氯化和臭氧预氧化处理对污水中溶解性有机物发光细菌急性毒性的影响

考察了氯化和臭氧预氧化对污水中DOM 的发光细菌急性毒性的影响. 结果表 明, 臭氧预氧化处理后发光细菌的急性毒性显著增强. 利用树脂吸附将臭氧预氧化前后 的DOM 分离为疏水性和亲水性等6 种组分, 对DOM 的6 种组分分别氯化, 考察了氯化 前后各组分的发光细菌急性毒性. 结果发现, 亲水性组分的比例在臭氧预氧化后明显增 加, 且亲水性有机物的急性毒性显著强于疏水性有机物. 结合电位滴定和傅立叶红外分 析发现, 与疏水性有机物相比, 亲水性有机物具有较高含量的ph-OH 官能团.     

Sonochemical reactions of dissolved organic matter

Property changes of Aldrich and Pahokee peat dissolved organic matter (DOM) at different ultrasonic frequencies and energy densities were systematically investigated. Exposure of DOM to ultrasound resulted in decreases in TOC, Color₄₆₅, specific UV absorbance (SUVA), aromaticity and molecular weight, while DOM acidity increased. Compared to 20 kHz ultrasound, greater sonochemical transformation of DOM occurred at 354 kHz and at higher energy density, due to greater ^·OH radical production. The changes to DOM properties suggest that ultrasound may significantly affect DOM-pollutant interactions (e.g.facilitate desorption of hydrophobic organics from DOM or promote complexation between metallic cations and DOM).     

Effect of solution chemistry on the fouling potential of dissolved organic matter in membrane bioreactor systems

Dissolved organic matter (DOM) as a potent foulant in membrane bioreactor (MBR) systems has attracted great attention in recent years. This paper attempts to elucidate the effect of solution chemistry (i.e. solution pH, ionic strength, and calcium concentration) on the fouling potential of DOM with different characteristics. Results of microfiltration experiments showed that the fouling potential of DOM having higher hydrophobic content increased more markedly at low pH due to the reduced ionization of carboxylic and phenolic functional groups of aquatic humic substances. In contrast, the fouling potential of hydrophilic DOM components and the molecular size of DOM appeared to be less affected by solution pH. The more compact molecular configuration of DOM at high ionic strength contributed to form a denser fouling layer, and limited the amount of foulants retained by the membranes on the other hand. DOM fouling potential greatly increased with increasing calcium concentration. The magnitude of the increase, however, was independent of the hydrophobicity of DOM, suggesting strong interactions exist between calcium ions and hydrophilic DOM components. Moreover, it was observed that the main mechanism governing the effect of calcium ions on the molecular size of DOM transited from charge shielding to complex formation as calcium concentration increased.     

饮用水消毒溴代副产物及其健康风险

受海水入侵影响严重的沿海地区,其饮用水源中常含有较高浓度的溴离子.研究表明,当原水中含有溴离子时,经氯化消毒、氯胺消毒或臭氧消毒后会增加溴代消毒副产物的形成,并且溴代副产物具有更高的遗传毒性.因此,对于溴代副产物的研究更具实际意义.现阶段国内对于消毒所产生的溴代副产物的研究很少.本文针对溴代副产物更高的健康风险,从其产生的原因、机理、影响因素及遗传毒性等方面进行了综述.     

Determinations of humic substances and other dissolved organic matter and their effects on the increase of COD in Lake Biwa.

Humic substances and other dissolved organic matter (DOM) in Lake Biwa and the surrounding rivers were investigated to elucidate their origins and behavior. An annual increase in chemical oxygen demand (COD) has been observed in the northern basin of Lake Biwa since 1985. The concentrations of dissolved organic carbon (DOC) in the northern and southern basins of Lake Biwa were 1.7-2.4 mgC/l and 1.9-2.6 mgC/l, respectively. The DOC concentrations tended to be high in summer and low in winter, and the seasonal changes in the concentrations of humic substances were small. The humic substances content of DOM was considered to be comparatively small because the ratio of the concentration of humic substances to DOC was in the range of 0.14-0.32. From the results of the fractionation of DOM in lake waters, it was estimated that hydrophobic acids, such as humic substances and hydrophilic acids, were about 25% and 45%, respectively. The main origin of hydrophobic acids in Lake Biwa may be humic substances from soils around the rivers that flow into Lake Biwa, while hydrophilic acids may be due to the inner production by phytoplankton. Therefore, the increase of COD in the northern basin of Lake Biwa may be attributed to the contributions of not only humic substances but also hydrophilic acids.     

