Surface Tension Reduction Research Articles

Preparation and performance analysis of polycarboxylate superplasticizer modified with fluorine-containing monomer and silicon dioxide nanoparticles

With the development of technology, the performance requirements for building materials in the modern construction industry are increasing. Nanomaterials and polycarboxylate superplasticizers (PCE) have good applicability in this field. Therefore, we develop a composite material by incorporating a fluorocarbon surfactant (FS) as a shrinkage-reducing agent into the PCE and modifying it with silicon dioxide nanoparticles (nano-SiO2) (SiO2-FS-PCE). Moreover, we investigate the preparation, dispersity, flowability, rheological properties, adsorption performance, and microstructure of the SiO2-FS-PCE composite. We observe that introducing an appropriate concentration of fluorine-containing monomer can effectively reduce surface tension in the solution and inhibit the shrinkage of the slurry. The rheological properties of the SiO2-FS-PCE1 slurry decrease significantly with time. When the dosage of nano-SiO2 exceeds 20%, the silicon hydroxyl groups on the material’s surface tend to polymerize, which affects the adsorption and dispersion of the superplasticizer, thereby reducing its fluidity. As the dosage of nano-SiO2 increases, there is a trend of increasing friction of SiO2-FS-PCE, followed by a decrease. This change is closely related to changes in the adsorption and morphology of SiO2-FS-PCE, providing higher adsorption sites than other materials. In conclusion, these findings provide insights for a deeper understanding of the synthesis and properties of nanocomposite materials, thereby offering a theoretical basis for further optimization of their preparation and performance.

A comprehensive review direct methods to overcome the limitations of gas injection during the EOR process

Among the Enhanced Oil Recovery (EOR) methods, gas-based EOR methods are very popular all over the world. The gas injection has a high ability to increase microscopic sweep efficiency and can increase production efficiency well. However, it should be noted that in addition to all the advantages of these methods, they have disadvantages such as damage due to asphaltene deposition, unfavorable mobility ratio, and reduced efficiency of macroscopic displacement. In this paper, the gas injection process and its challenges were investigated. Then the overcoming methods of these challenges were investigated. To inhibit asphaltene deposition during gas injection, the use of nanoparticles was proposed, which were examined in two categories: liquid-soluble and gas-soluble, and the limitations of each were examined. Various methods were used to overcome the problem of unfavorable mobility ratio and their advantages and disadvantages were discussed. Gas-phase modification has the potential to reduce the challenges and limitations of direct gas injection and significantly increase recovery efficiency. In the first part, the introduction of gas injection and the enhanced oil recovery mechanisms during gas injection were mentioned. In the next part, the challenges of gas injection, which included unfavorable mobility ratio and asphaltene deposition, were investigated. In the third step, gas-phase mobility control methods investigate, emphasizing thickeners, thickening mechanisms, and field applications of mobility control methods. In the last part, to investigate the effect of nanoparticles on asphaltene deposition and reducing the minimum miscible pressure in two main subsets: 1- use of nanoparticles indirectly to prevent asphaltene deposition and reduce surface tension and 2- use of nanoparticles as a direct asphaltene inhibitor and Reduce MMP of the gas phase in crude oil was investigated.

Advances in the production of biosurfactants as green ingredients in home and personal care products.

Home and personal care industry is currently witnessing a growing demand for sustainable and eco-friendly alternatives to synthetic surfactants. This increase is fueled by concerns over the delayed degradation and environmental impact of the latter. To this, biosurfactants possess important properties such as biodegradability, low toxicity, and renewable sourcing. These qualities position them as compelling replacements of traditional synthetic surfactants. Their diverse attributes including emulsification, antimicrobial efficacy, surface tension reduction, and foaming capability, make them well-suited choices for home and personal care products. Biosurfactants can be produced through several inexpensive and renewable sources which contributes to their commercialization potential. This article discusses various microbial derived biosurfactants including rhamnolipids, sophorolipids, mannosyl-erythritol lipids, trehalolipids and lipopeptides, unraveling and comparing their distinctive roles and advantages in the home and personal care industry. It also focuses on the recent patent innovations in the production of biosurfactants which have aimed at improving their economic viability and performance attributes. Finally, the article sheds light on the challenges and future trajectories for better integration of these sustainable biosurfactants into mainstream consumer products.

