Adsorption of surfactants on a <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> strain and the effect on cell surface lypohydrophilic property

The adsorption behavior of five surfactants, cetyltrimethylammonium bromide (CTAB), Triton X-100, Tween 80, sodium dodecyl sulfate (SDS), and rhamnolipid, on a Pseudomonas aeruginosa strain and the effect of temperature and ionic strength (IS) on the adsorption were studied. The change of cell surface lypohydrophilic property caused by surfactant adsorption was also investigated. The results showed that the adsorption kinetics of the surfactants on the cell followed the second-order law. CTAB adsorption was the fastest one under the experimental conditions, and it took longest for SDS adsorption to equilibrate because of electric repulsion. The adsorption of Triton X-100 and Tween 80 was characterized by short equilibration time, and rhamnolipid adsorption reached equilibrium in about 90 min. The adsorption isotherms of all the surfactants on the bacterium fitted Freundlich equation well, but the adsorption capacity and mode were variations for the surfactants as indicated by k and n parameters in the equations. The adsorption mode for all the surfactants except SDS is probably hydrophilic interaction because the adsorption totally turned the cell surface to be more hydrophobic. Neither the temperature nor the IS had significant effect on CTAB adsorption, but higher IS significantly enhanced SDS adsorption and modestly strengthened adsorption of Triton X-100, Tween 80, and rhamnolipid. Higher temperature strengthened adsorption of SDS but weakened the adsorption of Triton X-100, Tween 80, and rhamnolipid.     

不同类型表面活性剂在土壤上的吸附特征比较研究

应用平衡振荡法,研究了阴、阳和非离子表面活性剂在土壤上的吸附．结果表明,阳离子表面活性剂十六烷基三甲基溴化铵能强列吸附在6种不同性质的土壤上,吸附等温线为L型,分配常数Kd,为3．0×10^2～48×10^2L·kg^-1;阴离子表面活性剂十二烷基苯磺酸钠、非离子表面活性剂OP及Tween-20的吸附等温线随土壤类型不同而不同,有L、S等型,吸附强度远弱于阳离子表面活性剂,Kd分别大体处于5．3～39、0．13～0．44(Tween-20)和4．4～22．4L·kg^-1(OP)．阳离子表面活性剂的土壤最大吸附量与土壤阳离子交换容量呈线性相关．低浓度范围内,阴离子表面活性剂的土壤分配常数与土壤粘粒含量呈正相关．同时土壤颗粒表面的电荷特性也影响吸附．非离子表面活性剂的Kd与土壤粘粒、砂粒、粉沙含量及表面积存在经验函数关系．     

表面活性剂对链霉素在内蒙古牧区土壤中吸附解吸的影响

通过静态吸附实验,研究了3种不同类型的表面活性剂(阳离子:十六烷基三甲基溴化铵,CTAB;阴离子:十二烷基苯磺酸钠,SDBS;非离子,曲拉通100,TX-100)对链霉素(Streptomycin,STR)在内蒙古牧区土壤中吸附解吸的影响。结果表明,3种表面活性剂的存在均会增加STR在土壤中吸附的线性程度。CTAB的存在抑制了STR在土壤表面的吸附同时抑制了STR的解吸,然而SDBS的存在降低了STR在土壤中的吸附量并增加了吸附过程的可逆性。与CTAB和SDBS不同,TX-100对STR在土壤中的吸附的影响取决于其添加浓度。低浓度的TX-100对STR的吸附促进作用大于高浓度。随着TX-100浓度的增加,TX-100对STR的增溶作用加剧。促使吸附在土壤表面的STR迁移到水相中,从而抑制了STR的吸附,进而促进了STR的解吸。     

Sorption isotherms and kinetics in the primary biodegradation of anionic surfactants by immobilized bacteria: I. Pseudomonas C12B