Membrane adsorption bioreactor (MABR) for treating slightly polluted surface water supplies: As compared to membrane bioreactor (MBR)

In this paper, a submerged membrane adsorption bioreactor (MABR) was evaluated for drinking water treatment at a hydraulic retention time (HRT) as short as 0.5 h. As powdered activated carbon (PAC) was added to the bioreactor at 8 mg/L raw water, the MABR achieved much higher removal efficiency for organic matter in the raw water than the parallel-operated membrane bioreactor (MBR). Moreover, the trans-membrane pressure (TMP) of MABR developed much lower than that of MBR, demonstrating PAC in MABR could mitigate membrane fouling. It was also identified here that the removal of dissolved organic matter (DOM) in MABR was accomplished through the combination of three unit effects: rejection by ultrafiltration (UF) membrane, biodegradation by microorganism, and adsorption by PAC; the last was of great importance. A sludge layer was observed on the membranes surface in both MABR and MBR and PAC particles themselves constituted a part of the cake layer and helped to intercept DOM in the mixed liquor by adsorption in MABR, especially for organic molecules of 5000–500 Da. The UF membrane together with the sludge layer and PAC layer in the MABR was able to reject hydrophobic bases (HoBs), hydrophobic neutrals, hydrophobic acids (HoAs), weakly hydrophobic acids (WHoAs) and hydrophilic matter (HiM) in the mixed liquor by 40.0%, 43.9%, 71.8%, 56.6% and 35.9%, respectively.     

BRCMINATED,CHLORINATED AND HYDROXYLATED SURFACTANTS DERIVED FROM OLEYL CHAIN - PART II EMULSIFYING PROPERTIES

Bromination, chlorination and hydroxylation were carried out on the hydrophobic chain of several comnercially available nonionic surfactants in order to modify their hydrophobic characteristics without changing their hydrophilic moities. Ethoxy-lated oleyl alcohols, as well as ethoxylated oleic acid, and polyglycerol esters were examined and it was found that paraffinic oil-in-water emulsions can be stabilized using these new surfactants. The derivatization of the nonionic surfactants increased their overall hydrophilicity, and as a result higher HLB value was obtained for any of the surfactants. It should be noted that in spite of the fact that hydrophilic groups were introduced into the hydrocarbon chain, stable emulsions were prepared and in sane cases even better stabilities were observed.     

Interactions of ozone with organic surface films in the presence of simulated sunlight: impact on wettability of aerosols

Heterogeneous reactions between organic films, taken as proxies for atmospheric aerosols, with ozone in presence of simulated sunlight and the photosensitizer 4-carboxybenzophenone (4-CB) were observed to alter surface properties as monitored by contact angle during the reaction. Attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR) was used in addition for product identification. Two types of model surfaces were systematically studied: 4-CB/4-phenoxyphenol and 4-CB/catechol. Solid organic films made of 4-CB/catechol were observed to become hydrophilic by simultaneous exposure to ozone and simulated sunlight, whereas organic films made of 4-CB/4-phenoxyphenol become hydrophobic under the same conditions. These changes in contact angle indicate that photo-induced aging processes involving ozone (such as oligomerisation) not necessarily favour increased hygroscopicity of organic aerosols in the atmosphere. The ratio between hydrophobic and hydrophilic functional groups should reflect the chemical property of organic films with respect to wettability phenomena. Contact angles and surface tensions of the exposed organic film made of 4-CB/4-phenoxyphenol were found to correspond to the hydrophobic/hydrophilic ratios obtained from the FTIR-ATR spectra.     

Comparison of Green and Lowtran Radiation Schemes with a Discrete Ordinate Method UV Model

Abstract— Using the same input parameters for the calculations, the Green and Lowtran codes for calculating UV irradiances were compared to the discrete ordinate method (DOM) model by Stamnes et al , which was used as a reference. The comparisons were performed at 305 and 380 nm for different ozone concentrations, aerosol optical depths and aerosol absorption characteristics. No obvious dependencies on optical depth, single scattering albedo or column ozone were found for the ratio of the Green and the Lowtran code to the DOM model. At 380 nm the Green model agrees with DOM within 10%, whereas the Lowtran code shows discrepancies of ±25%. At 305 nm the Green model shows 10% higher values than the DOM model at low zenith angles and up to 80% lower values for zenith angles between 60 and 80°. The Lowtran code shows 60% higher values than DOM at small zenith angles and 60% lower values at large zenith angles. When the spectra from each model were weighted with the erythemal action spectrum the Green model overestimated the DOM results by less than 10% for zenith angles less than 50°. Discrepancies between DOM and Lowtran models exceeded 10% except for a small range of zenith angles.     

