Because the limitations of water-based fracturing fluids restrict their fracturing efficiency and scope of application, liquid CO₂ is regarded as a promising substitute, owing to its unique characteristics, including its greater environmental friendliness, shorter clean-up time, greater adsorption capacity than CH₄ and less formation damage. Conversely, the disadvantage of high leak-off rate of CO₂ fracturing due to its very low viscosity determines its applicability in gas shales with ultra-low permeability, accurate measurement of shale permeability to CO₂ is therefore crucial to evaluate the appropriate injection rate and total consumption of CO₂. The main purpose of this study is to accurately measure shale permeability to CO₂ flow during hydraulic fracturing, and to compare the leak-off of CO₂ and water fracturing. A series of permeability tests was conducted on cylindrical shale samples 38 mm in diameter and 19 mm long using water, CO₂ in different phases and N₂ considering multi... [more]

This paper proposes a new DC coil free hybrid excited machine concept, which has no external field windings. The technical novelty is the integration of field windings and armature windings. DC bias current is injected into the excitation and the field windings in the traditional hybrid excited machine are eliminated. Compared with traditional hybrid-excited machines with additional field windings, the proposed machine can realize a higher slot utilization ratio, hence achieve a higher torque density and a wider flux adjusting range. Another advantage of the proposed machine is that the voltage drop associated with flux regulation is small due to the small DC resistance, and the torque generating capability at the flux regulating region can be improved accordingly. The rotor is specifically designed with magnet-iron sequences and a consequent-pole, in which the permanent magnet and iron pole are alternatively employed. A bi-directional flux modulating effect can be achieved, which can... [more]

Over the past two decades, the alkaline persulfate oxidation (PO) with thermal and/or ultraviolet (UV) assisted digestion method has been widely used for digestion of nitrogen containing compounds (N-compounds) in water quality routine analysis in laboratory or on-line analysis, due to its simple principle, high conversion rate, high percent recovery, low-cost. However, this digestion method still has some inevitable problems such as complex operations, high contamination potential, batch N blanks, higher reaction temperature (120−124 °C) and time-consuming (30−60 min). In this study, ozone (O3) was selected as the oxidant for digestion of N-compounds through analysis and comparison firstly. Secondly, we proposed and compared the UV and/or ultrasound (US) combined with ozone (UV/O3, US/O3 and UV/US/O3) synergistic digestion methods based on O3 with sole O3 oxidation method on digestion efficiency (digestion time and conversion rate) of standard N-compounds. Simultaneously, the influenc... [more]

In this investigation, hydroxyapatite (HA) was synthesized using sea urchin spines (Strongylocentrotus purpuratus) via a precipitation and heat treatment method at three different temperatures (500, 600 and 700 °C). Biosynthesized HA was characterized to determine the vibration of functional groups, morphology, particle size, crystalline structure and chemical composition. For this, Fourier-Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were used, respectively. The FTIR-ATR results reveal that the most defined characteristic HA bonds (O-H, P-O and C-O bonds) were better defined at higher synthesis temperatures. SEM also presented evidence that temperature has a significant effect on morphology. EDS results showed that the Ca/P ratio increased in the samples at higher temperatures. XRD analysis prese... [more]

In this work, we explore the synthesis of layered double hydroxide (LDH) particles containing different molar ratios of Gd3+ and Dy3+ cations. A single crystalline phase was obtained for Zn2.0Al0.75Gd0.125Dy0.125-LDH and Zn2.0Al0.5Gd0.25Dy0.25-LDH, and their efficiency as contrast agents was evaluated by T1- and T2-weighted magnetic resonance imaging (MRI). Both GdDy-LDHs exhibited longitudinal relaxivity (r1) higher than a commercial reference. The highest contrast in the T1 mode was achieved with the Zn2.0Al0.75Gd0.125Dy0.125-LDH, which contained the lowest concentration of lanthanides; this efficiency is related to the lowest amount of carbonate anions complexing the lanthanide sites. On the contrary, the best contrast in the T2 mode was achieved with Zn2.0Al0.5Gd0.25Dy0.25-LDH. Zn2.0Al0.75Gd0.125Dy0.125-LDH and Zn2.0Al0.5Gd0.25Dy0.25-LDH presented r2/r1 ratios of 7.9 and 22.5, respectively, indicating that the inclusion of gadolinium and dysprosium into layered structures is a prom... [more]

Anaerobic bioelectrochemical digestion (ABD) is widely used for treating wastewater and recovering energy. The electrode is the key point for ABD system, which was sparsely studied with food waste. In this study, a carbon-modified copper foam was fabricated with copper foam and multiple wall carbon nanotubes (MWCNT) through electrophoretic deposition and screen-printing methods. The carbon-modified copper foam electrode was investigated in an ABD reactor for food waste. The features of bioelectrochemical methane production, process stability, and electrochemical characterization were evaluated in the ABD reactor, and were compared to the control reactor without equipping electrode. The ultimate methane production reached 338.1 mL CH4/L in the ABD reactor, which was significantly higher than the 181.0 mL CH4/L of the control reactor. The methane produced from the electrode was 137.8 mL CH4/L, which was up to 40.8% of total methane production in the ABD reactor. It was attributed to the... [more]

In September 2018, the global chemical engineering community lost a true pioneer in the field [...]

