Water Wettability Research Articles

Bifunctional MOF‐5@coal‐based fiber membrane for oil-water separation and dye adsorption

Water pollution caused by oily and textile wastewater has become a global concerned problem. Wastewater typically contains organic dyes, oil-water emulsions and other pollutants. Hence, it is crucially important to prepare materials that can separate oil-water mixtures/emulsions and adsorb organic dyes. In this work, the semi-encapsulated MOF-5 modified coal-based fiber membranes were prepared by one-step electrospinning method. The modified membrane exhibits superhydrophilic/underwater superoleophobic, excellent stability, high flux (oil-water mixture flux = 8861 L m-2 h-1, oil-in-water emulsion flux = 504 L m-2 h-1) and commendable separation efficiency (98.7%, 99.9%). The membrane could achieve a highly efficient dye absorption (94.9%). The semi-encapsulated construction makes the MOF-5 well protected and the active site can be greatly exposed, leading to significantly improved stability and adsorptive properties. The MOF-5 modification renders the surfaces hydrophilic and increases the roughness which improves water flux and wettability. The composite material provides a new idea for the separation of oil-water mixtures/emulsions and the adsorption of organic dyes.

Effects of Dodecyltrimethylammonium chloride (DAC) micelle’s shape transition on chemical enhanced oil recovery; experimental & mathematical modeling study

Surfactants are widely used for enhanced oil recovery (EOR) purposes by reducing interfacial tension (IFT) of oil–water phases and wettability alteration. Some surfactants with viscoelastic properties can be used as mobility control agents due to enhanced viscosity resulting from the spherical-to-cylindrical shape transition of micelles. Dodecyltrimethylammonium chloride (DAC) shows viscoelastic behavior coupled with dominantly cylindrical shape of the micelle in ambient conditions. Nevertheless, using DAC as an IFT reduction and mobility control agent needs to be industrialized for actual operating conditions. In this study, DAC, as a cationic surfactant, was experimentally studied in reservoir conditions considering dominantly cylindrical micelles for the first time. Results showed that the viscosity of DAC solution is a strong function of DAC concentration, especially at high temperature and high salinity conditions, while it does not depend on pressure significantly. Transmission electron microscope (TEM) images were taken for a better understanding of DAC micellar structures. Analysis of the TEM results indicated the shape transition of the micelles from small spherical to large cylindrical at higher concentrations of DAC. IFT of DAC microemulsion was studied for wide ranges of temperature and DAC concentration, ruling out any significant effect of the temperature on the IFT trend line. A general mathematical model for predicting the viscosity of surfactant solution was developed and evaluated for real reservoir conditions by including all effective terms. Results showed a very good agreement with experimental data of DAC and Cetyltrimethyl ammonium bromide (CTAB, as per previous studies), justifying the applicability of the developed model for predicting the viscosity wherever experimental data is unavailable. Core flood tests were performed with saltwater (SW) and DAC solutions with spherical (SS) and cylindrical (SC) micelles as injecting phases for evaluation of IFT reduction and mobility control effects. Results showed an additional recovery factor of 13 % for SS and 23 % for SC in comparison with SW injection.

Exploring novel organocatalytic-acetylated pea starch blends in the development of hot-pressed bioplastics

Acetylated starch shows enhanced thermal stability and moisture resistance, but its compatibilization with other more hydrophilic polysaccharides remains poor or unknown. In this study, the feasibility of thermomechanically compounding organocatalytically acetylated pea starch (APS), produced at two different degrees of substitution with alkanoyl groups (DSacyl, 0.39 and 1.00), with native pea starch (NPS), high (HMP) and low methoxyl (LMP) citrus pectin, and sugar beet pectin (SBP, a naturally acetylated pectin) for developing hot-pressed bioplastics was studied. Generally, APS decreased hydrogen bonding (ATR-FTIR) and crystallinity (XRD) of NPS films at different levels, depending on its DSacyl. The poor compatibility between APS and NPS or HMP was confirmed by ATR-FTIR imaging. Contrariwise, APS with DSacyl 1 was effectively thermomechanically mixed with the acetylated SBP matrix, maintaining homogeneous distribution within it (ATR-FTIR imaging). APS (any DSacyl) significantly increased the visible/UV light opacity of NPS-based films and decreased their water vapor transmission rate (WVTR, by ca. 11 %) and surface water wettability (by ca. 3 times). In comparison to NPS-APS films, pectin-APS showed higher visible/UV light absorption, tensile strength (ca.2.9–4.4 vs ca.2.4 MPa), and Young's modulus (ca.96–116 vs ca.60–70 MPa), with SBP-APS presenting significantly lower water wettability than the rest of the films.