The surfactant-degrading biocatalyst Pseudomonas C12B was immobilized by covalent linking on silanized inorganic supports and by physical entrapment of cells within reticulated polyurethane foam. Both immobilized biocatalysts have been shown to be appropriate for the effective primary biodegradation of the anionic surfactants sodium dodecyl sulphate (SDS), dodecylbenzene sulphonic acid (DBS), dioctyl sulphosuccinate (DOSS) and dihexyl sulphosuccinate (DHSS). The overall surfactant removal from water by cells entrapped in reticulated polyurethane foam exhibits a biphasic process, a rapid sorption step of the surfactant onto the cell-loaded support and the intrinsic primary biodegradation slower step, both acting cooperatively. The optimization of variables for the adsorption and the biodegradation processes (flow rate, particle size, substrate concentration) have been studied. Sorption isotherms for the surfactants on reticulated polyurethane foam have been established as type II of the Brunauer, Deming, Deming and Teller (BDDT) classification. The kinetics of the primary biodegradation of SDS by cells covalent linked on sepiolite treated with 3-aminopropyl triethoxysilane (APTS) were found to be first-order. In this case, surfactant adsorption does not exist.     

Equilibrium sorption isotherm for metal ions on tree fern

A new sorbent system for removing heavy metal ions, such as Zn(II), Cu(II) and Pb(II), from aqueous solutions has been investigated. This new sorbent is tree fern, an agriculture product. Variables of the system include solution temperature and sorbent particle size. The experimental results were fitted to the Langmuir, Freundlich and Redlich–Peterson isotherms to obtain the characteristic parameters of each model. Both the Langmuir and Redlich–Peterson isotherms were found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the maximum sorption capacities of metal ions onto tree fern were 7.58 mg/g for Zn(II), 10.6 mg/g for Cu(II) and 39.8 mg/g for Pb(II). It was noted that an increase in temperature resulted in a higher metal loading per unit weight of the sorbent. Decreasing the particle sizes of tree fern led in an increase in the metal uptake per unit weight of the sorbent.     

Importance of Environmental Black Carbon to Dissolved Petroleum Hydrocarbons Sorption on Soil

Importance of environmental black carbon (BC) to sorption of dissolved petroleum hydrocarbons (DPH) on two soils with high BC:TOC ratios (33% and 11%, respectively) was evaluated at a relatively high concentrations (mg/L ～ μ g/L range). Sorption isotherms of DPH were determined for the two original soils and soils combusted at 375°C (only BC). The sorption isotherms of the original soils were linear, whereas the isotherms of the combusted soils were highly nonlinear (n _F = 0.45, 0.60). It is indicated that intrinsic BC-water sorption coefficient is not possible to be used to estimate total sorption to the original soil, even in our relatively high concentrations. From the sorption isotherms, Freundlich coefficient of environmental BC sorption, K _F,BC ^env of 10 ^{2.55 ± 0.21} was calculated and could be used as a generic starting point for environmental modeling purposes. From the data, it could be deduced that BC was responsible for 50% of the total sorption at concentrations of 45 and 4 μ g/L (μ g/L range), which were significantly higher than literature concentrations (ng/L range). These results demonstrate that in soil with high BC:TOC ratio BC is the most important geosorbent constituent with respect to sorption of DPH at relatively high concentrations ranged in μ g/L.     

Effect of temperature on phosphorus sorption to sediments from shallow eutrophic lakes

The availability of phosphorus (P) in lakes is dependent on the sorption characteristics of the underlying sediments. Temperature is a crucial factor affecting the P sorption in sediments. The objective of this study was to evaluate the effect of temperature on sorption of P by sediments from two eutrophic lakes. The study was carried out using short-term batch experiments at 4, 20 and 30 °C. Phosphorus sorption kinetics, isotherms, fractionation and desorption were investigated. The P sorption was dependent on sediment type and temperature (p < 0.001). The Mei sediments showed a higher sorption rate and sorption capacity than Hua sediments. The P sorption kinetics were best described by a pseudo second order model (R² > 0.97). Activation energies derived from the kinetics rate constant indicated that P sorption onto the two sediments was controlled by a diffusion process. For both sediments, Freundlich model fit the P sorption isotherms well and the calculated apparent sorption heat was 6.37 kJ mol⁻¹ for Mei sediments and 8.67 kJ mol⁻¹ for Hua sediments. This indicated that P sorption onto both sediments was endothermic. Adding P significantly increased the soluble and loosely bound P (S/L-P), aluminum-bound P (Al-P) and iron-bound P (Fe-P) (p < 0.05). The amount of Al-P and Fe-P was markedly higher at 30 °C than at 4 °C (p < 0.05). Subsequent P desorption indicated that adsorbed P was highly labile, in particular for Hua sediment. The degree of P mobility that occurred during sediment sorption was inversely related to the temperature at the time of sorption. A significant relationship (R² = 0.978) between phosphorus sorption maximum and oxalate-extractable Fe and Al at different temperatures reflects that the amorphous contents of Fe and Al are responsible for the temperature effect on P sorption.     