Comparison of dialysis and solid-phase extraction for isolation and concentration of dissolved organic matter prior to Fourier transform ion cyclotron resonance mass spectrometry

We compare two methods, solid-phase extraction (SPE) and dialysis, commonly used for extraction and concentration of dissolved organic matter (DOM) prior to molecular characterization by electrospray ionization (ESI) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. Spectra of DOM samples from Minnesota and Sweden peatlands that were extracted with styrene divinyl benzene polymer SPE sorbents included ions with formulas that had higher oxygen to carbon (O/C) ratios than spectra of DOM from the same samples after de-salting by dialysis. The SPE method was not very effective in extracting several major classes of DOM compounds that had high ESI efficiencies, including carboxylic acids and organo-sulfur compounds, and that out-competed other less-functionalized compounds (e.g., carbohydrates) for charge in the ESI source. The large abundance of carboxylic acids in the dialysisextracted DOM, likely the result of in situ microbial production, makes it difficult to see other (mainly hydrophilic) compounds with high O/C ratios. Our results indicate that, while dialysis is generally preferable for the isolation of DOM, for samples with high microbial inputs, the use of both isolation methods is recommended for a more accurate molecular representation.     

Separation of cells and proteins from fermentation broth in a shear-enhanced cross-flow ultrafiltration module as the first step in the refinement of lactic acid

A shear-enhanced, cross-flow ultrafiltration module was used to separate cells and proteins from the fermentation broth. Three (fermented) media were studied: rich medium, rich medium with hydrolytic enzymes added after fermentation, and wheat flour hydrolysate. To find a membrane with as high a flux as possible, but still capable of separating cells and proteins from the lactic acid containing broth, the performance of three hydrophilic membranes of varying cutoffs (10,000, 20,000, and 30,000) and one hydrophobic membrane (cutoff 25,000) was investigated. The proteins produced by the lactic acid bacteria during fermentation and the hydrolytic proteins were retained by the hydrophilic membrane with a cutoff of 20,000, whereas wheat flour proteins were detected in the permeate. In the permeates from the hydrophobic membrane (cutoff 25,000), almost no proteins were detected. The flux of the whole-wheat flour hydrolysate was significantly lower than that of rich medium, for both the hydrophilic and the hydrophobic membranes. The flux was, in all cases, higher for the hydrophilic membrane (12–85 L/[m²·h], depending, on which medium was treated) than for the hydrophobic one (8–45 L/[m²·h]), even though the nominal cutoffs of the hydrophobic and hydrophilic membranes were almost the same. However, the difference in flux was smaller when the whole-wheat flour hydrolysate was processed (12 vs 8 L/[m²·h]) than when the rich medium was processed (85 vs 45 L/[m²·h]). Protein retention was higher for the hydrophobic membrane than for the hydrophilic membrane (cutoff 20,000) owing to blocking of the pores by proteins adsorbed on to the hydrophobic membrane surface.     

Three-dimensionally ordered macroporous cross-linked polystyrene incorporating functional group via hydrophilic spacer arm

<正>A versatile and effective method for incorporating functional groups on the pore wall of three-dimensionally ordered macroporous cross-linked polystyrene(3DOM CLPS) by hydrophilic spacer arm has been investigated.The 3DOM CLPS with pore size 865 nm was prepared by sacrifice template method.The hydrophilic spacer arm(polyethylene glycol,molecular weight is 600) was grafted to the 3DOM CLPS via nucleophilic substitution reaction.The other side of active hydroxyl can be further converted into a lot of other functional groups.In this report,the chelating ligand 2-mercaptobenzothiazole(MBZ) group was introduced on the end of the PGE chain to evidence the versatile functionalization approach.The functionalized ordered macroporous materials were characterized by FT-IR,element analyzer,SEM.The results reveal that the pores were successfully bonded with 2-mercaptobenzothiazole groups via hydrophilic spacer arms and the original morphology of ordered macroporous materials were remained after functionalization.The MBZ group density is 0.052 mmol/m~2.The functionalized 3DOM CLPS are expected to application as heavy metal ions adsorbent.     