Water-CO2 wettability on sandstone surface with asphaltene adsorption: Molecular dynamics simulation

The reactions between CO2 slugs and crude oil induce a substantial amount of asphaltene precipitation and adsorption on the rock surface during the CO2 alternative water flooding process. When the subsequent water slug passes through the core pores after asphaltene adsorption, it will displace the previous CO2 slug. The wettability of water and CO2 on the asphaltene-adsorbed rock surface will directly determine the magnitude and direction of the capillary force of the two media, which in turn affects their flow resistance and flow pattern analysis. In this paper, the systems of CO2/water/sandstone and CO2/water/asphaltene adsorption sandstone were established by molecular dynamics simulation technology. The effects of asphaltene adsorption, thickness of the asphaltene adsorption layer, CO2 density, mass fraction and type of salt in water on the wettability of water on sandstone surfaces were studied. The results reveal that asphaltene adsorption significantly reduces the wettability of water on the original powerful water-wetting sandstone surface, making it easier to see how CO2 density affects the wettability of water on the asphaltene-adsorbed sandstone surface. The increased CO2 density will continue to lower the wettability of water on the asphaltene-adsorbed sandstone surface, even causing it to become wet with CO2. The adsorption thickness of asphaltene does not affect the wettability of water and CO2 on the asphaltene-adsorbed sandstone surface, and just a layer of 5A-thick asphaltene adsorption can significantly reduce the wettability of water on sandstone surfaces. Furthermore, a rise in salinity in water has a detrimental impact on the wettability of water on the asphaltene-adsorbed sandstone surface, with divalent salts having a stronger negative effect than monovalent salts.

Microbial colonization patterns and biodegradation of petrochemical and biodegradable plastics in lake waters: insights from a field experiment.

Once dispersed in water, plastic materials become promptly colonized by biofilm-forming microorganisms, commonly known as plastisphere. By combining DNA sequencing and Confocal Laser Scanning Microscopy (CLSM), we investigated the plastisphere colonization patterns following exposure to natural lake waters (up to 77 days) of either petrochemical or biodegradable plastic materials (low density polyethylene - LDPE, polyethylene terephthalate - PET, polylactic acid - PLA, and the starch-based MaterBi® - Mb) in comparison to planktonic community composition. Chemical composition, water wettability, and morphology of plastic surfaces were evaluated, through Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM), and static contact angle analysis, to assess the possible effects of microbial colonization and biodegradation activity. The phylogenetic composition of plastisphere and planktonic communities was notably different. Pioneering microbial colonisers, likely selected from lake waters, were found associated with all plastic materials, along with a core of more than 30 abundant bacterial families associated with all polymers. The different plastic materials, either derived from petrochemical hydrocarbons (i.e., LDPE and PET) or biodegradable (PLA and Mb), were used by opportunistic aquatic microorganisms as adhesion surfaces rather than carbon sources. The Mb-associated microorganisms (i.e. mostly members of the family Burkholderiaceae) were likely able to degrade the starch residues on the polymer surfaces, although the Mb matrix maintained its original chemical structure and morphology. Overall, our findings provide insights into the complex interactions between aquatic microorganisms and plastic materials found in lake waters, highlighting the importance of understanding the plastisphere dynamics to better manage the fate of plastic debris in the environment.

Polyoxometalate-Guanosine Monophosphate Hydrogels with Haloperoxidase-like Activity for Antibacterial Performance.

