Three composite reverse osmosis membranes were prepared from m-phenylenediamine (MPD) and trimesoyl chloride (TMC), 5-chloroformate-isophthaloyl chloride (CFIC), 5-isocynate-isophthaloyl chloride (ICIC) respectively t...Three composite reverse osmosis membranes were prepared from m-phenylenediamine (MPD) and trimesoyl chloride (TMC), 5-chloroformate-isophthaloyl chloride (CFIC), 5-isocynate-isophthaloyl chloride (ICIC) respectively through the interfacial polymerization technique on the polysulphone supporting membrane.The membranes produced were characterized by using permeation experiments with salt water, attenuated total reflectance infrared (ATR-IR), and X-ray photoelectronic spectroscopy (XPS).This study showed that with the increase of NaCl concentration, the flux of the three membranes decreased; the rejection of TMC/MPD, ICIC/MPD composite membranes increased firstly and then decreased; but the rejection of CFIC/MPD composite membrane kept steady.According to the ATR-IR and XPS results, the active layer of three membranes was composed of crosslinked polymer and linear polymer with pendant; all three composite membranes contained amide functional group( —CONH? ゛nd carboxyl acid functional group( —COOH ); the ICIC/MPD composite membrane contained urea functional group( —NHCONH? ? the CFIC/MPD composite membrane also contains urethane functional group( —OCONH? ゛nd hydroxyl functional group( —OH ).The hydroxyl functional group could lead to high rejection and low flux.展开更多
Most commercial NF membranes are negatively charged at the pH range of a typical feed solution. In order to enhance the removal of cations （such as Mg2＋ or Ca2＋）, we utilized polyethyleneimine （PEI） and trimesoy...Most commercial NF membranes are negatively charged at the pH range of a typical feed solution. In order to enhance the removal of cations （such as Mg2＋ or Ca2＋）, we utilized polyethyleneimine （PEI） and trimesoyl chloride （TMC） to perform interfacial polymerization reaction on a polydopamine coated hydrolyzed polyacry-lonitrile substrate to obtain a positively charged nanofiltration membrane. Effects ofpolydopamine coating time, PEI concentration, TMC reaction time and concentration on the membrane physicochemical properties and separation performance were systematically investigated using scanning electron microscopy, streaming potential and water contact angle measurements. The optimal NF membrane showed high rejection for divalent ions （93.6±2.6% for MgSO4, 92.4±1.3% for MgCl2, and 90.4±2.1% for Na2SO4）, accompanied with NaCl rejection of 27.8±2.5% with a permeation flux of 17.2±2.8 L.m-2.h-1 at an applied pressure of 8 bar （salt concentrations were all 1000 mg.L-1）. The synthesized membranes showed promising potentials for the applications of water soft-ening.展开更多
Initial reverse osmosis composite membrane(IniM) is a thin-film-composite(TFC) membrane prepared through the interfacial polymerization technique without post-treatment,such as water washing,heating,etc.Trimesoyl chlo...Initial reverse osmosis composite membrane(IniM) is a thin-film-composite(TFC) membrane prepared through the interfacial polymerization technique without post-treatment,such as water washing,heating,etc.Trimesoyl chloride(TMC) and m-phenylenediamine(MPD) were used to prepare some IniMs through the interfacial polymerization technique on the polysulphone supporting membrane without heat-treatment and washing.Then the in situ modification was performed with tetraethylenepentamine(TEPA) on the surface of IniMs.Modified membranes were characterized by using X-ray photoelectronic spectroscopy(XPS),contacting angle and permeation experiments with salt water of different pH values.The results showed that tetraethylenepentamine reacted with acyl chloride(—COCl) on the surface of IniM,because the ratio of O/N of the modified membrane surface was lower than that of unmodified membrane.Furthermore,the contacting angle of modified membrane was larger than that of unmodified membrane.It is interesting that the water flux and rejection of modified membrane decreased with increasing pH value for sodium chloride solution,while the unmodified membrane was just on the contrary.The reason was that functional groups on the modified and unmodified membrane were different,the former were amino(—NH2) and imino(NH),and the latter was carboxyl(—COOH).展开更多
文摘Three composite reverse osmosis membranes were prepared from m-phenylenediamine (MPD) and trimesoyl chloride (TMC), 5-chloroformate-isophthaloyl chloride (CFIC), 5-isocynate-isophthaloyl chloride (ICIC) respectively through the interfacial polymerization technique on the polysulphone supporting membrane.The membranes produced were characterized by using permeation experiments with salt water, attenuated total reflectance infrared (ATR-IR), and X-ray photoelectronic spectroscopy (XPS).This study showed that with the increase of NaCl concentration, the flux of the three membranes decreased; the rejection of TMC/MPD, ICIC/MPD composite membranes increased firstly and then decreased; but the rejection of CFIC/MPD composite membrane kept steady.According to the ATR-IR and XPS results, the active layer of three membranes was composed of crosslinked polymer and linear polymer with pendant; all three composite membranes contained amide functional group( —CONH? ゛nd carboxyl acid functional group( —COOH ); the ICIC/MPD composite membrane contained urea functional group( —NHCONH? ? the CFIC/MPD composite membrane also contains urethane functional group( —OCONH? ゛nd hydroxyl functional group( —OH ).The hydroxyl functional group could lead to high rejection and low flux.
文摘Most commercial NF membranes are negatively charged at the pH range of a typical feed solution. In order to enhance the removal of cations （such as Mg2＋ or Ca2＋）, we utilized polyethyleneimine （PEI） and trimesoyl chloride （TMC） to perform interfacial polymerization reaction on a polydopamine coated hydrolyzed polyacry-lonitrile substrate to obtain a positively charged nanofiltration membrane. Effects ofpolydopamine coating time, PEI concentration, TMC reaction time and concentration on the membrane physicochemical properties and separation performance were systematically investigated using scanning electron microscopy, streaming potential and water contact angle measurements. The optimal NF membrane showed high rejection for divalent ions （93.6±2.6% for MgSO4, 92.4±1.3% for MgCl2, and 90.4±2.1% for Na2SO4）, accompanied with NaCl rejection of 27.8±2.5% with a permeation flux of 17.2±2.8 L.m-2.h-1 at an applied pressure of 8 bar （salt concentrations were all 1000 mg.L-1）. The synthesized membranes showed promising potentials for the applications of water soft-ening.
文摘Initial reverse osmosis composite membrane(IniM) is a thin-film-composite(TFC) membrane prepared through the interfacial polymerization technique without post-treatment,such as water washing,heating,etc.Trimesoyl chloride(TMC) and m-phenylenediamine(MPD) were used to prepare some IniMs through the interfacial polymerization technique on the polysulphone supporting membrane without heat-treatment and washing.Then the in situ modification was performed with tetraethylenepentamine(TEPA) on the surface of IniMs.Modified membranes were characterized by using X-ray photoelectronic spectroscopy(XPS),contacting angle and permeation experiments with salt water of different pH values.The results showed that tetraethylenepentamine reacted with acyl chloride(—COCl) on the surface of IniM,because the ratio of O/N of the modified membrane surface was lower than that of unmodified membrane.Furthermore,the contacting angle of modified membrane was larger than that of unmodified membrane.It is interesting that the water flux and rejection of modified membrane decreased with increasing pH value for sodium chloride solution,while the unmodified membrane was just on the contrary.The reason was that functional groups on the modified and unmodified membrane were different,the former were amino(—NH2) and imino(NH),and the latter was carboxyl(—COOH).
