Understanding and Modeling the Effect of Surfactants in Enhanced Particle Removal from Surfaces in Aqueous Media

The removal of particulate contamination is a critical issue for many manufacturing processes. It is particularly critical to the electronics industry in which small pieces of microscopic debris remaining after chemical mechanical planarization (cmp) using submicron polishing particles can cause device failure. One way to enhance particle removal following the cmp process is to utilize surfactants. Recent research has shown ways to model the effect of surfactants on enhanced particle removal. However, previous research has not demonstrated the effect of ionic strength on enhanced particle removal associated with surfactant use. Past research has also not shown the combined effects of ionic strength and surfactant concentration on enhanced particle removal using surfactants. This article summarizes the parameters affecting particle removal, and it provides data and analysis on the effect of ionic strength as well as the combined effects of ionic strength and surfactant concentration on particle removal following cmp processing.     

The effect of ionic strength and hardness of water on the non-ionic surfactant-enhanced remediation of perchloroethylene contamination

The objective of this study is to evaluate the perchloroethylene (PCE) removal by an aqueous surfactant solutions based on influential factors (ionic strength, hardness) of various groundwaters and surface waters contaminated with PCE. The experimental methods used in this study were separatory funnel experiments and batch experiments. Separatory funnel experiments were performed to determine which surfactants are good solubilizers for PCE. Batch experiments were performed to evaluate the effect of ions in sampled water for PCE removal. The results of separatory funnel experiments indicated that the surfactant polyoxyethylene (20) sorbitan monostearate (Tween 60) showed to be a predominant solubilizer for the removal of PCE (87.3%). Separatory funnel experiments also showed that the hydrophilic-lipophilic balance (HLB) number and the chemical structure of the surfactants were good indicators of surfactant effectiveness for removal of PCE from water. The results of batch experiments showed that non-ionic surfactants are affected by the ionic strength of sampled water. The % of PCE removal of the Tween 60 surfactant solution was measured to be 88.3% by batch experiments. This result was affected by the characteristics of the surfactant (HLB, chemical structures) and the ionic strength of water. Therefore, the ionic strength of contaminated water, HLB and chemical structures of surfactants must be considered in surfactant-enhanced remediation.     

Effects of concentration, head group, and structure of surfactants on the degradation of phenanthrene

The effects of concentration, polar/ionic head group, and structure of surfactants on the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in the aqueous phase, as well as their effects on the bacterial activity were investigated. The toxicity ranking of studied surfactants is: non-ionic surfactants (Tween 80, Brij30, 10LE and Brij35)相似文献   

表面活性剂结构对纳米CeO2在水中的分散性影响

采用悬浮液体系吸光度法,研究不同结构表面活性剂对纳米CeO2粉体在水中分散性影响。考察了影响分散稳定性的物理分散方式、表面活性剂的结构和浓度等因素。结果表明,超声波分散效率远优于机械搅拌。表面活性剂作为纳米CeO2在水介质中的分散剂,其分散性与表面活性剂结构有重要关系。非离子型表面活性剂效果优于离子型表面活性剂。非离子型表面活性剂以亲油基团朝向CeO2粒子,且亲油基团链长较长的效果更好;而离子型表面活性剂以亲水基团朝向CeO2粒子,亲水基团小的表面活性剂效果好,亲油基团的链长度影响不太明显。     

表面活性剂对高浓度石墨烯水分散液制备的影响

分别选取阴离子型、阳离子型和非离子型3种类型表面活性剂,通过紫外可见光谱研究表面活性剂结构和浓度对高压均质-液相剥离法制备的石墨烯水分散液浓度的影响。通过高分辨透射电镜和激光粒度仪对所制备的石墨烯的品质进行分析。结果表明:长的疏水链段、双键和苯环官能团是促进表面活性剂作用发挥的关键结构,表面活性剂最优浓度略高于其临界胶束浓度。在测试范围内,Tween80效果最佳,其最佳作用浓度为0.012mmol·L^-1,所得石墨烯水分散液浓度为564.3mg·L^-1。表面活性剂的结构和浓度对石墨烯的品质无明显影响。     

Multivariate analysis of anionic, cationic and nonionic textile surfactant degradation with the H(2)O(2)/UV-C process by using the capabilities of response surface methodology

Anionic, cationic and nonionic surfactants being frequently employed in the textile preparation process were subjected to H(2)O(2)/UV-C treatment. As a consequence of the considerable number of parameters affecting the H(2)O(2)/UV-C process, an experimental design methodology was used to mathematically describe and optimize the single and combined influences of the critical process variables treatment time, initial H(2)O(2)concentration and chemical oxygen demand (COD) on parent pollutant (surfactant) as well as organic carbon (COD and total organic carbon (TOC)) removal efficiencies. Multivariate analysis was based on two different photochemical treatment targets; (i) full oxidation/complete treatment of the surfactants or, alternatively, (ii) partial oxidation/pretreatment of the surfactants to comply with the legislative discharge requirements. According to the established polynomial regression models, the process independent variables "treatment time" (exerting a positive effect) and "initial COD content" (exerting a negative effect) played more significant roles in surfactant photodegradation than the process variable "initial H(2)O(2) concentration" under the studied experimental conditions.     