Haloperoxidases represent an important class of enzymes that nature adopts as a defense mechanism to combat the colonial buildup of microorganisms on surfaces, commonly known as biofouling. Subsequently, there has been tremendous focus on the development of artificial haloperoxidase mimics that can catalyze the oxidation of X- (halide ion) in the presence of H2O2 to form HOX. The natural intermediate HOX disrupts the bacterial quorum sensing, thus preventing biofilm formation. Herein, we report a simple method for the formation of supramolecular hydrogels through the self-assembly of Keggin-structured polyoxometalates, phosphotungstic acid, and silicotungstic acid with the small biomolecule guanosine monophosphate (GMP) in an aqueous medium. The polyoxometalate-GMP hydrogels that contained highly entangled nanofibers were mechanically robust and showed thixotropic properties. The gelation of the polyoxometalates with GMP not only rendered manifold enhancement in biocompatibility but also the fibril network in the hydrogel provided high water wettability and the polyoxometalates acted as an efficient haloperoxidase mimic to trigger oxidative iodination, as demonstrated by a haloperoxidase assay. The antifouling activity of the phosphotungstic acid-GMP hydrogel was demonstrated against both Gram-positive and Gram-negative bacteria, which showed enhanced antibacterial performance of the hydrogel as compared to the polyoxometalate alone. We envision that the polyoxometalate-GMP hydrogels may facilitate mechanically robust coatings in a simple pathway that can be useful for antifouling applications.

Synthesis of cost-effective Si-CQD for effective oil separation from core rock

Nanomaterials (NMs) based on carbon are suitable candidates for separating oil from core rock. Nowadays, the application of carbon-based NMs to enhanced oil recovery (EOR) is far less. The production of NMs based on carbon (water-wet) is of great importance due to the high recovery they create in reservoirs. The purpose of this study was to change the wettability of oil-wet (OW) carbonate rock (CR) towards water-wet (WW) conditions using cheap synthetic materials. In this regard, the effect of three quantum carbon dots (CQDs) on saltwaters has been used. The CQDs were synthesized by hydrothermal procedure and tetraethyl orthosilicate (TEOS) was used as the initial source of carbon. In this regard, Si-CQDs indicated great colloidal sustainability in saltwaters solutions. Therefore, to determine the morphological characteristics and structure of the synthesized NMs, Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR) were done. The stability of NMs was investigated using the zeta potential (ZP). The new compound showed acceptable results at a very low concentration of 100 ppm. The findings indicated that the nanofluid (100 ppm Si-CQDs + Seawater (SE)) reduced the interfacial tension value from 23.34 mN/m to 7 mN/m. Also, the results showed the solution of SE + 100 ppm Si-CQDs improved the oil recovery by 24 % and 23 %. Generally, this paper opens the door for the development of carbon-based NMs with the ability to absorb sediments in the porous media of the reservoir for the efficient separation of oil from core rock. Generally, our analysis supports the use of Si-CQDs as an efficient and economical additive for further oil recovery in carbonate reservoirs.

Effect of Irrigation Water Quality and Wetting and Drying Cycles on the Release of Sodium and Potassium in two Soils of different Orders

Effect of Irrigation Water Quality and Wetting and Drying Cycles on the Release of Sodium and Potassium in two Soils of different Orders

