Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use...Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.展开更多
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
Removal of nitrophenols （NPs） from aqueous solutions through the adsorption process by using cationic β-cyclodextrin （CCD） modified zeolite （CCDMZ） was investigated. The effects of particle size, contact time, ...Removal of nitrophenols （NPs） from aqueous solutions through the adsorption process by using cationic β-cyclodextrin （CCD） modified zeolite （CCDMZ） was investigated. The effects of particle size, contact time, solution pH values and sodium chloride content in the aqueous on adsorption capacity were evaluated through a series of batch experiments. The results showed that CCDMZ had a higher adsorption capacity for removing NPs at a size fraction of 0.45-0.9 mm while adsorption of NPs on CCDMZ reached equilibrium within 60 min. The adsorption process was apparently influenced by pH values and sodium chloride content in aqueous solution. To ascertain the mechanisms of sorption, the experimental data were modeled by using the pseudo-first and pseudo-second order kinetic equations, and the results indicated that the adsorption kinetics of NPs on CCDMZ well-matched with the pseudo-second order rate expression.展开更多
A silver-based metal-organic framework（Ag-MOFs）, [Ag2（H3 ddcba）（dpp）2]（1）（H5 ddcba = 3,5-（di（2’,5’-dicarboxylphenyl）benozoic acid, dpp = 1,3-di（4-pyridyl）propane）, was successfully constructed via hyd...A silver-based metal-organic framework（Ag-MOFs）, [Ag2（H3 ddcba）（dpp）2]（1）（H5 ddcba = 3,5-（di（2’,5’-dicarboxylphenyl）benozoic acid, dpp = 1,3-di（4-pyridyl）propane）, was successfully constructed via hydrothermal assembly of a pentacaboxylate ligand, a N-donor ligand and Ag（I） ions, which possesses a pcu topology and exhibits excellent catalytic properties in aqueous solution for the degradation of onitrophenol（2-NP）, m-nitrophenol（3-NP） and p-nitrophenol（4-NP）. Related kinetics of such catalytic reactions, photoluminescent and thermal stability of compound 1 were also investigated.展开更多
We investigated the biodegradation of 2-nitrophenol （2-NP）, 4-nitrophenol （4-NP）, and 2,4-dinitrophenol （2,4-DNP） in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with thre...We investigated the biodegradation of 2-nitrophenol （2-NP）, 4-nitrophenol （4-NP）, and 2,4-dinitrophenol （2,4-DNP） in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with three river water samples supplemented with each nitrophenol （NP）. We then isolated NP-degrading bacteria both from the S. polyrrhiza roots and from the river water. In the river water samples, removal of the three NP was accelerated in the presence of S. polyrrhiza plants. The three NPs persisted in an autoclaved solution with sterile plants suggests that NP removal was accelerated largely by bacterial NP biodegradation rather than by adsorption and uptake by the plants. We isolated 8 strains of NP-degrading bacteria： 6 strains from the S. polyrrhiza roots and 2 strains from river water without the plants. The 2-NP- and 2,4-DNP-degrading bacteria were isolated only from the S. polyrrhiza roots. The 4-NP- degrading bacteria different from those isolated from the river water samples were also found on S. polyrrhiza roots. The 2-NP- and 4-NP-degrading strains isolated from the roots utilized the corresponding NP （0.5 mmol/L） as the sole carbon and energy source. The 2,4-DNP-degrading strains isolated from the roots showed substantial 2,4-DNP-degrading activity, but the presence of other carbon and energy sources was required for their growth. The isolated NP-degrading bacteria from the roots must have contributed to the accelerated degradation of the three NPs in the rhizosphere of S. polyrrhiza. Our results suggested that rhizoremediation with S. polyrrhiza may be effective for NP-contaminated surface water.展开更多
Graphitic carbon nitride （g-C3N4） with high photocatalytic activity toward degradation of 4-nitrophenol under visible light irradiation was prepared by HCI etching followed by ammonia neutralization. The structure, ...Graphitic carbon nitride （g-C3N4） with high photocatalytic activity toward degradation of 4-nitrophenol under visible light irradiation was prepared by HCI etching followed by ammonia neutralization. The structure, morphology, surface area, and photocatalytic properties of the prepared samples were studied. After treatment, the size of the g-C3N4 decreased from several micrometers to several hundred nanometers, and the specific area of the g-C3N4 increased from 11.5 m2/g to 115 m2/g. Meanwhile, the photocatalytic activity of g-C3N4 was significantly improved after treatment toward degradation of 4- nitrophenol under visible light irradiation. The degradation rate constant of the small particle g-C3N4 is 5.7 times of that of bulk g-C3N4, which makes it a promising visible light photocatalyst for future applications for water treatment and environmental remediation.展开更多
