Foam Fractionation Method Research Articles

Foam fractionation for the separation and enrichment of trace m-phenylenediamine and o-phenylenediamine in solution

In this study, a foam fractionation technique was developed for the separation and enrichment of the trace m-phenylenediamine (MPD) and o-phenylenediamine (OPD) in solution. Firstly, a self-designed foam fractionation device was assembled and built, followed by a comprehensive characterization on gas types, foam fractionation column parameters, and porous sieve plate material used in the apparatus. Subsequently, the most crucial parameters for the separation and enrichment, such as surfactant species, solution pH, electrolyte categories, and gas flow rate, were identified and optimized. The mechanisms of key processes during foam fractionation under the influence of these parameters were thoroughly discussed. Other influencing factors, such as surfactant concentration, foam collection time, and solution volume in the fractionation column, were optimized using response surface methodology (RSM). Under these optimal conditions, maximal enrichment ratios of 138.2 and 85.5 were achieved for MPD and OPD, respectively. Finally, foam fractionation coupled with high-performance liquid chromatography (HPLC) was employed to detect MPD and OPD in the solution. The results demonstrated limits of detection (LOD) of 1.5 × 10−2 μg/L and 1.5 μg/L for MPD and OPD, with relative standard deviation (RSD) values of 4.1 % and 3.9 %. When testing various actual samples, the recoveries were in the range from 92.0 % or greater in all cases. The method exhibited advantages of high sensitivity, precision, and accuracy, attributed to the high enrichment efficiency of foam fractionation. In conclusion, the foam fractionation method established in this study offers simplicity in apparatus, operational convenience, environmental friendliness (minimized use of organic solvents), and high enrichment efficiency. It proves valuable for the quantitative analysis of trace amounts of MPD and OPD in solution, presenting a novel approach for the detection of trace organic compounds in solutions.

Plant polyphenol surfactant construction with strong surface activity and chelation properties as efficient decontamination of UO22+ on cotton fabric

Chemically synthesized surfactants have promising applications in the treatment of uranium, however, their hazardous environmental effects, non-biodegradability, and numerous drawbacks prevent them from being widely used in practice. Herein, we successfully synthesized a green chelating and foaming integrated surfactant (BTBS) by Mannich reaction and acylation of bayberry tannin for the effective removal of UO22+ from aqueous environments or solid surfaces. The as-prepared surfactant was systematically characterized by FT-IR, showing that the hydrophobic groups were successfully grafted onto tannin. The modified material showed better foaming and emulsifying properties, which proved this method could improve the amphiphilicity of tannin. Moreover, for the first time, a foam fractionation method in conjunction with a tannin-based surfactant was applied for UO22+ removal from water. This surfactant was used as a co-surfactant and could readily remove 90 % of UO22+ (20 mg L−1) from water. The removal of UO22+ could be completed in a short time (30 min), and the maximum adsorption capacity was determined as 175.9 mg g−1. This surfactant can also be used for efficient decontamination of uranium-contaminated cotton cloth with a high removal rate of 94.55 %. In addition, the mechanism studies show that the adsorption of BTBS for UO22+ can be mainly attributed to a chelating mechanism between UO22+ and the adjacent phenolic hydroxyls. The novel biomass-derived BTBS with advantages such as high capture capacity, environmental friendliness, and cost-effectiveness suggests that it plays an important role in the remediation of radionuclide pollution.

Using foam fractionation to estimate PFAS air-water interface adsorption behaviour at ng/L and µg/L concentrations

PFAS are biologically recalcitrant compounds that are persistent in the environment and have subsequently contaminated groundwater, landfill leachate and surface water. Due to their persistence and toxicity, there are environmental concentration limits imposed on some PFAS compounds that extend down to a few nanograms per litre and even proposals for reducing these to picogram per litre levels. Since PFAS concentrates at water-air interfaces as a result of their amphiphilic nature, this characteristic is important for the successful modelling and prediction of transport behaviour of PFAS through various systems. Here we present a procedure for using a foam fractionation method to experimentally determine the PFAS adsorption behaviour at ng/L and µg/L concentrations in the presence of salts. The equilibrium air-water adsorption coefficients for PFHxS and PFOA at different salinities and concentrations are experimentally shown to be constant across the range of PFAS concentrations investigated (approx. 0.1–100 µg/L). The adsorption isotherms may consequently be modelled by Henry or Langmuir style equations at these low concentrations.