Double-pass casting: A novel technique for developing high performance ultrafiltration membranes

Double-pass casting was evaluated as a technique to overcome hard-to-cast membranes or hard-to-mix solutions. Two types of polyethersulfone (PES) membranes were tested, one incorporating a hydrophilic surface modifying additive and the other with a hydrophobic one. It was found that the morphological improvement was more obvious for hydrophobic membranes since their solutions were not completely homogenous and hard-to-cast. The double-pass hydrophobic membranes had smoother surfaces and more porous support layers, resulting in higher fluxes, higher volume of treated water (67.4% increase) but decreased natural organic matters (NOM) rejection. The new casting approach produced hydrophilic membranes having a spongy structure (as opposed to finger-like cavities), yet they had similar NOM rejection, a 12.4% higher flux than the single-pass membranes prepared from the same dope. This is attributed to the quite homogenous hydrophilic casting solutions and to the performance of the original hydrophilic membranes (single-pass casting) that was relatively good.     

Role of eDNA on the adhesion forces between Streptococcus mutans and substratum surfaces: influence of ionic strength and substratum hydrophobicity

The aim of this study was to investigate the role of extracellular DNA (eDNA) on the adhesion strength of Streptococcus mutans LT11 on substrata with different hydrophobicities at high and low ionic strengths. AFM adhesion forces to a hydrophilic and hydrophobic substratum increased with increasing surface-delay times and ionic strength and were stronger on a hydrophobic than on a hydrophilic substratum. The presence of eDNA on the streptococcal cell surface enhanced its adhesion force to a hydrophobic substratum significantly more than to a hydrophilic substratum, especially after bond maturation. Bond maturation on a hydrophilic substratum was accompanied by an increasing number of minor adhesion peaks, indicating the involvement of acid-base interactions, whereas on the hydrophobic substratum surface the number of minor adhesion peaks remained low. More minor adhesion peaks developed on the hydrophilic substratum at low ionic strength than at high ionic strength. The final rupture distance in retraction force-distance curves was independent of ionic strength on a hydrophilic substratum and increased with increasing surface delay time. On the hydrophobic surface, the final rupture distance did not increase with surface delay time but was significantly smaller at low than at high ionic strength. Final rupture distances were different in presence and absence of eDNA, and the lower values of this difference coincided with the decrease in hydrodynamic radius of the streptococci upon increasing ionic strength, measured using dynamic light scattering. AFM also yielded higher values for the ionic strength induced difference in final rupture distance because in AFM rupture is forced, while in dynamic light scattering differences in radius are only induced by ionic strength differences.     

Anode Engineering of Highly Efficient Polymer Solar Cells Using Treated ITO

ITO substrates were treated with organic solvent cleaning(OSC), SC1 treatment[V(NH₄OH):V(H₂O₂): V(H₂O)=1:1:5], O₂ plasma and UV ozone, respectively. Combined investigations of atom force microscopy(AFM), water contact angle measurements, ultraviolet photoemission spectroscopy(UPS) and X-ray photoemission spectroscopy(XPS) demonstrated that UV ozone treatment could give rise to the smoothest surface, the most hydrophilic property and the highest work function(WF) of ITO due to the removal of hydrophobic C-O impurity from the ITO surface and the enrichments of more oxygen on the ITO surface. When PEDOT:PSS film[(poly(3,4-ethylenedioxy- thiophene):poly(styrene sulfonate)] was deposited on the ITO substrates treated with UV ozone, it showed a lower root-mean- square roughness in AFM images, a higher transmission in UV-Vis transmission spectra and a higher WF in UPS spectra than the PEDOT:PSS films deposited on the ITO substrates treated by other three methods. As a result, the power conversion efficiency of polymer solar cells(PSCs) based on PTB7:PC₇₁BM as an active layer and ITO treated by UV ozone as an anode can reach 8.48% because of the simultaneously improved short circuit current, open circuit voltage and fill factor compared to the PSCs with ITO treated with other three methods.     

Adsorption of the fusogenic peptide B18 onto solid surfaces: insights into the mechanism of peptide assembly

The adsorption and assembly of B18 peptide on various solid surfaces were studied by reflectometry techniques and atomic force microscopy. B18 is the minimal membrane binding and fusogenic motif of the sea urchin protein bindin, which mediates the fertilization process. Silicon substrates were modified to obtain hydrophilic charged surfaces (oxide layer and polyelectrolyte multilayers) and hydrophobic surfaces (octadecyltrichlorosilane). B18 does not adsorb on hydrophilic positively charged surfaces, which was attributed to electrostatic repulsion since the peptide is positively charged. In contrast, the peptide irreversibly adsorbs on negatively charged hydrophilic as well as on hydrophobic surfaces. B18 showed higher affinity for hydrophobic surfaces than for hydrophilic negatively charged surfaces, which must be due to the presence of hydrophobic side chains at both ends of the molecule. Atomic force microscopy provided the indication that lateral diffusion on the surface affects the adsorption process of B18 on hydrophobic surfaces. The adsorption of the peptide on negatively charged surfaces was characterized by the formation of globular clusters.     