The kinetics and mechanisms of p-nitrophenol （PNP） biodegradation by Pseudomonas aeruginosa HS-D38 were investigated. PNP could be used by HS-D38 strain as the sole carbon, nitrogen and energy sources, and PNP was m...The kinetics and mechanisms of p-nitrophenol （PNP） biodegradation by Pseudomonas aeruginosa HS-D38 were investigated. PNP could be used by HS-D38 strain as the sole carbon, nitrogen and energy sources, and PNP was mineralized at the maximum concentration of 500 mg/L within 24 h in an mineral salt medium （MSM）. The analytical results indicated that the biodegradation of PNP fit the first order kinetics model. The rate constant kpNp is 2.039 ×10^-2/h in MSM medium, KeNp＋N is 3.603 × 10^-2/h with the addition of ammonium chloride and KPNP＋c is 9.74 ×10^-3/h with additional glucose. The addition of ammonium chloride increased the degradation of PNP. On the contrary, the addition of glucose inhibited and delayed the biodegradation of PNP. Chemical analysis results by thin-layer chromatography （TLC）, UV-Vis spectroscopy and gas chromatography （GC） techniques suggested that PNP was converted to hydroquinone （HQ） and further degraded via 1,2,4-benzenetriol （1 ,2,4-BT） pathway.展开更多
The mutual effects of metal cations （Cu2＋, Pb2＋, Zn2＋, and Cd2＋） and p-nitrophenol （NP） on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2＋, Pb2＋, and Zn2＋ dimin...The mutual effects of metal cations （Cu2＋, Pb2＋, Zn2＋, and Cd2＋） and p-nitrophenol （NP） on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2＋, Pb2＋, and Zn2＋ diminished the adsorption and increased the desorption of NP remarkably, while Cd2＋ had no such effect. In contrast, NP diminished the adsorption of Cu2＋, Pb2＋, and Zn2＋ onto ash, however, this suppression effect depended on the initial concentrations of metal cations. NP had no effect on Cd〉 adsorption on ash. Fourier transform infrared （FT-IR） and X-ray absorption spectroscopic （XAS） studies suggested the following mechanisms responsible for the metal suppression effect on NP adsorption： （1） large hydrated Cu2＋, Pb2＋, and Zn〉 shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; （2） Cu2＋, Pb2＋, and Zn2＋ may block the micropores of ash, resulting in decreased adsorption of NP; （3） cornplexation of Cu2＋, Pb2＋, and Zn2＋ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a ＂soft acid＂, Cd2＋ is less efficient in the complexation of oxygencontaining acid groups than Cu2＋, Pb2＋, and Zn2＋. Thus, Cd2＋ had no effect on the adsorption of NP on wheat ash.展开更多
In this study,batch experiments were conducted to investigate the performance of microscale Fe/Cu bimetallic particles-air-persulfate system(mFe/Cu-air-PS)for p-nitrophenol(PNP)treatment in aqueous solution.First,the ...In this study,batch experiments were conducted to investigate the performance of microscale Fe/Cu bimetallic particles-air-persulfate system(mFe/Cu-air-PS)for p-nitrophenol(PNP)treatment in aqueous solution.First,the optimal operating parameters(i.e.,aeration rate of 1.0 L/min,theoretical Cu mass loading(TMLCu)of 0.110 g Cu/g Fe,mFe/Cu dosage of 15 g/L,PS total dosage of 15 mmol/L,feeding times of PS of 5,initial pH 5.4)were obtained successively by single-factor experiments.Under the optimal conditions,high COD and TOC removal efficiencies(71.0%,65.8%)were obtained after 60 min treatment.Afterword,compared with control experiments(i.e.,mFe/Cu,air,PS,mFe/Cu-air,mFe/Cu–PS,air-PS and mFe-air-PS),mFe/Cu-air-PS system exerted superior performance for pollutants removal due to the synergistic effect between mFe/Cu,air and PS.In addition,the results of control experiments and radical quenching experiments indicate this reinforcement by feeding of PS was greater than by aeration in m Fe/Cu-air-PS system.Furthermore,the degradation intermediates of PNP in mFe/Cu-air-PS process were identified and measured by HPLC.Based on the detected intermediates,the degradation pathways of PNP were proposed comprehensively,which revealed that toxic and refractory PNP in aqueous solution could be decomposed effectively and transformed into lower toxicity intermediates.As a result,m Fe/Cu-air-PS system with the performance of oxidation combined reduction can be also a potential technology for the treatment of toxic and refractory PNP contained wastewater.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
