Implications of membrane fouling toward the removal of the pharmaceutical sulfamethoxazole by nanofiltration processes

The influence of membrane fouling on the retention of the trace organic contaminant sulfamethoxazole by a nanofiltration (NF) process was investigated. Organic fouling caused a severe flux decline possibly due to pore blocking and adsorption directly after the commencement of the fouling layer development. Such membrane-foulant interactions were absent for colloidal fouling, which resulted in a more gradual flux decline. Membrane charge played a significant role in the separation process of inorganic salts, where the retention was the highest in a caustic environment (high pH) due to more swollen membrane material caused by the higher negative charge on the membrane. Organic fouling and a combination of colloidal and organic fouling led to a significant increase in the membrane negative charge. The influence of membrane fouling on solute retention was dependent on the fouling behaviour and the physicochemical properties of the model foulants, where the model foulants probably contributed to an increase in the retention of charged solutes due to enhanced electrostatic interactions. Organic fouling caused an increase in the retention of inorganic salts and sulfamethoxazole due to pore blocking. In contrast, colloidal fouling caused a decrease in the retention of inorganic salts due to cake-enhanced concentration polarisation. However, the presence of a colloidal fouling layer did not reduce the retention of sulfamethoxazole. A mixture of colloidal and organic matter improved the retention of inorganic salts. A similar conclusion can be inferred for sulfamethoxazole at pH 4 when the compound exists in a neutral form.     

Removal of aqueous phenol compound by vacuum membrane distillation

1.IntroductionPhenolisanimportantchemicalindustrymaterial,butitalsoaboundswithserioushazardtoenvironmentandthreatstohumanhealth.Rigidruleshavebeenmadeoutonthephenoldischargeconcentration.Researchesonthetreatmentofphenolwastewaterwerecarriedoutinvariouscountries[1-5].Membraneseparationmethodsincludingreverseosmosis,ultrafiltrationandpervaporationhaveattractedmuchattentionforphenolwastewatertreatment,withcelluloseacetate(CA)membraneemployedmostly[6].Membranedistillationisanewmembraneseparation…     

Fabrication of composite nanofiltration membranes by dopamine-assisted poly(ethylene imine) deposition and cross-linking

Positively charged composite nanofiltration (NF) membranes with good stability were prepared by dopamine (DA) assisted poly(ethylene imine) (PEI) deposition on a polysulfone ultrafiltration (UF) substrate followed by a cross-linking step. Attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electronic microscopy, and atom force microscopy were employed to characterize the surface chemistry and morphology of the obtained composite membranes. The DA and PEI co-deposition conditions were optimized based on knowledge of the co-deposition mechanism. The effects of the cross-linker concentration, cross-linking time, and reaction temperature on the permeation and separation properties of the prepared composite membranes were investigated in detail. Under optimized conditions, the MgCl₂ rejection and permeation flux of the composite membrane reached 80.4% and 19.6 L/(m²·h), respectively (the feed was 0.01 mol/L of MgCl₂ solution under a test pressure of 0.4 MPa). The rejection of various salts followed the order MgCl₂≈CaCl₂>MgSO₄>NaCl>Na₂SO₄, suggesting the membranes were positively charged. The composite membranes showed good durability under alkaline aqueous conditions. This study provided new insights into the fabrication of mussel-inspired thin-film composite nanofiltration membranes.     

Hg0 absorption in potassium persulfate solution

The aqueous phase oxidation of gaseous elemental mercury （Hg^0） by potassium persulfate （KPS） catalyzed by Ag^＋ was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured by cold vapor atom absorption （CVAA） and ion chromatograph （IC）, respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate （SN）, temperature, Hg^0 concentration in the reactor inlet and tertiary butanol （TBA）, free radical scavenger, on the removal efficiency of Hg^0 were studied. The results showed that the removal efficiency of Hg^0 increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg^0 was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO3. High Hg^0 concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed.     

