Surface Tension Test Research Articles

Effect of ionic emulsifiers on the properties of emulsified asphalts: An experimental and simulation study

The incorporation of emulsifiers into asphalt binder has significant advantages on decreasing mixing temperature, improving construction environment and saving energy. In this study, the effects of ionic emulsifiers on the service performances of emulsified asphalts were investigated by laboratory experiments and molecular dynamic (MD) simulation. To this aim, cationic stearyl trimethyl ammoium chloride (STAC) and anionic sodium dodecylbenzene sulfonate (SDBS) were selected. The effects of these two ionic emulsifiers on the stability and rheological response of emulsified asphalts were investigated via the surface tension, storage stability and dynamic shear rheology tests. Furthermore, the binary model of emulsifier/asphalt and the ternary model of water/emulsifier/asphalt were constructed, and a series of indices such as interaction energy, roughness, relative concentration distribution, mean square displacement (MSD) were analyzed to explain the performance differences of various emulsified asphalt from molecular perspective. The experimental results showed that the influence of STAC on stability and rheological properties of emulsified asphalt was more considerable by comparison to that of SDBS. The smaller surface tension could be detected for STAC emulsified asphalt considering the stronger hydrophilicity of STAC. Moreover, compared to SDBS, STAC significantly improved the deformation resistance and elastic recovery of emulsified asphalt. It was concluded from MD simulation that the adsorption system formed by STAC was more stable. Both of experimental and simulation results provide insight into understand the contribution of ionic emulsifiers to the stability and rheological properties of emulsified asphalts.

THE SYNERGIZATION OF SILICA NANOPARTICLE AND SODIUM DODECYL SULFATE FOR CHEMICAL FLOODING APPLICATION

Nowadays, enhanced oil recovery is vital in improving the oil recovery. However, the oil productions keep depleting due to production problem such as high surface tension and interfacial tension reservoirs. Therefore, chemical flooding is one of the methods used in enhanced oil recovery. The synergy between Silica nanoparticle and Sodium Dodecyl Sulfate has been proposed as a compound for chemical flooding in enhanced oil recovery in this project. The major aim of this study was to measure the effectiveness of synergization between Silica (SiO₂) nanoparticles SDS with different injection ratio by measuring the oil recovery using chemical flooding. After the synergization of surfactant with nanosilica solution take place, the surface tension and interfacial tension test have been conducted to identify the optimum concentration. The results showed that the optimum concentration for SDS is 2000 ppm with surface tension (ST) and interfacial tension (IFT) are 33.5 and 36.0 mN/m respectively. When the SiO₂ nanoparticles were added, it showed that 6000 ppm was the optimum concentration with reduction in surface tension and IFT to 31.0 and 34.5 mN/m respectively. The 20,000 ppm brine and paraffin oil have been injected into the sandpack followed by waterflooding and chemical flooding. The results from the experiment presented that the oil recovery for waterflooding were in between 23% to 28% therefore, more oil left in the sandpack. Then, surfactant with nanosilica solution was injected with 20,000 ppm of brine as a slug with injection ratio in between 0.1 to 0.5 as tertiary recovery. It showed that the oil recovery increases up to 48% for 0.1 of injection ratio and 64% for 0.5 injection ratio. As a conclusion, it is proved that the synergization of SiO₂ nanoparticle and SDS is applicable for chemical flooding as tertiary recovery because in can recover up to 64% of oil production.

Comparison of static tests and dynamic tests for coal dust surfactants evaluation: A review