This paper presents the results of an experimental study on the extraction of KCl and the improvement of the zinc grade of secondary dust obtained from rotary-hearth-furnace secondary dust (RHF secondary dust) using alkali leaching (Na2CO3 solution) and evaporation−crystallization processes. The effects of the liquid−solid ratio and Na2CO3 content on the element leaching ratio in the alkali leaching process, as well as the effects of the volume−evaporation ratio and cooling temperature on KCl extraction in the evaporation−crystallization process, were investigated. The results showed that the optimum liquid−solid ratio was 6:1, and the optimum quantity of Na2CO3 was 1.5 times the basic quantity. The recovery ratio of zinc reached 95.23%, and the leaching ratio of K reached 79.01%. The experimental results of the evaporation−crystallization process demonstrated that the evaporation temperature was 80 °C, the volume evaporation ratio was 50%, the cooling temperature was 25 °C, and the ma... [more]

Arsenic removal is a crucial issue in all copper smelters. Based on the Fangyuan 1# smelter, the effects of major elements (Cu, Fe and S) in sulfide concentrates on arsenic removal in the SKS copper smelting process were studied in this paper. The results show that Cu, Fe and S in concentrates have a significant influence on the oxygen/sulfur potential of smelting systems, and also affect the efficiency of arsenic removal. By regulating the proportion of the major elements in sulfide concentrates, the concentrate composition was changed from its original proportions (Cu 24.4%, Fe 26.8%, S 28.7%, and other 20%) to optimized proportions (Cu 19%, Fe 32%, S 29%, and other 20%). The distribution of arsenic among three phases in the original production process (gas 82.01%, slag 12.08%, matte 5.91%) was improved to obtain an optimal result (gas 94.37%, slag 3.45%, matte 2.18%). More arsenic was removed into the gas phase, and the mass fraction of arsenic in matte was reduced from 0.07% to 0.0... [more]

We investigated the effect of chlorine dioxide (ClO2) under low temperature drying to suppress rice cake stickiness during the cutting process by initiating the onset of retrogradation until the stickiness is minimized for shelf-life extension. The intermittent ClO2 application at low-temperature drying was conducted at 10 °C for different drying periods (0, 6, 12, 18, and 24 h). Texture analysis showed significant differences with increasing values of hardness (901.39 ± 53.87 to 12,653 ± 1689.35 g) and reduced values of modified adhesiveness (3614.37 ±578.23 to 534.81 ± 89.37 g). The evaluation of rice cake stickiness during the cutting process revealed an optimum drying period of 18 h with no significant difference (p ≤ 0.05) compared to the 24 h drying process. Microbial contamination during the drying process increased, with microbial load from 6.39 ± 0.37 to 7.94 ± 0.29 CFU/g. Intermittent ClO2 application at 22 ppm successfully reduced the microbial load by 63% during drying proc... [more]

This paper experimentally analyzes the chemical additives, i.e., methanol and ethanol, as alcohol solvents, and acetone as a ketone solvent, and the temperature influencing the minimum miscibility pressure (MMP) that is essential to design miscible CO2 flooding at an oil field, the South Sumatra basin, Indonesia. The experiments were designed to measure CO2-oil interfacial tension with the vanishing interfacial tension (VIT) method in the ranges up to 3000 psi (208.6 bar) and 300 degrees Celsius. The experiment results show that lower temperatures, larger solvent volumes, and the acetone were effective in reducing MMP. The acetone, an aprotic ketone solvent, reduced MMP more than the methanol and the ethanol in the CO2-oil system. The high temperature was negative to obtain the high CO2 solubility into the oil as well as the lower MMP. The experimental results confirm that the aprotic ketone solvent could be effective in decreasing the MMP for the design of miscible CO2 flooding at the... [more]

