In the present paper, a metal–organic framework Cr-BDC was prepared and used as adsorbent for adsorption of o-nitrophenol(ONP) and p-nitrophenol(PNP) from aqueous solutions. Cr-BDC was characterized by scanning elect...In the present paper, a metal–organic framework Cr-BDC was prepared and used as adsorbent for adsorption of o-nitrophenol(ONP) and p-nitrophenol(PNP) from aqueous solutions. Cr-BDC was characterized by scanning electron microscopy, transmission electron microscope, X-ray diffraction and BET methods. The results indicate that Cr-BDC gets a very large specific surface area of 4128 m^2·g^(-1)and pore sizes are concentrated in 1 nm, which is a benefit for using for wastewater treatment. The influences of the adsorption conditions, such as temperature,solution concentration, adsorption time and reusability on adsorption performance were investigated. Cr-BDC exhibited an encouraging uptake capacity of 310.0 mg·g^(-1)for ONP, and adsorption capacity of Cr-BDC for ONP is significantly higher than that for PNP under suitable adsorption conditions. The characterizations of adsorption process were examined with the Lagergren pseudo-first-order, the pseudo-second-order kinetic model, and the intra-particular diffusion model. Kinetics experiments indicated that the pseudo-second-order model displayed the best correlation with adsorption kinetics data. Furthermore, our adsorption equilibrium data could be better described by the Freundlich equation. The results indicate that the as-prepared Cr-BDC is promising for use as an effective and economical adsorbent for ONP removal.展开更多
Direct electrochemical reduction ofp-nitrophenol （PNP） was investigated on a room temperature ionic liquid N-butylpyridinium hexafluorophosphate （BPPF6） modified carbon paste electrode （CILE）. The cathodic peak ...Direct electrochemical reduction ofp-nitrophenol （PNP） was investigated on a room temperature ionic liquid N-butylpyridinium hexafluorophosphate （BPPF6） modified carbon paste electrode （CILE）. The cathodic peak potential was positively shifted and the peak currents were increased compared to that obtained on traditional carbon paste electrode （CPE）. The results indicated that the presence of ionic liquid BPPF6 on the electrode surface showed excellent catalytic ability to the electrochemical reduction of PNP. The electrochemical behaviors of PNP on the CILE were investigated by cyclic voltammetry and the conditions such as the scan rate, the buffer pH, the substrate concentration were optimized. The electrochemical parameters were further calculated with the results of the electron transfer number （n）, the charge-transfer coefficient （α） and the surface concentration （Гr） as 1.76, 0.37 and 2.47 × 10^-9 mol/cm^2, respectively, for the selected reductive peak. The results indicated that PNP showed an irreversible adsorption-controlled electrode process on the CILE.展开更多
Synergetic effects for p-nitrophenol degradation were observed in the combination of two-advanced oxidation processes, UV/Fe3+ and electrocatalysis. The enhancement of removal rate for p-nitrophenol and COD was aroun...Synergetic effects for p-nitrophenol degradation were observed in the combination of two-advanced oxidation processes, UV/Fe3+ and electrocatalysis. The enhancement of removal rate for p-nitrophenol and COD was around 123% and 278%, respectively. The possible contributions for the synergetic effects were the electrochemically regeneration of ferric ion and the role of the oxygen that formed on the anode.展开更多
The process of decomposing p-nitrophenol （PNP） with power ultrasound requires strict control of acoustic and electric conditions. In this study, the conditions, including acoustic power and acoustic intensity, but n...The process of decomposing p-nitrophenol （PNP） with power ultrasound requires strict control of acoustic and electric conditions. In this study, the conditions, including acoustic power and acoustic intensity, but not ultrasonic frequency, were controlled strictly at constant levels. The absorbency and the COD concentrations of the samples were measured in order to show the variation of the sample concentration. The results show significant differences in the trend of the solution degradation rate as acoustic power increases after the PNP solution （with a concentration of ll4 mg/L and a pH value of 5.4） is irradiated for 60 min with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1130.0 kHz. The degradation rate of the solution increases with time and acoustic power （acoustic intensity）. On the other hand, the degradation rate of the solution is distinctly dependent on frequency when the acoustic power and intensity are strictly controlled and maintained at constant levels, The degradation rate of the PNP solution declines with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1 130.0 kHz; the COD concentration, on the contrary, increase.展开更多
