检索结果-南通市图书馆

Fouling mechanisms in the early stage of an enhanced coagulation-ultrafiltration process

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2015年第1期9卷 73-83页

作者： Haiqing CHANG baicang liu Wanshen LUO Guibai LI State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 China College of Architecture and Environment Sichuan University Chengdu 610207 China Southwest Municipal Engineering Design and Research Institute of China Chengdu 610081 China

We investigated the fouling performances of ultrafiltration （UF） membrane for treating in-line coagulated water in an enhanced coagulation-UF hybrid process. Then we analyzed the fouling mechanisms in the early stage of UF using mathematical models and microscopy observation methods. Finally, we discussed the impact of aeration on membrane fouling in this paper. The results showed that a two-stage of trans-membrane pressure （-TMP） profile during the operation of enhanced coagulation-UF membrane was observed, and the relationship between permeability and operation time fitted well with a logarithmic curve. Membrane pores blocking and cake filtration were confirmed as main membrane fouling mechanisms using the mathematical models. The two stages of membrane fouling mechanisms were further deduced, namely, the membrane pore narrowing followed by the formation of cake layer. Membrane autopsy analysis using scanning electron microscopy （SEM） images of the membrane surface sampled from different filtration cycles also confirmed the mechanisms of pores blocking and cake filtration. Moreover, according to the variations of the permeability and membrane fouling resistance, aeration was able to mitigate and control the membrane fouling to a certain extent, but the optimization of aeration conditions still needs to be studied.

关键词： coagulation-UF trans-membrane pressure（TMP） permeability membrane fouling resistance scanning electron microscopy （SEM）

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2018年第2期12卷 29-40页

作者： Shuai Wang Tong Li Chen Chen baicang liu John C. Crittenden College of Architecture and Environment Sichuan University Chengdu 610207 China Institute of New Energy and Low Carbon Technology Sichuan University Chengdu 610207 China Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Litree Purifying Technology Co. Ltd Haikou 571126 China Brook Byers Institute for Sustainable Systems School of Civil and Environmental Engineering Georgia Institute of Technology Atlanta GA 30332 USA

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 mixtnre 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 rnore 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 I 1068 L- m 2.h land 1179 L.m 2.h I 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.

关键词： Polyvinylidene fluoride ultrafiltvation mem-braneAmphiphilic copolymerBlended modificationHigh fluxAtomic transfer radical polymerization

Effect of adding a smart potassium ion-responsive copolymer into polysulfone support membrane on the performance of thin-film composite nanofiltration membrane

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2019年第2期13卷 400-414页

作者： Meibo He Zhuang liu Tong Li Chen Chen baicang liu John C.Crittenden Institute of New Energy and Low-Carbon Technology Sichuan UniversityChengdu 610207China College of Architecture and Environment Sichuan UniversityChengdu 610065China School of Chemical Engineering Sichuan UniversityChengdu 610065China Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Litree Purifying Technology Co. LtdHaikou 571126China Brook Byers Institute for Sustainable Systems School of Civil and Environmental EngineeringGeorgia Institute of TechnologyAtlantaGA 30332USA

Thin-film composite (TFC) nanofiltration (NF) membranes were fabricated via the interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricart)oiiyl trichloride on polysulfone (PSf) support membranes blended with K^+-responsive poly(N-isopropylacryamideco- acryloylamidobenzo-15-crown-5)(P(NIPAM-co- AAB15C5)). Membranes were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscope, scanning electron microscope, contact angle, and filtration tests. The results showed that:(1) Under K^+-free conditions, the blended P(NIPAM-co-AAB15C5)/PSf supports had porous and hydrophilic surfaces, thereby producing NF membranes with smooth surfaces and low MgSO4 rejections;(2) With K^+ in the PIP solution, the surface roughness and water permeability of the resultant NF membrane were increased due to the K^+-induced transition of low-content P(NIPAM-co-AAB15C5) from hydrophilic to hydrophobic;(3) After a curing treatment at 95℃, the improved NF membrane achieved an even higher pure water permeability of 10.97 L·m^-2·h^-1 - bar1 under 200 psi. Overall, this study provides a novel method to improve the performance of NF membranes and helps understand the influence of supports on TFC membranes.

