Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts ...Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.展开更多
Cobalt-based phosphate/phosphonates are a class of promising water oxidation catalysts at neutralpH.Herein,we reported a facile hydrothermal synthesis of various nanostructured cobalt phe-nylphosphonates.It is found t...Cobalt-based phosphate/phosphonates are a class of promising water oxidation catalysts at neutralpH.Herein,we reported a facile hydrothermal synthesis of various nanostructured cobalt phe-nylphosphonates.It is found that the number of hydroxyl group of structure-directing reagent iscrucial for the construction of 3D hierarchical structures including hierarchical nanosheet flow-er-like assemblies and nanothorn microsphere.These samples were characterized by scanningelectron microscopy,transmission electron microscopy,X-ray diffraction,infrared,and X-ray pho-toelectron spectroscopy techniques.They can act as highly efficient electrocatalysts for the oxygenevolution reaction at neutral pH.Among these,hierarchical cobalt phenylphosphonate nanothornflowers present excellent performance,affording a current density of 1 mA cm^-2 required a smalloverpotential of 393 mV.This work offers a new clue to develop high-performance metal phospho-nate/phosphate catalysts toward electrochemical water oxidation.展开更多
A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carragee...A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carrageenan, kC, using ammonium persulfate （APS） as a free radical initiator in the presence of methylene bisacrylamide （MBA） as a crosslinker. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy （SEM）. The effect of MBA concentration and AA/NIPAM weight ratio on the water absorbency capacity has been investigated. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The temperature- and pH-reversibility properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.展开更多
In the present work, a novel heterogeneous photo-Fenton catalyst was prepared by iron and cerium pillared bentonite. The catalyst Fe-Ce/bentonite was characterized by X-ray diffraction （XRD）, X-ray fluorescence （XR...In the present work, a novel heterogeneous photo-Fenton catalyst was prepared by iron and cerium pillared bentonite. The catalyst Fe-Ce/bentonite was characterized by X-ray diffraction （XRD）, X-ray fluorescence （XRF）, Brunauer-Emmett-Teller （BET） and scanning electron microscopy （SEM） methods. It is found that Fe and Ce intercalate into the silicate layers of bentonite successfully. Tetracycline was removed by heterogeneous photo-Fenton reaction using the catalyst in this work. The effects of different reaction systems, hydrogen peroxide concentration, initial pH, catalyst dosage, UV power and introduction of different anions on degradation were investigated in details. The stability of catalyst was investigated through recycling experiment. The results show that removal rate of tetracycline is 98.13% under the conditions of 15 mmol/L H202, 0.50 g/L catalyst dosage, initial pH 3.0, 11 W UV lamp power and 60 min reaction time. However, the removal rate decreases after adding some anions. The hydroxyl radical plays an important role in heterogeneous photo-assisted Fenton degradation of tetracycline. The catalyst is very stable and can be recycled many times.展开更多
According to a great deal of experimental findings and theoretical analysis, when the COD of inlet is 1 000-1 200 mg/L, NH3--N is 200~250 mg/L, the periodic time of operation is 24 h, the aeration time is 16 h and the...According to a great deal of experimental findings and theoretical analysis, when the COD of inlet is 1 000-1 200 mg/L, NH3--N is 200~250 mg/L, the periodic time of operation is 24 h, the aeration time is 16 h and the sludge density is 5 000-7 000 mg/L, COD of outlet is 150-200 mg/L, NH3--N is less than 25 mg/L, the volume load of COD and NH3--N remove 0.50 and 0.12 kg/（m3od） respectively. Meanwhile, studied the influence of various crafts parameter change on the treating effect and absorbing the yielding water of the SBR reactor with pulverized coal ash for improving the removing effect of COD and chromaticity further.展开更多
Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the ...Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the present work, sodium hydroxide and acetic acid solutions were sent to the tubular flow reactor. The aim was to control p H at 7 in the nonlinear region. The p H control of a tubular flow reactor with high time delay and a highly nonlinear behavior in p H neutralization reaction was investigated experimentally in the face of the various load and set point changes. Firstly, efficiency of conventional Proportional-Integral-Derivative(PID) algorithm in the experiments was tested. Then self-tuning PID(STPID) control system was applied by using the ARMAX model. The model parameters were calculated from input–output data by using PRBS signal as disturbance and Bierman algorithm. Lastly, the experimental fuzzy control of p H based on fuzzy model was achieved to compare the success of fuzzy approach with the performance of other control cases studied.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.49971046 and 49831005).
