Using the surface of poly （sulfone） hollow fiber membrane segments as grafted layer, the hydrophilic acrylamide chain was grafted on by UV-photoinduced grafting polymerization. The gained improvement of surface wett...Using the surface of poly （sulfone） hollow fiber membrane segments as grafted layer, the hydrophilic acrylamide chain was grafted on by UV-photoinduced grafting polymerization. The gained improvement of surface wettability for the modified membrane was tested by measuring the contact-angle as well as FTIR spectra. Then correlation between the hydrophilic ability of support material and the biofilm adherence ability was demonstrated by comparing the pollutant removal rates from urban wastewater via two identical lab-scale up-flow biological aerated filters, one employed the surface wettability modified poly （sulfone） hollow fiber membrane segment as biofilm carder and the other employed unmodified membrane segment as biofilm carder. The experimental results showed that under the conditions of influent flux 5 L/h, hydraulic retention time 9 h and gas to liquid ratio （G/L） 10： 1, the removal rates of chemical oxygen demand （COD） and ammonium nitrogen （NH4^＋-N） for the modified packing filter and the unmodified packing filter was averaged at 83.64% and 96.25%, respectively, with the former filter being 5%-20% more than the latter. The effluent concentration of COD, NH4^＋-N and turbidity for the modified packing filter was 25.25 mg/L, 2 mg/L and 8 NTU, respectively. Moreover, the ammonium nitrogen removal performance of the filter packing the modified PSF was compared with the other bioreactor packing of an efficient floating medium. The biomass test indicated that the modified membrane matrixes provided better specific adhesion （3310-5653 mg TSS/L support）, which gave a mean of 1000 mg TSS/L more than the unmodified membrane did. In addition, the phenomenon of simultaneous denitrification on the inner surface of the support and nitrification on the outer surface was found in this work.展开更多
By dynamic method under UV irradiation, commercial melt-blown polypropylene （PPMB） filter element was modified with acrylamide （AAm） using benzophenone （BP） as initiator. Attenuated total reflection-Fourier tran...By dynamic method under UV irradiation, commercial melt-blown polypropylene （PPMB） filter element was modified with acrylamide （AAm） using benzophenone （BP） as initiator. Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element. Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer. Degree of grafting changed with initiator concentration, monomer concentration, reaction temperature and reached 2.6% at the reaction condition： CBp=0.06 mol/L, CAAm=2.0 mol/L, irradiation time： 80 min, temperature： 60℃. Relative water flux altered with the hydrophilicity and pore size of filter element. In the antifouling test, the modified filter gave greater flux recovery （approximately 70%） after filtration of the water extract of Liuweidihuang, suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.展开更多
We report the high power acousto-optically Q-switched operation of a dual-end-pumped Ho:YAG laser at room temperature.For the Q-swithched mode,a maximum pulse energy of 2.4 mJ and a minimum pulse width of 23 ns at the...We report the high power acousto-optically Q-switched operation of a dual-end-pumped Ho:YAG laser at room temperature.For the Q-swithched mode,a maximum pulse energy of 2.4 mJ and a minimum pulse width of 23 ns at the repetition rate of 10 kHz are achieved,resulting in a peak power of 104.3 kW.The beam quality factor of M^(2)~1.5,which is demonstrated by a knife-edge method.In addition,the Ho:YAG laser is employed as a pumping source of ZGP optical parametric oscillator,and its total average output power is 13.2 W at 3.9μm and 4.4μm with a slope efficiency of 68.4%.展开更多
Continuous-wave operation of room-temperature c-and a-cut Ho:YAP lasers resonantly end-pumped by a diodepumped Tm:YLF laser at 1.91μm are comparatively investigated.The maximum output powers of 7.8 W at 2103nm and 6....Continuous-wave operation of room-temperature c-and a-cut Ho:YAP lasers resonantly end-pumped by a diodepumped Tm:YLF laser at 1.91μm are comparatively investigated.The maximum output powers of 7.8 W at 2103nm and 6.09 W at 2130 nm for c-cut Ho:YAP crystal are obtained.The maximum output power of 8.78 W at 2119nm for a-cut Ho:YAlO_(3)crystal is achieved.The maximum slope efficiency in terms of absorbed pump power approximately reaches 57.8%for c-oriented crystal and about 52.7%for a-oriented crystal.展开更多
基金Project supported by the Natural Science Foundation of Beijing(No. 2051002)the Technologies R&D Program of Beijing (No.D0205004000011)the Hi-Tech Research and Development Program(863) of China (No. 2002AA601220).