Study of multicompound sorption of Lead and Pyrene on a reconstituted soil: batch and fixed bed column tests

Many polluted sites are simultaneously contaminated with polycyclic aromatic hydrocarbons and heavy metals. In the present study, batch and continuous column experiments were performed utilizing self-composition soil to describe the sorption behavior of two contaminants: lead (Pb²⁺) and pyrene (PYR). Operational conditions such as contact time, bed depth, and flow rate were optimized. The effect of soil organic matter content on the process of adsorption of both contaminants was investigated. The presence of PYR in solution at neutral pH (6.0–7.5) decreased Pb²⁺ sorption. Similar behavior was observed for PYR in the presence of Pb²⁺ in solution. At room temperature, batch experimental data conducted as a function of contact time were analyzed using the Langmuir and Freundlich isotherms. Results revealed that Pb²⁺ sorption isotherms were fitted better by the Langmuir model and PYR sorption isotherms were fitted better by the Freundlich model. Column adsorption experiments were carried out at room temperature and under operating parameters (bed depth, flow rate, and initial contaminant concentration). Breakthrough curves were well fitted to the two-site first-order kinetic model with a sum of square errors less than 0.14. The Pb²⁺ adsorption kinetic data were processed also for the Thomas model with a good accuracy.     

Surfactant-induced lipid peroxidation in a tropical euryhaline teleost Oreochromis mossambicus (Tilapia) adapted to fresh water

Exposure to anionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethyl ammonium bromide CTAB) and non ionic (Triton X-100) surfactants at a sub lethal concentration of 1 ppm resulted in severe oxidative stress in the hepatic, renal and cardiac tissues of fresh water adapted Oreochromis mossambicus. Hepatic catalase showed significant increase (P<0.001) in all the surfactant exposed fish, but the renal enzyme was significantly increased only in CTAB dosed fish (P<0.001) and the cardiac enzyme showed significant increase in Triton (P<0.05) and CTAB dosed fish (P<0.001). SOD levels were significantly increased (P<0.001) in hepatic, renal and cardiac tissues of all the surfactant-treated fish. Glutathione reductase also was significantly increased (P<0.001) in the hepatic and renal tissues of surfactant dosed fish except cardiac tissues of CTAB exposed animals. Glutathione levels in the tissues studied were significantly higher in the surfactant treated animals (P<0.001) whereas malondialdehyde levels were significantly elevated only in the hepatic tissues of animals exposed to Triton (P<0.001). The surfactants based on their charge, antioxidant profile and in vivo metabolism may be arranged in the order of decreasing toxicity as CTAB > Triton > SDS. Thus it may be inferred from the present study that the antioxidant defenses and the in vivo metabolism of the surfactants are key factors in deciding the surfactant toxicity.     

Fluorescence quenching of beta-carboline alkaloids in micellar media. A study to select the adequate surfactant to use in analytical techniques.

The study of fluorescence quenching of the fluorophores allows the localization of the alkaloids (harmane and harmine) in the micelles (SDS, CTAB, Brij-35) to be established. In aqueous micellar solutions (SDS and Brij-35) at pH 13.0, emission corresponding to the neutral or zwitterionic forms can be observed. In the presence of CTAB (pH = 13.0) it was possible to observe the emission of anionic form. These species are not present in buffered aqueous solutions at these pH values. Bromide ion was added to the different surfactant solutions and the quenching effect was studied according to the Stern-Volmer equation. In the presence of SDS the quenching effect is considerably reduced compared to the aqueous solutions without surfactants, while for Brij-35 micelles were similar to those observed in homogeneous aqueous solution. For CTAB micelles a notable fluorescence quenching was observed for the different pH values studied. The fluorescence quenching studies show that the neutral species are associated inside the micelles, instead of the ionic species (cationic, zwitterionic or anionic) remaining on the surface of the micelles. The anionic surface of SDS micelles prevents the quenching effect by anionic quenchers for both neutral and charged species.     