Synthesis and application of a green surfactant for the treatment of water containing PFAS/ hazardous metal ions

In this work, the effectiveness of a biodegradable and natural surfactant synthesized through a novel method has been studied through the ion flotation process to treat waters containing Per/Poly Fluoroalkyl Substances (PFAS) and heavy-metal ions. This cysteine-based surfactant, which is environmentally acceptable, showed considerable solubility and foaming ability over a wide range of pH. It also could remove 97–99(%) of 5 mg/L of cadmium, chromium, copper, nickel, zinc, and manganese ions in a single batch physicochemical process. Moreover, for the first time, a foam fractionation method in association with using this cysteine-based surfactant was applied for perfluorooctanoic acid (PFOA) removal from water. This surfactant was used as a co-surfactant and could readily remove 72% of PFOA (40 mg/L) from water. The characterization of the surfactant was undertaken using 1H NMR, FT-IR, elemental analysis, melting point, and determination of its critical micelle concentration (CMC). This environmentally friendly surfactant has high potential applications in green chemistry especially in the treatment of waters contaminated with PFAS/heavy-metal ions.

Removal and recovery of a cationic surfactant from its aqueous solution by foam fractionation

Extensive use of the surfactants helps the development of many consumer products, but it contaminates water in many cases. Thus, the removal and recovery of these surfactants has become essential. In this study, a cationic surfactant (i.e., cetyltrimethylammonium bromide) was recovered from its aqueous solution by employing the foam fractionation method in batch mode in a cylindrical column. The surfactant concentration was five times its critical micellar concentration (i.e., 1822 mg dm–3). The effects of three salts (i.e., NaCl, CaCl2, and Na2SO4) and airflow rate on the surfactant recovery were studied. The salt concentration was varied from 10 to 100 mol m−3, and the airflow rate was varied from 0.4 to 1.6 dm3 min−1. About 60 % of the surfactant was recovered from the top of the column in the form of a semi-solid paste. The foam volume and surfactant recovery were reduced by the addition of salt. The stability of the foam played a very important role in surfactant recovery. The recovery of water was excellent.

Fractionation of Nanocellulose by Foam Filter

The foam fractionation method was applied for nanocellulose. Experiments were carried out with enzymatically pretreated nano-fibrillated cellulose (NFC) from softwood, as well as commercial products. Narrow channels (plateaus) between bubbles prevent the flow of coarse particles along the water, so that foam acts like a filter. The advantage of the method is no risk of clogging, which could be a big problem for conventional filters or screens. Mean particle size (effective size by means of dynamic light scattering measurement) was reduced by foam fractionation, and the reduction range depended on the cellulose grade and the type of surfactant. The yield turned out to be low, probably because of particle aggregation due to the interaction with surfactant.

Foam fractionation of ZnO crystal growth and its photocatalysis of the degradation of methylene blue

Abstract

Visible light response of Ag+/TiO2–Ti2O3 prepared by photodeposition under foam fractionation

Abstract An Ag + /TiO 2 –Ti 2 O 3 nanocomposite was synthesized by a novel foam fractionation method: the foam traveled to a fixed vertical column and was fractionated. Silver was deposited (0–0.02 mol%) on titania photocatalytic nanoparticles by the foam fractionation method under UV irradiation. By TEM, the Ag particles were found to be highly dispersed on TiO 2 without any aggregation. XPS studies revealed the presence of both the Ti 3+ and Ti 4+ forms, and with an increase in Ag content, Ti 3+ increased. Ag was found mainly in the Ag + state. The obtained Ag–Ti oxides were investigated for photocatalytic activity by the degradation of methylene blue under visible light and sunlight, and the catalytic activity was better under sunlight than under visible light. The activity was found to increase with an increase in Ag loading. The Ag + /TiO 2 –Ti 2 O 3 obtained by the foam fractionation method was further investigated for bactericidal activity under visible light. Using 0.05 mol% Ag/Ti, the bacterial growth of Escherichia coli was completely inhibited under visible light.