Coal workers’ pneumoconiosis is one of the most severe occupational diseases due to long-term exposure to high concentrations of coal dust. Water spray with surfactant addition is an effective and commonly used method to control the coal dust in coal mines. Usually, the surfactant evaluation methods can be divided into two categories, including static and dynamic tests. The performance of surfactants may vary with different evaluation methods, which make the results hard to conclude. By critically reviewing previous studies, this paper highlighted the four surfactants’ evaluating methods for coal dust suppression, including the surface tension test, the sink test, the field test, and the wind tunnel test. Firstly, the basics of four evaluating methods were described, and the general result was concluded and presented. Secondly, static and dynamic tests were compared to reveal the consistency and discrepancy. It was found that the surface tension test takes dominations at lower concentrations of surfactants, while it cannot further take advantage after a critical concentration. The anionic and non-ionic surfactants showed better performance than cationic surfactants mostly in static tests. The field test and the wind tunnel test can directly evaluate the suppression efficiency of surfactants, with consideration of environmental factors such as the particle collision and the contact time. This paper is important for producing comparable results between static and dynamic tests and revealing the consistency and discrepancy. The outcomes of this study could be a guidance for evaluating and selecting the optimum surfactants for coal dust suppression.

Excellent foaming properties of anionic-zwitterionic-Gemini cationic compound surfactants for gas well deliquification: Experimental and computational investigations

Foams are often employed as an efficient and cleaner method to remove the liquid accumulated at the bottom of the gas wells and promote the production of natural gas. However, the extreme conditions (e.g., high content of condensate, high salinity, high temperature, etc.) in the wells would retard the performance of the foaming agents. Usually, mixtures of different foaming surfactants were used to achieve high performances under those extreme conditions. In this paper, foams stabilized by surfactant mixtures containing alpha-olefin sulfonate (AOS), synthesized green cocamidopropyl betaine (CAPB) and modified quaternary ammonium Gemini surfactant (CAGB) in a proportion of 0.2:0.2:0.2 (wt%/wt%/wt%) were developed to evaluate their industrial application potential in gas well deliquification. The ternary surfactant (CAPB-CAGB-AOS) foam exhibited higher stability than the other dual surfactant foams and singular surfactant foams. Additionally, the foaming efficiency (defined as the ratio of the mass of water converted into foam to the mass of the initial liquid) and liquid unloading efficiency of the CAPB-CAGB-AOS mixture could be improved with the presence of condensate. Salts and methanol had a weak influence on the performance of the CAPB-CAGB-AOS foam. The introduction of ethylenediamine tetraacetic acid disodium (EDTA‧2Na) can enhance the performance of the CAPB-CAGB-AOS foam against salts. The temperature (> 60 °C) favored the foaming efficiency and liquid unloading efficiency of the CAPB-CAGB-AOS mixture, which reached up to 100% and 88.5% at 90 °C. These results indicated that the synergy effect of these three surfactants on the stability and liquid unloading efficiency of the foam can be confirmed. Moreover, the synergy effect can also be confirmed by the surface tension test, the foam's microstructure observation and the computational studies on calculated binding energies and electrostatic interactions.

Investigation on the Stability of Janus SiO2-n Nanoparticle-Assisted Nonionic Surfactant-Stabilized Foam and Its Application in Enhanced Oil Recovery

The stability of the foam directly impacts the final efficiency of the foam flooding in enhanced oil recovery (EOR). In the present work, a series of Janus SiO2-n nanoparticles (JSn NPs) with various modification degrees were successfully prepared and employed to improve the stability of the nonionic surfactant polyethylene glycolmonoisodecylether (PMIE)-stabilized foam. The PMIE–JS3 system with a much low JS3 NP concentration (0.1 wt %) displayed extraordinary foamability and stabilizing foam ability via the foam volume, half-life, relative volume decay, and optical microscope photograph measurements. Then, the dynamic surface tension and dilatational viscoelasticity tests were conducted to explore the mechanism. It was found that the PMIE–JS3 system with great interfacial activity and intensive interfacial film highly facilitated the generation of the foam and improved the foam stability. Moreover, the PMIE–JS3-stabilized foam exhibited outstanding stability, even under the influence of crude oil. The sandpack flooding tests indicated that the PMIE–JS3-stabilized foam could effectively plug the high-permeability channels to modify the water injection profile and consequently greatly enhanced tertiary oil recovery (∼15.3% of the initial oil in place).