In this work,a simple synthesis of sulfur doped graphitic carbon nitride(S-g-C3N4)act as a support cum stabilizers for gold nanoparticles(Au)and its was characterized by UV–vis and XRD to measure the absorbance and c...In this work,a simple synthesis of sulfur doped graphitic carbon nitride(S-g-C3N4)act as a support cum stabilizers for gold nanoparticles(Au)and its was characterized by UV–vis and XRD to measure the absorbance and crystallinity,respectively.The functional group and morphology of the samples were identified using FT-IR and TEM.Finally,the Au@S-g-C3N4 nanocatalyst exhibits good catalytic performance and stability in the reduction of hazardous 4-nitrophenol(NP)compared to S-g-C3N4 using Na BH4.Moreover,the Au@S-g-C3N4 nanocomposite holds a good catalytic efficiency(near 100%)achieved by within 5 min.The highest catalytic reduction of NP is due to the synergistic effect of Au nanoparticles decorated on S-g-C3N4.The fast electron transfer reduction mechanism was elucidated and discussed.Excellent reusability and stability of the developed nanocomposites were also observed in consecutive reduction experiments.The filtering and catalyzing device was used for the direct conversion of NP polluted water.This method can open a new avenue for the metal nanoparticles based carbon materials heterogeneous catalyst and its reduction of toxic contaminants.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
Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal behavior under any temperature profile.Presented paper describes the application of the advanced kineti...Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal behavior under any temperature profile.Presented paper describes the application of the advanced kinetic approach for the determination of the thermal behavior also under adiabatic conditions occurring e.g.in batch reactors in case of cooling failure.The kinetics of the decomposition of different samples(different manufacturers and batches) of 3-methyl-4-nitrophenol were investigated by conventional DSC in non-isothermal(few heating rates varying from 0.25 to 8.0K/min) and isothermal(range of 200~260℃) modes.The kinetic parameters obtained with AKTS-Thermokinetics Software were applied for calculating reaction rate and progress under different heating rates and temperatures and verified by comparing simulated and experimental signals.After application of the heat balance to compare the amount of heat generated during reaction and its removal from the system,the knowledge of reaction rate at any temperature profiles allowed the determination of the temperature increase due to the self-heating in adiabatic and pseudo-adiabatic conditions.Applied advanced kinetic approach allowed simulation the course of the Heat-Wait-Search(HWS) mode of operation of adiabatic calorimeters.The thermal safety diagram depicting dependence of Time to Maximum Rate(TMR) on the initial temperature was calculated and compared with the results of HWS experiments carried out in the system with Ф-factor amounting to 3.2.The influence of the Ф-factor and reaction progress reached at the end of the HWS monitoring on the TMR is discussed.Presented calculations clearly indicate that even very minor reaction progress reduces the TMRad of 24h characteristic for a sample with initial reaction progress amounting to zero.Described estimation method can be verified by just one HWS-ARC,or by one correctly chosen ISO-ARC run of reasonable duration by knowing in advance the dependence of the TMR on the initial temperature for any Ф-factor.Proposed procedure results in significant shortening of the measuring time compared to a safety hazard approach based on series of ARC experiments carried out at the beginning of a process safety evaluation.展开更多
A complex {[Cu（tib）2（H2O）2]·（NO3）2}n（1） has been synthesized under N,N-dimethylacetamide（DMA） and water conditions. The structure of complex 1 was characterized by single-crystal X-ray crystallography. ...A complex {[Cu（tib）2（H2O）2]·（NO3）2}n（1） has been synthesized under N,N-dimethylacetamide（DMA） and water conditions. The structure of complex 1 was characterized by single-crystal X-ray crystallography. It crystallizes in monoclinic, space group P21/n with a = 10.6273（7）, b = 11.4184（7）, c = 13.4215（8） A, β = 108.290（2）°, V = 1546.38（17）A3, Z = 2, F（000） = 798, Dc = 1.667 g/cm3 and m = 0.786 mm-1） Complex 1 exhibits a 3D network due to the existence of O–H…O interaction between coordinated water and nitrate anions. Furthermore, complex 1 has a good catalytic activity for the reduction of 4-nitrophenol in Na BH4 solution.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
