Antifoaming Properties Research Articles

Self-assembling and foaming properties of nonionic, cardanol-based surfactants in aqueous solutions

Surfactants from renewable sources have gained attention due to their potential as substituents for petroleum-based chemicals. In this sense, surfactants based on cardanol, a compound abundant in the cashew nutshell liquid, have been proposed as suitable candidates for this purpose. However, their application is hindered by the lack of quantitative and reliable information about their bulk and surface properties in aqueous solutions. In this work, for the first time, three nonionic, cardanol-derived surfactants (7EO, 9EO, and 12EO), with different number of ethylene oxide (EO) units in the polar headgroup, had their foaming performances analyzed and correlated with their respective surface (equilibrium and dynamic surface tension and surface viscoelasticity) and bulk (cloud points, critical micelle concentration, micelle diameter, and viscosity) properties. Depending on the EO number, different scenarios were seen. Solutions containing the 7EO surfactant were below the cloud point at room temperature and presented antifoaming properties. Aqueous solutions of 9EO and 12EO displayed foamability comparable to solutions prepared with a traditionally employed anionic surfactant (sodium dodecyl sulfate, SDS) at the same concentrations. The surfactant 12EO presented a rapid surface adsorption, thus favoring the formation of large amounts of foam during aeration. Furthermore, solutions of 9EO resulted in foams that were considerably more stable than the ones formed by SDS. Such an enhanced stability was attributed to the presence of elongated micelles, formed at the vicinity of the cloud point, that increased solution viscosity and delayed the liquid drainage in the foams. This surfactant also promoted the formation of highly viscoelastic surface films that contributed to foam stabilization. The obtained results suggest that these surfactants can be used in the formulation of new products with a more sustainable character and with improved properties. Moreover, they indicate the important interchange among bulk aggregates, surface properties and foam stability in aqueous surfactant systems.

Green synthesis and performance evaluation of mixed fatty acids-based esters as nonionic antifoaming biosurfactants

Three different polyethylene glycol (PEG) esters of 1:1 fatty acid mixture of ricinoleic, oleic, and linseed oil fatty acids, as eco-friendly nonionic antifoaming biosurfactants were synthesized using a solventless biocatalytic route, to overcome challenges associated with chemical processes. Immobilized lipase Candida antarctica (NS 435) was found to be more effective as a biocatalyst (10 % w/w) than Rhizomucor meihei (RMIM), and Thermomyces lanuginous (TLIM) and led to the highest percentage of fatty acid conversion ∼97.5–98.5 %. The reusability of lipase enzymes was studied, and it has been found that the catalytic activity of NS 435 lipase remained almost intact up to the ninth successive cycle and gradually reduced by 4–5 % thereafter. Whereas RMIM and TLIM were effective till 5 and 4 cycles respectively. The produced esters were characterized, evaluated, and compared for surface activity, emulsification, and antifoaming properties against commercially available nonionic surfactants. The results revealed that the synthesized PEG esters have higher thermal stability, better emulsifying, and excellent antifoaming properties than conventional nonionic surfactants. Thus, the synthesized PEG esters have shown great potential to be used as environment-friendly (>90 % biodegradability) nonionic antifoaming biosurfactants to prepare emulsifiable industrial fluids.

Construction of high-branched derivatives based on melamine for highly effective defoaming and antifoaming

Foams can be seen everywhere in human production and life. An uncontrolled foam event usually leads to product losses, equipment damage, and clean-up costs. Defoamer is one of the most effective strategies to eliminate or inhibit foam activities, which has been proved by long-term practices. In this work, we report new molecular defoamers with high-branched structure, which adopts melamine molecule as the parent structure, by incorporating alkyl-isocyanates with different chain lengths into the high-branched melamine derivatives (Hb-MDs) formula to replace the R − NH2 (primary ammonia) on melamine structure. The substitution reaction processes can be readily tuned by varying the molar ratio or alkyl chain length of alkyl-isocyanate, enabling a facile control over the branched degree. The foam tests reveal that the high-branched melamine molecule defoamers exhibited excellent defoaming and anti-foaming properties for four typical foam systems, including an anionic SDBS, cationic DTAB, non-ionic AEO-9, and white cat (BM) detergent, with efficiency close to that of silicone-type LN1414 defoamer and far superior to that of high-carbon alcohol XS-02 defoamer, at the same addition level. Notably, the defoaming or anti-foaming performances of the high-branched melamine molecule defoamers were not always monotonically increased with the branched degree or hydrophobic chain length, but a suitable range needed to be maintained to support a good balance of defoamer structure with foam liquid films. Therefore, it is anticipated that this high-branched design principle could open a new avenue for the construction of molecular defoamers for complex industrial problems.

