表面改性铁刨花活化过硫酸盐降解水体中的对硝基苯酚

以机加工废料铁刨花为原料,采用盐溶液吸氧腐蚀的绿色制备方法,在铁刨花表面原位合成-FeOOH层,并用X射线衍射(XRD)对其物象进行表征。以对硝基苯酚(4-NP)为目标污染物,研究-FeOOH@Fe复合材料活化过硫酸钾(K_(2)S_(2)O_(8))降解污染物的性能。结果表明,-FeOOH@Fe复合材料活化K_(2)S_(2)O_(8)降解4-NP的效率明显优于单纯的铁刨花,在室温条件下,当pH值为7.0、4-NP初始质量浓度为10mg/L、K_(2)S_(2)0_(8)质量浓度为40mg/L-FeOOH@Fe投加量为2g/L时,反应24min后,4-NP降解率达到92.3%;水中无机阴离子H,PO和HCO;对-FeOOH@Fe活化K_(2)S_(2)O_(8)降解4-NP表现出不同程度的抑制作用,而Cl-对-FeOOH@Fe活化K_(2)S_(2)O_(3)降解4-NP表现出促进作用;-FeOOH@Fe可重复使用性能良好,重复使用5次后对4-NP降解率仍有约83%;-FeOOH@Fe活化K_(2)S_(2)0_(3)降解4-NP体系中同时存在SO_(4)^(-)·和·OH,由SO_(4)^(-)·起主导作用。

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.

Versatile bifunctional nitrogen-doped porous carbon derived from biomass in catalytic reduction of 4-nitrophenol and oxidation of styrene

The scarcity and weak durability of metal,especially precious metal catalysts are big obstacles for their large-scale application in many reactions.The state-of-the-art of the catalytic science prefers such type of catalysts,which can replace metal-based catalysts to alleviate energy and environmental crises and exhibit catalytic performance comparable to or even exceeding these metal catalysts.Herein,we report that N-doped porous carbon(NKC)derived from cheap and abundant radish can be employed as versatile and efficient bifunctional catalysts in both the catalytic reduction of 4-nitrophenol(NRR)and oxidation of styrene(SOR).The series of NKC catalysts were prepared with a simple and facile one-pot strategy by coupling the N-doping,carbonization and KOH activation processes.These catalysts show hierarchical porosity,with the specific surface area,total pore volume and N-doping content ranging from 918.9-3062.7 m^2 g^-1,1.01-2.04 cm^3 g^-1 and 1.29-15.3 at%,respectively.Interestingly,our finding suggests that the catalytic performance is not directly related to these parameters but correlates positively with the content of graphitic N dopants,which is the dominant contributor for impelling both the NRR and SOR.Another intriguing finding is that for both reactions,the optimal catalyst was found to be the NKC-3-800 which possesses the highest graphitic N content of 3.13 at%.In addition,to gain insight into the catalytic behavior,analyses of kinetics and thermodynamics were performed,and the catalytic mechanisms were postulated.This work paves the way for the construction of biomass-derived N-doped carbon catalysts for bi-or even multi-functional applications in various organic reactions.

Liquid-Liquid-Liquid Three Phase Extraction Apparatus:Operation Strategy and Influences on Mass Transfer Efficiency

Abstract A new mixer-settler-mixer three chamber integrated extractor is proposed in this work for liquid-liquid- liquid three phase countercurrent and continuous extraction. Experiments revealed the influences of the structural design of the three-liquid-phase extractor and some key operational parameters on three-phase partition of two phenolic isomers, p-nitrophenol （p-NP） and o-nitrophenol （o-NP）. The model three-liquid-phase extraction system used here is nonane （organic top-plaase）-polyethylene glycol （PEG 20UU） （polymer mlddle-phase）-（NH4）2SO4 aqueous solution （aqueous bottom-phase）. It is indicated that agitating speed and retention time in three-phase mixer are key parameters to extraction fraction of nitrophenol. Dispersion band behavior is related to agitating intensity, and its occurrence does not affect the extraction fraction of target compounds. The present work highlights the possibility of a feasible approach of scaling up of the proposed three-phase extraction apparatus for future in- dustrial-aimed applications.