p-Nitrophenol imprinted nanoparticles with a size range of 150-300 nm in diameter were prepared through miniemulsion polymerization. The imprinted polymer exhibited higher adsorption capacity for p-nitrophenol than th...p-Nitrophenol imprinted nanoparticles with a size range of 150-300 nm in diameter were prepared through miniemulsion polymerization. The imprinted polymer exhibited higher adsorption capacity for p-nitrophenol than the nonimprinted polymer. The hydrolysis of paraoxon in aqueous phase can be accelerated in the presence of the p-nitrophenol imprinted nanoparticles. The hydrolysis rate of paraoxon incorporated with the imprinted nanoparticles was 2.83×10-7 mol/（L·min）, which was about 3.7 times higher compared to the non-imprinted nanoparticles, 12.7 times higher to the spontaneous hydrolysis. The nanoparticles have been mixed with polyacrylonitrile solution and electrospun into nanofibers, which can also be used to accelerate the hydrolysis of paraoxon and conveniently separated from liquid phase for further processing.展开更多
The possible impacts on nitrogen-cycle in a p-nitrophenol （PNP） polluted soil and the effectiveness of wastewater sludge amendments in restoring nitrification potential and urease activity were evaluated by an incub...The possible impacts on nitrogen-cycle in a p-nitrophenol （PNP） polluted soil and the effectiveness of wastewater sludge amendments in restoring nitrification potential and urease activity were evaluated by an incubation study. The results indicated that PNP at 250 mg/kg soil inhibited urease activity, nitrification potential, arginine ammonification rate and heterotrophic bacteria counts to some extents. After exposure to PNP, the nitrification potential of the tested soil was dramatically reduced to zero over a period of 30 days. Based on the findings, nitrification potential was postulated as a simple biochemical indicator for PNP pollution in soils. Nitrogen-cycling processes in soils responded positively to the applications of wastewater sludges. A sludge application rate of 200 tons/ha was sufficient for successful biostimulation of these nitrogen processes. The microbial activities in sludge-amended, heavy PNP-polluted soils seemed to recover after 30–45 days, indicating the effectiveness of sludge as a useful soil amendment.展开更多
Objective To investigate the performance of soil-slurry bioreactor used for remediating contaminated soil with 4-nitrophenol (4-NP). Methods The slurry bioreactor was used to degrade different concentrations of 4-nitr...Objective To investigate the performance of soil-slurry bioreactor used for remediating contaminated soil with 4-nitrophenol (4-NP). Methods The slurry bioreactor was used to degrade different concentrations of 4-nitrophenol with or without inoculating the acclimated activated sludge. HPLC system (Hewlett-Packard model 5050 with a UV detector) was used for the quantification of 4-nitrophenol. Results The indigenous microorganisms exhibited a little activity for simulated soil with 50 mg 4-NP/kg soil. However, at the concentration of 10 mg 4-NPkg soil, a considerable degradation occurred within two weeks. It appeared that high concentrations of 4-nitrophenol apparently produced an inhibitory effect on microbial activity. For system receiving 50 mg 4-NP/kg soil, the maximum rate of 4-NP degradation measured in the reactor inoculated with 25 g sludge/kg soil was approximately 10 times higher than the uninoculated reactor, suggesting that the degradation rate of 4-nitrophenol could be enhanced greatly by means of inoculating acclimated sludge. Conclusion The addition of sludge capable of degrading 4-nitrophenol can result in enhance the degradation rate of 4-nitrophenol.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
The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent was studied as a function of the solution concentration and temperature. Adsorption isotherms of phenol and nitrophenols on hypercrossl...The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent was studied as a function of the solution concentration and temperature. Adsorption isotherms of phenol and nitrophenols on hypercrosslinked resin were determined. These isotherms were modeled according to the Freundlich adsorption isotherm. The isotherms for phenol and nitrophenols on hypercrosslinked resin were assigned as L curves. Thermodynamic parameters were calculated for all phenol and nitrophenols. The kinetics experiment results showed that the adsorption rates were of the first-order kinetics. The rate constants at 303K were calculated.展开更多
文摘Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.