Treatment of concentrated arsenic(V) solutions by micellar enhanced ultrafiltration with high molecular weight cut-off membrane

In this work arsenic removal by micellar enhanced ultrafiltration (MEUF) was investigated using cetylpyridinium chloride (CPC) and a cross-flow polyethersulphone (PES) membrane apparatus. The effects of some operating factors on permeate flux, arsenic and CPC rejections were investigated and, in particular, transmembrane pressure, pH, CPC concentration, As concentration and ionic strength. The novel aim of this work is evaluating the possible advantages of using large molecular weight cut-off membrane (100 kDa) and reduced surfactant concentrations (1-3 mM) for treating high fluxes of concentrated arsenic-bearing solutions (6-10 ppm). The experimental results reported in this paper show that PES membrane apparatus with high molecular weight cut-off allowed to treat large fluxes of concentrated arsenic-bearing solutions (6-10 ppm) even by using low surfactant concentration (1-3mM). In particular arsenic removal ranged from 93-98% to 70-74% depending on initial As concentration (6 and 10 ppm, respectively). In addition surfactant leakage in the permeate was always below CMC due to presieving of concentration polarisation layer. The favourable combination of high MWCO membranes and low surfactant concentration can benefit to overall process economics for the lower membrane area requirement (due to greater flux) and the reduced surfactant consumption.     

Influence of the coexisting contaminants on bisphenol A sorption and desorption in soil

The effects of different heavy metals (Cd, Pb), surfactants (cetyltrimethylammonium bromide (CTAB), cetylpyridine chloride (CPC)) and the ionic strength (Ca2+, NH4+) on breakthrough curves (BTCs) for sorption and desorption of bisphenol A (BPA) were studied using soil column experiment. Results showed that the presence of heavy metals and cationic surfactants caused a significant increase on the BPA sorption. In addition, the volume required when effluent concentration reached half of the influent concentration (VC1/2) increased due to the introduction of heavy metals and surfactants. It was also found that the larger amount of BPA was absorbed with higher ionic strength. The cationic surfactants enhanced the desorption ability of BPA from the soil. The results provided a better understanding of BPA behavior in environment and facilitated more accurate assessment of its ecological risk and identification of appropriate management strategies.     

Relative assessment of density and stability of foam produced with four synthetic surfactants

Selection of the surfactant has an impact on many of the foam properties as it affects the surface tension and gas–liquid interfacial properties. The objective is to produce stable aqueous foam of required density. These two characteristics are influenced by the type of surfactant, its concentration and foam generation pressure. This study compares the density and stability of foam produced using four synthetic surfactants namely sodium lauryl sulfate, sodium lauryl ether sulfate, sulfanol and cocodiethanolamide through a systematic experiment design based on response surface methodology. The relative performance has also been assessed in terms of their suitability for use in foamed concrete production based on ASTM test method. The effect of surfactant concentration has relatively lesser effect on foam density for sodium lauryl sulfate and sulfanol irrespective of foam generation pressure adopted. The drainage is proportional to the initial foam density for all the surfactant concentration for ionic surfactants at different foam generation pressures. For all the four surfactants under the optimum foam generation pressure, a stable foam with drainage less than 12% in 300 s (by considering economy as a factor) is achieved. From the foam stability test based on ASTM C 796-97, it is observed that all the four surfactants are suitable for use in foamed concrete production when optimized foam production parameters are adopted.     

Particle size and surfactant effects on chemical mechanical polishing of glass using silica-based slurry

This study explores the effect of particle size and surfactant on the chemical mechanical polishing (CMP) of glass using colloidal silica-based slurry. It was found that the material removal rate strongly depends on the particle size and the types of surfactants and that the rms roughness was independent of particle size and correlated to surfactants. On the basis of polishing results, it was concluded that the main polishing mechanism was changed from indentation mechanism to surface-area mechanism, with the variation of particle size. In addition, the molecular structure, charge type, and lubricating effect of the surfactants play an important role in the dispersion of abrasive particles and in the CMP performance.     

