibrils. The obtained gels are characterized by several properties such as morphological analysis (Morfi, optical microscopy, scanning electron microscopy, transmission electron microscopy) and turbidity measurements. Papers and nanopapers are prepared by filtration to investigate the mechanical properties. All these analysis methods allow discussing the efficiency of the different process combinations. It is concluded that steam explosion could be an alternative method for Posidona fiber extraction, while for refining the process conditions should be optimized. Finally, it is found that LCNF produced from extruded pulps (whatever the fiber extraction method) exhibit promising properties comparing with other unbleached CNF.

Wheat straw cellulose based fluorescent probe cum bioadsorbents for selective and sensitive alleviation of uranium(VI) in waste water

Twin functional ecofriendly fluorescent probe and bioadsorbents were fabricated from wheat straw (WS) for detection and alleviation of hazardous uranyl ions from wastewater. Cellulose nanofibers (CFs) were isolated from WS using alkaline steam explosion and were converted into cellulose dialdehyde (DCF) via selective oxidation followed by conversion to Fluorescent Schiff base cellulose fibres (FSCF) by condensation with L-Arginine, a natural amino acid. Fourier transform infra-red spectroscopy (FTIR), X-Ray Diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrometer (EDX) and thermo-gravimetric analysis (TGA) established formation of Schiff base evenly on CFs yielding robust, crystalline and thermally stable fibrous bioadsorbents. FCSF exhibited affinity for uranyl ions in presence of competing ions and linear increase in fluorescent intensity with concentration at 561 nm when excited at 279 nm in DMF with a low limit of detection (LOD) of 8.09 μM and binding constant of 10 M−1 m3. Under optimised conditions, adsorption studies revealed suitability of Pseudo-second order kinetics with maximum adsorption capacity of 192.7 mg g−1 and Langmuir isotherm confirming chemisorption of U(VI) ions. FSCF exhibited 97% adsorption efficiency after 5 cycles when tested for reusability. The results demonstrated potential application of FSCF for probing and removal of uranyl ions from wastewater.

Tratamiento de lodos activados de purga por explosión de vapor y acidogénesis alcalina

A process improvement of the anaerobic digestion of waste activated sludge (WAS) is needed to produce energy and chemicals to compensate the costs of the full wastewater treatment process. Alkaline steam explosion (A-SE) @160°C and 0.67 MPa absolute pressure, followed by thermophilic alkaline acidogenesis (50°C, pH 9) improves the WAS digestibility and the methane yields by breaking the cell walls and the extracellular polymers. This work studies the treatment time and alkalinity effects on the number of destroyed solids measured as cell damage and particle size reduction. To monitor the process a flow cytometer (FCM), through light scattering signals, proved to be an alternative to the measurement of total suspended solids by gravimetry. The effect of alkaline acidogenesis on the volatile fatty acids (VFA) yield is studied with the A-SE suspension which is cooled down to 50°C and fed to a continuous acidogenic reactor at pH 9 under several organic loads to find the optimum (6 g CODVSS/L.d) with the highest soluble COD and VFA production rates (1.4 and 0.8 g COD/L,d respectively). This effluent can be fed to a methanogenic reactor to produce 0.5 LCH4/L.d or the VFA can be separated for the chemical industry.

Bit coir fiber and sugarcane bagasse fiber reinforced eco-friendly polypropylene composites: Development and property evaluation thereof

Waste natural fibers, bit coir fiber residue of traditional coir industries, and sugarcane bagasse fibers were subjected to chemical modifications via alkaline steam explosion treatments toward the extraction of reinforcing fibers with better compatibility and reinforcing characteristics in the polymer matrix. The treated fibers were utilized in the fabrication of composites with polypropylene (PP) as the base polymer with the aid of maleic anhydride–grafted PP as the compatibilizer. Percent composition of fiber in the composites was decided to facilitate maximum replacement of the matrix and further applicability in large-scale continuous polymeric production processes. Mechanical, thermal, and morphological characterization of the composites reveals the best composition to be of 30% composition, in the added view of maximum replacement of polymer matrix with the reinforcing filler, retention of requisite properties, reduced cost of manufacture and inventory, and reduction in the carbon footprint per unit dimensions in comparison with the wholly polymer component. The thermal properties of coir fiber-reinforced composites showed good improvement up to 134.5°C increase in onset degradation temperature while retaining matrix properties for sugarcane bagasse-reinforced composites.