Immiscible Viscous Fingering: The Effects of Wettability/Capillarity and Scaling

AbstractRealistic immiscible viscous fingering, showing all of the complex finger structure observed in experiments, has proven to be very difficult to model using direct numerical simulation based on the two-phase flow equations in porous media. Recently, a method was proposed by the authors to solve the viscous-dominated immiscible fingering problem numerically. This method gave realistic complex immiscible fingering patterns and showed very good agreement with a set of viscous unstable 2D water → oil displacement experiments. In addition, the method also gave a very good prediction of the response of the system to tertiary polymer injection. In this paper, we extend our previous work by considering the effect of wettability/capillarity on immiscible viscous fingering, e.g. in a water → oil displacements where viscosity ratio $$\left( {\mu_{{\text{o}}} /\mu_{{\text{w}}} } \right) \gg 1$$ μ o / μ w ≫ 1 . We identify particular wetting states with the form of the corresponding capillary pressure used to simulate that system. It has long been known that the broad effect of capillarity is to act like a nonlinear diffusion term in the two-phase flow equations, denoted here as $$D(S_{w} )$$ D ( S w ) . Therefore, the addition of capillary pressure, $$P_{c} (S_{w} )$$ P c ( S w ) , into the equations acts as a damping or stabilisation term on viscous fingering, where it is the derivative of this quantity that is important, i.e. $$D(S_{w} )\sim\left( {dP_{c} (S_{w} )/dS_{w} } \right)$$ D ( S w ) ∼ d P c ( S w ) / d S w . If this capillary effect is sufficiently large, then we expect that the viscous fingering to be completely damped, and linear stability theory has supported this view. However, no convincing numerical simulations have been presented showing this effect clearly for systems of different wettability, due to the problem of simulating realistic immiscible fingering in the first place (i.e. for the viscous-dominated case where $$P_{c} = 0$$ P c = 0 ). Since we already have a good method for numerically generating complex realistic immiscible fingering for the $$P_{c} = 0$$ P c = 0 case, we are able for the first time to present a study examining both the viscous-dominated limit and the gradual change in the viscous/capillary force balance. This force balance also depends on the physical size of the system as well as on the length scale of the capillary damping. To address these issues, scaling theory is applied, using the classical approach of Rapport (1955), to study this scaling in a systematic manner. In this paper, we show that the effect of wettability/capillarity on immiscible viscous fingering is somewhat more complex and interesting than the (broadly correct) qualitative description above. From a “lab-scale” base case 2D water → oil displacement showing clear immiscible viscous fingering which we have already matched very well using our numerical method, we examine the effects of introducing either a water wet (WW) or an oil wet (OW) capillary pressure, of different “magnitudes”. The characteristics of these two cases (WW and OW) are important in how the value of corresponding $$D(S_{w} )$$ D ( S w ) functions, relate to the (Buckley–Leverett) shock front saturation, $$S_{wf}$$ S wf , of the viscous-dominated ($$P_{c} = 0$$ P c = 0 ) case. By analysing this, and carrying out some confirming calculations, we show clearly why we expect to see much clearer immiscible fingering at the lab scale in oil wet rather than in water wet systems. Indeed, we demonstrate why it is very difficult to see immiscible fingering in WW lab systems. From this finding, one might conclude that since no fingering is observed for the WW lab-scale case, then none would be expected at the larger “field” scale. However, by invoking scaling theory—specifically the viscous/capillary scaling group, $$C_{{{\text{VC1}}}}$$ C VC1 , (and a corresponding “shape group”, $$C_{{{\text{S}}1}}$$ C S 1 ), we demonstrate very clearly that, although the WW viscous fingers do not usually appear at the lab scale, they emerge very distinctly as we “inflate” the system in size in a systematic manner. In contrast, we demonstrate exactly why it is much more likely to observe viscous fingering for the OW (or weakly wetting) case at the lab scale. Finally, to confirm our analysis of the WW and OW immiscible fingering conclusions at the lab scale, we present two experiments in a lab-scale bead pack where $$\left( {\mu_{{\text{o}}} /\mu_{{\text{w}}} } \right) = 100$$ μ o / μ w = 100 ; no fingering is seen in the WW case, whereas clear developed immiscible fingering is observed in the OW case.

Preparation and properties of UiO-66 based hybrid materials via surface initiated metal-free ATRP

A metal-organic framework (MOFs) material UiO-66-Br was synthesized via hydrothermal method, and the surface initiated metal-free atom transfer radical polymerization (SI-metal-free ATRP) of methyl methacrylate (MMA) and Eu complex were initiated on UiO-66-Br surface with UiO-66-Br as initiator and 10-phenylphenthiazine (PTH) as catalyst, and UiO-66 based hybrid materials (UiO-66-g-PMMA and UiO-66-g-PMMA-co-Eu complex) were obtained. The materials were characterized by fourier infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) thermogravimetry analysis (TGA), gel permeation chromatography (GPC), scanning electron microscopy (SEM) and so on. The results showed that the MOFs material UiO-66-Br with octahedral crystal structure was successfully synthesized, the PMMA and Eu complex chains were successfully grafted from the surface of the UiO-66-Br, the polymer grafting rate of UiO-66-g-PMMA reached 3.01 %, and the Eu content of UiO-66-g-PMMA-co-Eu complex reached 11.81 %. Water wettability test indicated that the contact angles of the hybrid materials were 155.4° and 153.3° respectively. The oil-water separation and self-cleaning experiment confirmed that the UiO-66 based hybrid materials had good oil-water separation and self-cleaning properties.