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Supported by the National Natural Science Foundation of China （NEPCP 200809098） and the Natural Science Foundation ot Gansu Province （0803RJZA003）.
文摘Removal of nitrophenols （NPs） from aqueous solutions through the adsorption process by using cationic β-cyclodextrin （CCD） modified zeolite （CCDMZ） was investigated. The effects of particle size, contact time, solution pH values and sodium chloride content in the aqueous on adsorption capacity were evaluated through a series of batch experiments. The results showed that CCDMZ had a higher adsorption capacity for removing NPs at a size fraction of 0.45-0.9 mm while adsorption of NPs on CCDMZ reached equilibrium within 60 min. The adsorption process was apparently influenced by pH values and sodium chloride content in aqueous solution. To ascertain the mechanisms of sorption, the experimental data were modeled by using the pseudo-first and pseudo-second order kinetic equations, and the results indicated that the adsorption kinetics of NPs on CCDMZ well-matched with the pseudo-second order rate expression.
基金financial support from the National Science Foundation of China (Nos. 216731272, 2137312, 21671119, 51572152 and 51502155)
文摘A silver-based metal-organic framework（Ag-MOFs）, [Ag2（H3 ddcba）（dpp）2]（1）（H5 ddcba = 3,5-（di（2’,5’-dicarboxylphenyl）benozoic acid, dpp = 1,3-di（4-pyridyl）propane）, was successfully constructed via hydrothermal assembly of a pentacaboxylate ligand, a N-donor ligand and Ag（I） ions, which possesses a pcu topology and exhibits excellent catalytic properties in aqueous solution for the degradation of onitrophenol（2-NP）, m-nitrophenol（3-NP） and p-nitrophenol（4-NP）. Related kinetics of such catalytic reactions, photoluminescent and thermal stability of compound 1 were also investigated.
基金supported by Japan Science and Technology Agency (JST)the National Natural Science Foundation of China (NSFC) Project as the Japan-China Joint Research Program on Science and Technology (S&T) for Environmental Conservation and Construction of a Society with Less Environmental Burden with the research theme of Development of remediation technique for water environmental pollution using microorganisms and aquatic plants with purification ability-enhanced rhizosphere
文摘We investigated the biodegradation of 2-nitrophenol （2-NP）, 4-nitrophenol （4-NP）, and 2,4-dinitrophenol （2,4-DNP） in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with three river water samples supplemented with each nitrophenol （NP）. We then isolated NP-degrading bacteria both from the S. polyrrhiza roots and from the river water. In the river water samples, removal of the three NP was accelerated in the presence of S. polyrrhiza plants. The three NPs persisted in an autoclaved solution with sterile plants suggests that NP removal was accelerated largely by bacterial NP biodegradation rather than by adsorption and uptake by the plants. We isolated 8 strains of NP-degrading bacteria： 6 strains from the S. polyrrhiza roots and 2 strains from river water without the plants. The 2-NP- and 2,4-DNP-degrading bacteria were isolated only from the S. polyrrhiza roots. The 4-NP- degrading bacteria different from those isolated from the river water samples were also found on S. polyrrhiza roots. The 2-NP- and 4-NP-degrading strains isolated from the roots utilized the corresponding NP （0.5 mmol/L） as the sole carbon and energy source. The 2,4-DNP-degrading strains isolated from the roots showed substantial 2,4-DNP-degrading activity, but the presence of other carbon and energy sources was required for their growth. The isolated NP-degrading bacteria from the roots must have contributed to the accelerated degradation of the three NPs in the rhizosphere of S. polyrrhiza. Our results suggested that rhizoremediation with S. polyrrhiza may be effective for NP-contaminated surface water.
