Preparation of reverse osmosis membrane with high permselectivity and anti-biofouling properties for desalination

• Nanoparticle incorporation and anti-biofouling grafting were integrated. • Flux of modified membranes was enhanced without rejection sacrificing. • Anti-biofouling property of modified membranes was improved. High performance is essential for the polyamide (PA) reverse osmosis (RO) membranes during the desalination process. Herein, RO membranes with high permselectivity and anti-biofouling properties were fabricated by nanoparticles incorporation and anti-biofouling grafting. Hydrotalcite (HT) incorporation was performed with a dual role, enhancing water flux and acting as grafting sites. The HT incorporation increased the water flux without sacrificing the salt rejection, compensating for the loss caused by the following grafting reaction. The exposed surface of HT acted as grafting sites for anti-biofouling agent dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOTPAC). The combination of HT incorporation and DMOTPAC grafting endowed RO membranes with high permselectivity and anti-biofouling properties. The water flux of the modified membrane PA-HT-0.06 was 49.8 L/m²·h, which was 16.4% higher than that of the pristine membrane. The salt rejection of PA-HT-0.06 was 99.1%, which was comparable to that of the pristine membrane. As to the fouling of negatively charged lysozyme, the modified membrane’s water flux recovery was superior to that of the pristine membrane (e.g. 86.8% of PA-HT-0.06 compared to 78.2% of PA-pristine). The sterilization rates of PA-HT-0.06 for E. coli and B. subtilis were 97.3% and 98.7%, much higher than those of the pristine membrane (24.0% for E. coli and 26.7% for B. subtilis).     

平板陶瓷膜回收烟气水热的实验研究

将平板陶瓷膜组成膜组件对烟气水分和余热进行回收,考察了烟气的温度、相对湿度、流速和冷却水温度等参数对膜组件水热回收性能的影响。在实验工况下,水通量和水回收效率随着烟气温度、烟气相对湿度的增加和冷却水温度的降低而上升;水通量随着烟气流速的加快而上升,水回收效率随着烟气流速的加快先上升后降低;膜组件的水通量和水回收效率最高分别可达22.0 kg/(m²·h)和36.3%。平板陶瓷膜回收的热量主要来自烟气潜热,烟气潜热换热量与水通量呈正相关变化趋势。在实验工况下,平板陶瓷膜组件的总传热系数最高为412 W/(m²·℃),高于多通道管式陶瓷膜和单通道管式陶瓷膜。     

三峡库区万州段河流水-气界面CO2通量支干流对比及影响机制初探

以三峡库区万州段干流及典型支流澎溪河为研究对象,监测2019年4～9月水华期间水体中CO₂浓度以及12个环境指标,估算水-气界面CO₂通量并进行支干流对比.将12个环境指标分为气候因子、水环境因子、碳源因子、营养因子和沉积物因子,探讨5类因子对CO₂通量的影响途径和贡献率,进一步为控制水库温室气体排放提供数据积累和理论支持.结果表明,监测期间内高阳、黄石和万州平均CO₂通量分别为（1.445±1.739）、（3.118±2.963）和（2.899±1.144）mmol·（m²·h）^-1,表现为:澎溪河支流高阳<干流万州<澎溪河支流黄石.从变化幅度来看,支流水体CO₂通量变幅较大,干流水体变化幅度则相对较小,是较稳定的CO₂"源".长江干流作为陆地向海洋的生源物质运输枢纽,相比其支流碳含量和流速更高,这使得通常情况下干流CO₂通量大于支流.但水文情势的不同使得同一支流不同点位CO<...     