Enhancing the physical properties of polystyrene nanofibers by adding multiwall carbon nanotubes and natural dye

Polymeric nanocomposites of polystyrene nanofibers and multiwall carbon nanotubes and natural pigment were synthesized using electrospinning technique the polystyrene concentration was 12 wt.% and multiwall carbon nanotube was added by (0, 100, 140, 200 ppm), and natural pigment added by two drops (0.063 g) to the prepared solutions and many tests were carried out to the prepared solutions and the final samples. The solution tests included viscosity test by using cone-plate viscometer and surface tension test using du-nouy ring method. The nano textiles tests included the Fourier transform infrared spectroscope (FTIR) test, Field emission scanning electron microscopy (FESEM) test, contact angle test, and ultraviolet test to extract the energy bandgap using (tauc plot) method. The tests results showed that the viscosity increased by increasing the multiwall carbon nanotube and natural pigment and surface tension slightly increased at a high ratio of 200 ppm of multiwall carbon nanotube and natural pigment and physical type of reaction between the components were confirmed through FTIR, and the addition of multiwall carbon nanotube and natural pigment makes the fibers smoother and fewer beads formation and increase the multiwall carbon nanotube addition made the samples more hydrophobic and the charts of tauc plot show that increasing the MWCNT with natural pigment addition will increase the electrical sensitivity of the prepared samples in which the energy band gap dropped from 1.18 ev to 0.2 ev for the sample of Polystyrene/200 ppm MWCNT/natural pigment this is regarded as an indication of using it as a typical electrical sensor.

Determent of oil-soluble surfactants on aggregation of model asphaltene compound and synergistic effect of their mixtures on foaming property

Oil-based foam stabilized by dispersed asphaltene is potential in the oil recovery process of water-sensitive formations. But asphaltenes are prone to aggregate, which jeopardizes the stability of the foam. This paper investigated the effect of different VO79 (model asphaltene compound violanthrone-79) systems on the performance of oil-based foams through surface tension and foaming tests. And simulations were performed to investigate the microscopic mechanism of ODA (octadecyl amine) and Span20 (sorbitan monolaurate) on the dispersion effect of VO79 and the effect of their mixtures on the interfacial film formation. The experimental results showed that the mixed system of ODA, Span20, and VO79 significantly enhances the performance of the oil-based foam. According to simulative results, ODA and Span20 blending are able to form ODA: Span20 molecular pairs, inhibiting the aggregation of model asphaltenes. The blend of ODA, Span20, and VO79 tends to form a ternary supramolecular complex, assembling into a dense and stretchable interfacial film. The synergistic effect generated by the ternary blends is capable of optimizing the performance of oil-based foams.

Experimental investigation of multi-walled carbon nanotubes assisted surfactant/polymer flooding for enhanced oil recovery

For the first time, we investigated the effect of carbon nanotube (CNT) on surfactant/polymer flooding so as to improve oil recovery and explore its mechanisms. To this end, we performed wettability, surface tension (ST), and viscosity tests. Then, micromodel flooding was performed using design of experiments (DOE) method. The results demonstrated that the surfactant/polymer (SP) solution can reduce the contact angle from 143.6° to 24°; besides, the presence of nanoparticle in the solution approximates the contact angle to zero. Also, compared to the SP solution, the surfactant/nanoparticle/polymer (SNP) solution can lead to a more strongly water-wet surface wettability. In the case of SNP, increasing nanoparticle concentration slightly increases the fluid viscosity. Additionally, at fixed concentrations of surfactant and polymer, increasing nanoparticle concentration can raise ST values. Therefore, given the relationship between increasing ST and decreasing interfacial tension (IFT), it can be inferred that the presence of carbon nanotube in the SP solution can lead to a reduction in IFT. The emulsion tests illustrated that the presence of CNT in SP solution does not alter the emulsion type (water-in-oil). The results of micromodel flooding also showed that increasing the concentration of CNT in the SP solution improves oil recovery by 5–11%. Furthermore, an optimal concentration was defined for the surfactant in SNP flooding, up to which point increasing the surfactant concentration raises oil recovery but beyond which the oil recovery diminishes. The DOE method indicated that, in descending order, the polymer, CNT, and surfactant could have the greatest impact on boosting oil recovery. In other words, under SNP flooding, polymer concentration and surfactant concentration exert the most and the least impact on increasing oil recovery.