Statistical analysis in enrichment of total whey protein by continuous foam fractionation method

The objective of the present study was to optimize the operating conditions in the separation of the total whey proteins from whey by continuous foam fractionation method using response surface methodology (RSM). The effects of the different process variables such as pH (X 1 ) of proteins in feed, gas flow rate, (X 2 ) of initial feed solution, protein: surfactant ratio (X 3 ) and volumetric flow rate (X 4 ) where investigated on the performance criteria of fractionation of raw processed whey. Four factors, three levels Box-Behnken design was used for the optimization procedure. Quadratic model regression equations and response surface plots correlate independent variables (X 1 , X 2 , X 3 and X 4 ) and dependent variables (response) such as concentration of Foamate (C f ), Enrichment ratio (E r ), and percentage Recovery (% R p ) of total whey proteins. All the four factors had significant effects on the response variables. The model predicted that the optimized values of the factors (X 1 , X 2 , X 3 and X 4 ) such as 5, 290, 1.5 and 14, respectively. The predicted responses were (concentration of foamate, enrichment ratio, and percentage recovery) such as 6647.32, 13.27, and 78.02, respectively. Experiments were performed with the predicted values of factors.

Quantitative Characterization of Bovine Serum Albumin, α-Lactalbumin and β-Lactoglobulin in Commercial Whey Sample by RP-LC

A simple, sensitive and precise reverse phase liquid chromatographic method has been developed and validated for quantification of bovine serum albumin (BSA), α-lactalbumin (α-La) and β–lactoglobulin (β-Lg) that are removed from whey waste by foam fractionation method. The data is reproducible over a wide concentration range. This optimized method allowed analysis of BSA, α-La, β-Lg in a mixture within 5 min and could be applied to the analysis of a variety of commercial and laboratory whey products within a short time.

Batch production of biosurfactant with foam fractionation

AbstractMethods of producing the biosurfactant surfactin from cultures of Bacillus subtilis (BBK006) have been investigated. A reactor with integrated foam fractionation was designed and used in batch mode, and the performance compared with that of the same culture in shaken flasks. In the batch reactor, significant foaming occurred between 12.5 h and 14.5 h of culture time. During this period, the foam was routed through the foam fractionation column to a mechanical foam breaker, and a biosurfactant‐enriched foamate was collected. Concentration of surfactin in the foamate product was around 50 times greater than that in the culture medium. Using the integrated reactor, 136 mg L−1 of surfactin was produced, significantly more than was achieved in shaken flasks (92 mg L−1). The foam fractionation method allowed a real‐time measurement of the rate of surfactin production during growth. This showed that the maximum rate of production occurred at the interphase between log and stationary modes of growth, in contrast to previous work showing that surfactin is exclusively a secondary metabolite. The high value of surfactin yield in relation to biomass (YP/x = 0.262) indicated that surfactin was produced very efficiently by Bacillus subtilis (BBK006) in this integrated bioreactor. Copyright © 2006 Society of Chemical Industry

Observation of a Liquid−Gas Phase Transition in Monolayers of Alkyltrimethylammonium Alkyl Sulfates Adsorbed at the Air/Water Interface

The equilibrium adsorption layers of symmetric chain alkyltrimethylammonium alkyl sulfates (Cn+.Cn- for n = 8, 12) were investigated at the air/water interface by sum-frequency vibrational spectroscopy in the function of the bulk surfactant concentration. To ensure the surface purity of the solutions investigated, an improved version of the foam fractionation method was used for the purification of the constituent ionic surfactants and the surface purity of the solutions was also checked. In the monolayer of the C12+.C12- surfactant, a two-dimensional first-order gas/liquid phase transition was observed. At surfactant bulk concentrations just exceeding the concentration corresponding to the phase transition, the monolayer is conformationally disordered, liquidlike, but with increasing bulk surfactant concentration the conformational order of the monolayer increases. The SFG spectra of the C8+.C8- monolayer did not indicate the occurrence of phase transition at room temperature.