Lipopeptide biosurfactant as a potential root canal irrigation agent: Antimicrobial and anti-biofilm evaluation

ObjectivesLipopeptide Biosurfactant (LB) is a bacteria derived compound able to reduce surface tension between water and hydrophobic substances and exhibit antimicrobial and anti-biofilm properties. This study aimed to investigate the antimicrobial and anti-biofilm effect of a Lipopeptide Biosurfactant (LB) on Enterococcus faecalis, and its potential use in root canal treatment, either as a standalone irrigation solution or in conjunction with sodium hypochlorite (NaOCl). MethodsLB was extracted from Bacillus clausii isolate and the dry extract was diluted in deionized water. The antimicrobial effect of LB against planktonic E. faecalis was evaluated by determining the Minimal Inhibitory Concentration (MIC50). The anti-biofilm effect was evaluated by Minimal Biofilm Inhibitory Concentration (MBIC50) and Minimal Biofilm Eradication Concentration (MBEC50) assays on biofilm grown on dentin specimen surface. To evaluate the effectiveness of LB as a single irrigation solution and as a pre-irrigation prior to NaOCl, live and dead bacterial cells were quantified using Confocal Laser Scanning Microscopy (CLSM), and cell biomass was assessed. ResultsLB exhibited an MIC50 and MBIC50 of 100 ppm, with an MBEC50 of 1000 ppm, resulting in 52.94 % biofilm inhibition and 60.95 % biofilm eradication on dentin specimens. The effectiveness was concentration-dependent, at 500 ppm, LB demonstrated comparable antimicrobial efficacy to 2.5 % NaOCl. Pre-irrigation with LB resulted in lower biofilm biomass compared to NaOCl alone. ConclusionPre-irrigation with LB enhanced the antimicrobial effect when followed by NaOCl irrigation. Consequently, LB shows promise as both a standalone root canal irrigation solution and as an adjunct to NaOCl in root canal treatment. Clinical significanceThe study highlights the potential of Lipopeptide Biosurfactant (LB) as an environmentally friendly irrigation solution for root canal treatment, demonstrating potent antimicrobial and anti-biofilm properties against Enterococcus faecalis. LB exhibits concentration-dependent efficacy comparable to 2.5 % NaOCl and can be used as a standalone irrigation solution or in conjunction with NaOCl.

Performance evaluation of rhamnolipid biosurfactant produced by Pseudomonas aeruginosa and its effect on marine oil-spill remediation.

This study aimed to reveal that the effect of biosurfactant on the dispersion and degradation of crude oil. Whole genome analysis showed that Pseudomonas aeruginosa GB-3 contained abundant genes involved in biosurfactant synthesis and metabolic processes and had the potential to degrade oil. The biosurfactant produced by strain GB-3 was screened by various methods. The results showed that the surface tension reduction activity was 28.6 mN·m-1 and emulsification stability was exhibited at different pH, salinity and temperature. The biosurfactant was identified as rhamnolipid by LC-MS and FTIR. The fermentation conditions of strain GB-3 were optimized by response surface methodology, finally the optimal system (carbon source: glucose, nitrogen source: ammonium sulfate, C/N ratio:16:1, pH: 7, temperature: 30-35°C) was determined. Compared with the initial fermentation, the yield of biosurfactant increased by 4.4 times after optimization. In addition, rhamnolipid biosurfactant as a dispersant could make the dispersion of crude oil reach 38% within seven days, which enhanced the bioavailability of crude oil. As a biostimulant, it could also improve the activity of indigenous microorganism and increase the degradation rate of crude oil by 10-15%. This study suggested that rhamnolipid biosurfactant had application prospect in bioremediation of marine oil-spill.