基金the Guangdong Natural Science Foundation (No.S2012010008383) for financial support
文摘Graphitic carbon nitride （g-C3N4） with high photocatalytic activity toward degradation of 4-nitrophenol under visible light irradiation was prepared by HCI etching followed by ammonia neutralization. The structure, morphology, surface area, and photocatalytic properties of the prepared samples were studied. After treatment, the size of the g-C3N4 decreased from several micrometers to several hundred nanometers, and the specific area of the g-C3N4 increased from 11.5 m2/g to 115 m2/g. Meanwhile, the photocatalytic activity of g-C3N4 was significantly improved after treatment toward degradation of 4- nitrophenol under visible light irradiation. The degradation rate constant of the small particle g-C3N4 is 5.7 times of that of bulk g-C3N4, which makes it a promising visible light photocatalyst for future applications for water treatment and environmental remediation.
基金supported by the National Natural Science Foundation of China(No.30771429)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20060511002)the Construction Fund for"211" Project of the Ministry of Education of China and the Excellent Middle-aged and Younger Talents Foundation of Hubei Province of China(No.Q200727005)
文摘The kinetics and mechanisms of p-nitrophenol （PNP） biodegradation by Pseudomonas aeruginosa HS-D38 were investigated. PNP could be used by HS-D38 strain as the sole carbon, nitrogen and energy sources, and PNP was mineralized at the maximum concentration of 500 mg/L within 24 h in an mineral salt medium （MSM）. The analytical results indicated that the biodegradation of PNP fit the first order kinetics model. The rate constant kpNp is 2.039 ×10^-2/h in MSM medium, KeNp＋N is 3.603 × 10^-2/h with the addition of ammonium chloride and KPNP＋c is 9.74 ×10^-3/h with additional glucose. The addition of ammonium chloride increased the degradation of PNP. On the contrary, the addition of glucose inhibited and delayed the biodegradation of PNP. Chemical analysis results by thin-layer chromatography （TLC）, UV-Vis spectroscopy and gas chromatography （GC） techniques suggested that PNP was converted to hydroquinone （HQ） and further degraded via 1,2,4-benzenetriol （1 ,2,4-BT） pathway.
基金supported by the National Natural Science Foundation of China (No.20707037,40603023)
文摘The mutual effects of metal cations （Cu2＋, Pb2＋, Zn2＋, and Cd2＋） and p-nitrophenol （NP） on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2＋, Pb2＋, and Zn2＋ diminished the adsorption and increased the desorption of NP remarkably, while Cd2＋ had no such effect. In contrast, NP diminished the adsorption of Cu2＋, Pb2＋, and Zn2＋ onto ash, however, this suppression effect depended on the initial concentrations of metal cations. NP had no effect on Cd〉 adsorption on ash. Fourier transform infrared （FT-IR） and X-ray absorption spectroscopic （XAS） studies suggested the following mechanisms responsible for the metal suppression effect on NP adsorption： （1） large hydrated Cu2＋, Pb2＋, and Zn〉 shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; （2） Cu2＋, Pb2＋, and Zn2＋ may block the micropores of ash, resulting in decreased adsorption of NP; （3） cornplexation of Cu2＋, Pb2＋, and Zn2＋ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a ＂soft acid＂, Cd2＋ is less efficient in the complexation of oxygencontaining acid groups than Cu2＋, Pb2＋, and Zn2＋. Thus, Cd2＋ had no effect on the adsorption of NP on wheat ash.