沱江流域典型及新兴全氟/多氟化合物的污染特征及来源解析

为研究沱江流域表层水中全氟/多氟化合物（PFASs）的污染特征和来源,采用超高效液相色谱-串联质谱（UPLC-MS/MS）分析了沱江48个表层水样中的PFASs.结果表明,沱江流域水体中ρ（ΣPFASs）为12.5~3789 ng·L^-1,其中全氟辛烷羧酸（PFOA）为最主要污染组分,ρ（PFOA）为9.97~3764 ng·L^-1,占比高达73.6%~99.8%,说明传统PFASs仍是沱江流域主要的PFASs.所涉新兴PFASs检出率最高的为F-53B,检出率达100%,F-53B已在沱江流域被广泛使用.沱江流域浓度最高的新兴PFASs为6：2氟调聚磺酸（6：2 FTS）［nd~27.3 ng·L^-1,平均值为（9.12±7.70） ng·L^-1］,与国内外其它河流相比,处于较高污染水平.工业园区附近采样点的PFASs污染水平较高,其次为沱江下游的泸州河段,说明氟工业园区排放和人类日常生产活动是造成沱江流域PFASs污染的主要影响因素.最后,通过估算得出,沱江流域水相向长江排放的PFASs通量为353 kg·a^-1,其中排放通量最高组分为PFOA （348 kg·a^-1）,可为沱江流域PFASs管控提供基础数据.     

PVDF ultrafiltration membranes of controlled performance via blending PVDF-g-PEGMA copolymer synthesized under different reaction times

PVDF blended different graft ratio of PVDF-g-PEGMA were systematically studied. Tuning the amphiphilic copolymer synthesis time to control membrane performance. The PVDF membrane with PVDF-g-PEGMA at 19 h possesses most surface oxygen content. The synthesis time of PVDF-g-PEGMA at 9 h is good for high flux UF membrane. Polyvinylidene fluoride grafted with poly(ethylene glycol) methyl ether methacrylate (PVDF-g-PEGMA) was synthesized using atomic transfer radical polymerization (ATRP) at different reaction times (9 h, 19 h, and 29 h). The corresponding conversion rates were 10%, 20% and 30%, respectively. PVDF was blended with the copolymer mixture containing PVDF-g-PEGMA, solvent and residual PEGMA under different reaction times. In this study, we explored the effect of the copolymer mixture additives with different synthesis times on cast membrane performance. Increasing the reaction time of PVDF-g-PEGMA causes more PVDF-g-PEGMA and less residual PEGMA to be found in the casting solution. Incremental PVDF-g-PEGMA can dramatically increase the viscosity of the casting solution. An overly high viscosity led to a delayed phase inversion, thus hindering PEGMA segments in PVDF-g-PEGMA from migrating to the membrane surface. However, more residual PEGMA contributed to helping more PEGMA segments migrate to the membrane surface. The pure water fluxes of the blended membrane with reaction times of 9 h, 19 h, and 29 h are 5445 L·m⁻²·h⁻¹, 1068 L·m⁻²·h⁻¹and 1179 L·m⁻²·h⁻¹, respectively, at 0.07 MPa. Delayed phase inversion can form smaller surface pore size distributions, thus decreasing the water flux for the membranes with PVDF-g-PEGMA at 19 h and 29 h. Therefore, we can control the membrane pore size distribution by decreasing the reaction time of PVDF-g-PEGMA to obtain a better flux performance. The membrane with PVDF-g-PEGMA at 19 h exhibits the best foulant rejection and cleaning recovery due to its narrow pore size distribution and high surface oxygen content.     

夏季东海挥发性硫化物的空间分布与释放通量研究

挥发性硫化物（volatile sulfur compounds,VSCs）是大气中一类重要的痕量活性气体,对全球硫循环和气候变化有着重要的影响.于2018年6—7月运用冷阱捕集气相色谱和气-质联用法测定了东海海水与大气中3种重要的VSCs即羰基硫（carbonyl sulfide,COS）、二甲基硫（dimethyl sulfide,DMS）、二硫化碳（carbon disulfide,CS₂）的浓度,分析了其与相关环境因子的相关性,并估算了它们的海-气通量.研究结果表明,夏季东海表层海水中COS、DMS和CS₂的浓度平均值分别为（0.47±0.33）、（4.46±4.52）和（0.13±0.07） nmol·L^-1,海水中COS和CS₂的高值区出现在长江口附近海域,DMS在东海南部海域的浓度远低于北部海域.大气中COS、DMS和CS₂的浓度平均值分别为（564.0±37.5）×10^-12、（70.7±83.5）×10^-12和（177.6±232.3）×10^-12（以体积分数计）,COS分布均匀,CS₂的分布呈现近岸高远海低的特点,而DMS的分布受海-气扩散的影响.相关性分析表明,夏季东海海水中COS和CS₂与海水中的营养盐存在正相关关系,这可能是因为营养盐能促进浮游植物生长,而浮游植物生长过程中能释放COS和CS₂的前体进入水体,从而促进COS和CS₂的生产.此外,夏季东海中COS、DMS和CS₂的海-气通量平均值为（1.05±1.13）、（9.21±9.49）和（0.24±0.22）μmol·m^-2·d^-1,表明夏季东海是大气中3种VSCs的源.     