Pulsed discharge in water and over water surfaces generates ultraviolet radiation,local high temperature,shock waves,and chemical reactive species,including hydroxyl radicals,hydrogen peroxide,and ozone.Pulsed dischar...Pulsed discharge in water and over water surfaces generates ultraviolet radiation,local high temperature,shock waves,and chemical reactive species,including hydroxyl radicals,hydrogen peroxide,and ozone.Pulsed discharge plasma（PDP） can oxidize and mineralize pollutants very efficiently,but high energy consumption restricts its application for industrial wastewater treatment.A novel method for improving the energy efficiency of wastewater treatment by PDP was proposed,in which peroxydisulfate（PDS） was added to wastewater and PDS was activated by PDP to produce more strong oxidizing radicals,including sulfate radicals and hydroxyl radicals,leading to a higher oxidation capacity for the PDP system.The experimental results show that the increase in solution conductivity slightly decreased the discharge power of the pulse discharge over the water surface.An increase in the discharge intensity improved the activation of PDS and therefore the degradation efficiency and energy efficiency of p-nitrophenol（PNP）.An increase in the addition dosage of PDS greatly facilitated the degradation of PNP at a molar ratio of PDS to PNP of lower than 80：1,but the performance enhancement was no longer obvious at a dosage of more than 80：1.Under an applied voltage of 20 kV and a gas discharge gap of 2 mm,the degradation efficiency and energy efficiency of the PNP reached 90.7%and45.0 mg kWh^（-1） for the plasma/PDS system,respectively,which was 34%and 18.0 mg kWh^（-1）higher than for the discharge plasma treatment alone.Analysis of the physical and chemical effects indicated that ozone and hydrogen peroxide were important for PNP degradation and UV irradiation and heat from the discharge plasma might be the main physical effects for the activation of PDS.展开更多
Degradation of low-concentration p-nitrophenol(p-NP)aqueous solution was carried out in 254/185 nm photolysis.The effects of Mn^(2+),pH value,O_2 and O_3 on the degradation efficiency have been investigated.It was obs...Degradation of low-concentration p-nitrophenol(p-NP)aqueous solution was carried out in 254/185 nm photolysis.The effects of Mn^(2+),pH value,O_2 and O_3 on the degradation efficiency have been investigated.It was observed that the singlet oxygen scavenger Mn^(2+)did not affect the degradation of p-NP.In acidic and alkaline solutions,the degradation efficiency was enhanced in comparison to that in neutral solution.The presence of O_2 dramatically promoted the degradation of p-NP,while that of O_3 impeded it.展开更多
Ozonlysis in the treatment of p-nitrophenol solution was studied in this paper. The results indicated that the decomposition of pnitrophenol was accelerated as the gas flow rate or pH value increased. When gaseous ozo...Ozonlysis in the treatment of p-nitrophenol solution was studied in this paper. The results indicated that the decomposition of pnitrophenol was accelerated as the gas flow rate or pH value increased. When gaseous ozone concentration was 20.11 mg/L and pH was 3, after 24 m in reaction, the removal rate of p-nitrophenol reached 73.04%, 86. 11%, 91.71% and 95% at the gas flow rate of 32, 40, 48 and 56 ml/min respectively. And when pH was 3, 4, 5, 6, the decomposition rate was 66.38%, 82.09%, 90.46%, 97.50% after a 20 min reaction respectively. It was mainly O3 molecule that took part in the decomposition when pH was 3. The main intermediates during the decomposition include catechol, o-benzoquinone, hydroquinone, p-benzoquinone, phenol, fumaric acid, maleic acid, oxalic acid and formic acid. The decomposition mechanism of p-nitrophenol was also discussed.展开更多