Chemically Modified Silicone Oil with Enhanced Tribological and Anti-Foaming Properties

Two kinds of chemically modified silicone oil, diisooctyl phosphate-terminated silicone oil (UCP204) and dioctyl dithiophosphate-terminated silicone oil (UCT2003), were synthesized. The tribological properties of silicone oil were evaluated using an SRV tribometer, and the worn surface and chemical composition were examined by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The friction coefficients of UCP204 and UCT2003 were reduced by approximately 62.7% and 56.7% compared with untreated silicone oil. The results indicated that the incorporation of phosphorus and/or sulfur could significantly enhance the tribological performance of modified silicone oil. Benefiting from their unique chemical structure, chemically modified silicone fluids also exhibit good dispersion stability and excellent anti-foaming properties, which are mainly attributed to the low surface tension properties imparted by the silicone backbone and the better dispersion stability provided by the dialkyl dithiophosphate group in chemically modified silicone fluids. It is also found that lubricants containing modified silicone oil remain clear after three months of storage and still maintain good anti-foaming properties.

The Influence of the Surface Chemistry of Cellulose Nanocrystals on Ethyl Lauroyl Arginate Foam Stability.

Guanidine-based surfactant ethyl lauroyl arginate (LAE) and cellulose nanocrystals (CNCs) form complexes of enhanced surface activity when compared to pure surfactants. The LAE-CNC mixtures show enhanced foaming properties. The dynamic thin-film balance technique (DTFB) was used to study the morphology, drainage and rupture of LAE-CNC thin liquid films under constant driving pressure. A total of three concentrations of surfactant and the corresponding mixtures of LAE with sulfated (sCNC) and carboxylated (cCNC) cellulose nanocrystals were studied. The sCNC and cCNC suspension with LAE formed thin films, with stability increasing with surfactant concentration and with complex rheological properties. In the presence of LAE, the aggregation of CNC was observed. While the sCNC aggregates were preferentially present in the film volume with a small fraction at the surface, the cCNC aggregates, due to their higher hydrophobicity, were preferentially located at film interfaces, forming compact layers. The presence of both types of aggregates decreased the stability of the thin liquid film compared to the one for the LAE solution with the same concentration. The addition of CNC to LAE was critical for foam formation, and foam stability was in qualitative agreement with the thin films' lifetimes. The foam volume increased with the LAE concentration. However, there was an optimum surfactant concentration to achieve stable foam. In particular, the very resistant foam was obtained with cCNC suspensions that formed the interfaces with a complex structure and rheology. On the other hand, at high LAE concentrations, the aggregates of CNC may exhibit antifoaming properties.

ID: 3524600 EFFECT OF INCORPORATING SIMETHICONE IN BOWEL PREP ON POLYP AND ADENOMA DETECTION RATE IN NON-CLINICAL TRIAL SETTING

Simethicone’s antifoaming properties have potential to improve mucosal visualization during colonoscopy. Here, we evaluate effect of incorporating simethicone in bowel preparation on polyp and adenoma detection rate.

Study on the Development and Performance of a New Concrete Antifoaming Agent

Gemini surfactant acetylene glycol polyethers and polyhydrosilicone oil were used as raw materials to generate the acetylene glycol surfactants with defoaming, antifoaming properties, and polyether modification through a hydrolyzation reaction. A novel silicone surfactant based on acetylene glycol-modified polyoxysilane, which has the advantages of low surface tension and good water solubility. Its structure characterized by infrared. Finally, the new silicone surfactant prepared was emulsified with a composite emulsifier, and a new concrete defoamer was prepared by a mechanical method. The defoaming performance, foam suppression performance and surface tension were tested. The results showed that the new silicone surfactants contained functional groups of acetylene glycol and siloxane. The composite emulsifiers were Span40 and Tween60, which the HLB value was 10, the amount was 5% and the emulsification time was 30 minutes. The prepared new concrete defoamer has good defoaming and antifoaming properties with a low surface tension.

Randomized, double-blinded, placebo-controlled trial evaluating simethicone pretreatment with bowel preparation during colonoscopy.