文摘Using the surface of poly （sulfone） hollow fiber membrane segments as grafted layer, the hydrophilic acrylamide chain was grafted on by UV-photoinduced grafting polymerization. The gained improvement of surface wettability for the modified membrane was tested by measuring the contact-angle as well as FTIR spectra. Then correlation between the hydrophilic ability of support material and the biofilm adherence ability was demonstrated by comparing the pollutant removal rates from urban wastewater via two identical lab-scale up-flow biological aerated filters, one employed the surface wettability modified poly （sulfone） hollow fiber membrane segment as biofilm carder and the other employed unmodified membrane segment as biofilm carder. The experimental results showed that under the conditions of influent flux 5 L/h, hydraulic retention time 9 h and gas to liquid ratio （G/L） 10： 1, the removal rates of chemical oxygen demand （COD） and ammonium nitrogen （NH4^＋-N） for the modified packing filter and the unmodified packing filter was averaged at 83.64% and 96.25%, respectively, with the former filter being 5%-20% more than the latter. The effluent concentration of COD, NH4^＋-N and turbidity for the modified packing filter was 25.25 mg/L, 2 mg/L and 8 NTU, respectively. Moreover, the ammonium nitrogen removal performance of the filter packing the modified PSF was compared with the other bioreactor packing of an efficient floating medium. The biomass test indicated that the modified membrane matrixes provided better specific adhesion （3310-5653 mg TSS/L support）, which gave a mean of 1000 mg TSS/L more than the unmodified membrane did. In addition, the phenomenon of simultaneous denitrification on the inner surface of the support and nitrification on the outer surface was found in this work.
基金Project supported by the Natural Science Foundation of Beijing(No.2051002)Science and Technology Programme of Beijing(No.D0205004040421)
文摘By dynamic method under UV irradiation, commercial melt-blown polypropylene （PPMB） filter element was modified with acrylamide （AAm） using benzophenone （BP） as initiator. Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element. Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer. Degree of grafting changed with initiator concentration, monomer concentration, reaction temperature and reached 2.6% at the reaction condition： CBp=0.06 mol/L, CAAm=2.0 mol/L, irradiation time： 80 min, temperature： 60℃. Relative water flux altered with the hydrophilicity and pore size of filter element. In the antifouling test, the modified filter gave greater flux recovery （approximately 70%） after filtration of the water extract of Liuweidihuang, suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60878011 and 61078008the Program for New Century Excellent Talents in University(NCET-10-0067).
文摘We report the high power acousto-optically Q-switched operation of a dual-end-pumped Ho:YAG laser at room temperature.For the Q-swithched mode,a maximum pulse energy of 2.4 mJ and a minimum pulse width of 23 ns at the repetition rate of 10 kHz are achieved,resulting in a peak power of 104.3 kW.The beam quality factor of M^(2)~1.5,which is demonstrated by a knife-edge method.In addition,the Ho:YAG laser is employed as a pumping source of ZGP optical parametric oscillator,and its total average output power is 13.2 W at 3.9μm and 4.4μm with a slope efficiency of 68.4%.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60878011 and 61078008Program for New Century Excellent Talents in University(NCET-10-0067)。
文摘Continuous-wave operation of room-temperature c-and a-cut Ho:YAP lasers resonantly end-pumped by a diodepumped Tm:YLF laser at 1.91μm are comparatively investigated.The maximum output powers of 7.8 W at 2103nm and 6.09 W at 2130 nm for c-cut Ho:YAP crystal are obtained.The maximum output power of 8.78 W at 2119nm for a-cut Ho:YAlO_(3)crystal is achieved.The maximum slope efficiency in terms of absorbed pump power approximately reaches 57.8%for c-oriented crystal and about 52.7%for a-oriented crystal.