The potency of hydrophobic modification of alginate for a self-assembly matrix in fish oil encapsulation

To act as an emulsifier and a matrix for fish oil encapsulation, alginate is required to be modified due to its hydrophilicity. The purpose of this study was to modify alginate using dodecenyl succinic anhydride (DSA) under pH-controlled conditions and to apply it for stabilizing emulsion and encapsulating fish oil. The modification that followed the first-order reaction improved the hydrophobic properties of alginate as shown by the reduction of surface tension but improving the water contact angle, with CMC of 0.18 mg/l. A higher concentration of modified alginate was better in stabilizing fish-oil emulsion than the native one, as supported by the results of zeta potential, viscosity, and droplet size of the emulsion. Freeze-dried particle of this modified alginate emulsion showed better encapsulation efficiency and oxidation protection ability. Thermal properties of alginate were changed after hydrophobic modification and oil encapsulation. The freeze-dried particles of this modified alginate emulsion showed better encapsulation efficiency and protection ability. This study confirmed the protective ability of the modified alginate using DSA as an oil-based active ingredient encapsulant.

Production, characterization and biomedical potential of biosurfactants produced by haloalkaliphilic archaea from Wadi El-Natrun, Egypt

Extreme halophilic archaea that can live in high saline environments can offer potential applications in different biotechnological fields. This study delves into the fascinating field of halophilic archaea and their ability to produce biosurfactants. Some strains of haloarchaea were isolated from Wadi El-Natrun and were screened for biosurfactants production in a standard basal medium using emulsification index assay. Two strains were chosen as the potential strains for surface tension reduction. They were identified as Natrialba sp. BG1 and N3. The biosurfactants production was optimized and the produced emulsifiers were partially purified and identified using FTIR and NMR. Sequential statistical optimization, Plackett–Burman (PB) and Box–Behnken Designs (BBD) were carried out using 5 factors: oil, NaCl, casamino acids, pH, and inoculum size. The most significant factors were used for the next Response Surface Methodology experiment. The final optimal conditions for biosurfactants production were the inoculum size 2% pH 11 and NaCl 250 g/L, for Natrialba sp. BG1 and inoculum size 2.2%, pH 10 and NaCl 100 g/L for Natrialba sp. N3. The produced biosurfactants were tested for wound healing and the results indicated that Natrialba sp. BG1 biosurfactants is more efficient than Natrialba sp. N3 biosurfactants. Biosurfactants extracts were tested for their cytotoxic effects on normal cell line as well as on different cancer cells using MTT assay. The findings demonstrated that varying concentrations of the biosurfactants (31.25, 62.5, 125, 250, 500 and 1000 µg/mL) exhibited cytotoxic effects on the cell lines being tested. Additionally, the outcomes unveiled the presence of anti-inflammatory and antioxidant properties for both biosurfactants. Consequently, they could potentially serve as natural, safe, and efficient novel agents for combating cancer, promoting wound healing, and providing anti-inflammatory and antioxidant benefits.

Dynamics of Microcystis surface scum formation under different wind conditions: the role of hydrodynamic processes at the air-water interface.

Due to climate change, Microcystis blooms occur at increasing frequencies in aquatic ecosystems worldwide. Wind-generated turbulence is a crucial environmental stressor that can vertically disperse the Microcystis surface scum, reducing its light availability. Yet, the interactions of Microcystis scum with the wind-generated hydrodynamic processes, particularly those at the air-water interface, remain poorly understood. Here, we explore the response of Microcystis (including colony size and migration dynamics) to varying magnitudes and durations of intermittent wind disturbances in a mesocosm system. The flow velocities, size of Microcystis colonies, and the areal coverage of the water surface by scum were measured through video observations. Our results demonstrate that low wind speeds increase colony size by providing a stable condition where Microcystis forms a scum layer and aggregates into large colonies at the air-water interface. In contrast, wind disturbances disperse scum and generate turbulence, resulting in smaller colonies with higher magnitudes of wind disturbance. We observed that surface scum can form rapidly following a long period (6h) of high-magnitude (4.5m s-1) wind disturbance. Furthermore, our results indicate reduced water surface tension caused by the presence of Microcystis, which can decrease surface flow velocity and counteract wind-driven mixing. The reduced surface tension may also drive lateral convection at the water surface. These findings suggest that Microcystis reduces surface tension, likely by releasing surface-active materials, as an adaptive response to various wind conditions. This could result in an increased rate of surface scum re-formation under wind conditions and potentially facilitate the lateral expansion of scum patches during weak wind periods. This study reveals new insights into how Microcystis copes with different wind conditions and highlights the importance of the air-water interface for Microcystis scum dynamics.