Engineering antifouling membrane with surface segregation agents bearing crosslinked low surface energy segments

Low surface energy material has been considered as the promising material to solve membrane fouling owing to its superior fouling releasing ability, however, its low water wettability would result in decrease of water permeability, which limits its broad application in fabrication of high-performance membranes. Herein, we prepared the amphiphilic crosslinked surface segregation agents based on hydrophilic polyethylene glycol methyl acrylate (PEGMA) segments and crosslinked low surface energy poly(hexafluorobutyl methacrylate) (PHFBM) segments to fabricate antifouling membrane via nonsolvent induced phase separation. The surface segregation of the hydrophilic segments could drag the low surface energy segments onto membrane surface, meanwhile, the crosslinked structure of the low surface energy segment could influence the phase inversion to form a loose separation layer. As a result, amphiphilic membrane surface was constructed with hydrophilic microdomains and low surface energy microdomains as well as underwater superoleophobicity, and the flux of as-prepared membrane was increased slightly with the flux recovery ratio improved from 69.3 % to 92.8 % for separation of BSA solution. Meanwhile, after three cycles of filtration, the flux recovery ratio could maintain a high level. Our study may offer a new route to utilization of low surface energy materials for fabricating antifouling membranes.

Study Reviews Largest ASP Project From Laboratory to Pilots and Field Application

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215058, “A Systematic Review of the Largest ASP Flood Project in the World: From Laboratory to Pilots and Field Application,” by Yunan Wei, SPE, Xiaoguang Lu, SPE, and Jianhong Xu, SPE, C&C Reservoirs, et al. The paper has not been peer reviewed. _ The complete paper presents a systematic review of the largest alkaline-surfactant-polymer (ASP) flood project in the world, applied in the largest oil field in China. First, reservoir and fluid characteristics are highlighted to understand heterogeneity of the reservoir. Next, project history is summarized, including laboratory studies, pilot tests, industrial-scale tests, and fieldwide application. Finally, typical ASP flood performance and reservoir management measures from over 30 years of experience are presented. Performances of ASP flood and polymer floods in the same field also are compared.​​​​ Introduction In the La-Sa-Xing Field, ASP flooding was studied in the laboratory from 1987 to 1993 and followed by five small-scale pilots from 1994 to 1999, all successfully achieving incremental recoveries of approximately 20% stock-tank oil initially in place (STOIIP). As a result, industrial-scale pilots were conducted from 2000 to 2007, resulting in increased production by ASP flooding from 3,887 to greater than 19,000 BOPD in 2007. Fieldwide ASP expansion was launched in December 2007. By 2021, the ASP-flooded blocks registered a STOIIP of 1.9823 billion bbl. Daily production was approximately 96,000 BOPD through approximately 9,650 wells. Average incremental recovery factor was 20% STOIIP with waterflooding and 8% with polymer flooding, providing an ultimate recovery factor of 60%. Cumulative oil production by ASP flooding had reached 316 million bbl by 2021, making it the largest ASP flooding project in the world. Geological Background and Reservoir Characteristics The La-Sa-Xing Field is in the north of the Songliao Basin of northeast China, comprising the majority of the Daqing field complex. The field was placed onstream in 1960. The hydrocarbon-bearing reservoir has a gross thickness of 1,377 ft and a net thickness of 394 ft. Net pay averages 150 ft. Initial reservoir pressure ranges from 1,523 to 2,585 psi. Reservoir temperature varies from 113 to 122°F. Crude oil has an API gravity of 33°, a viscosity of 8.5–10.3 cp at reservoir conditions, an initial gas/oil ratio of 258 scf/STB, and a bubblepoint pressure of 1,291 psi. Formation water salinity is 7000 mg/L. Reservoir rock initially shows water or weak oil wettability. Depending on permeability, three types of reservoir sand (Type I, Type II, and Type III) have been identified. Currently, ASP flooding is mainly applied to Type I sand, with partial application to Type II Sand.