太湖出流河道藻颗粒变化及其水质效应

河湖连通是保障城市水体水生态健康的一种常用工程手段,但对于蓝藻水华严重的湖泊,湖泊出流携带的藻团颗粒会对河道水质产生明显的影响.为了分析富营养化湖泊引水对受水河道水质的影响程度,以太湖梅梁湾连通河道梁溪河为例,连续3a开展夏季河道蓝藻颗粒通量及其水质的高频监测,分析河道蓝藻水华颗粒物通量变化规律及其对河道水质的影响强度.结果表明：①梅梁湾藻情的好转及河道入口加压抑藻井运行显著降低了梁溪河的叶绿素a浓度与藻颗粒通量,2019年夏季河道叶绿素a浓度与通量均值分别为54.34 μg·L^-1和84.7 t·d^-1,显著低于2017年;②连通河道调水工程对改善受水水体的水质效果显著,除DTP外,梁溪河其余各形态氮、磷浓度2017~2019年整体呈下降趋势,说明调水工程将湖水外排后,对梁溪河水质有一定改善效果;③携带大量蓝藻水华颗粒物的湖水进入河道后,显著增加了河道颗粒态氮、磷等营养盐含量,2017~2019年梁溪河水体中氮、磷均以PN和PP为主,分别占TN和TP的62.5%和70.8%;④梅梁湾水体大量携带的藻颗粒未对连通的京杭大运河等其他河道产生水质影响,2019年8月京杭大运河水体中叶绿素a相较于6月下降了65%,说明蓝藻颗粒物未在运河中积累;⑤在湖泊藻情未能得到有效改观的前提下,调水携带的藻颗粒态会对连通河道局部河段水质和景观产生冲击.     

2016年1月京津冀地区大气污染特征与多尺度传输量化评估

基于大气环境监测数据和WRF-CAMx模式,分析了 2016年1月京津冀城市的大气污染特征,开展了 PM2.5跨界传输量化评估研究.结果表明,2016年1月京津冀地区PM2.5、PM10、SO2、NO2和CO的平均浓度分别为89.5μg·m-3、135.61μg·m-3、57.55 μg·m-3、60.79 μg·m-...     

塔里木河中下游柽柳群落土壤碳通量及其影响因子分析

利用LI-8100监测塔里木河中下游柽柳群落土壤呼吸的日变化,分析了塔里木河中下游干旱荒漠区的温度、地下水和土壤水分对土壤呼吸的影响.结果表明:土壤呼吸的日变化是不规律的单峰值曲线,碳通量的最大值出现在正午12:00～16:00不等,由于受当日云量、风速等气象因子的影响,因此各个断面差异较明显.土壤呼吸与地下水位、各层温度、各层土壤含水量的关系都很显著:地下水位与柽柳根系关系密切,因此土壤碳通量与地下水之间的关系极显著,适合三次曲线模型;气温、近地表气温、地表温度与土壤碳通量成正相关关系,适合指数模型,但是15cm、20cm、25cm、30cm土层温度与土壤碳通量成负相关关系,适合三次曲线模型;土壤含水量与土壤呼吸之间存在极显著关系,适合三次曲线模型;经过多元回归分析得到土壤呼吸与温度、土壤含水量之间的关系模型可以解释67%的土壤呼吸的变化情况.     

Flux enhancement during ultrafiltration of produced water using turbulence promoter

IntroductionThe application of ultrafiltration for producedwater treatment is still costly in terms of energyconsumption and equipment cost compared withconventional water treatment processes. Thehigh-energy consumption comes from the highcirculation velocity, and it is necessary for controllingconcentration polarization and membrane fouling,which still remain a topical problem for an industrialdevelopment of ultrafiltration processes. Membranefouling in ultrafiltration is complex, accumulatio…