Sorption isotherms and kinetics in the primary biodegradation of anionic surfactants by immobilized bacteria:: II. Comamonas terrigena N3H

Comamonas terrigena N3H was immobilized by covalent linking on silanized inorganic supports and by physical entrapment of cells within calcium alginate beads and reticulated polyurethane foam. Both entrapped cells were efficient for the primary biodegradation of the anionic surfactants dihexyl sulphosuccinate (DHSS) and dioctyl sulphosuccinate (DOSS), furthermore, exhibiting, in the case of polyurethane immobilized cells, a positive fractionating effect of the substrate by adsorption onto the polymer matrix. The overall kinetics for the surfactant removal from water were well-fitted to a biphasic process, a rapid passive sorption step of the surfactant onto the cell-loaded support and the intrinsic primary biodegradation slower step, both acting synergically.     

Comparison of Pesticide Sorption by Physicochemically Modified Soils with Natural Soils as a Function of Soil Properties and Pesticide Hydrophobicity

The objectives of this paper were to determine the efficiency of physicochemically modified soils with a surfactant in the sorption of pesticides, the stability against washing of the pesticides sorbed, and the effective sorption capacity of surfactant adsorbed by soils as a function of pesticide hydrophobicity and soil characteristics. Five soils of different characteristics and five pesticides (penconazole, linuron, alachlor, atrazine and metalaxyl) with different Kow values were selected and octadecyltrimethylammonium bromide (ODTMA) was chosen as model of cationic surfactants. Sorption-desorption isotherms were obtained and constants Kf and Kfd for natural soils (from Freundlich equation) and K and Kd for ODTMA-soils (from linear equation) were determined. Sorption on ODTMA-soils was higher than on natural soils. K increased 27–165 times for penconazole, 22–77 times for linuron, 7–14 times for alachlor, 9–23 times for atrazine, and 21–333 times for metalaxyl in relation to Kf. Sorption coefficients normalized to 100% of total organic matter (TOM) from organo soils K_OM (K 100/%TOM), were always higher than those from natural soils Kf_OM (Kf 100/%OM), indicating that the organic matter (OM) derived from the ODTMA (OM_ODTMA) had a greater sorption capacity than the OM of the natural soil. K_OM values were also higher than the Kow (octanol/water distribution coefficient) value for each pesticide. The similarity of the high K_OM values for the sorption of each pesticide by the five soils and the linearity of isotherms point to a partitioning of the pesticides between surfactant and water. The use in this work of different soils and various pesticides, unusual in this type of investigation, allowed us to obtain equations to know the sorbed amount of a given pesticide by the surfactant-modified soils as a function of the OM content derived from the cation and the Kow of the pesticide. The results obtained are of interest when it becomes necessary to increase the sorption capacity of soils with low OM contents with a view to delaying pesticide mobility in soils from pollution point sources (high concentration in small area), and preventing the pollution of waters.     

Biosorption of Lead from Industrial Wastewater Using Chrysophyllum albidum Seed Shell

The shell of the seed of Chrysophyllum albidum carbon was used to adsorb lead (Pb) from aqueous solution, the sorption process with respect to its equilibria and kinetics as well as the effects of pH, contact time, adsorbent mass, adsorbate concentration, and particle size on adsorption were also studied. The most effective pH range was found to be between 4.5 and 5 for the sorption of the metal ion. The first-order rate equation by Lagergren was tested on the kinetic data and the adsorption process followed first-order rate kinetics. Isotherm data were analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherms; the Freundlich and Langmuir models for dynamics of metal ion uptake proposed in this work fitted the experimental data reasonably well. However, equilibrium sorption data were better represented by Langmuir model than Freundlich. The adsorption capacity calculated from Langmuir isotherm was 72.1 mg Pb (II) g^{- 1} at initial pH of 5.0 at 30°C for the particle size of 1.00 to 1.25 mm with the use of 2.0 g/100 ml adsorbent mass. The structural features of the adsorbent were characterized by Fourier transform infrared (FTIR) spectrometry; the presence of hydroxyl, carbonyl, amide, and phosphate groups confirms the potential mechanism adsorption of the adsorbent. This readily available adsorbent is efficient in the uptake of Pb (II) ion in aqueous solution, thus, it could be an excellent alternative for the removal of heavy metals and organic matter from water and wastewater.     

