p-NP异构体^(13)C核磁共振碳谱模拟

将一种反映分子局部微环境描述子——原子电性相互作用矢量(Vector of atomic electronegative in-teraction,VAEI)和原子杂化状态指数(Atomic Hybridation State Index,AHSI)用于对位壬基酚(p-NP)异构体的共60个13C-NMR谱建模模拟,应用多元线性回归方法得到定量结构波谱关系(QSSR)模型的复相关系数(RM1)为0.996,标准误差(SDM1)为4.982.采用留一法交互检验的复相关系数(RCV1)为0.994,标准误差(SDCV1)为5.505.随机抽出两部分样本进行检验,得到测试集的复相关系数(Rest1及Rest2)分别为0.996和0.995,标准误差(SDest1及SDest2)分别为5.005和5.322.研究结果表明,使用VAEI和AHSI所建模型具有良好的预测能力和稳定性.

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.

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.

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.

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.

不同前处理方式对铁屑还原降解土壤中对硝基苯酚的影响

为推动铁屑在治理受硝基酚类化合物污染土壤中的实际应用,常温(25±1℃)常压下,利用不同前处理方式处理的铁屑、还原铁粉对土壤中的对硝基苯酚(p-NP)进行了还原降解研究;分析了土壤部分理化性质对p-NP还原效果的影响;并对反应时间、铁屑用量和土壤含水量3个人工易控因素作了最优化选择。结果表明:铁屑和铁粉对p-NP还原降解效果影响的大小顺序为:酸洗铁屑>还原铁粉>水洗铁屑>碱洗铁屑;适中的土壤含水量、偏酸性的土壤初始pH值及较高的土壤有机质含量均可显著提高铁屑对p-NP的还原率;正交实验结果显示反应时间对p-NP还原效果影响最大,铁屑用量次之,土壤含水量最小;处理1.5 g p-NP浓度约为1.3×10-5mol/g的模拟污染土壤的反应最优化条件为:酸洗铁屑用量26 mg,土壤含水量0.35 mL,反应时间130 m in,还原率可达到96.4%。

US/Fenton试剂法在水体系中降解对硝基苯酚的研究

将超声波(US)/Fenton试剂法有机地结合起来,用于对硝基苯酚(p-NP)的降解实验,实验中发现US/Fenton试剂法降解p-NP具有明显的协同效应,结果优于Fenton试剂法与US法的简单加合。全面考察了初始pH值、H2O2浓度和Fe2+浓度等因素对US/Fenton试剂法降解p-NP过程的影响。结果表明,在实验范围内,溶液的初始pH值越小,分子态的p-NP比例越大,越易于进行反应;同时H2O2的利用率越高,US/Fenton试剂法对p-NP的降解效果越好。H2O2和Fe2+浓度越高,·OH自由基的数量越多,·OH自由基有利于p-NP的降解,因此US/Fenton试剂法对p-NP的降解效果越好。

超声波/Fenton联用对对硝基苯酚的处理

采用超声/Fenton联用技术对水中对硝基苯酚(P-NP)进行处理,探讨了单纯超声(US)、Fenton试剂法、US/Fenton试剂法联用对P-NP的处理效果和影响因素,结果表明,对于浓度为10mg/L的P-NP,当pH=3、H2O2与Fe2+投加量之比为10∶1、H2O2投加量为40mg/L时降解效果最好,通过动力学分析发现US/Fenton试剂法对P-NP的降解具有明显的协同效应。