Synthesis of lignin-grafted polycarboxylate superplasticizer and the dispersion performance in the cement paste

It is common that high-performance concrete is highly viscous, which is not conducive to transportation and pumping. In order to reduce the viscosity of fresh high-performance concrete, a lignin-based polycarboxylate superplasticizer (PCE-ACLx) was synthesized through a novel process and the structure was characterized by FTIR, 1H NMR and GPC. The performance of PCE-ACLx in cement paste was evaluated through the surface tension test, slump test, and the adsorption behavior study. The results show that among the PCE-ACLx, PCE-ACL1 had favorable dispersion effect. At the w/c (ratio of water to cement) ratio of 0.29, the fluidity of cement paste was 283 mm when the PCE-ACL1 dosage was 0.2 wt%. At the w/c ratio of 0.35, the emptying time of fresh paste with 0.2 wt% PCE-ACL1 was 13.9 s, showing good viscosity-reducing effect. Furthermore, the adsorption of PCE-ACLx on the cement particles could be described by Langmuir model and pseudo-second-order model. The saturated adsorption capacity of PCE-ACL1 on the cement particles was less than traditional PCE, but it had thicker adsorption layer, so it had larger steric hindrance. Compared with ordinary PCE polymers, lignin grafted PCE polymers make the polymer as a water reducer have higher easeability and gas-inducing properties, and it will be better to use as a water reducer. Lignin grafted PCE polymer has a relatively large application prospects, in this production process the source of lignin can be papermaking black liquor, which has a relatively large contribution to the protection of the environment.

Experimental study on coal dust wettability strengthened by surface active ionic liquids.

The water wettability of coal dust was very important for dust control when using water-based dust suppressant materials. The coal dust wettability strengthened by surface active ionic liquid was studied in this paper. The surface activity of ten ionic liquids with different anions Cl-, Br-, [BF4]-, [NTf2]- and cations [HOEtMIm]+, [Cnmim]+ (n = 4, 12, 14, 16) was studied by surface tension test. The water wettability of raw coal dust can be improved individually by adding ionic liquid to water or pre-treating coal dust by ionic liquids. The wettability of lignite was improved little, but that of bituminous coal and anthracite were improved much. The dual strengthened effects of ionic liquids on coal dust wettability were studied by the wetting results between ionic liquids solutions and ionic liquid-treated coal samples. The wettability of lignite can be strengthened under the combined action of [HOEtMIm][NTf2] and [C12MIm]Br, while other dual effects were not satisfactory. All ionic liquids combination had strengthened effects on the wettability of bituminous coal and anthracite, especially the [C12MIm]Br treatment and [C12MIm]Br solutions together had the best dual effects. The functional groups results indicated that the hydrophilic oxygen-containing functional groups in treated coal samples increased, the hydrophobic aliphatic hydrocarbon functional groups decreased and part of ionic liquids were adsorbed on the coal surface. These changes together enhanced the wettability of coal with high coalification degrees.

Research on the Synthesis and Application of AminoSulfonic Acid Gemini Surfactant

Oil is a non-renewable resource, and it is essential to improve oil recovery. Surfactant flooding is a key technology in enhancing oil recovery. The present work aims to develop a new surfactant to the combination flooding system in oil displacement. The Aminosulfonic Acid Gemini Surfactant was prepared by using Hexadecylamine, 1-Butanaminium,N,N,N-tributyl-,bromide (1:1) and Sodium 2-chloroethyl sulfonate. The AminoSulfonic Acid Gemini Surfactant Sodium N,N’-Dihexadecyl-2-propanol- 1,3-ethylsulfonate SNNDPE) has better reaction temperature at 80℃. The best reaction time of SNNDPE is 12 h. Next, We made a characterization of SNNDPE. A new gemini surfactant was developed, which is beneficial to the research of material science. Then the performance of the new Gemini surfactant was tested. The surface tension tests suggested that the newly synthesized Aminosulfonic Acid Gemini Surfactant has higher surface activity. The resistance temperature of the Aminosulfonic Acid Gemini Surfactant solution is 80℃. Moreover, the oil-water interfacial tension experiment suggested that the minimum aqueous solution of the combination flooding system reaches an ultra-low level of 9.4 × 10−4 mN/m. The combination flooding system experiment results can be considered as a guidance in the design and studies of the combination flooding system for a selective.