Comparative evaluation for the sorption capacity of four carbonaceous sorbents to phenol

Sorption kinetics and isotherms of phenol by four carbonaceous sorbents (activated carbon (AC), mesoporous carbon (MPC), bamboo biochar (BBC) and oak wood biochar (OBC)) were compared in this study. MPC has the fastest sorption rate and initial sorption potential, which were indicated by sorption rate constants and initial sorption rate “h” in a pseudo-second-order kinetic model. The ordered and straight pore structure of MPC facilitated the accessibility of phenol. The AC showed the greatest sorption capacity towards phenol with maximum sorption of 123 mg/g as calculated by the Langmuir model. High surface area, complexity of pore structure, and the strong binding force of the π–π electron-donor-acceptor interaction between phenol molecules and AC were the main mechanisms. The BBC and OBC had much slower sorption and lower sorption capacity (33.04 and 29.86 mg/g, respectively), compared to MPC (73.00 mg/g) and AC, indicating an ineffective potential for phenol removal from water.     

The effects of pH and surfactants on the absorption and fluorescence properties of ochratoxin A and zearalenone

The pH and surfactant dependencies of the absorption and fluorescence properties of ochratoxin A (OTA) and zearalenone (ZEN), the main mycotoxins found as contaminants in foods and feeds, were evaluated. Three surfactants with different ionic properties were investigated, namely sodium dodecyl sulfate (SDS, anionic), Tween 20 (nonionic) and hexadecyltrimethylammonium bromide (CTAB, cationic). The results show that the effects of pH on the absorption wavelength maxima and fluorescence efficiencies of the mycotoxins, which are a consequence of the presence of acidic phenol and/or carboxyl containing fluorophores, are dependent on the ionic nature of the added surfactants. Specifically, the fluorescence responses to pH changes of OTA and ZEN are similar in the presence or absence of Tween 20 and SDS. By contrast, the pH‐dependent fluorescence properties of these mycotoxins are altered when CTAB is present in the solutions. Moreover, unlike OTA, ZEN in aqueous solution displays almost no fluorescence. However, fluorescence enhancement takes place when surfactants are present in aqueous solutions of this mycotoxin. The results of this study demonstrate that the different microenvironments, present in the organized micellar systems created by the individual surfactants, can be potentially employed to modulate the sensitivities and selectivities of the fluorescence detection of OTA or ZEN. Copyright © 2015 John Wiley & Sons, Ltd.     

Studies on heme release from normal and metal ion reconstituted hemoglobin mediated through ionic surfactant

The interaction of metal-substituted hemoglobin (MHb), where M = Ni and Cu (T-state with no O2 and CO binding capability) and Fe (R-state when CO is bound), with cationic cityl trimethyl ammonium bromide (CTAB) and anionic (sodium dodecyl sulfate-SDS) surfactants has been studied using spectroscopic techniques-UV-visible, electron paramagnetic resonance (EPR), and Fourier transform-Raman-with additional supportive evidence coming from conductivity measurements. We observed the loss of 5-coordination in all three hemoglobins below the critical micelle concentration (CMC) of surfactant, with noticeable differences, suggesting differing mechanisms involved in this process. In addition, above the CMC, Ni- and Cu-hemes were found to leave their proteins more easily than Fe-heme, presumably due to weaker or no bond with the proximal histidine in the former. The released heme is stabilized by micellar media through a hydrophobic interaction process. Of the two surfactants, CTAB seems to be capable of releasing the heme better than SDS and it is attributed to the greater hydrophobicity of CTAB though the charge of the surfactant plays an important role.     