文摘Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.
文摘Cobalt-based phosphate/phosphonates are a class of promising water oxidation catalysts at neutralpH.Herein,we reported a facile hydrothermal synthesis of various nanostructured cobalt phe-nylphosphonates.It is found that the number of hydroxyl group of structure-directing reagent iscrucial for the construction of 3D hierarchical structures including hierarchical nanosheet flow-er-like assemblies and nanothorn microsphere.These samples were characterized by scanningelectron microscopy,transmission electron microscopy,X-ray diffraction,infrared,and X-ray pho-toelectron spectroscopy techniques.They can act as highly efficient electrocatalysts for the oxygenevolution reaction at neutral pH.Among these,hierarchical cobalt phenylphosphonate nanothornflowers present excellent performance,affording a current density of 1 mA cm^-2 required a smalloverpotential of 393 mV.This work offers a new clue to develop high-performance metal phospho-nate/phosphate catalysts toward electrochemical water oxidation.
文摘A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carrageenan, kC, using ammonium persulfate （APS） as a free radical initiator in the presence of methylene bisacrylamide （MBA） as a crosslinker. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy （SEM）. The effect of MBA concentration and AA/NIPAM weight ratio on the water absorbency capacity has been investigated. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The temperature- and pH-reversibility properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.
基金Project(51004053)supported by National Natural Science Foundation of ChinaProject(2009J01033)supported by Natural Science Foundation of Fujian Province,China+2 种基金Project(3502Z20116008)supported by the Science and Technology Research Project of Xiamen City,ChinaProject(JA11146)supported by Program for Fostering Distinguished Young Scholars in University of Fujian Province,ChinaProject(2011B003)supported by the Foundation for Young Professors of Jimei University,China
文摘In the present work, a novel heterogeneous photo-Fenton catalyst was prepared by iron and cerium pillared bentonite. The catalyst Fe-Ce/bentonite was characterized by X-ray diffraction （XRD）, X-ray fluorescence （XRF）, Brunauer-Emmett-Teller （BET） and scanning electron microscopy （SEM） methods. It is found that Fe and Ce intercalate into the silicate layers of bentonite successfully. Tetracycline was removed by heterogeneous photo-Fenton reaction using the catalyst in this work. The effects of different reaction systems, hydrogen peroxide concentration, initial pH, catalyst dosage, UV power and introduction of different anions on degradation were investigated in details. The stability of catalyst was investigated through recycling experiment. The results show that removal rate of tetracycline is 98.13% under the conditions of 15 mmol/L H202, 0.50 g/L catalyst dosage, initial pH 3.0, 11 W UV lamp power and 60 min reaction time. However, the removal rate decreases after adding some anions. The hydroxyl radical plays an important role in heterogeneous photo-assisted Fenton degradation of tetracycline. The catalyst is very stable and can be recycled many times.
文摘According to a great deal of experimental findings and theoretical analysis, when the COD of inlet is 1 000-1 200 mg/L, NH3--N is 200~250 mg/L, the periodic time of operation is 24 h, the aeration time is 16 h and the sludge density is 5 000-7 000 mg/L, COD of outlet is 150-200 mg/L, NH3--N is less than 25 mg/L, the volume load of COD and NH3--N remove 0.50 and 0.12 kg/（m3od） respectively. Meanwhile, studied the influence of various crafts parameter change on the treating effect and absorbing the yielding water of the SBR reactor with pulverized coal ash for improving the removing effect of COD and chromaticity further.
文摘Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the present work, sodium hydroxide and acetic acid solutions were sent to the tubular flow reactor. The aim was to control p H at 7 in the nonlinear region. The p H control of a tubular flow reactor with high time delay and a highly nonlinear behavior in p H neutralization reaction was investigated experimentally in the face of the various load and set point changes. Firstly, efficiency of conventional Proportional-Integral-Derivative(PID) algorithm in the experiments was tested. Then self-tuning PID(STPID) control system was applied by using the ARMAX model. The model parameters were calculated from input–output data by using PRBS signal as disturbance and Bierman algorithm. Lastly, the experimental fuzzy control of p H based on fuzzy model was achieved to compare the success of fuzzy approach with the performance of other control cases studied.