关键词： nanofiltration interfacial polymerization support membrane potassium ion-responsive thin-film composite

Thin-film composite forward osmosis membranes with substrate layer composed of polysulfone blended with PEG or polysulfone grafted PEG methyl ether methacrylate

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2016年第4期10卷 562-574页

作者： baicang liu Chen Chen Pingju Zhao Tong Li Caihong liu Qingyuan Wang Yongsheng Chen John Crittenden College of Architecture and Environment Sichuan University Chengdu 610065 China Institute of New Energy and Low Carbon Technology Siehnan University Chengdu 610207 China Litree Purifying Technology Co. Ltd Haikou 571126 China Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 China School of Civil and Environmental Engineering Georgia Institute of Technology Atlanta GA 30332 USA

To advance commercial application of forward osmosis （FO）, we investigated the effects of two additives on the performance of polysulfone （PSf） based FO membranes： one is poly（ethylene glycol）（PEG）, and another is PSf grafted with PEG methyl ether methacrylate （PSf-g-PEGMA）. PSf blended with PEG or PSf-g- PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaC1 （1 mol·L^-1） and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSfwith 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L·m^-2·h^-1 than the commercial HTI membranes （6-8 L·m^-2·h^-1） under the FO mode. Our study suggests that hydrophobic interface is very important for the formation ofpolyamide, and a small amount of PSf- g-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization.

关键词： thin-film composite forward osmosis amphi-philic copolymer interfacial polymerization poly（ethyleneglycol）

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

纳米复合膜高效去除有机污染物的实验设计

实验科学与技术 2024年第2期22卷 87-93页

作者：黄艳萍杨博刘百仓赵伟锋四川大学化学工程学院成都610065 四川大学高分子科学与工程学院成都610065 四川大学建筑与环境学院成都610065

为解决水体污染日趋严重的问题,结合光催化降解有机物的研究前沿,设计了基于吸附与光催化协同效应的“纳米复合膜高效去除有机污染物”交叉性综合实验。该实验合成了带有羧酸根的聚合物p(MMA-AA),将其和聚醚砜(PES)及二氧化钛(TiO_(2))... 详细信息

为解决水体污染日趋严重的问题,结合光催化降解有机物的研究前沿,设计了基于吸附与光催化协同效应的“纳米复合膜高效去除有机污染物”交叉性综合实验。该实验合成了带有羧酸根的聚合物p(MMA-AA),将其和聚醚砜(PES)及二氧化钛(TiO_(2))进行复合制成平板膜。实验结果表明,在没有光照的环境中,仅靠膜的吸附作用对污染物的清除效率较低。在光照作用下,羧酸根不断静电吸附罗丹明B,同时被TiO_(2)通过光催化降解,实现了污染物的快速清除。

关键词：光催化水污染污染物去除交叉性综合实验高分子

磁分离-精细过滤-超滤-碟管式反渗透耦合工艺高效回用页岩气压裂返排液

在线全文

学校读者我要写书评

暂无评论

环境工程学报 2023年第9期17卷 2928-2936页

作者：纪轩宇胡敏莉刘百仓四川大学建筑与环境学院成都610065

页岩气压裂返排液高效处理回用是页岩气开发中亟待解决的关键问题之一。本研究在某页岩气开采平台上,构建了“磁分离-精细过滤-超滤(UF)-碟管式反渗透(DTRO)”返排液处理工艺装备,进行现场实验研究并分析污染物去除效能和机理。在优化... 详细信息

页岩气压裂返排液高效处理回用是页岩气开发中亟待解决的关键问题之一。本研究在某页岩气开采平台上,构建了“磁分离-精细过滤-超滤(UF)-碟管式反渗透(DTRO)”返排液处理工艺装备,进行现场实验研究并分析污染物去除效能和机理。在优化运行条件下,磁分离-精细过滤对浊度去除率达95.5%,精细过滤出水可内部回用于复配水力压裂液;DTRO工艺对TDS、DOC、总荧光强度去除率分别达99.9%、98.7%和96.3%,出水满足《污水综合排放标准》(GB 8978-1996)和《农田灌溉水质标准》(GB 5084-2021),有望通过外排和灌溉等方式进行外部回用。此外,装备运行直接处理成本约34.90元·m^(−3)。相较其他技术,本工艺兼具高效性与经济性。因此,该工艺装备具有实现返排液高效回用的巨大应用潜力。

关键词：压裂返排液回用磁分离超滤碟管式反渗透(DTRO)

Effectiveness and safety of acupuncture in treatment of pregnancyrelated symptoms:a systematic review and Meta-analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Traditional Chinese Medicine 2024年第1期44卷 16-26页