BACKGROUNDThe presence of small air bubbles and foam are an impediment to a successful colonoscopy. They impair an endoscopist’s view and diminish the diagnostic accuracy of the study. This has been particularly noted to be of concern with the switch to lower volume polyethylene glycol (PEG) and bisacodyl combination preparation.AIMTo evaluate the effect of oral simethicone addition to bowel preparation on intraluminal bubbles reduction during colonoscopy.METHODSDescribed is a prospective, randomized, multi-center, double-blinded, placebo-controlled study to evaluate the use of premixed simethicone formulation with split-regimen, low-volume PEG-bisacodyl combination bowel preparation for 168 outpatients undergoing screening, surveillance, and diagnostic colonoscopies. Primary outcome includes evaluation of bubbles during colonoscopy graded using the Intraluminal Bubbles Scale. Secondary outcomes include evaluation of the Boston Bowel Preparation Scale (BBPS), total number of polyps, polyp size differentiation, polyp laterality, adenoma detection, mass detection, cecal insertion time, withdrawal time, and patient-reported adverse events.RESULTSHigher Intraluminal Bubbles grades III and IV (less than 75% of the mucosa cleared of bubbles/foam requiring intervention with simethicone infused wash) were detected in the placebo group [Simethicone n = 4/84 vs Placebo n = 20/84 (P = 0.007)]. BBPS total score was 7.42 [standard deviation (SD) = ± 1.51] in the simethicone group and 7.28 (SD = ± 1.44) in the placebo group (P = 0.542) from a total of 9. Significantly higher number of adenomas were detected in the simethicone group (P = 0.001).CONCLUSIONThe addition of simethicone to bowel preparation is well advised for its anti-foaming properties. The results of this study suggest that addition of oral simethicone can improve bowel wall visibility.

Simethicone Pre-Treatment With Polyethylene Glycol and Bisacodyl Combination Preparation in an Effort to Improve Bowel Wall Visualization

Introduction: The presence of small air bubbles and foam can lead to impaired endoscopist view and diminish the diagnostic accuracy of a colonoscopy. Few studies have evaluated the efficacy of simethicone as an anti-foaming component with bowel preparations. This has been particularly noted to be of concern with the switch to lower volume polyethylene glycol (PEG) and bisacodyl combination preparations. Methods: We designed a prospective, randomized, multi-center, double blinded study to evaluate the use of simethicone formulation with split regimen, low volume PEG-Bisacodyl combination bowel preparation for outpatients undergoing elective colonoscopies. 124 adults are allocated into the treatment arm consisting of 200 mg of liquid simethicone and 126 adults are allotted to the control arm containing placebo water preparation to be mixed along with the bowel preparation. Intra-luminal bubbles scale is used as a primary endpoint defined by the percentage of the mucosa obscured by bubbles as seen by endoscopists during the procedure and whether intervention with simethicone infused saline wash is required. Secondary outcomes include the evaluations of adequacy of bowel preparation using the validated Boston Bowel Preparation Scale (BBPS), the number and types of polyps/masses detected, cecal insertion time, withdrawal time, and patient reported adverse effects. In an effort to reduce and measure inter-observer variability, 10 gastroenterologists are provided imaging examples of the Bubbles Scale and the Boston Bowel Preparation Scale for reference during rating and intermittently assessed through grading various images of intra-luminal bubbles. Results: The incidence of high levels of bubbles (Grade III and IV, less than 75% of the mucosa cleared of bubbles/foam requiring intervention with simethicone infused saline wash) is 5% and 30% respectively in simethicone vs. placebo group (P=<0.001). BBPS total score is 7.42 (+/- 1.62) simethicone and 7.29 (+/- 1.40) with the placebo group (P=0.474). Polyp detection rate is 1.51 in simethicone group vs. 1.13 in control group (P=0.825). Conclusion: Although recruiting has been completed, the study is in progress and 139 out of 250 participants have undergone endoscopies. Remaining participants are scheduled for the study duration ending in July 2018. Due to the fewer number of existing studies and lack of significant data, simethicone has not been incorporated in most commercially available bowel preparations for its anti-foaming properties.516_A Figure 1. Bubbles Scale516_B Figure 2. Logos

Treatment and restoration of used mineral-oil-based hydraulic fluids from different machines. Part 2: Effect of additives on oil properties restoration

ABSTRACTThis work is an extension of our previous work, (Ahmed et al. 2018). In this work, we investigate the effect of additives on restoration of properties of used mineral-based hydraulic oils. The additives were added to improve water separation, pour point, oxidation stability, thermal stability and anti-foaming properties. The effect of additives concentration was assessed, exhibiting optimum concentrations that yield maximum recovery of oil properties. The results show that the treated oil samples passed the tests of water separability and foaming tendency (seq. I and III). However, the other properties; such as oxidation stability, thermal stability, and foaming tendency (seq. Π) were improved but still fail to reach the allowable limits.