Extraction and functionalization of bagasse cellulose nanofibres to Schiff-base based antimicrobial membranes

The work reported in this paper involves synthesis of a nanocellulose/chitosan composite and its further modification to antimicrobial films. Bagasse, an easily available biowaste, was used as source to extract nanocellulose fibres (CNFs) by subjecting it to mechanical and chemical treatments including alkaline steam explosion and high shear homogenization. The CNFs were subjected to periodate oxidation to obtain nanocellulose dialdehyde (CDA). The aldehyde groups of CDA were reacted with amino groups of chitosan to form Schiff-base. The resulting CDA/chitosan composite fibres were characterized at various steps. The fibres were then cast into films using cellulose acetate as a binder. The films have good physical strength. The composite films show excellent antimicrobial properties when tested against Staphylococcus aureus and Escherichia coli. Such antimicrobial films have potential applications in the formation of antimicrobial packaging material.

Steam-on-a-chip for oil recovery: the role of alkaline additives in steam assisted gravity drainage

We present a lab-on-a-chip approach to informing thermal oil recovery processes. Bitumen - a major global resource - is an extremely viscous oil which is extracted by injecting steam underground in a process known as Steam Assisted Gravity Drainage (SAGD). Here, a microfluidic network saturated with bitumen provides a physical model of the SAGD reservoir; steam is injected into the chip, and the oil recovery dynamics are visualized and quantified in real-time. The unique advantage of this approach is the pore-scale quantification of fluid phase dynamics under relevant reservoir conditions and pore sizes. High resolution is achieved by leveraging the inherent fluorescence of the native bitumen. The approach is applied to quantify the efficacy of an alkaline steam additive. With the additive, the mean characteristic size of oil-in-water emulsions formed during SAGD is reduced from 150 μm to 6 μm, and the corresponding recovery effectiveness is improved by ~50%. These results demonstrate that pore-scale process quantification enabled by lab-on-a-chip methods can improve the efficacy, and the associated carbon footprint, of energy intensive thermal oil recovery processes.

Alkaline Steam Foam: Concepts and Experimental Results

Summary Experimental studies have shown that the steam-foam process can be enhanced significantly by injecting a suitably formulated alkali/surfactant mixture in the aqueous phase of steam. Emulsionscreening tests, corefloods, and flow-visualization experiments using an alpha olefin sulfonate (AOS) surfactant with 16–18 carbon, Na2CO3, and a heavy Californian crude have shown that alkaline steam foam offers significant advantages over regular steam foam by combining the benefits of thermal and chemical enhanced-oil-recovery (EOR) processes. First, Na2CO3 reduces surfactant consumption by adsorption by rendering the clay surface more negatively charged. Second, by precipitating divalent ions that get ion exchanged off the clays, Na2CO3 reduces surfactant consumption by precipitation. Third, a suitably formulated alkali/surfactant system reduces the oil/water interfacial tension (IFT) sufficiently to enable the heavy oil to be emulsified into the aqueous phase in the presence of steam. This oil-in-water emulsion is less viscous than the oil alone and can be readily transported. Consequently, the residual-oil saturation (ROS) is reduced to a value less than that of steam. Fourth, this lower ROS reduces the destabilizing effect of oil on foam, resulting in stronger steam foam that provides better mobility control than regular steam foam. Therefore, it has the potential to further reduce steam gravity override. Fifth, the reduction in gravity override also reduces loss of heat to the cap rock, thereby improving steam utilization. When applied to steamdrive, alkaline steam foam has the benefit of increasing foam-propagation rate, improving mobility control, improving steam use, and reducing the ROS. Potential applications of alkaline steam foam to steam soaks and steam-assisted gravity drainage (SAGD) are also discussed.