Biocompatibility of electrospun cell culture scaffolds made from balangu seed mucilage/PVA composites

Synthesis of Balangu (Lallemantia royleana) seed mucilage (BSM) solutions combined with polyvinyl alcohol (PVA) was studied for the purpose of producing 3D electrospun cell culture scaffolds. Production of pure BSM nanofibers proved to be difficult, yet integration of PVA contributed to a facile and successful formation of BSM/PVA nanofibers. Different BSM/PVA ratios were fabricated to achieve the desired nanofibrous structure for cell proliferation. It is found that the optimal bead-free ratio of 50/50 with a mean fiber diameter of ≈180 nm presents the most desirable scaffold structure for cell growth. The positive effect of PVA incorporation was approved by analyzing BSM/PVA solutions through physiochemical assays such as electrical conductivity, viscosity and surface tension tests. According to the thermal analysis (TGA/DSC), incorporation of PVA enhanced thermal stability of the samples. Successful fabrication of the nanofibers is verified by FT-IR spectra, where no major chemical interaction between BSM and PVA is detected. The crystallinity of the electrospun nanofibers is investigated by XRD, revealing the nearly amorphous structure of BSM/PVA scaffolds. The MTT assay is employed to verify the biocompatibility of the scaffolds. The cell culture experiment using epithelial Vero cells shows the affinity of the cells to adhere to their nanofibrous substrate and grow to form continuous cell layers after 72 h of incubation.

Synthesis and characterization of chitosan-based ‘comb-like’ zwitterionic surfactants

Low-cost surfactants are of great importance for many applications. Chitosan is one of the abundant promising candidates as a raw material for low-cost surfactants. However, how to tune the molecular structure to achieve high solubility, low surface tension, and good foam stability is a great challenge. Herein, the ‘comb-like’ zwitterionic polymer surfactant based on chitosan by partial N-alkylation and quaternization was prepared. The experimental results demonstrate that the length and degree of substitution of the alkyl chain have a significant influence on the properties of the products. Such comb-type zwitterionic polymer surfactants have good water solubility, and the water solubility can reach up to 85 g/L. Surface tension and foam performance tests reveal that such ‘comb-like’ zwitterionic polymer surfactants have excellent surface activity and good foam stability, especially for the products with a degree of substitution of 20%; their surface tension can be as low as 27.1 mN/m, and the foam stability can be improved by 59.32%.

Experimental study on the influence of surfactants in compound solution on the wetting-agglomeration properties of bituminous coal dust

To investigate the effect of surfactants in compound solution on the wetting-agglomeration properties of the bituminous coal dust, this paper selected anionic surfactants SDS, SDBS and non-ionic surfactants APG0810 and PPG400 for compounding with agglomerated solutions 0.05 wt% XTG (xanthan gum). The sink test, surface tension test, viscosity test, fourier transform infrared spectroscopy(FTIR) and scanning electron microscope(SEM) were used to investigate the wettability and agglomeration of the four compound solutions and analyze the agglomeration wetting mechanism. The results show that SDBS has the most obvious improvement in the wettability of compound solution. The surface tension of SDBS + 0.05 wt% XTG is 28.98 mN/m after CMC value and sinking rate will reach 14.29 mg/s with 0.6 wt% SDBS in compound solution; Furthermore, FTIR results showed that surface hydroxyl content of bituminous coal dust treated by 0.2 wt% SDBS + 0.05 wt% XTG solutions has increased 26.3% than that treated by 0.05 wt% XTG, which promoted the adsorption of xanthan gum molecules on the coal surface. The presence of surfactants decreases the viscosity and surface tension of compound solution, and xanthan gum–surfactants interaction will promote bituminous coal dust agglomeration effect. This agglomeration mechanism is mainly reflected in the distribution mechanism and bituminous coal dust can form to large agglomerates under this action.