基金the financial support from the National Natural Science Foundation of China(No.51878423)China Postdoctoral Science Foundation(No.2018M631077)
文摘In this study,batch experiments were conducted to investigate the performance of microscale Fe/Cu bimetallic particles-air-persulfate system(mFe/Cu-air-PS)for p-nitrophenol(PNP)treatment in aqueous solution.First,the optimal operating parameters(i.e.,aeration rate of 1.0 L/min,theoretical Cu mass loading(TMLCu)of 0.110 g Cu/g Fe,mFe/Cu dosage of 15 g/L,PS total dosage of 15 mmol/L,feeding times of PS of 5,initial pH 5.4)were obtained successively by single-factor experiments.Under the optimal conditions,high COD and TOC removal efficiencies(71.0%,65.8%)were obtained after 60 min treatment.Afterword,compared with control experiments(i.e.,mFe/Cu,air,PS,mFe/Cu-air,mFe/Cu–PS,air-PS and mFe-air-PS),mFe/Cu-air-PS system exerted superior performance for pollutants removal due to the synergistic effect between mFe/Cu,air and PS.In addition,the results of control experiments and radical quenching experiments indicate this reinforcement by feeding of PS was greater than by aeration in m Fe/Cu-air-PS system.Furthermore,the degradation intermediates of PNP in mFe/Cu-air-PS process were identified and measured by HPLC.Based on the detected intermediates,the degradation pathways of PNP were proposed comprehensively,which revealed that toxic and refractory PNP in aqueous solution could be decomposed effectively and transformed into lower toxicity intermediates.As a result,m Fe/Cu-air-PS system with the performance of oxidation combined reduction can be also a potential technology for the treatment of toxic and refractory PNP contained wastewater.
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.
基金supported financially by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT and Future Planning(No.NRF-2017R1E1A1A01074266)the Industrial Fundamental Technology Development Program(No.10076350)funded by the Ministry of Trade,Industry and Energy(MOTIE)of Korea.
文摘In this work,a simple synthesis of sulfur doped graphitic carbon nitride(S-g-C3N4)act as a support cum stabilizers for gold nanoparticles(Au)and its was characterized by UV–vis and XRD to measure the absorbance and crystallinity,respectively.The functional group and morphology of the samples were identified using FT-IR and TEM.Finally,the Au@S-g-C3N4 nanocatalyst exhibits good catalytic performance and stability in the reduction of hazardous 4-nitrophenol(NP)compared to S-g-C3N4 using Na BH4.Moreover,the Au@S-g-C3N4 nanocomposite holds a good catalytic efficiency(near 100%)achieved by within 5 min.The highest catalytic reduction of NP is due to the synergistic effect of Au nanoparticles decorated on S-g-C3N4.The fast electron transfer reduction mechanism was elucidated and discussed.Excellent reusability and stability of the developed nanocomposites were also observed in consecutive reduction experiments.The filtering and catalyzing device was used for the direct conversion of NP polluted water.This method can open a new avenue for the metal nanoparticles based carbon materials heterogeneous catalyst and its reduction of toxic contaminants.
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.
文摘Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal behavior under any temperature profile.Presented paper describes the application of the advanced kinetic approach for the determination of the thermal behavior also under adiabatic conditions occurring e.g.in batch reactors in case of cooling failure.The kinetics of the decomposition of different samples(different manufacturers and batches) of 3-methyl-4-nitrophenol were investigated by conventional DSC in non-isothermal(few heating rates varying from 0.25 to 8.0K/min) and isothermal(range of 200~260℃) modes.The kinetic parameters obtained with AKTS-Thermokinetics Software were applied for calculating reaction rate and progress under different heating rates and temperatures and verified by comparing simulated and experimental signals.After application of the heat balance to compare the amount of heat generated during reaction and its removal from the system,the knowledge of reaction rate at any temperature profiles allowed the determination of the temperature increase due to the self-heating in adiabatic and pseudo-adiabatic conditions.Applied advanced kinetic approach allowed simulation the course of the Heat-Wait-Search(HWS) mode of operation of adiabatic calorimeters.The thermal safety diagram depicting dependence of Time to Maximum Rate(TMR) on the initial temperature was calculated and compared with the results of HWS experiments carried out in the system with Ф-factor amounting to 3.2.The influence of the Ф-factor and reaction progress reached at the end of the HWS monitoring on the TMR is discussed.Presented calculations clearly indicate that even very minor reaction progress reduces the TMRad of 24h characteristic for a sample with initial reaction progress amounting to zero.Described estimation method can be verified by just one HWS-ARC,or by one correctly chosen ISO-ARC run of reasonable duration by knowing in advance the dependence of the TMR on the initial temperature for any Ф-factor.Proposed procedure results in significant shortening of the measuring time compared to a safety hazard approach based on series of ARC experiments carried out at the beginning of a process safety evaluation.