Characterization and evaluation of biosurfactant produced from a thermophilc Bacillus licheniformis

The study emphasizes on the production of biosurfactant from thermophilic isolate BITSL006, found in Ramkund hotspring of Jharkhand. The isolate was cultivated in MSM using paneer whey with 16 g/L dextrose for biosurfactant production. The cell free supernatant was used to screen the ability of the isolate to produce biosurfactant. Based on screening methods, BITSL006 was selected as potent producer of biosurfactant and molecular sequencing confirm that the isolate was Bacillus licheniformis (ON795916). Optimization resulted in biosurfactant concentrations of 2.6 g/L in mineral salt medium (MSM) and 3.3 g/L in paneer water supplemented with mineral salt medium (PWSMSM). The biosurfactant was characterized as lipopeptide by FTIR and TLC analysis. FESEM-EDX analysis shows surface morphology and chemical composition of biosurfactant. Tensiometric analysis demonstrated its effectiveness in reducing surface tension from 71.78 mN/m (distilled water) to 44.54 mN/m (paneer water supplemented mineral salt medium) and 46.62 mN/m (mineral salt medium) indicating its surface activity. Moreover the biosurfactant displayed significant activity against various hydrocarbons and oils such as olive oil, mustard oil, diesel and crude oil, attributing to its increased cell surface hydrophobicity. Furthermore, it demonstrated potent antibacterial activity against E.coli, P. aeruginosa and S. aureus, along with effective antibiofilm activity against Bacillus sp. and S. aureus. Therefore, this marks the first report on biosurfactant production from thermophilic bacteria in Jharkhand using paneer whey. This highlights their thermostability, prolonged antibacterial and antibiofilm activity, as well as emulsification activity proposing it to be a potent candidate in pharmaceuticals, medical and environmental remediation.

Experimental investigation of the impact of soybean oil-derived surfactant as a surface-active agent during gas well deliquification

The inability of the gas rate to overcome the gas critical (minimum) flow rate leads to liquid loading in a gas well. To avoid premature well shut-in, the injection of surfactants is one of the standard methods used in gas well deliquification, although many commercial surfactants pose environmental toxicity concerns. This project investigates the suitability of biosurfactants in generating foam that will reduce the surface tension of the liquid by adsorbing at the liquid-gas interface to create a more significant mass than the liquid droplets which can be easily extracted from the walls of the wellbore. An experimental setup simulating gas well conditions introduce a surfactant derived from soybean oil, subjecting it to tests for foam stability, unloading efficiency, and dynamic surface tension. The results from the modified ASTM D-892 test show that Soybean Oil Derived Surfactant (SODS) exhibits promising surface tension reduction properties and effectively alters the gas-liquid interface. With the increase in concentration from 200 ppm, 400 ppm, and 600 ppm, the expelled water increased from 17%, 28%, and 70% respectively. Similarly, Gao-Rosen adsorption isotherms confirmed SODS appropriate for the prediction of the adsorption from solution with the R2 values of approximately 1.0. This study introduces a cost-effective and environmentally friendly surfactant that performs favorably for gas well deliquification.

Optimization of kerosene/oleic acid/water mixture for emulsion formation

Abstract The objective of the research was to investigate the influence of kerosene and oleic acid on emulsion formation. The two solutions were combined to form an emulsion by dispersing the kerosene solution into small droplets within the aqueous phase with the assistance of oleic acid. The surfactant reduced the interfacial tension between the two solutions, facilitating the emulsification process and stabilizing the droplets formed. A comprehensive understanding of the variables that control to the formation and stability of emulsions is essential for their effective development. For this purpose, the stability of oil-in-water emulsions was evaluated by measuring droplet size, turbidity, zeta potential, surface tension, and conductivity. Improved emulsion stability was correlated with smaller droplet size, increased turbidity, and reduced surface tension. The results of this research have significant potential for a variety of industrial applications.

