周勇;高从堦
【摘 要】采用均苯三甲酰氯和间苯二胺通过界面合法分别得到苦咸水反渗透复合膜和海水反渗透复合膜.两者在低盐浓度时,对氯化钠的脱除率相近;在高盐浓度时,苦咸水反渗透复合膜对氯化钠的脱除率明显低于海水反渗透复合膜.用扫描电镜、原子力显微镜分析两者表面形态发现海水反渗透复合膜表面粗糙度更小.X射线光电子能谱分析结果表明,海水反渗透复合膜表面的羧酸根含量更多. 【期刊名称】《化工学报》
【年(卷),期】2010(061)010
【总页数】6页(P2590-2595)
【关键词】反渗透膜;均苯三甲酰氯;间苯二胺
【作 者】周勇;高从堦
【作者单位】中国海洋大学化学化工学院,山东,青岛,266003;杭州水处理技术研究开发中心,浙江,杭州,310012;中国海洋大学化学化工学院,山东,青岛,266003;杭州水处理技术研究开发中心,浙江,杭州,310012 【正文语种】中 文
【中图分类】TQ028.8
Shortage of water in many countries becomes a major problem to agricultural, economic and technological development1Reverse osmosis(RO)is one of the best ways to obtain fresh water and expands very fast,because the RO composite membrane presents some advantages,such as energy saving,convenient operation, and compact equipment,compared to other desalination methods[1]1 The thin2 film2composite(TFC)RO membrane by interfacial polymerization was introduced in 1972[2]1Nowadays various RO membranes have been developed to obtain pure water from the sea water(SW),brackish water(BW),or wastewater[327]1
Two important membrane parameters,the membrane rejection and the flux,in the RO process were determined by solubility and diff usivity of solutes and solvents in the thin skin layer of polymer[829]1 The relationship of RO membrane rejection to polymer/solute/solvent interactions and chemical structure of the thin skin layer of polymer was studied[10211]1 Hirose et al[12]investigated the surface structure of skin layers of cross2linked aromatic polyamide RO membranes and their RO performance1Seung[13]related the RO permeability to the macromolecular structures and inherent polymer propertiesfor crosslink and linear model aromatic polyamides by cross polarization/magic angle spinning1 Roh et al[14]proposed that the mechanical strength of the barrier layer should be an important factor determining its performance1 Permeation experiments were then performed to correlate the mechanical strength to the permeation performance of the composite membranes1
In this study,two kinds of reverse osmosis(RO)membrane for brackish water(BW)and sea water(SW)are p repared with trimesoyl chloride(TMC)and m2phenylenediamine(MPD)on the polysulphone(PS)supporting film with interfacial polymerization technique1 The memb
ranes are compared using permeation experiments with salt water,scanning electronic microscopy(SEM),X2 ray photoelectronic spectroscopy(XPS)and atomic force microscopy(AFM)in order to investigate the difference of the separation performance and structure between SWRO and BWRO membrane1
1.1 Preparation of TFC membrane
To fabricate the TFC membrane,a supporting membrane composed of microporous polysulphone(1 m width,the Development Center of Water Treatment Technology, SOA, China) was clamped between two Teflon f rames with 018cm height and inner cavity 15 cm×20 cm in a clean room1An aqueous solution of m2phenylenediamine(MPD,Shanghai AMINO2CHEM Co1,Ltd1)was poured on the supporting membrane,which was soaked for 2 min1A sof t rubber roller rolled on the surface to eliminate some small bubbles during the soaking procedure1 Excess solution was drained off the surface with a holder at the top and bottom edge1 The holder was inclined at an angle of 30 degree and an organic solution of trimesoyl chloride(TMC,Qindao Ocean Chem1Co1)was poured into the f rame
f rom top to bottom,and then the holder was lowered quickly1Af ter a 20 s residence time,the excess organic solution was drained off the surface1 The f rame with the membrane was held at 80℃to obtain the BWRO membrane and then in a hot air dryer at 105℃for 15 min so that a skin layer formed on the supporting membrane1 The composite reverse osmosis membranes were washed in pure water(<2μs·cm-1)and kept in 1%Na HSO3 solution(Fig11).
The aqueous solutions in this study contained total 210% (mass/volume)of MPD,110%of triethylamine,and camphor sulfonic acid,which was used to regulate the p H value to 815 to absorb the hydrochloric acid(HCl)f rom the interfacial reaction1 The organic solution was IP1016 solution(isoparaphin type hydrocarbon oil made by IDEMITSU Chemical Co1,Ltd1)containing 0110% (mass/volume)of TMC for BWRO membrane and 0115%(mass/volume)of TMCfor SWRO membrane1
1.2 RO performance of TFC membrane
All tests for RO performance were conducted at 1—6 MPa using NaCl solution(p H710)at
复合膜25℃in cross2flow cells1 The resulting permeate concentration(C p)and feed concentration (C f)were measured by titrating the content of chloride ion and used to calculate the solute rejections(R=1-C p/C f).
1.3 Characterization of TFC membrane
The membranes used to analyze the chemical structure and morphology of skin layer were kept in pure water(<2μs·cm-1)at 015 MPa for 4 h in order to remove MPD and SMPD in the membranes1 Then the samples were dried in a vacuum dryer at 80℃and 200 Pa for 10 h1
Scanning electron microscopy (SEM)was performed with a JSM25610LV instrument1 The cross2section of sample was viewed by first taking a thin strip of membrane(2154 cm×41572 cm),holding the ends to form a hoop,immersing the strip in liquid nitrogen,then removing it and flattening the hoop with a forceps1Magnifications up to 20000 were obtained1 The surface features of the TFC membrane were observed with atom force microscopy(Park Scientific AFM CP).
Surface chemical characterization was carried out by X2ray photoelectron spectra(XPS),which was a Perkin Elmer PHI 5000C ESCA System with Mg/Al Dual Anode Hel/Hell ultra violet source(400 W,15 k V,125316 eV).The spectra were taken with the electron emission angle at 54°to give a sampling depth 10 nm,by a concentric hemispherical energy electron analyzer operated in the constant pass energy mode at 29135 eV,using a 720μm diameter analysis area1Membranes were mounted on a sample holder without adhesive tape and kept overnight at high vacuum in the preparation chamber before they were transferred to the analysis chamber of the spectrometer for their analysis1 Each spectral region was scanned several sweeps until a satisfactory signal2to2noise ratio was observed1 For each membrane,XPS analysis was carried out three times using different samples1Membranes were irradiated separately and for a maximum of 20 min to minimize X2ray2 induced sample damage1
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