基金Supported by the National Natural Science foundation of China(21301005,21671004,51404006)Natural Science Foundation of Anhui Province(1408085QB31)the open fund of Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control(KFK201508)
文摘A complex {[Cu（tib）2（H2O）2]·（NO3）2}n（1） has been synthesized under N,N-dimethylacetamide（DMA） and water conditions. The structure of complex 1 was characterized by single-crystal X-ray crystallography. It crystallizes in monoclinic, space group P21/n with a = 10.6273（7）, b = 11.4184（7）, c = 13.4215（8） A, β = 108.290（2）°, V = 1546.38（17）A3, Z = 2, F（000） = 798, Dc = 1.667 g/cm3 and m = 0.786 mm-1） Complex 1 exhibits a 3D network due to the existence of O–H…O interaction between coordinated water and nitrate anions. Furthermore, complex 1 has a good catalytic activity for the reduction of 4-nitrophenol in Na BH4 solution.
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 the National Natural Science Foundation of China(No.50978138)PCSIRT(IRT1257)NFFTBS(No.J1103306)
文摘p-Nitrophenol imprinted nanoparticles with a size range of 150-300 nm in diameter were prepared through miniemulsion polymerization. The imprinted polymer exhibited higher adsorption capacity for p-nitrophenol than the nonimprinted polymer. The hydrolysis of paraoxon in aqueous phase can be accelerated in the presence of the p-nitrophenol imprinted nanoparticles. The hydrolysis rate of paraoxon incorporated with the imprinted nanoparticles was 2.83×10-7 mol/（L·min）, which was about 3.7 times higher compared to the non-imprinted nanoparticles, 12.7 times higher to the spontaneous hydrolysis. The nanoparticles have been mixed with polyacrylonitrile solution and electrospun into nanofibers, which can also be used to accelerate the hydrolysis of paraoxon and conveniently separated from liquid phase for further processing.
文摘The possible impacts on nitrogen-cycle in a p-nitrophenol （PNP） polluted soil and the effectiveness of wastewater sludge amendments in restoring nitrification potential and urease activity were evaluated by an incubation study. The results indicated that PNP at 250 mg/kg soil inhibited urease activity, nitrification potential, arginine ammonification rate and heterotrophic bacteria counts to some extents. After exposure to PNP, the nitrification potential of the tested soil was dramatically reduced to zero over a period of 30 days. Based on the findings, nitrification potential was postulated as a simple biochemical indicator for PNP pollution in soils. Nitrogen-cycling processes in soils responded positively to the applications of wastewater sludges. A sludge application rate of 200 tons/ha was sufficient for successful biostimulation of these nitrogen processes. The microbial activities in sludge-amended, heavy PNP-polluted soils seemed to recover after 30–45 days, indicating the effectiveness of sludge as a useful soil amendment.
文摘Objective To investigate the performance of soil-slurry bioreactor used for remediating contaminated soil with 4-nitrophenol (4-NP). Methods The slurry bioreactor was used to degrade different concentrations of 4-nitrophenol with or without inoculating the acclimated activated sludge. HPLC system (Hewlett-Packard model 5050 with a UV detector) was used for the quantification of 4-nitrophenol. Results The indigenous microorganisms exhibited a little activity for simulated soil with 50 mg 4-NP/kg soil. However, at the concentration of 10 mg 4-NPkg soil, a considerable degradation occurred within two weeks. It appeared that high concentrations of 4-nitrophenol apparently produced an inhibitory effect on microbial activity. For system receiving 50 mg 4-NP/kg soil, the maximum rate of 4-NP degradation measured in the reactor inoculated with 25 g sludge/kg soil was approximately 10 times higher than the uninoculated reactor, suggesting that the degradation rate of 4-nitrophenol could be enhanced greatly by means of inoculating acclimated sludge. Conclusion The addition of sludge capable of degrading 4-nitrophenol can result in enhance the degradation rate of 4-nitrophenol.
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The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent was studied as a function of the solution concentration and temperature. Adsorption isotherms of phenol and nitrophenols on hypercrosslinked resin were determined. These isotherms were modeled according to the Freundlich adsorption isotherm. The isotherms for phenol and nitrophenols on hypercrosslinked resin were assigned as L curves. Thermodynamic parameters were calculated for all phenol and nitrophenols. The kinetics experiment results showed that the adsorption rates were of the first-order kinetics. The rate constants at 303K were calculated.