Identification of surfactin lipopeptides isoforms produced by a newly isolated strain Bacillus sp. MI27 with potential use as main ingredients in detergent formulation: Application of mixture design for the formulation of a bio-based detergent

Abstract The purification and characterization of lipopeptide biosurfactants produced by Bacillus sp. MI27 permits to identify two clusters of cyclic and linear surfactin isoforms. Aiming for a potential application in industrial biotechnology, we studied its potential washing capacity. The results show a good ability to wash oil stains, motor oil and mayonnaise evaluated by the determination of the % of stain removal and tissue bleaching indices after washing. Optimal washing capacities were unregistered for 300 and 400 mg/L at pH values ranging from 5 to 9 and temperatures ranging from 20 to 40°C. Using a 4-factor mixing design, we optimized a liquid formula composed only of BioS; silicate; carboxymethyl cellulose and calcium phosphate. The washing efficiency of the formula is of the order of 43.46% for petroleum and 49.10% for motor oil with a percentage reduction in surface tension of about 55.79% corresponding to 25.7 mN/m.

Coupled effects of temperature and suction on the shear behaviour of saturated and unsaturated clayey sand–structure interfaces

The thermo-mechanical behaviour of saturated and unsaturated soil–structure interfaces plays a key role in analysing the performance of energy piles. Previous studies focused on saturated interfaces and did not investigate the coupled effects of temperature and suction on interface behaviour. In this study, a clayey sand–structure interface with a normalised roughness of one was tested through a new temperature- and suction-controlled direct shear apparatus. A variety of temperatures (8, 20 and 42°C), net normal stresses (25, 50, 100, 150, 225 and 300 kPa) and suctions (0, 50 and 200 kPa) were considered. The results show that temperature can have a minor impact on the friction angle, whose value at 42°C is smaller by about 2·2° than that at 8°C, probably because heating can reduce the shearing-induced contraction in the shear zone. More importantly, the interface strength increases non-linearly with increasing suction, and the incremental rate is temperature dependent. Heating the interface at a net normal stress of 50 kPa reduces this incremental rate due to reduction in surface tension and thermally induced changes in soil fabric. In contrast, this incremental rate increases at a net normal stress of 150 kPa with the same temperature increment, probably because the heated specimen has more small pores due to thermal contraction and more menisci water lenses, whose influence outweighs the effects of surface tension.

Heat transfer enhancement and long-term test of non-ionic Triton surfactant with different hydrophilic chain lengths

Surfactant aids boiling enhancement, but the related mechanism is not yet comprehensively understood. For mechanism investigation on surfactant molecule, most of existing studies focused on its hydrophobic part, while research on hydrophilic part is scarce. In this paper, a group of non-ionic Triton surfactants with same functional group but different hydrophilic chain lengths were experimentally tested for pool boiling on flat copper. At critical micelle concentration (CMC), long-chain Tx-405 exhibited higher heat transfer coefficient (97.4 kW/(m2·K)) than Tx-100 (77.1 kW/(m2·K)) and Tx-114 (77.4 kW/(m2·K)). Long-term test indicated a gradually deteriorating trend of heat transfer performance from days on. Solution properties and bubble dynamics were measured. At low concentration, surfactant with shorter hydrophilic chain has better heat transfer performance due to greater surface tension reduction. The increase of hydrophilic chain length improves water affinity of surfactant and thus leads to higher CMC. If there is no restriction for surfactant concentration, a longer hydrophilic chain is favorable for higher heat transfer coefficient at CMC. The results in this paper provide insights for mechanism investigation on surfactant, promote further design of new surfactant, and contribute to the prediction of heat transfer enhancement effect.

