Effects of Surfactants and Temperature on PCP Biodegradation

The effects of temperature and surfactant concentration on the degradation of pentachlorophenol (PCP) by a pure culture of Sphingomonas chlorophenolicum sp. Strain RA2 were studied. An anionic, a cationic, and two nonionic surfactants were tested at concentrations above and below their critical micellar concentrations (CMC). Each surfactant was tested at four temperatures between 10 and 25°C. PCP degradation curves were modeled based on Monod growth kinetics. Degradation curves were also fit using inhibition models accounting for the effects of temperature and surfactant concentration. No PCP degradation activity was observed in the presence of the cationic surfactant. The anionic surfactant had a more inhibitory effect at lower concentrations than the nonionic surfactants, which occurred at surfactant concentrations well below the CMC at all temperatures. Nonionic surfactants showed no inhibition at sub-CMC concentrations and higher temperatures. In general, the surfactants caused more inhibition at lower temperatures. The exception was a slight enhancement of PCP degradation at 10°C for low concentrations of the nonionic surfactants.     

The effect of cationic and anionic surfactants on the nanostructure and magnetic properties of Yttrium Iron Garnet (YIG) synthesized by a sol-gel auto combustion method

Yttrium Iron Garnet (YIG) powders were synthesized by a sol-gel auto-combustion method using cationic and anionic surfactants with different values and different calcination times and temperatures. The final products were characterized by DTA/TG, XRD, TEM and VSM techniques. The results showed a decrease in calcination temperature and crystallite size in the presence of a cationic surfactant, while no significant effect was observed using an anionic surfactant. Magnetic properties of YIG powders were improved as an optimum value of cationic surfactant was used.     

表面活性剂对磷钾伴生矿提钾过程的影响

在HCl-H3PO4混酸处理磷钾伴生矿提钾过程中,考察不同类型的表面活性剂对钾浸出率的影响。结果表明,阴离子表面活性剂(十二烷基磺酸钠和十二烷基硫酸钠)的加入能将钾的浸出率提高10~15个百分点,最高可达95.01%。阳离子表面活性剂(十二烷基三甲基氯化铵)以及非离子表面活性剂(聚乙二醇-6000及聚乙二醇-10000)的加入对钾的浸出产生抑制效果。     

Partitioning of SSOCs into Straight-Chained Surfactants

The purpose of this research was to study the effect of surfactant structure and micelle composition on the partitioning of sparingly soluble organic compounds (SSOCs) into surfactant micelles. The surfactants used in this research were sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium bromide (DDTMA), tetradecyl trimethyl ammonium bromide (TDTMA), hexadecyl trimethyl ammonium bromide (HDTMA), Mega-9 (nonanoyl-n-methyl glucamide) and polyoxyethylene ether (POE). The SSOCs used were toluene, trichloroethylene and p-xylene. SSOC partitioning into the micelles of cationic surfactants increased with increasing number of carbon atoms in the surfactant tail. However, when the amount of partitioned SSOC was normalized by the length of the straight-chain tail, there was no difference in SSOC removal between SDS, DDTMA, TDTMA, and HDTMA. Using these data and previously published data, correlations were developed between the normalized partition coefficient and hydrophobicity for both cationic and anionic straight chain surfactants. Mixed surfactant systems had lower CMCs and lower partition coefficients than did single surfactants in the 1–10 mM concentration range. The presence of a mixture of SSOCs did not affect SSOC partitioning into micelles in this study.     

Effect of Y2 （CO3）3 and Surfactants on Electrorheological Performance of SiO2 Particle Materials

The SiO2 particle material has weak electrorheological (ER) activity. The ER performance of the SiO2 particlescan be ameliorated after adsorbing Y2(CO3)3. In this paper, the effect of Y2(CO3)3 and different surfactants on the ER performance of the SiO2 particle materials is investigated. The results show lhat anionic or cationic surfactants maybe enhance the ER activity of SiO2 material, and nonionic surfactants cannot when surfactants are added during the process of the SiO2 particle preparation, only the anionic surfactant, AES, can enhance markedly the ER performance of the material. The surface area, pore volume and pore diameter of the particles were measured. The effect of Y2(CO3)3 and the surfactants on the microstructure of SiO2 materials and the relationship between ER effect and the microstructure are described.     

