Significant Reduction In Contact Angle Research Articles

Experimental study on nanoparticles-assisted low-salinity water for enhanced oil recovery in asphaltenic oil reservoirs

The purpose of this research is to look into the augmentation of silica nanoparticles (NPs) with low salinity (LowSal) brine for EOR. A series of analyses, including oil/water interfacial tension (IFT) and rock wettability tests were undertaken to determine an optimal dispersion to flood into a porous carbonate core with a defined pore size distribution. At 60 °C and 14.5 psi, the maximum drop (i.e., roughly 12.5 mN/m) in oil/water IFT by 0.3 wt.% brine occurred, but when 0.08 wt.% silica was added to the brine, the IFT reduced to 14.51 mN/m at 60 °C and 14.5 psi. The wettability analysis revealed a significant reduction in contact angle, from 142° to 72° and 59°, using 0.04 and 0.08 wt.% silica in LowSal brine, but the extent reduced by brine alone was insufficient. The results of rock pore size characterization were discussed in terms of the accomplishment of operating EOR in the porous medium in the presence of NPs. The addition of 0.08 wt. % silica to the injected brine resulted in an additional oil recovery of 16.3% OOIP as well as a significant shift in the endpoints/cross-points of the oil/water relative permeability curves. The findings of this research might help improve oil recovery from asphaltenic oil reservoirs or, more environmentally friendly, remediate petroleum crude-oil polluted soil.

Experimental investigation of the effect of a quinoa-derived saponin-based green natural surfactant on enhanced oil recovery

In this study, a unique surfactant extracted from a quinoa plant was introduced for enhanced oil recovery (EOR). The physico-chemical characteristics of extracted saponin as the surfactant agent were confirmed by 1H NMR, FESEM, and FT-IR analyses. The natural surfactant extracted from quinoa exhibited appropriate thermal stability at reservoir temperature, even at very high temperatures, according to TGA test. Then, the efficiency of the quinoa-derived surfactant was compared against two common commercial surfactants, TR-880 and NX-610. Interfacial tension (IFT) and contact angle tests were performed, and the obtained results show that the novel surfactant, at its critical micelle concentration (CMC), contributes to an additional 24.1% of the original oil in place (OOIP) due to a significant reduction in contact angle from 146° to 26.3°, and a substantial reduction in IFT from 33.2 to 8.7 mN/m. Moreover, at the CMC point, contact angles of 72° and 58.8° were obtained for TR-880 and NX-610, respectively, which were higher than the natural surfactant value, although NX-610 and TR-880 surfactants both resulted in lower IFT values of 4.9, and 3.4 mN/m, respectively. Contact angle and zeta potential measurement confirmed that all three tested surfactants could change the wettability of the reservoir rock from oil-wetting to water-wetting, with natural surfactant achieving the most promising results in both tests. Emulsion tests showed that the quinoa surfactant produced more stable and denser emulsions compared to commercial surfactants. Therefore, this study introduces a novel surfactant that not only is cost effective and environmentally friendly, but also performs promisingly for EOR purposes.

MWCNT-based surfaces with tunable wettability obtained by He+ ion irradiation

A study of He+ ion irradiation influence on the wettability of the multi-walled carbon nanotubes is presented. Tablets of pressed nanotubes of two types with different diameters were prepared and irradiated by 80 keV He+ ions. Raman and X-ray photoelectron spectroscopies showed the differences in the rate of radiation-induced defect formation for different types of nanotubes. The formation of cross-links between the layers of nanotubes under ion irradiation was demonstrated by the molecular dynamics simulation. Contact angle changes drastically with an increase in the fluence for both types of nanotubes: at low fluences superhydrophobic surfaces are formed, with an increase in the fluence a significant reduction in contact angle is observed, especially for the nanotubes of smaller diameters.

Surface-Functionalized Polypropylene Surgical Mesh for Enhanced Performance and Biocompatibility.

Polypropylene (PP) surgical mesh has attracted vast attention due to its chemical inertness and excellent mechanical properties. However, improvement is necessary to enhance its biocompatibility and to prevent unwanted tissue adhesion. This study addresses these issues through surface modification of plasma-activated PP mesh with a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. Reaction time and monomer concentration have been optimized to achieve the optimal biocompatibility with reduction in protein adsorption. Attenuated total reflection-Fourier transform infrared spectra confirmed the grafting of the MPC polymer (PMPC) to the plasma-activated polypropylene (PPP) mesh. Scanning electron microscopy images and energy-dispersive X-ray (EDX) line spectra exhibited morphological changes and specifically PMPC grafting to the surface of PPP mesh, due to the presence of a significant amount of phosphorus (P) on the grafted PPP mesh. PMPC-grafted polypropylene (PPP-PMPC) showed a significant reduction in contact angle as well as the amount of adsorbed bovine serum albumin (BSA) protein in comparison with pristine PP mesh. The highest reduction in protein adsorption and the lowest contact angle were achieved at the monomer concentration of 0.3 M and the reaction time of 90 min. A longer reaction time and higher monomer concentration resulted in clogging within the mesh pores. MTT assay results (∼90% cell viability) confirmed the nontoxicity of the PMPC-grafted mesh, while optical microscopic and SEM images showed increased resistance of cell attachment to the surface of PMPC-grafted mesh. The results show that PPP-PMPC can be a promising biomaterial to address the current issues in biocompatibility and reduction in adhesion after surgery.

