Adsorption removal of o-nitrophenol and p-nitrophenol from wastewater by metal–organic framework Cr-BDC

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.

The Effect of Titania Structure on Ni/TiO_2 Catalysts for p-Nitrophenol Hydrogenation

The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/TiO2 catalysts prepared by a liquid-phase chemical reduction method. The catalysts were characterized by inductively coupled plasma (ICP), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR). Results show that the titania structure has favorable influence on physio-chemical and catalytic properties of Ni/TiO2 catalysts. Compared to commercial Raney nickel, the catalytic activity of Ni/TiO2 catalyst is much superior, irrespective of the titania structure. The catalytic activity of anatase titania supported nickel catalyst Ni/TiO2(A) is higher than that of rutile titania supported nickel catalyst Ni/TiO2(R), possibly because the reduction of nickel oxide to metallic nickel for Ni/TiO2(A) is easier than that for Ni/TiO2(R) at similar reaction conditions.

Direct electrocatalytic reduction of p-nitrophenol at room temperature ionic liquid modified electrode

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.

Synergetic Effects of UV/Fe^(3+) Combined with Electrocatalysis for p-Nitrophenol Degradation

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.

Effect of Alumina Particle Size on Ni/Al2O3 Catalysts for p-Nitrophenol Hydrogenation

The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.

Ozonation with ultrasonic enhancement of p-nitrophenol wastewater

Synergetic effects for p-nitrophenol degradation were observed in the ozonation with ultrasonic enhancement. The enhancements of removal rate for p-nitrophenol and TOC were around 116% and 294% respectively in comparison with the individual ultrasound and ozonation systems. The synergetic phenomenon is attributed to two physicochemical mechanisms: (1) Ultrasound decomposes ozone causing augmentation of the activity of free radicals; (2) Ultrasonic wave increased the concen- tration of O3 in solution because of ultrasonic dispersion.

Frequency effect on p-nitrophenol degradation under conditions of strict acoustic and electric control

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.

Activation of peroxydisulfate by gas-liquid pulsed discharge plasma to enhance the degradation of p-nitrophenol

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.

Synergetic effects for p-nitrophenol abatement using a combinedactivated carbon adsorption-electrooxidation process

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%-30%. In such a combined process, synergetic effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively. AC could be electrochemically regenerated and reused, indicating the combined process would be promising for treatment of biorefractory organic pollutants.

Mechanistic study of ozonation of p-nitrophenol in aqueous solution

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.

Complex Formation between Heptakis(2,3,6-tri-O-butyl)-β-cyclodextrin with p-Nitrophenol in Heptane

Heptakis(2, 3, 6-tri-o-n-butyl)- β-cyclodextrin(TB- β-CD) has been found to form an inclusion compound with p-nitrophenol in heptane. The stability constent of the inclusion compound of p-nitrophenol with TB-β-CD in heptane is an order of magnitude greater than that in water.

Quality Control of Paracetamol Generic Tablets Marketed in Benin and Search of Its Two Impurities P-Aminophenol and P-Nitrophenol by HPLC-UV/Visible

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.

Adsorptive Removal of p-Nitrophenol from Aqueous Solution by Bone Char： Equilibrium and Kinetic Studies

Para-nitrophenol adsorbed on bone char synthesized from cow bones has been studied. The Langmuir Freundlich and Sips models were applied to the equilibrium data to describe the adsorption process. The Langmuir model best described the adsorption process with R^2 = 0.919; and maximum adsorption capacity, qmax of 365.76 mg/g. Batch kinetic studies conformed to pseudo-second-order indicating that several mechanisms may be involved in the process and gave a value of 2.5×10^4 g/mg/min for the rate constant for the sorption ofp-nitrophenol on bone char. The values of thermodynamic parameters, free energy ≈ -22.0 kJ/mol, enthalpy -20.2 kJ/mol and entropy 5.34 J/K mol for the adsorption of p-nitrophenol on bone char showed that the adsorption was spontaneous and exothermic.

RESEARCH ON THE ESTIMATE OF SAFETY AND TOXICITY OF P-NITROPHENOL SODIUM WITHA PHYSIOLOGICALLY BASED PHARMACOKINETICS MODEL

The safety and toxicity of chemicals given first to animals and finally to humans are generally estimated with a method of safe coefficient, which is scientifically a way lack of grounds. To make a change of the old method, we designed a Physiologically Based Pharmacokinetics Medel for the estimate of safety and toxicity of chemicais. As an example,p-nitrophenol sodium (PNP-Na) is used in the research work. Studies of the PNP-Na pharmacokinetics in bodies of rat as well as humans are made, and possibilities of making use of the Model in the estimate of safety and toxicity of chemicals are discussed.