Correlated and Noncorrelated Lineshape Models under Small Lineshift Condition: Analysis of Self-Perturbed CH3D

We studied the effects of four soluble surfactants on DPPC monolayers to elucidate the action of these membrane perturbants. The presence of nonionic N-9 and amphoteric C31G strongly affected the pure DPPC isotherm, while anionic SDS and cationic DTAB had little effect. The impact of surfactant on DPPC domain shape in the liquid condensed-liquid expanded coexistence region showed the opposite result. Neutral surfactants had minimal effect on the shape of DPPC domains; charged surfactants, on the other hand, induced a new shape transition at high surface pressures previously unreported for DPPC domains. All of these results are discussed with particular attention given to electrostatic effects at the interface.     

表面活性剂强化铜矿石浸出

为了解决铜矿石浸出速度慢、浸出率低的问题,在浸出液中加入表面活性剂进行摇瓶试验.通过测量浸出前后溶液表面张力以及铜浸出率,考察了三种不同类型的表面活性剂对铜矿石浸出的影响.研究发现溶液表面张力对矿石浸出影响较大,阴离子表面活性剂的强化浸出作用最为明显,铜浸出率达62.5%.在柱浸试验中,添加阴离子表面活性剂使铜浸出率提高了近10%.利用物理化学和渗流力学对表面活性剂强化浸出机理的分析表明,溶液表面张力和表面活性剂在矿石表面的吸附对矿石表面润湿作用影响较大,表面活性剂在浸出液的持久性也是影响浸出的因素之一.

     

Rheological Characterization of Sludges during Belt Filtration Dewatering Using an Immobilization Cell

An immobilization cell was successfully coupled to a controlled stress rheometer to quantify rheological properties of a sludge during its dewatering. An anaerobically digested sludge and a synthetic sludge were analyzed and conditioned at various doses with a cationic flocculant. Direct strain-controlled oscillatory analyses could not be performed due to rapid dewatering, but controlled shear rate analysis quantified the increases in sludge viscosity as the solid’s concentration increased. Immobilization times determined by these experiments—viscosity versus dewatering time—agree with capillary suction times, since both indicate the time required for water removal (r2 from 0.81 to 0.99). However, capillary suction time tests were more strongly influenced by filtrate viscosity at high polymer doses. The immobilization cell allowed quantified amounts of shear to be imposed during dewatering, with greater shearing found to provide more rapid immobilization. This finding is consistent with the design of belt filtration dewatering devices, but demonstrates that current models do not account for a critical aspect of this process.     

表面活性剂对钛合金复合微弧氧化膜结构与耐磨性能的影响

为了在钛合金表面制备耐磨性能良好的复合微弧氧化膜层,研究了4种不同类型的表面活性剂对复合六方氮化硼(hBN)固体润滑微粒微弧氧化膜层微观结构及其耐磨性能的影响。结果表明,表面活性剂对复合微弧氧化(MAO)膜层的微观结构和耐磨性能有明显的影响,阳离子型表面活性剂十六烷基三甲基溴化铵降低了复合MAO膜层中h BN微粒含量,削弱了膜基结合,因而不利于膜层耐磨性能的改善;非离子型表面活性剂无水乙醇由于挥发性强导致膜层的致密性下降,降低了膜层的耐磨性能;阴离子型表面活性剂十二烷基苯磺酸钠对复合MAO膜层的结构和耐磨性能影响较小;阴离子型表面活性剂羧甲基纤维素钠则有效改善了hBN微粒在电解液中的分散性,进而改善其在MAO膜层中的复合及分布状况,从而明显改进了复合MAO膜层的耐磨性能。     

Competitive Substrate Biodegradation during Surfactant-Enhanced Remediation

The impact of synthetic surfactants on the aqueous phase biodegradation of benzene, toluene, and p-xylene (BTpX) was studied using two anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), and two nonionic surfactants, POE(20) sorbitan monooleate (T-maz-80) and octylphenolpoly(ethyleneoxy) ethanol (CA-620). Batch biodegradation experiments were performed to evaluate surfactant biodegradability using two different microbial cultures. Of the four surfactants used in this study, SDS and T-maz-80 were readily degraded by a microbial consortium obtained from an activated sludge treatment system, whereas only SDS was degraded by a microbial culture that was acclimated to BTpX. Biodegradation kinetic parameters associated with SDS and T-maz-80 degradation by the activated sludge consortium were estimated using respirometric data in conjunction with a nonlinear parameter estimation technique as μmax = 0.93 h?1, Ks = 96.18 mg∕L and μmax = 0.41 h?1, Ks = 31.92 mg∕L, respectively. When both BTpX and surfactant were present in the reactor along with BTpX-acclimated microorganisms, two distinct biodegradation patterns were seen. SDS was preferentially utilized inhibiting hydrocarbon biodegradation, whereas the other three surfactants had no impact on BTpX biodegradation. None of the four surfactants were toxic to the microbial cultures used in this study. Readily biodegradable surfactants are not very effective for subsurface remediation applications as they are rapidly consumed, and also because of their potential inhibitory effects on intrinsic hydrocarbon biodegradation. This greatly increases treatment costs as surfactant recovery and reuse are adversely affected.     