Bioethanol Fermentation from Untreated and Pretreated Bagasse Using Fusarium oxysporum

Comparisons were studied for untreated and pretreated bagasse with dilute alkaline peroxide and steam for bioethanol production by simultaneous saccharification and fermentation (SSF) process in a continuous stirred batch bioreactor using fungi Fusarium oxysporum. The optimum parameters for bioethanol fermentation were: time, 48 h; pH, 6.0; temperature, 50°C; stirring speed, 35 rpm; and bagasse loading, 35 g/L. Maximum concentrations of bioethanol at optimum fermentation process parameters were 18.73 g/L, 19.69 g/L and 20.45 g/L for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. Maximum yields of bioethanol were 0.706 g/g, 0.734 g/g and 0.764 g/g of bagasse at optimum parameters for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The sp. growth rate (µ) of fungi Fusarium oxysporum was determined at 5.91 s−1, 6.25 s−1 and 7.11 s−1 and maximum sp. growth rate (µmax) was calculated at 11.81 s−1, 12.50 s−1 and 14.22 s−1 for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The sp. enzyme activity (ν) was found at 138a0 min−1, 1565 min−1 and 1695 min−1 and maximum sp. activity (νmax) was calculated at 2760 min−1, 3130 min−1 and 3390 min−1 for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The first order rate constants (k) were determined as 0.12 h−1, 0.14 h−1 and 0.156 h−1 for untreated, steam and dilute alkaline peroxide pretreated bagasse for fermentation in continuous stirred batch bioreactor, respectively.

Condition for Lead-Induced Corrosion of Alloy 690 in an Alkaline Steam Generator Crevice Solution

Abstract The effects of dissolved lead on the anodic dissolution behavior of Alloy 690 (UNS N06690) were experimentally investigated in an alkaline solution that is used to simulate the environment in a nuclear steam generator crevice. Lead inoculation and scratch techniques were applied to exclude the inference of the impact of oxidization of the metallic lead deposit. It has been found that lead deposit can promote transient dissolution on the bare metal surface in the alkaline crevice solution before a fully passive state is achieved. The experimental measurements suggest that the promoted transient dissolution is likely to result from the selected dissolution of nickel. The presence of dissolved lead contamination may retard the passivation or repassivation of the alloy. The effect of lead contamination is very limited on the uniform anodic dissolution of the alloy at stable passive state in the alkaline crevice solution.

Studies on Hydrogen Embrittlement of Ti-2Al-2.5Zr Alloy

Abstract The effects of hydrogen on the hydrogen embrittlement of Ti-2Al-2.5Zr alloy was investigated by tensile test, slow strain rate test (SSRT), and the amount of absorbed hydrogen of Ti-2Al-2.5Zr alloy was studied by immersion test in alkaline steam water at a pressure of 8.5MPa. The results indicated that the hydrides(TiH2) in Ti-2Al-2.5Zr alloy formed as platelets and were identified as face-centered cubic δ-hydride. At room temperature, hydrogen and formed hydrides induced increase of the intensity and caused loss in the ductility. In alkaline steam water at a pressure of 8.5MPa, the hydrogen embrittlement susceptibility index (IHE) of Ti-2Al-2.5Zr alloy increased with increasing hydrogen content, and the IHE value of the alloy with 350ppm H was less than 0.1. Moreover the amount of absorbed hydrogen of Ti-2Al-2.5Zr alloy increased with increasing of immersion time, and absorbed hydrogen was still less than 50ppmH even when immersion time reached 13000h.