Foam separation of chromium (Ⅵ) from aqueous solution

Removal of chromium (Ⅵ) dissolved in water by intermittent foam separation was implemented with cetyl trimethy-ammonium bromide as surfactant. The influence of various factors on removal efficiency was systematically studied. The removal efficiency has a maximum value near pH 4.0; thus, most experiments were carried out at pH 4.0. The orthogonal experiment was conducted to confirm the optimal operating parameters. The orthogonal experimental results show that when the liquid feed concentration is 10 mg/L, the pH value of feed solution is 4.00, air flow rates 0.9 L/min, surfactant dosage is 300 mg/L, the maximum removal efficiency of chromium (Ⅵ) reaches 97.80%, and condense multiple reaches 1711. The kinetic test indicates that the foam separation of chromium is a first-order process. The equivalent rate constant calculated from the slope is 0.406 4, and the equivalent rate equation is obtained.     

Foam separation of chromium （VI） from aqueous solution

Removal of chromium (VI) dissolved in water by intermittent foam separation was implemented with cetyl trimethy-ammonium bromide as surfactant. The influence of various factors on removal efficiency was systematically studied. The removal efficiency has a maximum value near pH 4.0; thus, most experiments were carried out at pH 4.0. The orthogonal experiment was conducted to confirm the optimal operating parameters. The orthogonal experimental results show that when the liquid feed concentration is 10 mg/L, the pH value of feed solution is 4.00, air flow rates 0.9 L/min, surfactant dosage is 300 mg/L, the maximum removal efficiency of chromium (VI) reaches 97.80%, and condense multiple reaches 1 711. The kinetic test indicates that the foam separation of chromium is a first-order process. The equivalent rate constant calculated from the slope is 0.406 4, and the equivalent rate equation is obtained.     

Removal of copper ions from electroplating rinse water using electrodeionization

An improved configuration of the membrane stack was adopted in the electrodeionization （EDI） cell to prevent precipitation of bivalent metal hydroxide during the running. The operational parameters that influenced the removal of copper ions from the dilute solution were optimized. The result showed that a moderate decrease in the inlet pH value and a moderate increase in the applied voltage could achieve a better removal effect. The steady process of electroplating wastewater treatment could be achieved with a removal efficiency of more than 99.5% and an enrichment factor of 5-14. The concentration of copper in purified water was less than 0.23 mg/L. This demonstrated the applicability of recovering heavy metal ions and purified water from electroplating effluent for industrial reuse.     

竹炭负载纳米级零价铁去除水中的甲基橙

采用竹炭负载纳米级零价铁,分别考察了竹炭、纳米级零价铁和竹炭负载纳米级零价铁对0.2 L、200 mg/L的甲基橙溶液的去除率,并探讨了竹炭投加量、溶液pH值、染料初始浓度和反应温度对竹炭负载纳米级零价铁去除甲基橙能力的影响.结果表明：在0.20 L浓度为200 mg/L的甲基橙溶液中,竹炭投加量为0.015 g、30℃、pH为6.0、反应时间为60 min时,竹炭负载纳米级零价铁对甲基橙染料的去除率最高可达99.94％,而竹炭本身的去除率仅为13.6％.     

TiO2/壳聚糖复合膜降解甲基橙的研究

采用流延成膜法,以戊二醛为交联剂制备Ti O2/壳聚糖复合膜。用X射线衍射仪,傅立叶红外光谱仪以及扫描电镜对复合膜进行表征,并研究了不同戊二醛含量对壳聚糖膜溶胀率的影响。以甲基橙降解反应为模型,研究Ti O2/壳聚糖复合膜降解染料废水的性能。结果表明：Ti O2与壳聚糖相容性较好,加入Ti O2可提高复合膜的机械强度,戊二醛交联能有效抑制膜的过度溶胀;复合膜对甲基橙的降解效果良好：当复合膜用量为0.30g,初始浓度为5mg/L甲基橙溶液50m L,p H为2.36,紫外光照射80min,降解率可达到85%以上,具有较好的应用前景。     