p nitrophenol is synthesized using p nitrochlorobenzene and sodium hydroxide with phase transfer catalyst. Several reaction factors, such as catalyst type, the amounts of catalysts and sodium hydroxide, the concentrat...p nitrophenol is synthesized using p nitrochlorobenzene and sodium hydroxide with phase transfer catalyst. Several reaction factors, such as catalyst type, the amounts of catalysts and sodium hydroxide, the concentration of sodium hydroxide solution as well as reaction time, affect greatly the yield of p nitrophenol. The optimum reaction conditions are as follows: A 1 used as phase transfer catalyst whose consumption is 6% (mole fraction) of p nitrochlorobenzene; the molar ratio of sodium hydroxide to p nitrochlorobenzene is 3:1; the concentration of sodium hydroxide solution is 50% (mass fraction). Nitrobenzene, whose molar amount is 2.45 times as much as that of p nitrochlorobenzene; reaction time is 7 h at 140 ℃ under normal pressure. The final yield of p nitrophenol is 83.6%.展开更多
In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic propert...In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic properties. Ninety-four (94) samples were collected at various levels of the medicine supply chain and illegal markets in Benin for quality control tests such as visual inspection, pharmacotechnical tests as mass variation, disintegration test, dissolution test, followed by HPLC UV-Vis identification and assay of paracetamol, 4-AP and 4-NP. The analytes were separated on C18 Lichrocart column (250 mm × 4.0 mm i.d, 5 μm);the mobile phase was MeOH:10 mM ammonium acetate buffer pH 6.8 (35:65) pumped at a flow rate of 1 ml/min. The detection was done at 245 nm. Analysis of our results shows that 77.7% of the samples did not comply with the visual inspection test requirements, 2.1% did not pass the mass variation test, 24.3% of the sample batches didn’t comply with the disintegration test requirements. In addition none of these uncomply batches passed the dissolution test, even if the identification test indicated that all samples contained paracetamol. None contained 4-NP (acceptance limit < 0.05% m/m;BP), while 3 of 94 samples contained 4-AP but within acceptance limit (4-AP < 0.1% m/m;BP). As for the paracetamol assay, 80.9% complied with the specifications of the pharmacopoeias taken as reference (90% - 110%;USP). Further, broader studies should be conducted according to the same rules of good practice for a more comprehensive analysis of the situation. Generally the quality control of paracetamol in most African countries, particularly in Benin, is based on pharmacotechnical tests and paracetamol assay. This work, in addition to the usual tests, showed the importance to search for paracetamol and other drugs’ impurities during their routine quality control.展开更多
基金Supported by the National Natural Science Foundation of China(No.21676133)the Natural Science Foundation of Fujian Province(2014J01051)
文摘In the present paper, a metal–organic framework Cr-BDC was prepared and used as adsorbent for adsorption of o-nitrophenol(ONP) and p-nitrophenol(PNP) from aqueous solutions. Cr-BDC was characterized by scanning electron microscopy, transmission electron microscope, X-ray diffraction and BET methods. The results indicate that Cr-BDC gets a very large specific surface area of 4128 m^2·g^(-1)and pore sizes are concentrated in 1 nm, which is a benefit for using for wastewater treatment. The influences of the adsorption conditions, such as temperature,solution concentration, adsorption time and reusability on adsorption performance were investigated. Cr-BDC exhibited an encouraging uptake capacity of 310.0 mg·g^(-1)for ONP, and adsorption capacity of Cr-BDC for ONP is significantly higher than that for PNP under suitable adsorption conditions. The characterizations of adsorption process were examined with the Lagergren pseudo-first-order, the pseudo-second-order kinetic model, and the intra-particular diffusion model. Kinetics experiments indicated that the pseudo-second-order model displayed the best correlation with adsorption kinetics data. Furthermore, our adsorption equilibrium data could be better described by the Freundlich equation. The results indicate that the as-prepared Cr-BDC is promising for use as an effective and economical adsorbent for ONP removal.