Influence of extractable organic components on shale wettability: Dongyuemiao member of Jurassic Ziliujing formation in the Fuxing area, Eastern Sichuan Basin

The wettability of reservoir rocks is a critical factor for the petroleum exploration and recovery, which plays an important role on relative permeability, capillary pressure, and ultimate recovery. This study aims to characterize the difference in wettability before and after soxhlet extraction, and reveal the influences of mineral composition, pore structure and extractable organic components on wettability of shales with different lithofacies. Several organic shale samples from the Dongyuemiao (DYM) section of the Jurassic Ziliujing (ZLJ) formation were collected to investigate the mineral composition, pore-size distribution, wettability characteristics and determine the main controlling factors on wettability alteration. Pore type and abundant are observed using argon ion polishing scanning electron microscopy. The pore volume (PV) and pore size distribution (PSD) characteristics before and after extraction were obtained using a combination of nitrogen physisorption and high-pressure mercury intrusion porosimetry (MIP). Spontaneous imbibition (SI) and nuclear magnetic resonance (NMR) experiments were used to investigate the wettability characteristics before and after extraction.Results show that clay, quartz and calcite are dominant minerals in the DYM shales, and three typical lithofacies are identified, including mixed shale (M), argillaceous shale (CM) and calcareous shale (C). Clay mineral interP pore is the dominant pore type in the DYM shales, followed by organic matter (OM) pore. Before the extraction, the DYM shale is more oil lipophilic, while its wettability alters slightly after the extraction. The M shales and C shales maintain lipophilic, while as the CM shales alters from oil wet to mixed wet. Samples with higher quartz have better connectivity of the hydrophilic and lipophilic pore networks, and carbonate minerals play an opposite role. During the extraction process, polar solvents could react with clay minerals to cause pore space expansion, which enhances the water wettability after extraction. Due to the low OM content and poor organic clay complex related pores in the study area, clay minerals have not significant correlation with oil wettability, but influence the water wettability. No correlation occurs between total organic carbon (TOC) content and oil/water wettability of shales before and after extraction. In comparison, macropore has a significant impact on water wettability, while micropore and mesopore play significant impact on oil wettability.

A comparative study of the effects of gas bubbles generated from hydrazine or/and water on the surface morphology and hydrophobicity of electrodeposited polymer films

The electrodeposition of polymeric films of a fluorene-bridged dicarbazole monomer containing linear polyfluorinated side chains is here investigated, with regard to the use of on-site electrochemically generated gas bubbles from hydrazine or water as soft template agent. The interconnected effects of the bubbles precursor and electrochemical parameters employed on the morphology and water wettability properties of the electrodeposited films are demonstrated. The use of N2H4 as a gas precursor proved to be a versatile, complementary alternative to water, which allows a finer tuning of the electrodeposited polymer film morphology.

Electron-Beam Processing of Aluminum-Containing Ceramics in the Forevacuum Pressure Range

Aluminum–ceramic materials based on Al2O3 and AlN are widely used in the electronics industry and, according to a number of electrophysical and technical and economic parameters, are among the most suitable for the production of electrical and radio engineering products. In this study, it is shown that the treatment of ceramics based on Al2O3 with an electron beam with a power of 200–1100 W and a current of 10–50 mA leads to heating of the ceramic surface to a temperature of 1700 °C. When heated to a temperature of 1500 °C and kept at this temperature for no more than 10 s, an increase in the roughness of the ceramic surface is observed by more than an order of magnitude. At the same time, for ceramic substrates based on aluminum nitride, an increase in the temperature of electron beam treatment from 1300 to 1700 °C leads to an increase in thermal conductivity from 1.5 to 2 times. The edge angle of water wetting of the AlN surface can vary from 20 to 100 degrees depending on the processing temperature, which allows one to control the transition of the material from a hydrophilic to a hydrophobic state. At the same time, electron beam exposure to Al2O3 does not change the wettability of this material so much. Electron beam processing in the forevacuum pressure region allows controlled changes in the electrophysical properties of ceramic materials based on Al2O3 and AlN.