Dechlorination mechanism of 2,4-dichlorophenol by Ni/Fe nanoparticles in the presence of humic acid

To understand the feasibility of its application to the in situ remediation of contaminated groundwater, the dechlorination of 2,4-dichlorophenol （2,4-DCP） by Ni/Fe nanoparticles in the presence of humic acid （HA） was investigated. We found that, as high performance liquid chromatography （HPLC） was used, the 2,4-DCP was first quickly reduced to o-chlorophenol （o-CP） andp-chlorophenol （p-CP）, and then reduced to phenol as the final product. Our experimental results indicated that HA had an adverse effect on the dechlorination of 2,4-DCP by Ni/Fe nanoparticles, as the HA concentration increased, the removal rate decreased evidently. It also demonstrated that 2,4-DCP was reduced more easily to o-CP than to p-CP, and that the sequence of the tendency in dechlorination of intermediates was p-CP〉o-CP. Transmission electron microscope （TEM） showed that HA could act as an adsorbate to compete reactive sites on the surface of Ni/Fe nanoparticles to decrease the dechlorination rate. Also we concluded that the dechlorination reaction of 2,4-DCP over Ni/Fe nanoparticles progressed through catalytic reductive dechlorination.     

抗肿瘤阳离子肽：特征、作用机制及展望

恶性肿瘤（癌症）是尚未被攻克的重大疾病之一,主要原因之一是临床上抗肿瘤药物效用不大．具有抗肿瘤活性的阳离子肽（CAP）主要结合肿瘤细胞膜并破坏膜结构,这是通过肽的正电荷与肿瘤细胞膜的负电荷之静电吸引来实现的．与传统化疗药物相比,绕过肿瘤细胞的耐药机制是CAP最突出的优势．本文对抗肿瘤肽的主要结构特征、抗肿瘤效果和抗肿瘤机制（以鲎素为例）进行了综述．作者认为,寻找靶向肿瘤干细胞的CAP对于治愈肿瘤具有特别重要的意义．另外,通过化学改构和新剂型研制,CAP将具有高靶向性和低毒性,给抗肿瘤药物开发提供新的动力．     

改性粉煤灰对含铅废水的吸附研究

通过对粉煤灰的硫酸改性得到酸改性粉煤灰,用其对含铅模拟废水进行吸附实验,探讨改性的最佳条件,并在最佳改性条件下制得改性粉煤灰,研究改性粉煤灰投加量、吸附时间、吸附温度以及pH值对Pb2＋吸附效果的影响.结果表明,在投加量为10 g/L,吸附时间为50 min,吸附温度为50℃,pH-6时,改性粉煤灰对40 μg/mL的Pb2＋的去除率可达90.34％,能够较好的去除废水中的Pb2＋.     

麦秸秆热解炭对水溶液中亚甲基蓝的吸附研究

利用麦秸秆热解炭作为吸附剂,研究对溶液中亚甲基蓝(MB)的吸附特征。溶液pH、吸附时间和染料浓度影响吸附量。当pH>8时有利于MB的吸附,吸附时间增加,单位质量的吸附剂的吸附量增加,随着MB浓度增加,吸附量增加。吸附等温线用Langmuir、Freundlich、Sip模型拟合,Sip模型拟合效果最好。293K时最大吸附量为12.03±0.41mg/g,吸附过程是自发的吸热过程。     

二氧化钛电催化氧化处理甲基橙

以半导体材料二氧化钛为催化剂,对偶氮染料甲基橙溶液进行了电催化氧化降解实验;考察了催化剂量、槽电压、pH值、电解质浓度、反应时间等因素对处理效果的影响.实验结果表明:二氧化钛的催化效果显著,其色度和COD去除效果可比无催化剂时效果分别提高35%和28%;去除机制主要是电催化体系中产生的·OH对有机物的氧化、降解.     