TEM Observation of Oxide Scale Formed on a Ti-Al-Zr Alloy Oxidized at 3600 C in an Alkaline Steam

TEM Observation of Oxide Scale Formed on a Ti-Al-Zr Alloy Oxidized at 3600 C in an Alkaline Steam

TEM observation of oxide scale formed on a Ti–Al–Zr alloy oxidized at 360°C in alkaline steam

Ti–Al–Zr alloy has been oxidized at 360°C in alkaline steam at a pressure of 10.3 ± 0.7 MPa. Cross-sectional transmission electron microscopy (TEM) observations indicated that the oxide scale of Ti–Al–Zr alloy was composed of outer and inner subscales, in which the outer layer consists of anatase-TiO2 and the inner layer a mixture of TiO and Ti2O. The thickness of the Ti2O, TiO and anatase-TiO2 were approximately 50, 100 and 400 nm, respectively. These results were confirmed by X-ray energy dispersive spectrometry (EDS) measurements. The enhanced corrosion of titanium alloys in LiOH solution is attributed to a high hexagonal Ti2O to tetragonal TiO2 phase transformation rate induced by the substitution of Li+ for Ti4+ in the oxide layer.

Characterisation of the oxide scale on a Ti–2Al–2.5Zr alloy with and without pre-oxidation in an alkaline steam at 300°C

The oxide scales on a Ti–2Al–2.5Zr alloy with and without pre-oxidation oxidised at 300°C in an alkaline steam for approximately 13 000 h were studied by SEM, XRD, XPS and in situ AES techniques. Some of the samples were subjected to 400°C deionised water steam at a pressure of 10 MPa for 72 h for pre-oxidation. The result showed that the oxide scales on the Ti–2Al–2.5Zr alloy were composed of Al 2TiO 5 (TiO 2Al 2O 3), TiO 2, Ti 3O 5, Ti 2O 3, Al 2O 3 and TiO. A comparison study has been carried out between the pre-oxidised and without pre-oxidised Ti–2Al–2.5Zr to determine the influence of pre-oxidation upon the properties of oxidation resistance. The oxidation kinetics showed that the weight gains of the pre-oxidised samples were much less than that of the controlled samples, which was consistent with the results by in situ AES analysis. The AES results showed that the whole thickness of the pre-oxidised sample (approx. 33 000 Å) was thinner than that of the controlled one (approx. 40 000 Å), in contrast the pattern for the stable oxide scale was reversed, i.e. the pre-oxidised sample was much thicker. Thus pre-oxidation is an effective method to improve the oxidation resistance of Ti–2Al–2.5Zr.

The effect of pre-oxidation on the oxidation behaviour of Ti-alloy at 300°C in an alkaline steam

The oxide scales on Ti-alloy with and without pre-oxidation, oxidised at 300°C in an alkaline steam for approximately 13 000 h, were studied by SEM, XRD, XPS and in situ AES techniques. The result showed that the oxide scales on Ti-alloy were composed of Al 2TiO 5(TiO 2Al 2O 3), TiO 2, Ti 3O 5, Ti 2O 3, Al 2O 3 and TiO. A comparison study has been carried out between the Ti-alloy pre-oxidised and Ti-alloy without pre-oxidation, to determine the influence of pre-oxidation upon the properties of oxidation resistance. The oxidation kinetics showed that the weight gains of the pre-oxidised samples were much less than in the controlled samples. The results showed that the whole thickness of the pre-oxidised sample was thinner than that of the controlled one. In contrast, the pattern for the stable oxide scale was reversed, i.e. the pre-oxidised sample was much thicker. Thus pre-oxidation is an effective method to improve the oxidation resistance of Ti-alloys.