4种具有α-季碳结构的对位壬基酚异构体的合成和表征

不同来源工业壬基酚混合物(t-NP)中对位壬基酚(p-NP)异构体的组成各不相同,各异构体之间在环境行为等方面也存在着较大差异,因此在壬基酚的环境归趋、生态毒性以及雌激素活性等研究中迫切需要t-NP中不同单个异构体作为模型化合物,然而目前市场上能购买到的直链壬基酚(4-n-NP)异构体不能作为代表.以苯酚和4种含分支结构的壬醇为原料(苯酚与壬醇摩尔比为4:1),以BF3为催化剂,按照Friedel-Crafts烷基化方法合成了t-NP中常见的4种烷基链具有α-季碳结构的对位壬基酚的异构体,即4(3′,5′-二甲基-3′-庚基)-苯酚(p353NP),4(3′,6′-二甲基-3′-庚基)-苯酚(p363NP),4(2′,6′-二甲基-2′-庚基)-苯酚(p262NP)和4(3′-甲基-3′-辛基)-苯酚(p33NP).合成的壬基酚粗产物用硅胶柱色谱法提纯后的纯度达99%,并经紫外可见分光光度计、荧光分光光度计、HPLC、GC-MS、1H-和13C-NMR进行了表征.合成的4种p-NP异构体可被用于壬基酚的雌激素活性、毒理、代谢和环境归趋等研究.

受限外部信息源计算的P─NP性质

本文对Ｏｒａｃｌｅ图灵机在接受计算中的查询次数加以限制，并且得到结果：存在无穷多个非多项式等价的递归集Ａ，Ｂ，Ａ′，Ｂ″，Ａ″，Ｂ″，Ａ，Ｂ，它们满足性质：Ｐ（Ａ，ｑ）＝Ｐ（Ａ，ｑ＋１），Ｐ（Ｂ，ｑ）≠Ｐ（Ｂ，ｑ＋１），ｐ（Ａ′，ｑ）＝Ｐ（Ａ′），Ｐ（Ｂ′，ｑ）≠Ｐ（Ｂ′）．ＮＰ（Ａ″，ｑ）＝ＮＰ（Ａ″，ｑ＋１），ＮＰ（Ｂ″，ｑ）≠ＮＰ（Ｂ″，ｑ＋１），ＮＰ（Ａ，ｑ）＝ＮＰ（Ａ），ＮＰ（Ｂ，ｑ）≠ＮＰ（Ｂ）．

UP、β_n和FewP完全问题的相对同构性

本文引进相对的多项式化归和相对多一多项式同构等概念，对ＵＰ、βｎ的ＦｅｗＰ的相对完全集讨论它们的相对同构问题。并得到如下结果：１（１）对任何ｍＰ，Ｂｎ─βｎＢｎ完全集Ｃ，Ｃ≈ＰＢｎＡｎ←→Ｃ为ＰＢｎ柱。（２）对任何ｍＰ，Ｂ─ＦｅｗＰＢ完全集Ｃ，Ｃ≈ＰＢ∪ｎ∈ＮＡｎ←→Ｃ为ＰＢ柱，其中Ｂ＝ＳＡＴ－∪ｎ∈ＮＡｎ。（３）对任意ＯｒａｃｌｅＣ和任何ｍＰ，Ｃ－ＮＰＣ完全集Ａ，Ａ≈ＰＣＳＡＴ←→Ａ为ＰＣ柱。２（１）存在Ａ使得≤ｍＰ，Ａ—ＵＰＡ完全集非ＰＡ同构。（２）存在Ａ使得ｍＰ，Ａ－βｎＡ完全集非ＰＡ同构。（３）存在Ａ使得ｍＰ，Ａ—ＦｅｗＰＡ完全集非ＰＡ同构。

介孔碳及其铁改性材料吸附水中对硝基苯酚

采用水热合成法以F127为模板剂制备介孔碳材料(MC),一步合成法引入Fe(NO_3)_3·9H_2O得到铁改性介孔碳材料(Fe/MC-x,x为合成原料中铁源与间苯二酚的摩尔比,x=0.5、1.0、1.5),对改性前后的材料进行TEM、N_2吸-脱附、XRD及FI-TR表征,通过考察吸附剂量、吸附等温线、吸附动力学对其吸附水中对硝基苯酚(p-NP)进行了研究。结果表明,所得MC和Fe/MC-x的孔径分布集中于3～4nm,比表面积分别为643.6、635.6、636.0和587.2 m^2/g。实验条件下,Fe/MC-x的吸附性能优于MC,其中Fe/MC-1.0有最大吸附量220.35mg/g,对应去除率为92.33%;平衡吸附量均与初始浓度呈正相关,与吸附剂投加量呈负相关,高温不利于吸附,p-NP在MC和Fe/MC-x上的吸附行为符合Freundlich模型;改性行为加快了吸附速率,吸附过程符合准二级动力学模型,主要为化学吸附控制吸附速率。