Photochemical Degradation of Phenols in Water Using Flavin-based Photosensitizers

A slightly modified method for 10-ethyl flavin was developed in the present study. The synthetic product was characterized by nuclear magnetic resonance(NMR) and mass spectrometry, and used to catalyze the photocatalytic degradation of phenol, 2, 4-dichlorophenoxyacetic acid, p-nitrophenol, 4-chlorophenol, 4-methoxyphenol, 4-chloro-2-methyl-phenoxyacetic acid and2, 4, 5-trichloro-phenoxyacetic acid. Both HPLC(high performance liquid chromatography) and GC-MS data suggested that all phenols were degraded in the presence of either flavin at micromolar concentrations under direct sun light. A rapid breakdown of the phenols was observed. The degradation efficiency was clearly dependent on phenol type. In a decreasing order of degradation efficiency over a 2-h period, the phenols were 4-chlorophenol and 4-methoxyphenol(-80%) > phenoxyacetic acids(60%-65%) > nitrophenol and phenol(-35%).

Biodegradation of High Concentration of p-Nitrophenol （PNP） by Wastewater Microflora

Many nitrophenols tend to persist in the environment and they may become public health hazards. Among nitrophenols, p-nitrophenol （PNP） is a priority pollutant that has been widely used as pesticide. PNP is a toxic compound that enters the environment during manufacturing and processing of a variety of industrial products. This situation generalized its presence in multiple natural ecosystems： rivers, wastewaters, subterranean waters, soil treated by pesticides and urban atmosphere. This study aims to test the ability of wastewater microflora to degrade high concentration of PNP （500 rag/L） aerobically. An identification of the dominant microorganisms involved in the biodegradation is also carried. The cultures are performed using a minimum medium, where PNP is the sole source of carbon, energy and nitrogen. The kinetic of biodegradation is followed for more than 30 days of incubation at 30 ~C on a shaker （150 tours/min）. The obtained results show that more than 90% of PNP initial concentration is decomposed at the end of incubation. The isolation of microorganisms degrading PNP gave two bacterial colonies with different macroscopic aspects. Sequence analysis of 16S ribosomal DNA indicated that the PNP degrading isolates were closely related to members of the species： Pseudomonas aeruginosa and Bacillus cereus.

Purification and Biochemical Characterization of N-methyl-Histidylesterase from Camel （Camelus dromedarius） Liver

Camel Liver Esterase （LE） was isolated through five consecutive steps： Extraction with Tris/HCl buffer, pH 8, precipitation with ammonium sulfate, affinity chromatography on Affi-gel-butyric acid and on Affi-gel-oleic acid, and preparative polyacrylamide gel electrophoresis （PAGE）. The Km values were found as： methyl butyrate （8.3 mM）, α-naphthyl acetate （3.65 mM）, 13-naphthyl myristate （66.7 mM）, p-nitrophenyl acetate （0.29 mM）, and phenyl acetate （5.26 mM）. The Ki of LE inhibition by bis（4-nitrophenyl） phosphate was 7.9 p.M, and 58 μM by phenyl-methyl-sulfonyl fluoride. The inhibition by these inhibitors is irreversible. p-Hydroxymercuribenzoate or ethylenediamine-tetra-acetic acid did not inhibit the enzyme. LE showed a dimeric structure with molecular weight of 129 kD. The energy of activation of LE was 15.0, 5.5 and 10.75 Kcal, using the substrates： a-naphthyl acetate, p-nitrophenyl acetate, and methyl butyrate, respectively. The optimal pH for LE was between 8 and 10. The N-terminus was found as aspartic acid. The percentage of glycine residues （13.3%） was the highest whereas the percentage of cysteine residues （0.68%） was the lowest in LE. Amino acid composition shows that LE has -50% of its histidine residues as N-methylhistidines.