Pi electron cloud mediated separation of aromatics using supported ionic liquid (SIL) membrane having antibacterial activity

Supported ionic liquid (SIL) membranes using imidazolium based ionic liquids and hydrophobic PTFE base membrane were used for the π electron mediated separation of aromatic compounds including dyes in aqueous and non-aqueous medium. The FTIR of SIL membranes showed the signature of the functionalities for both base membrane and the imidazolium moiety. A significant reduction in contact angle, especially the dynamic contact angle, was observed for SIL membranes compared to the virgin membrane indicating the enhancement in surface hydrophilicity of the membrane, while considerable changes zeta potential was seen at different pH indicating the modification in surface charge. The SEM image confirmed the pore filling of base membrane with ionic liquids. The stability of the SIL membranes were studied using hexane, water and DMF as solvents. Tuning the anionic moieties, ionic liquids were utilized for aqueous and non-aqueous application through SIL membranes. For non-aqueous applications, the trend in separation efficiency was found to be divinylbenzene > styrene > toluene, which was attributed to the more π electron cloud density on extended conjugation leading to favorable interaction with ionic liquid influencing its transfer through SIL membranes. Preferential separation of Congo red (CR) and Ramazol Brilliant Blue R (RBBR) was achieved in water based application of the SIL membranes. The anti-microbial activity of these SIL membranes were investigated using gram-positive bacteria (Staphylococcus aureus and Pseudomonas aeruginosa). More the number of carbon atom on the side chain of the imidazolium ring, more antimicrobial activity was observed.

The effect of benzalkonium chloride additions to AH Plus sealer. Antimicrobial, physical and chemical properties

ObjectivesThe aim of this study was to determine the antimicrobial and antibiofilm activities and physicochemical properties of AH Plus sealer mixed with different concentrations of benzalkonium chloride (BC). MethodsAH Plus was tested alone and mixed with 1%, 2% and 3% of BC. The antimicrobial and antibiofilm activities of the sealers against Enterococcus faecalis were evaluated by the direct contact test (DCT) and by confocal laser scanning microscopy, respectively. Setting time, flow and solubility were assessed according to ANSI/ADA specifications. Microhardness and contact angle tests were also performed. The chemical changes of the sealers were evaluated by X-ray diffraction analysis, and both Fourier transform infrared spectroscopy (FT-IR) and attenuated total reflectance Fourier transform infrared (ATR FT-IR). ResultsAH Plus+3% BC was the only sealer to promote total elimination of E. faecalis and the biovolume in this group was significantly lower than in the rest of the sealers (p>0.05). The physical properties of the sealers were according to the ANSI/ADA specifications. The microhardness decreased significantly when BC was added and a significant reduction in contact angle was obtained when incorporating 2% and 3% BC (p<0.05). No phase changes were observed with the modified sealers. ConclusionsThe addition of 2% or higher concentrations BC to AH Plus showed antimicrobial and antibiofilm activities without affecting the properties specified in ANSI/ADA standards. However, additives to the root canal sealer altered other physical and chemical properties that are not commonly found in the literature to evaluate filling materials. Clinical significanceThe present study highlights that the antimicrobial properties of AH Plus can be significantly improved with the addition of BC. Testing beyond what is specified in standards may be indicated.

Surface Modification of Poly(lactic acid) (PLA) via Alkaline Hydrolysis Degradation

Surface hydrophobicity of poly (lactic acid) have raise the concerns of surface incompatibility of PLA to function as biomaterial. Thus, various approaches have been made to improve the surface hydrophilicity of PLA. In the present paper, PLA materials were surface modified by alkaline hydrolysis. The indication of the reduction in water contact angle value, from 65 ̊ to 50 ̊ and 15 ̊, in 0.01M and 1M alkaline concentration respectively, proven surface hydrophilicity of PLA film was improved. Further alkaline treatment after 24 hours shows not significant reduction in contact angle. Whereas, the erosion of film surfaces treated under 1M alkaline solution have been observed under polarized optical microscopy. Intrinsic viscosity measurement was also conducted to monitor the surface treatment process. As a whole, surface treatment was successful and sufficient when no further decreased in contact angle value, thus prevent extensive surface erosion.

Wettability and compositional analysis of hydroxyapatite films modified by low and high energy ion irradiation

Hydroxyapatite-like thin films on silicon substrate were deposited using atomic layer deposition and were subjected to irradiation with Ar ions accelerated through 0.6–1.2kV as well as 2MeV 16O+ ions. After low energy Ar irradiation a significant reduction in contact angle was observed. However, the Ca/P atomic ratio remained unchanged. No reduction in contact angle was seen for high energy 16O+ irradiation. Atomic force microscopy showed the enhancement of floral-like pattern after low energy Ar bombardment while high energy oxygen irradiation lead to raised islands on as-deposited films.