Removal of Lead from Contaminated Water and Clay Soil Using a Biosurfactant

Lead removal from water and contaminated soils was investigated using biosurfactant, anionic, and nonionic surfactants in continuously stirred batch reactors. Lead-contaminated water up to 100?mg/L and clay soil up to 3,000?mg/kg were used in this investigation. The surfactant concentration up to 10 critical micelle concentration was used. The speciation of lead into the micelles was quantified and the lead removal efficiency depended on the level of contamination, surfactant type, and concentration. Of the surfactants used, biosurfactant (produced from used vegetable oil) had the best removal efficiency (75%) at a lead contamination of 100?mg/L in water at pH of over 12. The Fourier-transformed infrared spectroscopy study showed that the carboxyl group in the biosurfactant was effective in removing the lead from the solution. Langmuir and Freundlich relationships were used to represent the micelle partitioning of lead in the surfactant solutions. Desorption of lead from contaminated kaolinite clay was represented using linear isotherms. The biosurfactant solution had a higher micelle partitioning for the lead from contaminated water and desorbing the lead from the contaminated soil compared to the other chemical surfactants.     

Domains in cationic lipid plus polyelectrolyte bilayer membranes: detection and characterization via 2H nuclear magnetic resonance

2H nuclear magnetic resonance (NMR) spectroscopy of choline-deuterolabeled 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC-alpha-d2 and POPC-beta-d2) has been used to detect and quantify domain formation induced in cationic lipid-containing bilayers upon the addition of anionic polyelectrolytes. Three different polyelectrolytes, poly(sodium 4-styrenesulfonate) or PSSS, poly(sodium acrylate) or PACA, and poly(sodium glutamate) or PGLU, were added to POPC lipid bilayers containing 1,2-dioleoyl-3-(dimethylamino)propane (DODAP) as the cationic amphiphile. All three polyelectrolytes produced two-component 2H NMR spectra, consistent with two populations of POPC, one polyelectrolyte-bound and another polyelectrolyte-free. The relative intensities of the two spectral components provided the relative amounts of the two POPC populations. The 2H NMR quadrupolar splitting from either spectral component provided the DODAP content of the particular POPC population. The two POPC populations differed in that the polyelectrolyte-bound population contained a stoichiometric polyelectrolyte anion:DODAP cation ratio leading to enrichment with respect to DODAP, while the polyelectrolyte-free population was depleted of DODAP. Estimates of the size of a polyelectrolyte-defined domain revealed a constant number of bound DODAP but a flexible number of bound POPC, which increased in proportion to the global POPC content. The most compact domains were formed by the most hydrophobic polyelectrolyte, PSSS, while the most expansive domains were formed by the most hydrophilic polyelectrolyte, PGLU.     

Pulse Reverse Electrodeposition of Cu-SiC Nanocomposite Coating: Effects of Surfactants and Deposition Parameters

Cu-SiC nanocomposite coatings have been deposited from an aqueous sulfate electrolyte using the technique of pulse reverse electrodeposition both in the absence and presence of three different types of surfactants, anionic, cationic, or nonionic. The effects of different electrodeposition parameters on some properties of the coatings have been studied. In all cases, it has been observed that the surface roughness, hardness, and resistivity increase with the increase in cathodic current density. However, they have been observed to decrease with the increase in anodic current density and the anodic current time. The variation in the amount of incorporated reinforcement with different deposition parameters has been observed to be dependent on the nature of the surfactant used. In the presence of cationic and nonionic surfactant, a noticeable increase in the amount of incorporated reinforcement and hardness has been observed. Samples prepared under higher anodic current density have been observed to possess lower stress, but intense texture. An increase in cathodic current density has been observed to decrease the extent of texturing.     

Relevance of Expression Phase in Dewatering of Sludge with Chamber Filter Presses

Biological sludge contains a large quantity of water and the decrease of its content constitutes one of the main issues for wastewater treatment plant operation. Laboratory tests to estimate the sludge dewaterability, i.e., its capability of being dehydrated, have been developed in the past, but there is no evidence of the tests’ direct correlation with the behavior of the real-scale dewatering devices. Different methods (specific resistance to filtration at different pressure, capillary suction time, expression tests, and drying test) have been applied on civil sludge conditioned with ferric chloride/lime or polymer/ferric chloride and results have been compared with operational data obtained from a full scale plant. The results presented in this paper highlight the role of the expression phase in the sludge dewatering using frame filter presses. To predict the sludge behavior and then to optimize the conditioning step, the laboratory procedure used for selecting the chemicals and doses has also to consider the effect of the expression of the cake.     