Structural and mechanistic understanding of an active and durable graphene carbocatalyst for reduction of 4-nitrophenol at room temperature

The development of an active, durable, and metal-free carbocatalyst that is able to replace metal-based catalysts is of increasing scientific and technological importance. The use of such a catalyst would avoid problems caused by metal- containing catalysts, for example, environmental pollution by heavy metals and depletion of rare metal resources. Herein, an active and durable graphene carbocatalyst is presented for the carbocatalytic conversion of 4-nitrophenol to 4-aminophenol at ambient temperature. The carbocatalyst was prepared via a mild, water-based reaction between L-ascorbic acid （AA） and graphene oxide （GO） and did not involve any other reactants. During the structure and catalytic property optimization, a series of carbocatalysts were fabricated at various reaction temperatures and AA/GO ratios. Using several characterization techniques, detailed structural features of these carbocatalysts were identified. Possible active species and sites on the carbocatalysts were also identified such as certain oxygen-containing groups, the ~x-conjugated system, and graphene sheet edges. In addition, the synergistic effect between these active species and sites on the resulting catalytic activity is highlighted. Furthermore, we clarified the origin of the high stability and durability of the optimized carbocatalyst. The work presented here aids the design of high-performance carbocatalysts for hydrogenation reactions, and increases understanding of the structural and mechanistic aspects at the molecular level that lead to high catalyst activity and durability.

Ternary Fe3O4@PANI@Au nanocomposites as a magnetic catalyst for degradation of organic dyes

Magnetic Fe_3O_4@PANI@Au nanocomposites are fabricated through electrostatic self-assembly and seed growth methods.The rate constant K_(app) is calculated to be 8.63×10^(-3) s^(-1) at room temperature for the reduction of 4-nitrophenol to 4-aminophenol with an excessive amount of NaBH_4 as a model system showing outstanding catalytic efficiency and stability.For recyclable performance,the catalyst exhibits slight loss in catalytic performance on the conversion of 4-nitrophenol after running for more than 10 cycles.Besides,the smaller and simpler the structure,the easier the molecular structure can be degraded,and the faster the cationic dyes can be degraded than the anionic dyes,which can reveal the selectivity.For practical application,Congo red as a pollutant of the lake water is degraded rapidly after Fe_3O_4@PANI@Au is added to the solution in a few minutes.It has been demonstrated that magnetic Fe_3O_4@PANI@Au nanoparticle composite is a promising catalyst for environment sewage.

An anti-passivation ink for the preparation of electrodes for use in electrochemical immunoassays

p-Nitrophenylphosphate （PNPP） is usually employed as the substrate for enzyme-linked immunosorbent assays, p-Nitrophenol （PNP）, the product of PNPP, with the catalyst alkaline phosphatase （ALP）, will passivate an electrode, which limits applications in electrochemical analysis. A novel anti-passivation ink used in the preparation of a graphene/ionic liquid/chitosan composited （rGO/IL/Ghi） electrode is proposed to solve the problem. The anti-passivation electrode was fabricated by directly writing the graphene-ionic liquid-chitosan composite on a single-side conductive gold strip. A glassy carbon electrode, a screen-printed electrode, and a graphene-chitosan composite-modified screen-printed electrode were investigated for comparison. Scanning electron microscopy was used to characterize the surface structure of the four different electrodes and cyclic voltammetry was carried out to compare their performance. The results showed that the rGO/IL/Ghi electrode had the best performance according to its low peak potential and large peak current. Amperometdc responses of the different electrodes to PNP proved that only the rGO/IL/Chi electrode was capable of anti-passivation. The detection of cardiac troponin I was used as a test example for electrochemical immunoassay. Differential pulse voltammetry was performed to detect cardiac troponin I and obtain a calibration curve. The limit of detection was 0.05 ng/ml.

Quality-control method for the determination of biological activity of engineered calcineurin subunit B

The aim of this study was to establish a quality-control method for calcineurin subunit B(CNB) biological activity determinations. CNB enhances the p-nitrophenylphosphate(p NPP) dephosphorylating activity of calcineurin subunit A Δ316 mutant(CNAΔ316). A series of CNB concentrations were fitted to a four-parameter equation to calculate the corresponding p NPP maximum dephosphorylation rates. Values were calculated based on biological activity references using a parallel line method. The method was then validated for accuracy, precision, linearity, linear range, sensitivity, specificity, and robustness. The recovery results were greater than 98%. Intra-plate precision was 6.7%, with inter-plate precision of 10.8%. The coefficient of determination was greater than 0.98. The linear range was 0.05–50 μg m L?1, with sensitivity of 50 μg m L?1. Tested cytokines did not induce CNAΔ316 dephosphorylation of p NPP. The chosen CNAΔ316 concentration range did not affect activity determinations.