Interfacial tension of critical liquid mixtures in the presence of a surfactant

The interfacial tension of a liquid-liquid interface in the critical region has been obtained as a function of the surfactant concentration on the basis of the Landau-Ginzburg model for critical phenomena. It is shown that surfactants may reduce significantly the interfacial tension in addition to the well-known near-critical reduction.     

Enhanced collection of fine particles in a cyclone using ultrasonic vapor with surfactants

Using water vapor to improve the efficiency of dust removal in gas cyclones was recently proposed. However, some dust particles are not hydrophilic which can reduce the effectiveness of the vapor. This paper investigates using surfactants to overcome such a difficulty. In particular, surfactants are added to the water solution which is atomized into vapor and added in a cyclone dust collector. The effects of surfactant type and quantity on the removal efficiency of the cyclone are studied by a series of experiments. Three surfactants are used to change the wettability of the two types of fine particles to be collected: molecular sieve dust and white carbon black. The particles in the cyclone are found to form agglomerates, which are measured by using a laser particle size analyzer and scanning electron microscopy. The results show that the addition of surfactants can greatly enhance the agglomeration and thus improve the collection efficiency, especially for particles approximately two microns in size. This indicates that using the atomized vapor with containing surfactants is an effective way to enhance the collection of fine particles in a cyclone separator.     

Functionalized and postfunctionalizable porous polymeric films through evaporation-induced phase separation using mixed solvents

Condensation of water droplets during rapid evaporation of a polymer solution, under humid conditions, has been known to generate uniformly porous polymer films. Similar porous films are also formed when a solution of the polymer in THF containing small amounts of water, is allowed to evaporate rapidly under air flow; this suggests that water droplets may be formed during the final stages of film formation. In the presence of added surfactants, the interface of water droplets could become lined with the surfactants and consequently the internal walls of the pores generated, upon removal of the water, could become decorated with the hydrophilic head groups of the surfactant molecules. In a series of carefully designed experiments, we have examined the effect of added surfactants, both anionic and cationic, on the formation of porous PMMA films; the films were prepared by evaporating a solution of the polymer in THF containing controlled amounts of aqueous surfactant solutions. We observed that the average size of the pores decreases with increasing surfactant concentration, while it increases with increasing amounts of added water. The size of the pores and their distribution were examined using AFM and IR imaging methods. Although IR imaging possessed inadequate resolution to confirm the presence of surfactants at the pore surface, exchange of the inorganic counterion, such as the sodium-ion of SDS, with suitable ionic organic dyes permitted the unequivocal demonstration of the presence of the surfactants at the interface by the use of confocal fluorescence microscopy.     

Comprehensive study on surfactant role on silver nanoparticles (NPs) prepared via modified Tollens process

Surfactants represent not only commonly used wetting agents but also substances that can be used as growth modifiers in the process of solid nanoparticle (NP) preparation. In this study we report influential character of different types of surfactants – i.e. ionic (SDS, CTAC) and non-ionic (Tween 80) – on fundamental characteristics of silver NPs, which were prepared by a modified Tollens process. The influential character of surfactants was evaluated throughout a reasonable improvement of the polydispersity (in the case of the tested non-ionic surfactants from 8.5% even down to 2.5%) and in the case of ionic surfactant, SDS and CTAC, also significant change of zeta potential (from −20 to −50 mV for the highest tested concentration of SDS). A slight influence of the tested surfactants was observed on the sizes of the prepared silver NPs. Therefore the obtained results from the performed surfactant-assisted syntheses revealed a possibility how to tailor silver NPs by means of their polydispersity and zeta potential according to the application demands.     

稳态荧光探针法测定脂肪醇聚氧乙烯醚型非离子表面活性剂聚集行为

以芘为荧光探针、二苯甲酮为猝灭剂,采用稳态荧光探针法测定了3种不同结构的脂肪醇聚氧乙烯醚(FAPE)表面活性剂增溶芘后的稳态荧光光谱,建立了FAPE非离子表面活性剂的临界胶束浓度(CMC)和临界胶束聚集数(Nm)的测试方法。确定了荧光探针芘的适宜浓度Cp为6×10-6 mol/L,猝灭剂的适宜浓度CQ取0.06～0.12mmol/L,根据I336/I394与FAPE浓度变化的关系,可得到直链、支链、芳香族的脂肪醇聚氧乙烯醚的临界胶束浓度分别为0.2mmol/L、0.1mmol/L、0.05mmol/L。直链、支链、芳香族的脂肪醇聚氧乙烯醚的临界胶束聚集数依次为1168、255、6.0。结果表明,同系列非离子表面活性剂,不同碳链结构呈现出由直链→支链→芳香族,以及临界胶束浓度和聚集数依次减小的趋势。     

EFFECT OF SURFACTANT ADDITION ON THE MICROSTRUCTURE OF COAL FILTER CAKES

Currently, water removal from fine coal fractions is affected by vacuum filtration of a coal slurry followed by thermal drying. Due to high operating costs and the potentially hazardous nature of the drying operation, alternate methods are sought.