254/185 nm photolysis of p-nitrophenol

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.

Synthesis of p-nitrophenol under normal pressure with A-1 phase transfer catalysis

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%.

超细铂纳米催化剂的光化学合成及其催化还原硝基苯酚的应用

以乙二醇(EG)为还原剂,通过波长为395 nm近紫外光和450、650 nm的可见光照射C_(60)及K_(2)[PtCl_(4)]混合液,制备了超细铂纳米颗粒(Pt/C_(60)-E)。利用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)以及高分辨率透射电子显微镜(HR-TEM)等表征手段对Pt/C_(60)催化剂的组成及形貌进行了研究,结果表明,铂纳米颗粒在C_(60)表面分散良好,平均粒径约为2.6 nm。在催化p-NP还原实验中,在近紫外光(395 nm)照射下所制备催化剂(Pt/C_(60)-E3)表现出最高的催化活性,其速率常数k=0.12 min^(-1)。在催化剂循环实验中,多次循环催化剂仍具有较高的活性,实验证明光化学法对前驱体铂催化剂制备起到良好的作用。

碳笼负载镍基磁性催化剂Ni@Cage-C的制备与性能研究

以自然结晶法制备的ZIF-67为前驱体,采用包裹-刻蚀-碳化策略,得到大小均匀的纳米碳笼(Cage-C),再于液相条件下以碳笼为载体负载上活性金属镍(Ni),成功制备了非贵金属磁性催化剂Ni@Cage-C,并应用于对硝基苯酚催化还原反应以考察其多相催化性能。结果表明:优化条件下制备的Ni@Cage-C催化剂为碳笼包裹单质镍结构,其平均颗粒大小为550 nm;将Ni@Cage-C用于对硝基苯酚催化还原反应时,催化性能明显优于参照催化剂雷尼镍(Raney-Ni)。质量反应速率常数kM为6.11 mg^(-1)·min^(-1),催化效率达到98.87%,循环反应十圈后活性仍高于初始活性的85%。

铜纳米颗粒修饰多孔氮化硼高效还原对硝基苯酚的研究

为了寻找高催化活性、环境友好、价格低廉、稳定性好的催化剂,研究金属与载体之间的协同催化效应,采用煅烧前驱体法制备了表面富含羟基和氨基的高比表面积多孔h-BN载体,通过简单的液相还原法成功地制备出粒径分布均匀的Cu/h-BN纳米复合材料,并对复合材料的组成、微观结构和性能进行表征。结果显示,铜纳米粒子的引入并未破坏多孔h-BN的二维片状结构,但比表面积及孔径均有不同程度的下降。以对硝基苯酚(4-NP)还原为对氨基苯酚(4-AP)为模型反应,考察Cu/h-BN复合材料的催化性能,当Cu含量为6%(质量分数)时,复合纳米材料具有最高的催化性能(表观反应速率常数k=4.62×10^(-2) s^(-1))和稳定性,催化活性在5个循环内基本保持不变。因此,具有高比表面积的h-BN载体负载可稳定Cu纳米颗粒,它们之间的协同催化作用使Cu/h-BN具有优异的催化活性和稳定性。此研究为今后进一步研究金属与h-BN协同催化提供了理论基础。

高分散Ag/C_(3)N_(4)的制备及对硝基苯酚催化还原性能的研究

金属纳米颗粒的聚集现象严重影响了催化效率,利用简单的方法制备高分散的金属基催化剂具有一定的挑战性;首先利用柔喷雾技术在液液界面上制备了3种银配位的超分子前驱体膜,即三聚氰胺/三聚氰酸/硝酸银超分子(MC-Ag)、三聚氰胺/巴比妥酸/硝酸银超分子(MB-Ag)和三聚氰胺/三聚氰酸/巴比妥酸/硝酸银超分子(MCB-Ag);再热缩聚得到高分散的MC-Ag/C_(3)N_(4)、MB-Ag/NC和MCB-Ag/NC这3种银负载材料。在对硝基苯酚的催化还原实验中,MC-Ag/C_(3)N_(4)、MB-Ag/NC和MCB-Ag/NC表观速率常数(k_(app))分别为192.5×10^(-3)、126.8×10^(-3)和128.8×10^(-3)min^(-1);MC-Ag/C_(3)N_(4)展现出了优良的催化性能,在20 min内催化效率高达99.8%,经过5次循环后催化效果仍保持在97%以上,催化性能主要是MC-Ag/C_(3)N_(4)具有g-C_(3)N_(4)二维结构使银纳米粒子更加分散,更有利于接触更多的活性位点;同时柔喷雾技术为纳米颗粒的制备和形貌的调控提供了新的思路。