影响方解石去除水体中高浓度磷酸盐的因素

通过探讨方解石去除水体中高浓度磷酸盐的影响因素,为能够有效地对工业废水中磷酸盐污染物进行深度处理提供理论基础。研究了典型pH值条件下以及水体中可能存在的其他离子对方解石去除磷效率的影响。结果表明,pH值显著影响方解石对高浓度磷的去除,当pH=6.0时,方解石溶解游离出的Ca2＋与水体中的H2PO4-形成磷酸钙的沉淀,同时溶液中的其他离子（例如Mg2＋,SO42-,NH4＋和草酸）对方解石去除磷起到抑制作用。当pH=10.0时,方解石对磷的去除主要以吸附过程为主,溶液中的Mg2＋对方解石去除磷有促进作用,NH4＋与草酸都对其有抑制作用,而SO42-的影响作用不明显。当Mg2＋和NH4＋共存时,通过生成磷酸铵镁沉淀物与方解石共同去除水体中的磷。     

Characterization of the start-up period of single-step autotrophic nitrogen removal in a sequencing batch reactor

The characteristics of the start-up period of single-step autotrophic nitrogen removal process were investigated. The autotrophic nitrogen removal process used a sequencing batch reactor to treat wastewater of medium to low ammonia-nitrogen concentration, with dissolved oxygen （DO）, hydraulic retention time （HRT） and temperature controlled. The experimental conditions were temperature at （30±2） ℃, ammonia concentration of （60 to 120） mg/L, DO of （0.8 to 1.0） mg/L, pH from 7.8 to 8.5 and HRT of 24 h. The rates of nitrification and nitrogen removal turn out to be 77% and 40%, respectively, after a start up period going through three stages divided according to nitrite accumulation： sludge domestication, nitrifying bacteria selection and sludge adaptation, It is demonstrated that dissolved oxygen is critical to nitrite accumulation and elastic YJZH soft compound packing is superior to polyhedral hollow balls in helping the bacteria adhere to the membrane.     

Promoting retention and successful completion on Masters courses in education: a study comparing e‐tuition using asynchronous conferencing software with face‐to‐face tuition

This paper considers the influence of e‐tuition using an asynchronous written conferencing package, FirstClass, upon retention and success rates for Masters‐level courses in a distance learning programme as compared with similar courses that were supported in a traditional manner using face‐to‐face tuition. The paper investigates the common assumption that the use of e‐tuition might negatively influence both retention and success rates by studying data gathered on UK Open University Masters courses in education. These data have allowed direct comparisons between e‐tutored and face‐to‐face tutored courses to be made. The effect of linking assessment to participation in activities using FirstClass is also considered in this study. This research has revealed that e‐tutoring using FirstClass appears to have no significant positive or negative influence on either retention or success on such courses.     

铁碳内电解前置处理染料废水的试验

采用铁碳内电解法前置处理染料废水,主要研究了铁粉粒径、pH值、停留时间对处理效果的影响。结果表明,采用铁粉粒径18目、原水pH值为6、停留时间60~90min,废水的BOD/COD值从原来的0.23提高到0.59,为后续生化处理提供有利条件.     

高取代醋酸酯淀粉膜的制备及其耐水性能研究

采用溶液浇铸法制备了醋酸酯淀粉膜。利用扫描电镜手段考察了醋酸酯淀粉取代度、铸膜液溶剂及铸膜液浓度等因素对醋酸酯淀粉膜制备的影响并研究了该膜的耐水性能。结果表明,醋酸酯淀粉取代度越大,铸膜液溶剂挥发速度越低,铸膜液浓度8~20 wt%,能制备出较好致密性的醋酸酯淀粉膜。在水中24h后膜失重率约为13%,高取代醋酸酯淀粉膜具有较好耐水性能。     

Reomoval of Heavy Metals from Aqueous Solutions using Bascteria

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