基金the National Natural Science Foundation of China(Nos.20405008,20635020)
文摘Direct electrochemical reduction ofp-nitrophenol （PNP） was investigated on a room temperature ionic liquid N-butylpyridinium hexafluorophosphate （BPPF6） modified carbon paste electrode （CILE）. The cathodic peak potential was positively shifted and the peak currents were increased compared to that obtained on traditional carbon paste electrode （CPE）. The results indicated that the presence of ionic liquid BPPF6 on the electrode surface showed excellent catalytic ability to the electrochemical reduction of PNP. The electrochemical behaviors of PNP on the CILE were investigated by cyclic voltammetry and the conditions such as the scan rate, the buffer pH, the substrate concentration were optimized. The electrochemical parameters were further calculated with the results of the electron transfer number （n）, the charge-transfer coefficient （α） and the surface concentration （Гr） as 1.76, 0.37 and 2.47 × 10^-9 mol/cm^2, respectively, for the selected reductive peak. The results indicated that PNP showed an irreversible adsorption-controlled electrode process on the CILE.
文摘Synergetic effects for p-nitrophenol degradation were observed in the combination of two-advanced oxidation processes, UV/Fe3+ and electrocatalysis. The enhancement of removal rate for p-nitrophenol and COD was around 123% and 278%, respectively. The possible contributions for the synergetic effects were the electrochemically regeneration of ferric ion and the role of the oxygen that formed on the anode.
基金supported by the National Natural Science Foundation of China (Grant No. 10974044)the Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (Grant No. 2010490911)the Fundamental Research Funds for the Central Universities (Grant No. 2009B31514)
文摘The process of decomposing p-nitrophenol （PNP） with power ultrasound requires strict control of acoustic and electric conditions. In this study, the conditions, including acoustic power and acoustic intensity, but not ultrasonic frequency, were controlled strictly at constant levels. The absorbency and the COD concentrations of the samples were measured in order to show the variation of the sample concentration. The results show significant differences in the trend of the solution degradation rate as acoustic power increases after the PNP solution （with a concentration of ll4 mg/L and a pH value of 5.4） is irradiated for 60 min with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1130.0 kHz. The degradation rate of the solution increases with time and acoustic power （acoustic intensity）. On the other hand, the degradation rate of the solution is distinctly dependent on frequency when the acoustic power and intensity are strictly controlled and maintained at constant levels, The degradation rate of the PNP solution declines with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1 130.0 kHz; the COD concentration, on the contrary, increase.
基金supported by National Natural Science Foundation of China(Grant No.21577011)the Fundamental Research Funds for the Central Universities(Grant No. DUT15QY23)
文摘Pulsed discharge in water and over water surfaces generates ultraviolet radiation,local high temperature,shock waves,and chemical reactive species,including hydroxyl radicals,hydrogen peroxide,and ozone.Pulsed discharge plasma（PDP） can oxidize and mineralize pollutants very efficiently,but high energy consumption restricts its application for industrial wastewater treatment.A novel method for improving the energy efficiency of wastewater treatment by PDP was proposed,in which peroxydisulfate（PDS） was added to wastewater and PDS was activated by PDP to produce more strong oxidizing radicals,including sulfate radicals and hydroxyl radicals,leading to a higher oxidation capacity for the PDP system.The experimental results show that the increase in solution conductivity slightly decreased the discharge power of the pulse discharge over the water surface.An increase in the discharge intensity improved the activation of PDS and therefore the degradation efficiency and energy efficiency of p-nitrophenol（PNP）.An increase in the addition dosage of PDS greatly facilitated the degradation of PNP at a molar ratio of PDS to PNP of lower than 80：1,but the performance enhancement was no longer obvious at a dosage of more than 80：1.Under an applied voltage of 20 kV and a gas discharge gap of 2 mm,the degradation efficiency and energy efficiency of the PNP reached 90.7%and45.0 mg kWh^（-1） for the plasma/PDS system,respectively,which was 34%and 18.0 mg kWh^（-1）higher than for the discharge plasma treatment alone.Analysis of the physical and chemical effects indicated that ozone and hydrogen peroxide were important for PNP degradation and UV irradiation and heat from the discharge plasma might be the main physical effects for the activation of PDS.