Foam Fractionation of Binary Mixtures of Lysozyme and Albumin

A nitrogen gas‐based foam fractionation method was employed to separate model proteins, bovine serum albumin (BSA) and hen egg white lysozyme, from each other. Fractionation was characterized by the separation ratio and by recovery of proteins in the retentate as a function of the nominal pore size of the gas dispersion frit and solution conditions (pH and ionic strength). For binary mixtures of the proteins at pH 7.4, and ionic strength (μ) of 0.18 M, the recovery of lysozyme and the separation ratio were both dependent on the frit size employed to generate the foam. At low ionic strength (μ = 0.01 M), separation was only somewhat greater with the small pore size frits, although at values significantly lower than those found for high ionic strength. The diminished separations appear to be due to the only slight changes in recoveries observed for BSA and lysozyme.%Separation ratios of lysozyme from BSA in solutions either of high or low ionic strength were maximal at pH values equal to or less than the isoelectric point (pI) of BSA. Separation ratios were lower when foaming was carried out under low compared with high ionic strength. The recovery of lysozyme was enhanced by foaming from solutions of low pH and high ionic strength. Recoveries of BSA were greatest when the molecule was negatively charged. Electrical interactions between the positively charged lysozyme and negatively charged BSA may explain the diminished separation ratios and enhanced recoveries. Enzyme activity studies of lysozyme remaining in the retentate showed no change from prefoam activity. © 2000 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 89: 693–704, 2000

泡まつ分離法によるタンパク質の分離濃縮

From the point of view of the protection of our circumstances and recycling of materials, it is important to separate and recover proteins economically and in an industrial scale. Protein is easily affected by heat, pH, solvent and so on, by which it changes the chemical properties. In this work, the effect of several factors on the separation and recovery of protein, especially albumin and hemoglobin was investigated using a foam fractionation method. Also we measured the stability of the froth and foaming ability of protein solution. We tried to express them quantitatively into the grade.At the low flow rate of gas, both proteins can be separated from the solution at high percentage. Also, the highest recovery was obtained at pH of the point of zero charge. It is another way to add some salts in the solution which have influence to the improvement of the recovery. Compared with the life span of the froth between albumin and hemoglobin, albumin is superior to hemoglobin. The life of the froth of albumin is considerably affected by pH value of the solution. On the contrary, that of hemoglobin strongly depends on the concentration in stead of pH. We can get the high concentration ratio only by using the higher froth layer, namely the higher column length.We achieved a selective separation between albumin and hemoglobin at the concentration ratio of 10: 1 at the pH of point of zero charge of albumin; moreover by using a surface active agent, e.g. Tween 20, the separation ratio was improved up to 43: 1.

Aqueous solubility and acidity constants of cholic, deoxycholic, chenodeoxycholic, and ursodeoxycholic acids.

Cholic acid, deoxycholic acid, chenodeoxycholic acid, and ursodeoxycholic acid were purified by a foam fractionation method. Using thermogravimetric analysis, the attached water molecule was found to be completely removed from solids of the latter three at 100 degrees C, while cholic acid still had one water molecule of crystallization per two cholic acid molecules at that temperature. The acidity constants of the acids were accurately determined from aqueous solubility measurements at different pH values and at 15, 25, 35, and 45 degrees C. The enthalpy change of dissolution from temperature dependence of solubility as undissociated acid monomer was much less than those of common ionic surfactants. This results from a smaller entropy increase on dissolution due to the hardly flexible hydrophobic structure of these bile acids.

Adsorption and Removal of p-Nonylphenyl Poly (oxyethylene) Ether by Foam Fractionation Method

The removal of a small quantity of p-nonylphenyl poly (oxyethylene) ether (EO 10 moles) in water was studied by foam fractionation method.Air was bubbled through water at a constant flow rate (150cm3/min), and the adsorption of the surfactant on the (generated) bubble surface and its removal (effect) were measured.The results were as follows : 1) The adsorption of the surfactant on the bubble surface was found to come to an equilibrium in about two or three seconds, and the adsorption isotherm was confirmed to be in good agreement with Langmuir equation.2) In the continuous foam fractionation at a constant air flow rate, the removal effect was better as the concentration of the fed liquid was lower and the feeding rate was smaller.