Osseointegration enhancement by controlling dispersion state of carbonate apatite in polylactic acid implant

Osteoconductive ceramics (OCs) are often used to endow polylactic acid (PLA) with osseointegration ability. Conventionally, OC powder is dispersed in PLA. However, considering cell attachment to the implant, OCs may be more favorable when they exist in the form of aggregations, such as granules, and are larger than the cells rather than being dispersed like a powder. In this study, to clarify the effects of the dispersion state of OCs on the osseointegration ability, carbonate apatite (CAp), a bone mineral analog that is osteoconductive and bioresorbable, powder–PLA (P-PLA), and CAp granule–PLA (G-PLA) composite implants were fabricated via thermal pressing. The powder and granule sizes of CAp were approximately 1 and 300–600 µm, respectively. G-PLA exhibited a higher water wettability and released calcium and phosphate ions faster than P-PLA. When cylindrical G-PLA, P-PLA, and PLA were implanted in rabbit tibial bone defects, G-PLA promoted bone maturation compared to P-PLA and pure PLA. Furthermore, G-PLA bonded directly to the host bone, whereas P-PLA bonded across the osteoid layers. Consequently, the bone-to-implant contact of G-PLA was 1.8- and 5.6-fold higher than those of P-PLA and PLA, respectively. Furthermore, the adhesive shear strength of G-PLA was 1.9- and 3.0-fold higher than those of P-PLA and PLA, respectively. Thus, G-PLA achieved earlier and stronger osseointegration than P-PLA or PLA. The findings of this study highlight the significance of the state of dispersion of OCs in implants as a novel strategy for material development.

Changes of wettability of shale exposed to supercritical CO2-water and its alteration mechanism: Implication for CO2 geo-sequestration

The wettability of shale are the key factors determining the shale gas production efficiency and CO2 storage safety. However, the effects of the supercritical CO2 (ScCO2)-water-shale interactions on the wettability in shale is unclear. To address this issue, water wettability alterations in shale at different ScCO2-water exposure pressure and temperature conditions were evaluated based on a nuclear magnetic resonance (NMR) test method, and the mineral composition, element mobilization and pore of shale were analyzed to interpret the alterations. After ScCO2-water exposure, the water wettability of shale was reduced, and the reduction enhanced with the increase of exposure pressure while weakened with the increase of exposure temperature. The weakening of water wettability in shale is closely related to the exposure pressure and temperature dependent mineral and pores alteration in shale. ScCO2-water exposure induced the increase in the content of hydrophobic quartz, and the decrease in the contents of hydrophilicity clay and carbonate minerals, leading to the weakening of water wettability in shale. In addition, the micro and mesopores gradually transfer to larger pores after ScCO2-water exposure, reducing capillary pressure and the hydrophilicity of shale, also responsible for the decrease of water wettability in shale. The weakening of water wettability may enhance the sweep efficiency of CO2 in shale reservoirs or reduce the capillary trapping capacity of CO2 when shale served as caprocks. Thus, this study contributes to the evaluation of CO2 storage capacity and security in shale reservoirs.

Effects of powder surface conditions on the rheological behavior of Ti–6Al–4 V alloy powders for additive manufacturing

Laser powder-bed fusion (L-PBF) is a promising manufacturing process for fabricating metallic parts with tailored architectures. A feedstock powder with good flowability is required to homogeneously deposit the powder on the building substrate and obtain reliable and high-quality L-PBF products. Although the effects of powder morphology and particle size on flowability have been widely investigated, the relationship between powder surface conditions and rheological behaviors is not well established. Therefore, in this study, the surface conditions of Ti–6Al–4 V alloy powders were intentionally adjusted through conventional heat treatments under different gas atmospheres. The morphology and particle size distribution of the Ti–6Al–4 V powder heat treated at 773 K in air (Air773) and Ar (Ar773) atmospheres remained unchanged compared to those of the untreated powder. However, the quantity of surface oxides on the Air773 powder increased, enhancing the decoration of surface hydroxyl groups, as illustrated by water wettability tests. By contrast, the oxide layer of the Ar773 powder decomposed and dissolved into the matrix, resulting in the generation of fresh metallic surfaces. Consequently, the flowability of the Air773 powder increased, whereas that of the Ar773 powder tended to decrease, thereby deteriorating the quality of powder beds during the recoating process. The results prove that the cohesive strength of Ti–6Al–4 V powder is more strongly determined by metallic TiTi interactions than by hydrogen bonds. Thus, the effective approach for adjusting the powder surface conditions presented in this study offers new insights into the potential for economically developing high-performance Ti alloy components by controlling the powder properties and L-PBF process.