Research on the performances of VPEG macromonomer grafted different functional groups to prepare polycarboxylate superplasticizers

AbstractThe advent of novel polyether macromonomer has garnered significant attention within the industrial domain. In this study, a range of polycarboxylate superplasticizers (PCEs) was produced via free radical polymerization, employing a new polyether monomer, 4‐hydroxybutyl vinyl polyethylene glycol ether (VPEG). This monomer served as the predominant component and was grafted with various functional monomers on its main chain. The molecular configuration of the resultant PCEs was discerned through Fourier infrared spectroscopy and gel permeation chromatography, while the surface tension underwent assessment via a surface tension meter. Both the initial and subsequent fluidity of cement paste and mortar were leveraged to ascertain the dispersion and retention efficacy of the synthetic PCEs. The ramifications of diverse functional group grafts of the new polyether monomer on the cement hydration procedure and strength attributes were elucidated via setting time, hydration heat assays of cement paste, SEM analysis, and compressive strength evaluations of mortar. Observations reveal that the carboxylic acid group significantly reduces surface tension, whereas the sulfonic acid group's effect remains minimal. The incorporation of both the amide and sulfonic acid groups marginally impacts the preliminary dispersion efficacy of PCEs but notably affects dispersion retention. Furthermore, these functional groups facilitate cement hydration, expedite the primary setting time of the cement paste, and bolster the initial compressive strength of the mortar. Specifically, the grafted of sodium methacrylsulfonate (SMAS) yields the most noticeable results. Finally, the working mechanism of PCEs with varying molecular structures has been explained in light both theoretical and experimental results. This research offers valuable insights for subsequent investigations into the fabrication of polycarboxylate superplasticizers using the VPEG macromonomer.

Rhamnolipids production by Pseudomonas aeruginosa RW9 using palm oil mill effluent sludge oil as a carbon source

The production of biosurfactants has garnered considerable attention in recent years due to their unique properties, which include the ability to enhance oil solubility in water, reduce surface tension, and exhibit low environmental toxicity. In this study, we investigated the production of biosurfactants by Pseudomonas aeruginosa RW9, using a renewable and non-food competitive, palm oil mill effluent (POME) sludge oil as a carbon source. Various carbon and nitrogen sources were introduced into the mineral salt medium to optimize biosurfactant production. The results demonstrated that P. aeruginosa RW9 successfully generated 1.57 g/L of rhamnolipids (RLs) biosurfactant. Liquid chromatography-mass spectrometry (LC-MS) analysis confirmed the presence of mono-RLs and di-RLs congeners. Furthermore, the RLs produced from POME sludge oil exhibited a significant reduction in surface tension, reaching 28.55 mN/m, and demonstrated efficient emulsification of diesel, with an emulsion index of up to 56.6 %. This research underscores the promising potential of using POME sludge oil as a sustainable substrate for RLs production. This approach not only adds value to a vastly available resource but also contributes to the production of environmentally friendly biochemicals.

Reductive behavior of nickel and iron metallization in magnesian siliceous nickel laterite ores under the action of sulfur-bearing natural gas

Abstract This study is a process for the preparation of advanced nickel–iron alloys by selective reduction of nickel-poor laterite ores using a variety of reducing agents. The first part of the experiment was the reduction of nickel laterite ore using natural gas; the reduction yielded mostly nickel metal and a small amount of iron forming fine nickel–iron particles. Fine nickel–iron particles are formed through the reduction of nickel and a small amount of iron oxides. These particles are dispersed and embedded within silicates. Additionally, H2S present in natural gas reacts with iron oxide, resulting in the formation of FeS. This, in turn, forms a low melting point eutectic with Fe, which reduces surface tension and promotes the growth and aggregation of nickel–iron particles. This study aimed to investigate the effects of various parameters such as roasting temperature, roasting time, natural gas concentration, and nickel laterite pellet on the formation and aggregation of ferronickel particles in low-grade nickel laterite ores. The results showed that the optimum reduction parameters were achieved at 900°C, 120 min, 40% natural gas concentration, and 40–60 mesh nickel laterite size, with roasting temperature being the most important factor followed by natural gas concentration, roasting time, and nickel laterite pellet. Using these parameters, the metallization rates of Ni and Fe were found to be as high as 95.3 and 8.5%, respectively.