作者： liu Tingting liu Tongou liu Mingfu School of Traditional Chinese Medicine Clinical Medicine Hubei University of Traditional Chinese MedicineWuhan 430000China First Clinical College of Hubei University of Traditional Chinese Medicine Wuhan 430000China Department of Acupuncture and Tuina Affiliated Hospital of Hubei University of Traditional Chinese MedicineHubei Provincial Hospital of Traditional Chinese MedicineWuhan 430000China

OBJECTIVE:To systematically evaluate the efficacy and safety of acupuncture(AM)in the treatment of pregnancyrelated symptoms such as acute vomiting during pregnancy.METHODS:We comprehensively searched the available literature up to November 2021,including Pub Med,Embase,Cochrane Library,Chinese Biomedical Literature Database,and China National Knowledge Infrastructure Database,for randomized controlled trials(RCTs)on AM for the treatment of severe vomiting,insomnia,pharyngeal and pelvic pain,mood abnormalities,and dyspepsia during pregnancy.RESULTS:Sixteen RCTs with a cumulative sample size of 1178 cases were included.Of these,964 patients were included in the Meta-analysis.The Meta-analysis results showed that AM was more efficient than Western medicine in treating discomfort during pregnancy[odds ratio(OR)=1.19,95%confidence interval(CI)(1.11,1.28),P<0.01].AM was better than the control group in improving the visual analog scale scores[standard mean difference(SMD)=0.62,95%CI(0.53,0.71),P<0.01].AM was superior to the control group in improving Numerical Rating Scale(NRS)symptom scores[OR=7.31,95%CI(3.36,15.94),P<0.01].There was no significant difference in adverse effects between the AM and sham-AM groups and the analgesic drug group[OR=0.70,95%CI(0.39,1.28),P=0.25],but the treatment and control groups had mild adverse effects with a low incidence.CONCLUSIONS:AM is more effective than other treatments or pharmacotherapy alone in the treatment of pregnancy-related symptoms,and is relatively safe.However,the quality of the included trials was rather poor,and high-quality studies are required to confirm our findings.

关键词： acupuncture pregnancy nausea vomiting sleep initiation and maintenance disorders low back pain pelvic pain mood abnormalities Meta-analysis systematic review

Removal of Cr(Ⅵ)by glutaraldehyde-crosslinked chitosan encapsulating microscale zero-valent iron:Synthesis,mechanism,and longevity

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第8期142卷 115-128页

作者： Yijun Duan Fang liu Xiang liu Miao Li School of Environment Tsinghua UniversityBeijing 100084China Transportation Institute of Inner Mongolia University Hohhot 010070China

Microscale zero-valent iron(mZVI)has shown great potential for groundwater Cr(Ⅵ)remediation.However,low Cr(Ⅵ)removal capacity caused by passivation restricted the wide use of mZVI.We prepared mZVI/GCS by encapsulating mZVI in a porous glutaraldehydecrosslinked chitosan matrix,and the formation of the passivation layer was alleviated by reducing the contact between zero-valent iron particles.The average pore diameter of mZVI/GCS was 8.775 nm,which confirmed the mesoporous characteristic of this material.Results of batch experiments demonstrated that mZVI/GCS exhibited high Cr(Ⅵ)removal efficiency in a wide range of pH(2-10)and temperature(5-35℃).Common groundwater coexisting ions slightly affected m ZVI/GCS.The material showed great reusability,and the average Cr(Ⅵ)removal efficiency was 90.41%during eight cycles.In this study,we also conducted kinetics and isotherms analysis.Pseudo-second-order model was the most matched kinetics model.The Cr(Ⅵ)adsorption process was fitted by both Langmuir and Freundlich isotherms models,and the maximum Langmuir adsorption capacity of m ZVI/GCS reached243.63 mg/g,which is higher than the adsorption capacities of materials reported in most of the previous studies.Notably,the column capacity for Cr(Ⅵ)removal of a mZVI/GCS-packed column was 6.4 times higher than that of a mZVI-packed column in a 50-day experiment.Therefore,mZVI/GCS with a porous structure effectively relieved passivation problems of mZVI and showed practical application prospects as groundwater Cr(Ⅵ)remediation material with practical application prospects.

关键词： Chitosan Glutaraldehyde mZVI Cr(Ⅵ) Groundwater

Frequency Regulation of VSC-MTDC System with Offshore Wind Farms

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 275-286页

作者： Haoyu liu Chongru liu North China Electric Power University Beijing 102206China

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC system.However,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC system.Moreover,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is high.Thus,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind farms.The simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

关键词： Wind generation voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC) frequency regulation cooperative control adaptive control variable wind speed