Effect of siloxane backbone length on butynediol-ethoxylate based polysiloxanes

A series of butynediol-ethoxylate based polysiloxanes (PSi-EOs) with same composition but different lengths of siloxane backbone were designed and synthesized via hydrosilylation reaction. Their physicochemical properties and application performances have been discussed. With the increase of the length of siloxane backbone, the critical aggregation concentration (CAC) decreases and the surface tension at CAC (γCAC) increases, but the dynamic adsorption at the air/water interface has no significant change. Above the CAC, all of these three surfactants can self-assemble into spherical aggregates of 100 to 500nm in aqueous solution. Moreover, the contact angle measurement on Paraffin film demonstrates that shorter siloxane backbone length of PSi-EO leads to lower contact angle and shows better spreading and wetting abilities. Using the foaming power test, PSi-EO with a longer siloxane backbone exhibits lower foaming and more effective anti-foaming properties in water.

고급지방산 메틸 에스테르류의 합성 및 소포특성

고급지방산 메틸 에스테르류의 합성 및 소포특성

Poloxamer 188 as a Supplement to Barium Cross-Linked Ultra-High Viscosity Alginate for Immunoisolation of Transplanted Islet Cells

Transplantation of Langerhans islets is a potential cure for diabetes mellitus. The main problem for routine clinical use remains the prevention of rejection without drastic side effects. Immuno-isolation is an experimental strategy to prevent graft rejection by separating the transplanted cells from the host immune system using a barrier device. The aim of the current study was to improve the physical features of encapsulated islets in a barium cross-linked ultra-high viscosity alginate by adding Poloxamer 188 (P188). Empty alginate capsules, and especially encapsulated islets, could be easily generated using UHV-P188 alginate because of its anti-foaming properties. Diabetic mice were used for evaluation of biocompatibility and graft function. Biocompatibility testing with empty capsules showed no inflammatory reaction or fibrotic overgrowth. The capsules remained intact in the intraperitoneal and intramuscular implant sites over a period of 4 weeks. Transplantation of encapsulated islets, however, led to a strong systemic inflammatory response with fibrotic overgrowth of the islet-containing capsules but no graft failure. This finding likely reflected the complementactivating property of P188. Our results clearly showed that the complex interaction of additives, xenogeneic tissue, and alginate with the host immune system could not be predicted by the behavior of the individual components. Furthermore, the mouse model described herein was an excellent tool to evaluate the physico-chemical properties and the in vivo biocompatibility and functionality of various additives. Our results will improve the biomaterials used for alginate microbeads in a clinical setting in the future.

Effect of thermal hydrolysis and ultrasounds pretreatments on foaming in anaerobic digesters

Foam appears regularly in anaerobic digesters producing operational and safety problems. In this research, based on the operational observation at semi-industrial pilot scale where sludge pretreatment mitigated foaming in anaerobic digesters, this study aimed at evaluating any potential relationship between foaming tools applied to activated sludge at lab-scale (foam potential, foam stability and Microthrix parvicella abundance) and the experimental behavior observed in pilot scale and full-scale anaerobic digesters. The potential of thermal hydrolysis and ultrasounds for reducing foaming capacity was also evaluated. Filamentous bacteria abundance was directly linked to foaming capacity in anaerobic processes. A maximum reduction of M.parvicella abundance (from 5 to 2) was reached using thermal hydrolysis with steam explosion at 170°C and ultrasounds at 66.7kWh/m3, showing both good anti-foaming properties. On the other hand, foam potential and stability determinations showed a lack of consistency with the bacteria abundance results and experimental evidences.

Enhanced production of pullulan by two strains of A. pullulans with different concentrations of soybean oil in sucrose solution in batch fermentations

Aureobasidium pullulans is a microorganism that produces pullulan (homopolysaccharide) extracellularly through a fermentation process with sugars (maltose, d-xylose, sucrose and starch) as its carbon source. Pullulan is a linear polysaccharide of D-glycopyranose containing (1 ®4)-a and (1 ® 6)-a linkages at a 2:1 ratio, is highly soluble in water and has various applications in the food, packaging, film and pharmaceutical industries. Lipids, primarily oils, having antifoaming properties as well as nutritional particularities, are considered an essential additional carbon source for the growth of microorganisms, especially fungi. These nutrient sources are very important for the maintenance of microorganism cells. In fact, these positive effects are only achieved when the right source is added at both the right time and the right dosage into the broth of the fermentation process. In this research on pullulan production with the strains NRRL Y-6220 and NRRL Y-2311-1, it was found that the latter strain achieved better results for undesirable pigment formation, pullulan titer, time of maximum production (96 hours) and biomass yields than strain NRRL Y-6220, which also showed suitable results for biomass yields and cell morphology. However, the dark pigmentation of the strain NRRL Y-6220, formed through the process, makes its application unacceptable for foods and pharmaceuticals. Strain NRRL Y-2311-1 was shown to be a promising potential industrial microorganism, whose applications should be studied more in depth.

