Hydroxamated polyacrylamide（HPAM） was synthesized from polyacrylamide（PAM） with high relative molecular mass under the optimum reaction conditions（p H 12 and a molar ratio of hydroxylamine to amide groups of 1.5 ...Hydroxamated polyacrylamide（HPAM） was synthesized from polyacrylamide（PAM） with high relative molecular mass under the optimum reaction conditions（p H 12 and a molar ratio of hydroxylamine to amide groups of 1.5 at 50 ℃for 12 h）. The hydroxamate groups of HPAM were verified by Fourier transform infrared spectrum（FT-IR）. 46%（molar fration） hydroxamate groups and 23%（molar fraction） carbonyl groups on HPAM were determined by conductometric titration combined with Kjeldahl＇s microanalysis method. The settling performance achieved at different flocculant dosages was investigated with high goethite-containing red mud slurry of simulated Bayer process synthesized in laboratory. It turns out that the settling performance of high goethite-containing red mud was better with HPAM. The average settling rate of red mud in the first 5 min and the turbidity of supernatant after settling for 30 min are 2.36 m/h and 507 NTU, respectively, at a flocculant dosage of 120 g/t, which is similar to that achieved with Hx-600.展开更多
We show that by scanning the frequency of a single mode infrared （IR） optical parametric oscillator （IR- OPO） laser to excite the molecular species of interest and fixing the frequency of a vacuum ultraviolet （VU...We show that by scanning the frequency of a single mode infrared （IR） optical parametric oscillator （IR- OPO） laser to excite the molecular species of interest and fixing the frequency of a vacuum ultraviolet （VUV） laser to photoionize the IR excited species, high-resolution IR spectra of polyatomic neutrals can be obtained with high sensitivity. The fact that this IR-VUV-photoion （IR-VUV-PI） method is based on VUV photoionization probe, and thus, allows the identification of the neutral IR absorber, makes it applicable for IR spectroscopy measurements of isotopemers, radicals, and clusters, which usually exist as impure samples. The highly resolved IR-VUV-PI measurements achieved using the single mode IR-OPO laser have made possible the selection of single rovibrational states of CH3X （X=Br and I）, C2H4, and C3H4 for VUV-pulsed field ionization-photoelectron （VUV-PFI-PE） measurements, resulting in rovibrationally resolved photoelectron spectra for these polyatomic molecules. These experiments show that the signal- to-noise ratios of the IR-VUV-PI and IR-VUV-PFI-PE spectra obtained by employing the high-resolution IR-OPO laser are significantly higher than those observed in previous IR-VUV-PI and IR-VUV-PFI-PE studies using a low-resolution IR-OPO laser. Further improvement in sensitivity of IR-VUV-PI and IR- VUV-PFI-PE measurements by using the collinear arrangement of IR-VUV lasers and molecular beam is discussed.展开更多
基金Project(51174231)supported by the National Natural Science Foundation of China
文摘Hydroxamated polyacrylamide（HPAM） was synthesized from polyacrylamide（PAM） with high relative molecular mass under the optimum reaction conditions（p H 12 and a molar ratio of hydroxylamine to amide groups of 1.5 at 50 ℃for 12 h）. The hydroxamate groups of HPAM were verified by Fourier transform infrared spectrum（FT-IR）. 46%（molar fration） hydroxamate groups and 23%（molar fraction） carbonyl groups on HPAM were determined by conductometric titration combined with Kjeldahl＇s microanalysis method. The settling performance achieved at different flocculant dosages was investigated with high goethite-containing red mud slurry of simulated Bayer process synthesized in laboratory. It turns out that the settling performance of high goethite-containing red mud was better with HPAM. The average settling rate of red mud in the first 5 min and the turbidity of supernatant after settling for 30 min are 2.36 m/h and 507 NTU, respectively, at a flocculant dosage of 120 g/t, which is similar to that achieved with Hx-600.
文摘We show that by scanning the frequency of a single mode infrared （IR） optical parametric oscillator （IR- OPO） laser to excite the molecular species of interest and fixing the frequency of a vacuum ultraviolet （VUV） laser to photoionize the IR excited species, high-resolution IR spectra of polyatomic neutrals can be obtained with high sensitivity. The fact that this IR-VUV-photoion （IR-VUV-PI） method is based on VUV photoionization probe, and thus, allows the identification of the neutral IR absorber, makes it applicable for IR spectroscopy measurements of isotopemers, radicals, and clusters, which usually exist as impure samples. The highly resolved IR-VUV-PI measurements achieved using the single mode IR-OPO laser have made possible the selection of single rovibrational states of CH3X （X=Br and I）, C2H4, and C3H4 for VUV-pulsed field ionization-photoelectron （VUV-PFI-PE） measurements, resulting in rovibrationally resolved photoelectron spectra for these polyatomic molecules. These experiments show that the signal- to-noise ratios of the IR-VUV-PI and IR-VUV-PFI-PE spectra obtained by employing the high-resolution IR-OPO laser are significantly higher than those observed in previous IR-VUV-PI and IR-VUV-PFI-PE studies using a low-resolution IR-OPO laser. Further improvement in sensitivity of IR-VUV-PI and IR- VUV-PFI-PE measurements by using the collinear arrangement of IR-VUV lasers and molecular beam is discussed.