CHARACTERIZATION OF AN ALKALINE ENDO-POLYGALACTURONASE (PGase LBW 5117) FROM ALKALIPHILIC BACILLUS HALODURANS LBW 5117 AND DEMONSTRATION OF ITS BIO-SCOURING POTENTIAL

The demand for pectinases in the global market has been on the rise in recent years due to their significant biotechnological uses. The present study involves the characterization of a crude alkaline pectinase from Bacillus halodurans LBW 5117 and the demonstration of its bioscouring potential. The enzyme was an endo polygalacturonase (PGase LBW 5117) that was brown and had a slight fermentation odor. It exhibited an activity of 0.21 U/ml and retained 67, 90.5, 95.2, and 95.2 % of this activity after 1 year of storage at -20, 4, 20, and 30 oC, respectively. Its operational pH and temperature ranged between 10.2 - 11.0 (optimum, 10.5) and 45 - 57 oC (optimum 50 oC), respectively. Metal ions e.g., K+, Ca2+, Mg2+, Fe3+, Cu2+, Na+, Mn2+, and Zn2+ either stimulated or did not significantly affect its activity at 1 mM. The enzyme retained only 15 % of its activity after 8 h of incubation at 50 oC, but this improved to 200 % in the presence of 1.5 mM Ca2+ and 0.05 mM Tween 20. The enzyme was cellulase-free and hydrolyzed pectin in an endo-manner. Moreover, when used under the established optimized operating conditions, it degraded and eliminated pectin (and other non-cellulosic hydrophobic impurities that adhere to it) from woven cotton (weight loss = 0.68 %) and produced a more hydrophilic fabric with improved wettability for water (drop test = 10 sec) and dye (capillary rise test = 28 mm after 30 min). This result shows that PGase LBW 5117 possesses good operational properties, potentially making it a good bioscouring agent. It is, however, recommended that the bioscouring process be optimized, and its effectiveness be compared with that of standard bio- and/or chemical-scouring process(es).

Effect of wettability and phase distribution on critical salt concentration for fines migration initiation in sandstone reservoirs

Fines migration in sandstone oil reservoirs during different field operations is influenced by the salinity of injected brine. When salinity drops below a critical salt concentration (CSC), fines migration is initiated, leading to pore throat blockage and formation damage. Factors such as rock wettability, fluid type, fines size and concentration, and flow rate contribute to the severity of this issue. However, the impact of phase distribution and rock wettability on the CSC remains unexplored. Most results are reported for water-wet systems, but in many cases, assuming a strong water-wet state is not accurate. The current research fills that gap and provides new insights by investigating the relationship between the CSC, phase distribution, and rock wettability.Upper Berea sandstone cores were used in this study, and the CSC was experimentally determined. Brine was injected into strong water-wet and weak water-wet core samples. The injection brine salinity was gradually reduced to identify the salinity at which fines migration initiated within the core. The analysis of pressure drops and effluent analysis was applied to estimate CSC at different wettability states.The step-by-step reduction in salinity led to CSCs of 0.12 M and 0.09 M NaCl for the weak water-wet core and strong water-wet core in the presence of oil, respectively. A weak water-wet system results in a higher CSC value compared to a strong water-wet system because fine particles are contained within a thin water film, and weak water wettability facilitates their easy migration under low reduced salinity conditions. The CSC corresponded to the point of maximum pressure difference and the highest concentrations of produced fines. The findings of this research provide valuable insights into the significant influence of rock wettability and phase distribution on the initiation of fines migration. These parameters must be carefully determined and considered during the design phase of production and enhanced oil recovery in sandstone reservoirs to ensure efficient operations.