In this study, three microfluidic devices with different geometries are fabricated on silicon and are bonded to glass to withstand high-pressure fluid flows in order to observe bacteria deactivation effects of micro cavitating flows. The general geometry of the devices was a micro orifice with macroscopic wall roughness elements. The width of the microchannel and geometry of the roughness elements were varied in the devices. First, the thermophysical property effect (with deionized water and phosphate-buffered saline (PBS)) on flow behavior was revealed. The results showed a better performance of the device in terms of cavitation generation and intensity with PBS due to its higher density, higher saturation vapor pressure, and lower surface tension in comparison with water. Moreover, the second and third microfluidic devices were tested with water and Salmonella typhimurium bacteria suspension in PBS. Accordingly, the presence of the bacteria intensified cavitating flows. As a result,... [more]

With the wide application of ASP (alkali/surfactant/polymer) flooding oil recovery technology, the produced water from ASP flooding has increased greatly. The clay particles carried by crude oil in the process of flow have a synergetic effect with oil displacement agents in the produced water, which increases the treatment difficulty of produced water. The stability of produced water is decided by the stability of oil droplets in the ASP-flooding-produced water system. The oil content, Zeta potential, interfacial tension and oil droplet size are important parameters to characterize the stability of produced water. In this paper, the changes of the oil content, Zeta potential, interfacial tension and oil droplet size of ASP flooding oily wastewater under the synergetic effect of different concentrations of quartz sand particles and oil displacement agents were studied by laboratory experiments. The experimental results show that the negatively charged quartz sand particles can absorb ac... [more]

In order to solve the problem of the poor oil displacement effect of high molecular weight alkali/surfactant/polymer (ASP) solution in low permeability reservoirs, Daqing Oilfield uses a partial quality tool to improve the oil displacement effect in low permeability reservoirs. In the formation, the partial quality tool degrades the polymer through active shearing action, reducing the molecular weight of the polymer, to improve the matching degree to the low permeability oil layer and the oil recovery. In order to study the ability of the partial quality tool to improve the oil displacement effect, the matching degree of high molecular weight ASP solution to low permeability cores is studied, and the ability of quality control tools to change the molecular weight is studied. Then, experimental research on the pressure and oil displacement effect of high molecular weight ASP solution before and after the actions of the partial quality tool is carried out. The results show that ASP solut... [more]

From the perspective of resource recovery and environmental protection, coal gangue-fly ash cemented backfill coal mining has become an important direction for the green development of coal mines in recent years. Analysis of the rheological parameters of backfill slurry is the basic principle to design a backfill pipeline system. Coal gangue-fly ash backfill slurry has a mass concentration of 76% to 79% and a maximum particle size 20 mm. Therefore, it is difficult to use conventional rheometers for experimental analyses of the rheological parameters of such fluids. We developed a rheometer for high-concentration coal gangue backfill slurry (HCGS rheometer) based on the coal gangue-fly ash backfill practice of Gonggeying Mine, and analyzed the rheological properties of the backfill slurry. The experimental results showed that the Reynolds number of the coal gangue-fly ash backfill slurry was much smaller than the critical Reynolds number, indicating the flow state in the pipeline was la... [more]

In order to achieve proficient combustion with the present technologies, the flow through an aircraft intake operating at supersonic and hypersonic Mach numbers must be decelerated to a low-subsonic level before entering the combustion chamber. High-speed intakes are generally designed to act as a flow compressor even in the absence of mechanical compressors. The reduction in flow velocity is essentially achieved by generating a series of oblique as well as normal shock waves in the external ramp region and also in the internal isolator region of the intake. Thus, these intakes are also referred to as mixed-compression intakes. Nevertheless, the benefits of shock-generated compression do not arise independently but with enormous losses because of the shockwave and boundary layer interactions (SBLIs). These interactions should be manipulated to minimize or alleviate the losses. In the present investigation a wall ventilation using a new cavity configuration (having a cross-section simil... [more]

We were not aware of an error made in the proofreading phase; therefore, we wish to make the following correction to Figure 1b from this paper [...]

Polymer flooding emulsions and microemulsions caused by tertiary oil recovery technologies are harmful to the environment due to their excellent stability. Two cationic hyperbranched polyamidoamines (H-PAMAM), named as H-PAMAM-HA and H-PAMAM-ETA, were obtained by changing the terminal denotation agents to H-PAMAM, which was characterized by 1H NMR, FT-IR, and amine possession, thereby confirmed the modification. Samples (300 mg/L) were added to the polymer flooding emulsion (1500 mg/L oil concentration) at 30 °C for 30 min and the H-PAMAM-HA and H-PAMAM-ETA were shown to perform at 88% and 91% deoil efficiency. Additionally, the increased settling time and the raised temperature enhanced performance. For example, an oil removal ratio of 97.7% was observed after dealing with the emulsion for 30 min at 60 °C, while 98.5% deoil efficiency was obtained after 90 min at 45 °C for the 300 mg/L H-PAMAM-ETA. To determine the differences when dealing with the emulsion, the interfacial tension, ζ... [more]