Low-temperature bioremediation of a waste water contaminated with anionic surfactants and fuel oil

We conducted a laboratory study at 10 degrees C on the biological decontamination of the waste water from a garage and car-wash that was contaminated with anionic surfactants (57 mg 1(-1)) and fuel oil (184 mg hydrocarbons 1(-1)). The indigenous microorganisms degraded both contaminants efficiently after biostimulation by an inorganic nutrient supply. After 7 days at 10 degrees C, the residual contaminations were 11 mg anionic surfactants 1(-1) and 26 mg hydrocarbons 1(-1). After 35 days, only the anionic surfactants had been further reduced to 3 mg 1(-1). Bioaugmentation of the unfertilized waste water with a cold-adapted inoculum, able to degrade both hydrocarbons (diesel oil) and anionic surfactants (sodium dodecyl sulphate), resulted in a significant increase of the hydrocarbon biodegradation during the first 3 days of decontamination, whereas biodegradation of anionic surfactants was inhibited during the first 21 days following inoculation. Bioaugmentation of the nutrient-amended waste water was without any effect.     

Organo-Illite as a Low Permeability Sorbent to Retard Migration of Anionic Contaminants

Landfill leachate, often having high concentrations of metal cations, anions, and organic compounds, presents a great threat to nearby groundwater. Due to negative charges on soil particles, regular clay liners cannot effectively retard the movement of anionic contaminants such as chromate. In this paper, a natural illite was modified by cationic surfactants with different chain lengths and tested for its chromate removal efficiency. When the surfactant tail group is relatively short and the solution critical micelle concentration is high, the sorbed surfactant molecules form a monolayer on illite, resulting no chromate sorption by the organo-illite. As the chain length of surfactant tail group increases, the critical micelle concentration reduces and the surfactant molecules sorb as admicelles on illite with the surfactant sorption exceeding the illite’s cation-exchange capacity. Such admicelle modification makes the organoclay capable of retaining chromate instantaneously and retarding the movement of chromate by 1–2 orders of magnitude. The illite’s hydraulic conductivity showed a slight increase after surfactant modification, from 1×10?7 to 8×10?7?cm/s, probably due to reduced packing density after modification. Chromate breakthrough data from column transport experiments were well described by a one-dimensional advection-dispersion model that incorporated Langmuir sorption.     

Antenatal diagnosis of velamentous umbilical cord insertion and vasa previa with color Doppler imaging

The effect of various anionic surfactants on the initial rate of 5-aminosalicylic acid peroxidation with horseradish peroxidase was studied. With increasing surfactant concentration, this rate first decreased, then increased, and again decreased. We conclude that these changes were due to an inhibition of the enzyme, a subsequent change in the enzyme conformation accompanied by the enhanced accessibility of its active site to the substrate, and the final protein denaturation, respectively.     

离心污泥脱水机在钢铁行业污泥脱水中的应用

介绍了离心机使用的工作原理、结构特点及其与其他类型污泥脱水设备相比的优点。并根据钢铁行业的污泥的特性,在设备内部结构进行了局部的特殊改进,使其在钢铁行业污泥脱水工艺应用中优于其他类型的污泥脱水设备     

聚丙烯酰胺对铝土矿浮选尾矿沉降性能的影响

不同离子类型、分子量及用量的聚丙烯酰胺对尾矿沉降性能的影响表明,阴离子型聚丙烯酰胺的效果好于阳离子和非离子型。调节矿浆pH=7以下,加入阴离子聚丙烯酰胺就能实现尾矿的较快沉降,分子量为1 400万的阴离子型聚丙烯酰胺能取得最佳的沉降效果。经聚丙烯酰胺处理后的尾矿水能回用至浮选流程中,低含量的聚丙烯酰胺能改善铝土矿的浮选指标。     

净水站污泥脱水系统的技术改造

针对净水站污泥脱水系统中存在运行不稳、脱泥效果差、导致系统工作效率低、操作人员劳动强度大等问题,分析影响污泥脱水效果的主要因素,并进行污泥脱水系统技术改造,取得了较好效果,提高了循环利用率;文章还介绍了取代板式压滤机的卧式螺旋卸料离心机的结构原理、分离过程、使用效果以及技术参数。