Comparative Evaluation of the Penetration Depth into Dentinal Tubules of Three Endodontic Irrigants.

This study aimed to examine the penetration depth into dentinal tubules of some chelating agents. The 17% EDTA and two preparations containing surfactants (Smear Clear, Bioakt Endo) were tested. Surface tension and liquid viscosity were measured using a Dynamic Contact Angle Analyzer and a Haake rotational rheometer. To measure the penetration depth inside dentinal tubules, thirty maxillary central incisors were selected from a pool of extracted human permanent teeth and allocated to three experimental groups (10 samples each), as well as were mechanically shaped and cleansed with 5.25% NaOCl, followed by each of the chelators being labeled with 0.1 wt % Rhodamine B according to final irrigation protocol established. The samples were embedded in an epoxy resin, after which 200 μm thick transverse sections were obtained at 2, 5, and 8 mm from the apex with a saw microtome. The specimens were then observed using a confocal laser microscope (CLSM) and the penetration of the labeled solution was measured in every third of each sample. Statistical analysis was performed using ANOVA or Kruskal–Wallis tests according to the distribution of data, evaluated with the Shapiro–Wilk normality test. Viscosity and surface tension tests have shown that BioAKT Endo has the lowest values compared to EDTA and Smear Clear. The medium penetration depth did not significantly differ among the three irrigants, while it increased considerably from the apical to the coronal level in all groups. Additionally, the maximum penetration depth increased significantly from the apical to coronal level, while among groups, BioAKT Endo showed the highest values at the apical and middle level compared to the other irrigants. No significant differences were observed among the three groups in medium and maximum penetration depths when the entire root was considered. New irrigants containing surfactants show reduced surface tension and, in one case (BioAKT Endo), viscosity. The lowering of the surface tension allows for better penetration of liquids into dentinal tubules than EDTA alone, thus improving the cleaning of the root canal system.

Detailed insights into improved chlorite removal during hematite reverse flotation by sodium alginate

Hematite reverse flotation pulp is seriously deteriorated by chlorite due to the dissolution of chemical components (e.g., metal ions) on its surface. This study focused on the effect of sodium alginate on hematite reverse flotation. The results indicated that the addition of sodium alginate contributes to improving the chlorite entrainment recovery rate. The results of surface tension and solution viscosity tests along with the foam properties measured by the Foamscan analyzer demonstrated that the foam generation time reduces and the liquid volume in the foam layer increases with the addition of sodium alginate, further increasing the foam stability and chlorite entrainment rate. In addition, theoretical analysis of Plateau’s foam structure balance law supports this conclusion. This paper is significant as it addresses the challenging problem of chlorite-containing hematite reverse flotation.

Natural surfactant for sustainable carbon utilization in cleaner production of fossil fuels: Extraction, characterization and application studies

In this study, the extraction, characterization, and performance evaluation of a green surfactant, derived from bio-resource (Fenugreek seeds), is reported for effective carbon utilization in subsurface applications. Several characterization tools such as Fourier-transform infrared spectroscope, ultraviolet–visible spectroscope, methylene blue active substance test, surface tension tests, and scanning electron microscope were used to confirm saponin (surface activity) in synthesized surfactant and suitably compared with the properties of conventional surfactants in literature. The prepared green surfactant exhibited anionic behavior as validated by elemental analysis and adsorption studies. The critical micellar concentration of surfactant was determined by surface tension and electrical conductivity and its value was found to be around 0.2 wt%. Carbon dioxide absorption potential of green surfactant was envisaged by molality tests which confirmed that carbon dioxide absorption rate of surfactant was 7–18% higher than pure water. As a result, the surfactant showed high foam volume (> 40 ml) and foaming stability (8–10 h). The high temperature performance was also better. At 90 °C, carbon dioxide bubbles of larger size were present in sufficient quantity which indicated that foaming potential of surfactant was not severely affected by temperature. During adsorption studies, the green surfactant solution showed a mass-loss of 48–60% on a sandstone surface, which is better than the one of a conventional surfactant. It also showed superior property than conventional surfactants in adsorption isotherm investigations. Thus, the use of these green surfactants in subsurface scenario for carbon utilization and oil recovery from a porous media is recommended.