This work investigated the change of filter cake microstructure resulting from one such method, namely, surfactant addition to the coal slurry. By impregnating a coal filter cake with an epoxy resin, micrographic analysis of the cake structure could be made by using an image analyzer with the aid of quantitative stereology. This analysis provided a particle and pore size distribution of the filter cake which is fundamental to the understanding of the dewatering mechanism.

Three surfactants were investigated in this work: non-ionic Triton X-114, anionic Aerosol-OT, and cationic dodecyl pyrindinium chloride. The behavior of Triton X-114 and DPC was similar; they both enhanced dewatering by reducing the amount of particle segregation while increasing the pore size of the cake. Conversely, Aerosol-OT, while exhibiting enhanced dewatering characteristics, did not significantly alter the filter cake structure. At low concentrations all three surfactants exhibited little change in particle and pore size distributions when compared to a filter cake formed at the same conditions without surfactant.

Additionally, a linear relationship was shown to exist between the volume-surface mean diameters of the particles and that of the pores. Similar relationships are also presented for the geometric mean diameter and the geometric deviation. The best correlation between particles and pores was obtained from coal cakes formed with Aerosol-OT.     

Effect of Surface Modification on Flow Properties and Pressure Filtration of Alumina Slurries

ABSTRACT

The purpose of this research is to evaluate the effectiveness of various dispersants in fine particle processing. The surface of alumina in aqueous solution was modified by using both non-ionic and ionic surfactants. The rheological properties of highly loaded alumina suspensions were studied as a function of surfactant concentration. Pressure filtration experiments were also carried out in order to evaluate the dispersion properties and consolidation behavior. The pressure filtration results could be used to distinguish between well-dispersed and flocculated slurries. The results of rheology measurements and pressure filtration experiments are interpreted using suitable models. To assist the analysis, electrokinetic sonic amplitude (ESA) technique was used for characterization of electrical double layer.     

Influence of surfactant interaction on ultrafine copper powder electrodeposition

Ultrafine copper powder with uniform morphology and size was synthesized by electrodeposition. By using the Box‐Behnken design of response surface methodology, to study the interaction between anionic surfactants and nonionic surfactants at different concentrations of copper sulfate pentahydrate. The resulting copper powder was characterized by scanning electron microscopy. The results show that it is difficult to obtain uniform copper powder by using a single anionic surfactant. The staggered adsorption mechanism of the non‐ionic surfactant and the anionic surfactant at the interface disperses and stabilizes the micellar interface and prevents continued growth of the copper powder. The resulting copper powder is nearly spherical with uniform morphology and particle size. Through the optimization of the response surface methodology, a nearly spherical copper powder with an average particle size of 0.61 μm and uniform shape was finally obtained.     

聚磺酸甜菜碱与表面活性剂在水溶液中复合与相分离

通过浊点法研究了表面活性剂的结构与浓度对聚N、N-二甲基-N-甲基丙烯酰氧乙基-N-丁基磺酸铵（PDMABS）水溶液相分离温度的影响。选用的表面活性剂包括阴离子、阳离子和非离子型表面活性剂,以及大分子的聚丙烯酸、聚对乙烯基苯磺酸钠、聚甲基丙烯酰氧乙基二甲基苄基氯化铵。结果显示,各种表面活性剂对PDMABS有不同程度的增...     

Preparation and application of visible-light-responsive Ni-doped and SnO2-coupled TiO2 nanocomposite photocatalysts

Soil contamination with petroleum hydrocarbons has caused critical environmental and health defects and increasing attention has been paid for developing innovative technology for cleaning up this contamination. In this work, the washing process of a soil column by ionic surfactant sodium dodecyl sulfate (SDS) was investigated. Water flow rate and the contamination duration (age) have been studied. The performance of water in the removal of diesel fuel was found to be non-negligible, while water contributed by 24.7% in the global elimination of n-alkanes. The effect of SDS is significant beyond a concentration of 8mM. After 4h of treatment with surfactant solution, the diesel soil content remains constant, which shows the existence of a necessary contact time needed to the surfactant to be efficient. The soil washing process at a rate of 3.2 mL/min has removed 97% of the diesel fuel. This surfactant soil remediation process was shown to be governed by the first-order kinetics. These results are of practical interest in developing effective surfactant remediation technology of diesel fuel contaminated soils.