Unraveling the permeation-enhancing effect of didecyl dimethyl ammonium chloride (DDAC) on poplar wood (Populus cathayana Rehd.)

ABSTRACT Wood is a sustainable, porous material with a diverse range of applications. However, the low permeability of liquids within wood poses significant challenges for the widespread application of advanced wood-based materials such as oil–water separation, as well as traditional chemical modification processes of wood. Surfactants exhibit potential to improve permeability of liquids within wood by effectively enhancing liquid wettability on solid surfaces. In this study, the effects of didecyl dimethyl ammonium chloride (DDAC) on liquid absorption of water and copper ethanolamine (CE) by wood were explored under atmospheric temperature and pressure. With an increase in concentration of DDAC, its promotion effect on liquid absorption of wood became more pronounced. The most notable enhancement was observed in wicking test where 0.10% DDAC increased liquid absorption of wood to water by 156.7% and to CE by 65.5%. The enhancement of liquid wettability on wood surface cannot be solely attributed to reduction of liquid surface tension, the adsorption of DDAC onto wood surface also plays a crucial role in this process. This study investigated the intrinsic mechanisms by which DDAC enhanced the permeability of liquids within wood, contributing to increased productivity and reduced energy consumption.

Screening biosurfactant-producing actinomycetes: Identification of Streptomyces sp. RP1 as a potent species for bioremediation.

This study aimed to isolate biosurfactant-producing and hydrocarbon-degrading actinomycetes from different soils using glycerol-asparagine and starch-casein media with an antifungal agent. The glycerol-asparagine agar exhibited the highest number of actinomycetes, with a white, low-opacity medium supporting pigment production and high growth. Biosurfactant analyses, such as drop collapse, oil displacement, emulsification, tributyrin agar test, and surface tension measurement, were conducted. Out of 25 positive isolates, seven could utilize both olive oil and black oil for biosurfactant production, and only isolate RP1 could produce biosurfactant when grown in constrained conditions with black oil as the sole carbon source and inducer, demonstrating in situ bioremediation potential. Isolate RP1 from oil-spilled garden soil is Gram-staining-positive with a distinct earthy odor, melanin formation, and white filamentous colonies. It has a molecular size of ~621 bp and 100% sequence similarity to many Streptomyces spp. Morphological, biochemical, and 16 S rRNA analysis confirmed it as Streptomyces sp. RP1, showing positive results in all screenings, including high emulsification activity against kerosene (27.2%) and engine oil (95.8%), oil displacement efficiency against crude oil (7.45 cm), and a significant reduction in surface tension (56.7 dynes/cm). Streptomyces sp. RP1 can utilize citrate as a carbon source, tolerate sodium chloride, resist lysozyme, degrade petroleum hydrocarbons, and produce biosurfactant at 37°C in a 15 mL medium culture, indicating great potential for bioremediation and various downstream industrial applications with optimization.

Gelatin‐based air‐entraining agents for ordinary portland cement: Chelate Ca2+ and reduce surface tension

AbstractIntroducing uniform, stable, and small pores by adding air‐entraining agents (AEAs) is an effective strategy for improving the freeze–thaw resistance and workability of cement concrete materials. In this study, the gelatin with hydrophobic and hydrophilic functional groups was used as an AEA for cement concrete materials and systematically studied its effect on the performance of cement mortar specimens. The results showed that gelatin has a surfactant‐like function and can effectively reduce the surface tension of the gas–liquid interface. In an alkaline environment, Ca2+ ions in cement pore solution chelate with carboxylate ions formed by carboxyl ionization, further enhancing the performance of gelatin‐based AEAs. Thanks to the reduction in surface activity and carboxyl ionization, introducing gelatin increased the porosity of cement mortar specimens from 0.53% to 2.69%. Furthermore, introducing an appropriate amount (>0.1 wt%) of gelatin does not significantly impact the workability or mechanical properties of cement mortar. Based on these characteristics, gelatin has potential as an AEA for cement concrete materials.