文摘Degradation of low-concentration p-nitrophenol(p-NP)aqueous solution was carried out in 254/185 nm photolysis.The effects of Mn^(2+),pH value,O_2 and O_3 on the degradation efficiency have been investigated.It was observed that the singlet oxygen scavenger Mn^(2+)did not affect the degradation of p-NP.In acidic and alkaline solutions,the degradation efficiency was enhanced in comparison to that in neutral solution.The presence of O_2 dramatically promoted the degradation of p-NP,while that of O_3 impeded it.
文摘Ozonlysis in the treatment of p-nitrophenol solution was studied in this paper. The results indicated that the decomposition of pnitrophenol was accelerated as the gas flow rate or pH value increased. When gaseous ozone concentration was 20.11 mg/L and pH was 3, after 24 m in reaction, the removal rate of p-nitrophenol reached 73.04%, 86. 11%, 91.71% and 95% at the gas flow rate of 32, 40, 48 and 56 ml/min respectively. And when pH was 3, 4, 5, 6, the decomposition rate was 66.38%, 82.09%, 90.46%, 97.50% after a 20 min reaction respectively. It was mainly O3 molecule that took part in the decomposition when pH was 3. The main intermediates during the decomposition include catechol, o-benzoquinone, hydroquinone, p-benzoquinone, phenol, fumaric acid, maleic acid, oxalic acid and formic acid. The decomposition mechanism of p-nitrophenol was also discussed.
文摘p nitrophenol is synthesized using p nitrochlorobenzene and sodium hydroxide with phase transfer catalyst. Several reaction factors, such as catalyst type, the amounts of catalysts and sodium hydroxide, the concentration of sodium hydroxide solution as well as reaction time, affect greatly the yield of p nitrophenol. The optimum reaction conditions are as follows: A 1 used as phase transfer catalyst whose consumption is 6% (mole fraction) of p nitrochlorobenzene; the molar ratio of sodium hydroxide to p nitrochlorobenzene is 3:1; the concentration of sodium hydroxide solution is 50% (mass fraction). Nitrobenzene, whose molar amount is 2.45 times as much as that of p nitrochlorobenzene; reaction time is 7 h at 140 ℃ under normal pressure. The final yield of p nitrophenol is 83.6%.
文摘In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic properties. Ninety-four (94) samples were collected at various levels of the medicine supply chain and illegal markets in Benin for quality control tests such as visual inspection, pharmacotechnical tests as mass variation, disintegration test, dissolution test, followed by HPLC UV-Vis identification and assay of paracetamol, 4-AP and 4-NP. The analytes were separated on C18 Lichrocart column (250 mm × 4.0 mm i.d, 5 μm);the mobile phase was MeOH:10 mM ammonium acetate buffer pH 6.8 (35:65) pumped at a flow rate of 1 ml/min. The detection was done at 245 nm. Analysis of our results shows that 77.7% of the samples did not comply with the visual inspection test requirements, 2.1% did not pass the mass variation test, 24.3% of the sample batches didn’t comply with the disintegration test requirements. In addition none of these uncomply batches passed the dissolution test, even if the identification test indicated that all samples contained paracetamol. None contained 4-NP (acceptance limit < 0.05% m/m;BP), while 3 of 94 samples contained 4-AP but within acceptance limit (4-AP < 0.1% m/m;BP). As for the paracetamol assay, 80.9% complied with the specifications of the pharmacopoeias taken as reference (90% - 110%;USP). Further, broader studies should be conducted according to the same rules of good practice for a more comprehensive analysis of the situation. Generally the quality control of paracetamol in most African countries, particularly in Benin, is based on pharmacotechnical tests and paracetamol assay. This work, in addition to the usual tests, showed the importance to search for paracetamol and other drugs’ impurities during their routine quality control.