Foam formation in a biotechnological process for the removal of hydrogen sulfide from gas streams

Foam formation in aqueous suspensions of biologically produced sulfur is studied in a foam generator at 30 °C, with the objective of describing trends and phenomena that govern foam formation in a biotechnological hydrogen sulfide removal process. Air is bubbled through a suspension and the development of the foam height in time is measured, showing essentially two types of foam, unstable foam of constant foam height and stable foam with a rapidly increasing foam height. The transition between these types of foam can occur when the local sulfur concentration near the surface of the liquid is higher than a critical concentration, so that a stable network structure can be formed. Sulfur particles are transported to the top of the liquid by flotation. Upon foam formation large aggregates of sulfur fall apart into smaller fractions. Especially the larger fraction of the sulfur particles is present in the foam, indicating that these particles have the right hydrophobicity to form a network structure. Furthermore, polysulfide anions were found to have antifoaming properties in biologically produced sulfur suspensions, either because of the changing of the surface properties of the biologically produced sulfur or because of the antifoaming properties of the hydrophobic elemental sulfur formed upon the chemical oxidation of polysulfide ions.

Development of powder antifoamer by atmospheric pressure glow plasma

Atmospheric pressure glow (APG) plasma treatment does not require a vacuum pump that is equipped with a low pressure plasma device. With treatment for organic powder, APG plasma can modify the surface roughness and wettability. In this study, we treated polystyrene films and powder by APG plasma, surveyed the changes of surface morphology, and examined the antifoaming effects of powders. A high exposure time (for this study, 20 min) in He+CF 4 plasma, polystyrene powders were introduced onto approximately 55% of fluorine atoms. This powder gave a better result for antifoaming properties.

Antifoaming Properties of Lubricating Oils

Antifoaming properties of lubricating oils are reviewed. There are two types of foaming in lubricating oils. One is surface foaming and another is air bubbles in oils. Surface foaming causes overflow of the oil from the reservoir, and air bubbles in oils promote cavitation erosion and wear brought about breakdown of oil film by bubbles. Usually antifoaming agents are added into lubricating oils. However, effects of antifoaming additives are influenced by base oils and other additives or mixing methods. In this review, effects of these several factors on antifoaming properties are summarized.

The Test Methods for Measuring Foaming and Antifoaming Properties of Liquid

The existing test methods for measuring foaming and antifoaming properties of liquids are reviewed. The foaminess of liquids strongly depends on the test method. A number of methods cover most aspects of foam formation and stabilization. According to the principal of the foam generation, the foaming methods have been classified into two groups ; static and dynamic. The foam stability are expressed in terms of defined parameter such as the lifetime of bubbles, bubble size distribution and the gradual transformation of foam film caused by drainage.

Antifoaming additives to turbine oils

In the current design of oil reservoirs the presence of foam affects only the oil level and increases its consumption due to losses through the ventilation openings. Aeration of the oil represents a more serious hazard. The deaerating properties of turbine oils deteriorate in the presence of siloxane additives, which are added to prevent excessive foaming [3]. These additives effectively destroy surface foam, however, they enhance the formation of a highly dispersed air-oil emulsion and reduce significantly its sedimentation rate. The search for new additives which would inhibit foaming and at the same time would not affect negatively the deaerating properties therefore represents an acute task. From thermodynamic concepts it follows that single-component liquids are not capable of forming a stable foam; it breaks down rapidly, regardless of the surface tension. A stable foam can occur 0nly in a multicomponent system, where even one of the components possesses surface-active properties and is capable of adsorbing at the interface. Lubricating oils .represent complicated multicomponentsystems which contain different surfactants in the base oil as well as in the additives. Consequently, many oils are inclined to foaming in the exploitation process which leads to the need of adding antifoam agents. Turbine oils manufactured according to GOST 9972-74 contain the antifoam PMS-200A organosilicon additive. Organosilicon compounds are being widely used as antifoaming agents. They are chemically inert, stable and effective at high temperatures~ available~ and inexpensive. Their viscosity and surface tension vary within wide limits [4]. The antifoaming properties of siloxane polymers are due to the unusually low surfice strength of their films and to the ability of displacing the not strongly enough adsorbed molecules of the foam stabilizer. The mechanical strength of the mixed adsorbed film is lost due to deep changes related to the occurrence of weakened sections. These sections are the first to break down under