Effect of Pre-Oxidation on The Oxidation Behavior of Ti-2Al-2.5Zr Alloy at 300°C in An Alkaline Steam

AbstractThe long-term oxidation behavior on a Ti-2Al-2.5Zr alloy with and without pre-oxidation oxidized at 300 in an alkaline steam for about 13000h were studied. Some of the samples were subjected to 400°C deionized water steam at a pressure of 10MPa for 72 hours for pre-oxidation. A comparison study has been carried out between the pre-oxidized and without pre-oxidized Ti-2Al-2.5Zr to determine the influence of pre-oxidation upon the properties of oxidation resistance. The result analysis showed that the oxide scales on the Ti-2Al-2.5Zr alloy consisted of Al2TiO5, TiO2, Ti3O5, Ti2O3, Al2O3 and TiO. The oxidation kinetics showed that the weight gains of the pre-oxidized samples were much less than that of the without pre-oxidized samples. The AES results showed that the whole thickness of the pre-oxidized sample thinner than that of the without pre-oxidized one, in contrast the pattern for the stable oxide scale was reversed, i.e. the pre-oxidized sample was much thicker. It is thought that pre-oxidation is an effective method to enhance the oxidation resistance of Ti-2Al-2.5Zr.

Experimental Investigation of Surfactant Alkaline Steam Flooding Process.

Continued research and field application of steam flooding have confirmed an early conclusion that the process is a powerful method for recovering heavy and intermediate gravity crude oils. This experimental study investigates the feasibility of using low concentrated solution of alkaline or surfactant as an additive to steam flooding for water flooded reservoirs. This research is also designed to search for optimization of steam flooding process through recovering additional oil via using a steam with low concentration of alkaline-surfactant mixture. This process is designed as surfactant alkaline steam flood. To achieve these goals, four flow experiments are conducted as follows: (1) conventional steam flood (SF), (2) surfactant steam flood (SSF), (3) alkaline steam flood (ASF), and (4) low concentrated surfactant alkaline steam flood (SASF).The results of this study confirmed using steam flooding for a substantial improvement of oil recovery. Using low concentrated alkaline into steam drive recovered additional oil than conventional steam flooding. Mixing steam flooding with surfactant improved oil recovery than either conventional steam drive or alkaline steam flood. The proposed technique of surfactant alkaline steam flood (SASF) significantly enhanced oil recovery.A comparison of the obtained results of the four undertaken experiments results in two major conclusions, which are (1) addition of 3wt% of surfactant or alkaline into steam drive improves its performance and consequently recovers additional oil than conventional steam flood, and (2) using low concentrated surfactant alkaline (1.5wt% for both) into steam flood produces the highest oil recovery.The results of this study have validated the proposed technique of surfactant alkaline steam flooding. Furthermore, this technique is expected to have a significant impact to attain potential oil recovery, if applied in current projects of conventional steam flood and/or water flooded reservoirs.

Experimental Study of Surfactant Alkaline Steam Flood through Vertical Wells

Experimental Study of Surfactant Alkaline Steam Flood through Vertical Wells

Investigations into the potential degradation of polycarbonate baby bottles during sterilization with consequent release of bisphenol A

Twenty‐four brands of plastic baby feeding bottles were purchased and all were found to be made of polycarbonate. Taking a batch of one representative sample, the polymer was tested for stability and possible release of bisphenol A following domestic practice of sterilization. Sterilization was by alkaline hypochlorite, steam, or washing in an automatic dishwasher at 65°C with detergent. A total of 20 cycles of sterilization and subsequent food use were performed for each of the three procedures. Bisphenol A migration was in all cases not detectable in infant feed using a very sensitive method of liquid chromatography with fluorescence detection with a 0.03 mg/kg detection limit.

Novel Sand Consolidation Completion Technique Using Alkaline Steam Injection in the Tar Zone, Wilmington Field, California: ABSTRACT

This is a case study of a novel sand consolidation completion technique. We have competed 11 vertical wells and 2 horizontal wells over five years with minor or no sand problems to date or noticeable in 80% quality steam causes silica dissolution which bonds the sand grains and controls sand movement into the wellbore. Although tested in the field, we do not know the long term effects of this process, the formation around the wellbore which is being treated, and the hot water and steam volumes needed to optimize the process. The results of the laboratory study will be the subject of a future paper.