臭氧化对水厂水中消毒副产物生成势的影响

以某饮用水厂沿程工艺出水为研究对象,研究了臭氧化预处理对水体中消毒副产物(DBPs)氯化生成势的影响。结果表明,水厂生物处理单元产生的胞外聚合物(EPS)和溶解性微生物产物(SMP)等生物源有机物是非常有效的DBPs前体物,但其更易于氯化生成三卤甲烷(THMs)而非卤乙酸(HAAs)。水厂水中存在的THMs前体物主要是各类大分子量有机物,并且臭氧工艺对其有较好的氧化去除效果。水厂水中经臭氧氧化产生的小分子量有机物可能是更为有效的一氯乙酸(MCAA)和一溴乙酸(MBAA)前体物。此外,当水体中三氯乙酸(TCAA)前体物浓度较高时,臭氧工艺对TCAA生成势具有很好的去除效果。     

Friction and nanowear of polystyrene against hydrophobic and hydrophilic substrates

The ambition of this study is to analyze the role of interfacial interactions in friction and nanowear of polystyrene, by comparing friction against hydrophobic wafers (methyl‐terminated) and hydrophilic wafers (hydroxyl‐terminated) as a function of sliding velocity and normal force. Friction experiments are performed with a translation tribometer and nanowear investigation is achieved by using atomic force microscopy (AFM) analysis of the wafer surfaces after friction. Experimental results show that the friction coefficients measured on hydrophilic surfaces are always larger than those obtained with hydrophobic surfaces, indicating a relationship between friction and interfacial interactions. Elsewhere, AFM analysis shows that polystyrene transfer appears for a higher normal force in the case of hydrophobic substrates compared to hydrophilic one. However, the corresponding tangential (or friction) force necessary to detect transfer is quite similar for both types of substrates, indicating that the initial wear of polystyrene occurs for a similar threshold interfacial shear. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2449–2454, 2006     

CPI induction of liquid crystal behaviour in triphenylenes with a mixture of hydrophobic and hydrophilic side chains

2,3,6,7,10,11-Hexasubstituted triphenylenes have been synthesized that contain a mixture of hydrophobic (C₆H₁₃O) and hydrophilic (CH₃OCH₂CH₂OCH₂CH₂O) side chains. At one extreme HAT6 (1a) (six hydrophobic chains) shows thermotropic behaviour and at the other TP6EO2M (1e) (six hydrophilic chains) shows lyotropic behaviour. Of the triphenylenes with a mixture of hydrophobic and hydrophilic side chains, only the triphenylene with one hydrophilic side chain and five hydrophobic side chains (1b) gives a thermotropic columnar phase. None of the others show liquid crystal behaviour. However, all of these triphenylenes form binary 1:1 compounds when mixed with PDQ9 (2a) and with PTP9 (2b). These CPI (complimentary polytopic interaction) stabilized compounds give thermotropic hexagonal columnar phases over wide temperature ranges.     

How can azobenzene block copolymer vesicles be dissociated and reformed by light?

The underlying mechanism of UV light-induced dissociation and visible light-induced reformation of vesicles formed by an azobenzene diblock copolymer was investigated. These processes were studied in situ by monitoring changes in optical transmittance of the vesicular solution while being exposed to UV or visible light irradiation. The results indicate that the UV-induced dissociation of the vesicles results from their thermodynamic instability due to a shift of the hydrophilic/hydrophobic balance arising from the trans-cis isomerization, while their reaggregation takes place upon visible light irradiation that shifts the hydrophilic/hydrophobic balance in the opposite direction after the reverse cis-trans isomerization. The study suggests a specific design principle for obtaining UV light-dissociable and visible light-recoverable vesicles based on azobenzene block copolymers. On one hand, the structure of azobenzene moiety used in the hydrophobic block should have a small (near zero) dipole moment in the trans form and a significantly higher dipole moment in the cis form, which ensures a significant increase in polarity of the hydrophobic block under UV light irradiation. On the other hand, the hydrophilic block should be weakly hydrophilic. The conjunction of the two conditions can make the light-induced shift of the hydrophilic/hydrophobic balance important enough to lead to the reversible change in vesicular aggregation.