Isolation and Characterization of Biosurfactant-Producing Bacteria from Amapaense Amazon Soils.

The objective of this research was to perform screening of biosurfactant-producing bacteria from Amapaense Amazon soils. Floodplain- and upland-forest soils of three municipalities of the Amapá state were isolated and identified. The isolates were cultured in nutrient broth with olive oil, and their extracts were evaluated according to drop collapse, oil dispersion, emulsification, and surface tension tests. From three hundred and eighteen isolates, the 43 bacteria were selected and identified by 16S rDNA gene sequencing, indicating the presence of three different genera, Serratia, Paenibacillus, and Citrobacter. The extracellular biosurfactant production pointed out the 15 most efficient bacteria that presented high emulsification capacity (E24 > 48%) and stability (less than 10% of drop after 72 h) and great potential to reduce the surface tension (varying from 49.40 to 34.50 mN·m−1). Cluster analysis classified genetically related isolates in different groups, which can be connected to differences in the amount or the sort of biosurfactants. Isolates from Serratia genus presented better emulsification capacity and produced a more significant surface tension drop, indicating a promising potential for biotechnological applications.

Adsorption mechanism of efficient flotation separation of scheelite from calcite by a novel mixed collector

The separation of scheelite and calcite is a challenging problem in flotation production. In this study, the effects and mechanisms of oxidized paraffin soap (OPS) and octylphenol polyoxyxyethylene ether with 10 oxyethylene glycol ethers (OP-10) as a mixed collector to collect scheelite from calcite were surveyed by micro-flotation, Fourier transform infrared spectroscopy (FT-IR), surface tension tests, ultraviolet (UV) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The flotation results showed that the recovery of scheelite increased from 57.59% of 50 mg/L OPS to 94.75% of 30 mg/L OPS/OP-10 at pH 8, which proved that OP-10 could reduce the dosage of the OPS, and OPS/OP-10 was suitable for natural pH pulp. The surface tension tests demonstrated that OP-10 reduced the CMC of OPS aqueous solution and enhanced its solubilization. FT-IR analysis confirmed that OPS and OPS/OP-10 had strong chemisorption on the surface of scheelite and calcite. UV analysis further indicated preferential adsorption of OPS compared with OP-10, and the adsorption mechanism of the mixed collector can be confirmed as a co-adsorption. XPS analysis showed that OPS was chemically adsorbed on Ca sites on the scheelite surface, while the characteristic peak of the mixed collector did not shift significantly compared with that of OPS, indicating that OP-10 played a synergistic role mainly by co-adsorbing with OPS on the surface of scheelite. In a word, the mixed collector OPS/OP-10 was utilized for scheelite separation with satisfactory outcomes and exhibited an extensive prospect in scheelite production.

Molecular identification and primary evaluation of bio-surfactant production in edible paddy straw mushroom

Bio-surfactants have a unique structure that makes them suitable and attractive for many purposes such as removing crude oil, pharmaceutical production, oil industry (MEOR), and food industry. Using microorganisms instead of chemical surfactants for bio-surfactant production is confirmed by many researchers. So far, many efforts have been made to find more potent microorganisms for bio-surfactant production and almost all of these researches have been conducted on bacterial species and yeasts. Present study was performed in order to molecular identification and evaluation of bio-surfactant production potential of a previously isolated edible paddy straw mushroom. Bio-surfactant production by this microorganism was screened using emulsification index (E24%), oil spreading activity, and surface tension tests. DNA sequencing showed that this fungous belongs to new species of Volvariella volvacea. Also, reduction in surface tension, emulsification index and oil spreading activity were 35.15 dyne/cm, 80% and 11 cm, respectively.