Curcumin was microencapsulated by porous starch using a spray dryer with a particle size between 1.5 and 2.0 µm and subjected to water bath (40−100 °C) and oven heating (150−200 °C) in comparison to non-encapsulated samples. The minimum possible encapsulation rate ranged from 26.75 to 52.23%. A reasonable thermal stability was observed after water bath heating with regard to 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging activity. On the other hand, the increase in oven heating temperature caused significant alterations compared with the control samples (p < 0.05). The encapsulated particles subjected to oven heating at 170 °C demonstrated serious collapse. The DPPH scavenging activity of non-encapsulated curcumin was significantly reduced (p < 0.05) from 48.94% ± 3.72% (control, 0 °C) to 40.42% ± 2.23% (oven heating, 160 °C); however, remained stable for the encapsulated samples (51.18% ± 4.86%−50.02% ± 1.79%) without significant difference (p < 0.05). The ABTS... [more]

The microbial oxidation of CH4 in biochar-modified soil cover is considered a potent option for the mitigation of emissions from old landfills or sites containing wastes full of low CH4 generation rates. The mechanism of methane oxidizing bacteria (MOB) can be enhanced by amending the landfill cover soil with biochar, which is recalcitrant to biological degradation and can adsorb CH4 while facilitating the growth and activity of MOB within its porous structure. However, the increase in the permeability coefficient and water content of the cover due to the addition of biochar also affects the methane removal efficiency. A hydrophobic biochar modified by KH-570 was employed to reduce the water content and to promote the diffusion and oxidation of CH4 in the cover. Several series of small-scale column tests were conducted to quantify the CH4 oxidation properties of the landfill cover soil amended with biochar and hydrophobic biochar under different levels of exposed CH4 concentrations (5%... [more]

In this study, a well-to-wheels life cycle assessment was conducted to determine the environmental impacts from disposing of petroleum coke by converting it into liquid fuel. Specifically, three processes for converting petroleum coke and natural gas to Fischer Tropsch diesel were investigated, both with and without carbon capture and sequestration (CCS). Impact categories were calculated using the EPA’s TRACI 2.1 US-Canada 2008 midpoint method in SimaPro software. In addition, the impact of grid emissions on the overall process was assessed using two representative Canadian locations with high (Alberta) and low (Ontario) grid emissions. The results of each impact category were compared among the designs and against conventional petroleum and oil-sands derived diesel. Key findings showed that the proposed designs when operated using CCS in the low-emissions-grid location had lower life cycle GHG emissions than conventional petroleum and oil-sands derived diesel. Nevertheless, the vario... [more]

The editorial team greatly appreciates the reviewers who have dedicated their considerable timeand expertise to the journal’s rigorous editorial process over the past 12 months, regardless ofwhether the papers are finally published or not [...]

This is a submission of source file of the life cycle analysis of steel manufacturing off-gas utilization systems using SimaPro V9. It includes five locations: Ontario, the USA, Finland, Mexico, and China.

Bedded pack manure has long been considered an unsuitable feedstock for conventional anaerobic digestion systems due to its high solids content. However, solid-state anaerobic digestion (SS-AD) provides an opportunity to generate methane from such high-solids feedstocks. This study was conducted to determine the influence of moisture content on the digestion of bedded pack dairy manure using SS-AD. Mixtures of sawdust bedding and dairy manure were prepared with moisture contents (MCs) of 70, 76, and 83% and digested at 37 °C for 85 days. The performance of digesters containing manure at 83% MC was 1.3 to 1.4-fold higher than that of digesters containing 70% MC manure in terms of volatile solids (VS) reduction and biogas production. VS reduction rates were 55 to 75% and cumulative methane yield ranged from 64 to 90 NmL (gVS)−1. These values are lower than those from SS-AD of fresh manure and this is likely due to the partial decomposition of biodegradable materials during the two to thr... [more]

The paper presents the possibility of applying a twin-screw press for juice extraction from apples with different textural properties. The research was carried out with six different varieties; namely, Granny Smith, Modi, Ligol, Lobo, Boscop and Szampion. During the experiment, the following properties were measured: texture properties, pressing yield and polyphenolic content; and ascorbic acid content and antioxidant activity both in raw apples and apple juice. Based on the analysis, three hardness levels of apples can be distinguished, impacting the course of juice pressing in a twin-screw press (low hardness below 30 N, medium hardness 30−50 N and high hardness 50 N). The study showed that only high hardness apples are suitable for pressing on a twin-screw press. The mechanism by which texture properties influence the juice pressing process in the studied press was explained. It was further demonstrated that the hardness of apples has a positive impact on the degree of extraction of... [more]