不同污染负荷土壤中镉和铅的吸附－解吸行为

采用一次平衡法,对3种不同污染负荷土壤Cd2 和Pb2 的吸附-解吸行为进行了比较.结果表明,低污染负荷土壤对Cd2 和Pb2 的吸附能力高于高污染负荷土壤.3种土壤对Cd2 的吸附等温线与Freundlich方程有较好的拟合性,Pb2 的等温吸附过程可用Langmuir方程与Freundlich方程来描述.双常数方程是描述这3种不同污染负荷土壤中Cd2 和Pb2 吸附动力学行为的最优模型,其次为Elovich方程,最差模型是一级动力学方程.Pb2 的解吸滞后现象较Cd2 明显.高污染负荷土壤的吸附态Cd2 、Pb2 解吸率高于低污染负荷土壤,Cd2 、Pb2 解吸量与其初始吸附量之间的关系符合二次幂方程.3种土壤Cd2 、Pb2 的解吸速率随重金属初始浓度的增加而增加,随解吸时间的延长而降低.     

Effects of surfactants on emulsification and secondary structure of lysozyme in aqueous solutions

This paper reports our investigations on the secondary structure of lysozyme in aqueous solution with D₂O and comparing systems emulsified with ionic and non-ionic amphiphiles, respectively. The opposite effect of concentration of surfactants on the lysozyme aqueous system was studied and the activity of lysozyme by the turbidimetric assay with different kinds of surfactant was compared. The effect of different surfactants on emulsification volume formed was observed and discussed. The different interactive patterns between lysozyme and ionic and non-ionic surfactants, such as sodium dodecyl sulfate (SDS), cetyl trimethyl ammonium bromide (CTAB) and Triton-X100 (Isooctoylphenoxypolyethoxy ethanol), respectively, was studied with FTIR. A simple relationship between the secondary structure and denaturation of protein is given for the emulsification of lysozyme in aqueous solutions. It is important for understanding the stabilization and avoiding the emulsions in the extraction process that the interactions between the proteins and surfactants which leads to the formation of such complexes are characterized. The utility of surfactants as a de-emulsifying agent for the commercial process to extract penicillin G from the filtrate of fermentation broth was consistent with these results.     

Bioremediation potential of live and dead Spirulina: spectroscopic, kinetics and SEM studies

Metal binding by algae has enormous potential for environmental bioremediation targeting towards detoxification of water bodies. The present work reports the use of live and dead Spirulina sp. for sorption of metals like Cr(3+), Ni(2+), Cu(2+), and Cr(6+) in form of Cr(2)O(7)(2-). Preliminary investigation shows that this biomass takes up substantial amount of metal ions indicated above. IR spectroscopic study, kinetics models, Langmuir and Freundlich adsorption isotherms, SEM analysis, and fluorescence microscopic study of Spirulina sp. and the Spirulina sp. treated with different metal ions have been employed to understand the sorption mechanism. It is hoped that live Spirulina sp. will be a strong candidate for management of industrial wastewater.     

Effect of surfactants on stability of Acinetobacter johnsonii S35 and Oligotropha carboxidovorans S23 coaggregates

The effect of anionic (sodium dodecyl sulphate or SDS) and cationic (cetyltrimethylammonium bromide or CTAB) surfactants on the stability of binary bacterial coaggregates comprising Acinetobacter johnsonii S35 and Oligotropha carboxidovorans S23 (both sewage sludge isolates) was studied and compared with that on the complex sewage sludge flocs. Both SDS and CTAB enhanced the bacterial coaggregation at their lower concentrations of 0.2 and 0.07 mg ml(-1), respectively. However, complete deflocculation of coaggregates was observed at 1 mg ml(-1) SDS and 0.3 mg l(-1) CTAB concentrations. Further, sewage sludge flocs did not deflocculate in the presence of CTAB, although a concentration-dependent deflocculation was observed in the presence of SDS. A. johnsonii S35 and O. carboxidovorans S23 cells were separately pretreated (prior to coaggregation) with the surfactants. In spite of the partial (complete) loss of viability during SDS (CTAB) pretreatment, washed cells still retained hydrophobic character and displayed significant coaggregation (aggregation index ranging from 84% to 97% in comparison to 96% in the case of non-treated cells), demonstrating reversibility of the surfactant induced deflocculation. Further, when exposed to lower concentration of surfactants (0.2 mg ml(-1) SDS), coaggregates were more resistant (76% viability) as compared to the individual partner (S35: 52%; S23: 39% viability). Since the coaggregates are stable and provide protection from surfactants at lower concentrations (those normally expected in the sewage treatment plants), their presence as well as a sustained role in the sewage sludge bioflocculation is evident.