一致与非一致复杂类的模型论性质

自从1965年J.Edmonds和A.Cobham提出P-NP问题以来已有30年的研究历史。目前环绕这个问题的大量学术论文和研究专著已使它发展成为计算机科学中最新和最活跃的研究领域之一,近年来,人们除了对由各种类型的图灵机确定的复杂类(如P,NP,PSPACE等)进行研究外,对一些用其他方法定义的非一致复杂类(如P/poly,P/log,NP/poly等)也越来越有兴趣。

离子液体对PbO2电极性能的影响

目的提升PbO2电极寿命以及对酚类废水的电氧化催化活性和选择性。方法分别添加离子液体1-丁基-3-甲基-咪唑六氟磷酸盐([BMIM]PF6)和1-乙基-3-甲基-咪唑四氟硼酸盐([Emim]BF4)至Pb(NO3)2溶液中,用阳极电积法制备了有SnO2+Sb2O3中间层的PbO2电极。通过扫描电镜(SEM)、X射线衍射仪(XRD)、加速寿命实验、线性扫描和循环伏安测试、电氧化降解实验等考察了不同离子液体的电离产物对电极性能的影响,并与采用F-修饰的常规PbO2电极的性能进行了对比。结果离子液体修饰的PbO2电极晶粒结晶度高,晶面取向发生改变,晶粒大小均一度高,表面平整致密、棱角多,电极有效表面积和活性点增多,且[BMIM]PF6修饰的PbO2优于[Emim]BF4修饰的PbO2。[BMIM]PF6修饰的PbO2和F-修饰的PbO2的加速寿命和电极性能稳定期分别为168.8、162.6 h和101.2、69.8 h,析氧电位分别为1.71 V和1.59 V。循环伏安显示,[BMIM]PF6修饰PbO2氧化峰电位更小,氧化峰电流更大,相同条件下,[BMIM]PF6和F-修饰PbO2对p-NP废水的电氧化降解率和有机碳去除率分别为95.7%、87.1%和85.2%、61.5%,而电解槽槽压分别为3.26 V和3.47 V。结论离子液体[BMIM]PF6、[Emim]BF4修饰PbO2电极的结晶度、晶粒均一性、致密性增强,电极活性点增多,且由于两种离子液体电离的离子大小不同,导致对电沉积晶粒的空间位阻不同,使得前者强于后者。晶粒形态和组织结构的差异,使得[BMIM]PF6修饰PbO2对酚类废水的电氧化催化活性、选择性和寿命显著增强。

硝酸与硝基苯在SiO_2表面的光化学反应

文章采用傅里叶变换红外光谱仪(Fourier transform infrared spectroscopy,FTIR)和高效液相色谱仪(high performance liquid chromatography,HPLC)研究了308nm光照下硝酸(HNO_3)和硝基苯分别在气相及SiO_2表面的光化学反应。探究了光照时间、硝基苯初始浓度和相对湿度(relative humidity,RH)等因素对反应的影响。结果表明:无论有无水汽,无光照条件下HNO_3和硝基苯在气相和SiO_2表面均不直接发生反应;308nm光照下均反应生成对硝基苯酚(p-NP),当有水汽时,水汽会促进反应的进行;随着光照时间、硝基苯初始浓度和RH的增加,气相和SiO_2表面产生的p-NP浓度均呈指数增加;200Pa HNO_3和80Pa硝基苯,在RH=0、25℃,光照90min条件下,SiO_2表面产生的p-NP浓度约是气相的2.17倍,SiO_2的表面效应在HNO_3与硝基苯的反应中起主要作用。