Evaluation of the influences of solution path length and additives concentrations on the solar photo-Fenton degradation of 4-chlorophenol using multivariate analysis

This study reports the photodegradation of 4-chlorophenol (4-CP) in aqueous solution by the photo-Fenton process using solar irradiation. The influence of solution path length, and Fe(NO(3))(3) and H(2)O(2) concentrations on the degradation of 4-CP is evaluated by response surface methodology. The degradation process was monitored by the removal of total organic carbon (TOC) and the release of chloride ion. The results showed a very important role of iron concentration either for TOC removal or dechlorination. On the other hand, a negative effect of increasing solution path length on mineralization was observed, which can be compensated by increasing the iron concentration. This permits an adjustment of the iron concentration according to the irradiation exposure area and path length (depth of a tank reactor). Under optimum conditions of 1.5 mM Fe(NO(3))(3), 20.0 mM H(2)O(2) and 4.5 cm solution path length, 17 min irradiation under solar light were sufficient to reduce a 72 mg CL(-1) solution of 4-CP by 91%.     

Catalytic peroxygen activation by biosynthesized iron nanoparticles for enhanced degradation of Congo red dye

In this study, biogenic iron (Fe) NPs (B-Fe) were synthesized using Terminalia Bellirica plant extracts and used to activate persulfate (PS) and peroxymonosulfate (PMS) oxidants for degradation of Congo red (CR) dye. Chemogenic Fe-NPs (C-Fe) were also synthesized using borohydride reduction method for comparison. The synthesized Fe NPs were characterized for their surface morphology using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS)-based particle size analysis. Biogenic B-Fe NPs were more uniform in size and smaller (67–125 nm), compared to chemogenic C-Fe (59–277 nm), due to the capping effect of the biomolecules in plant extracts. Degradation efficiencies using the nanoparticle – oxidant system followed the order: C-Fe-PMS (86%) ∼ B-Fe-PMS (83%) > C-Fe-PS (75%) > B-Fe-PS (63%). Post-degradation UV–Vis absorbance spectra indicated the absence of intermediates in the PS/PMS systems, suggesting complete mineralization of the dye. The kinetics of the process is best described by shifting order rate kinetics. Alkaline pH conditions, low oxidant loading and high initial dye concentration hindered degradation kinetics, while catalyst loading had minimal impact on the oxidation process. The data strongly suggested that biogenic Fe NPs activated oxidant system is an effective alternative to existing hydroxyl – radical based advanced oxidation processes.     

Effect of magnetic field on the zero valent iron induced oxidation reaction

The magnetic field (MF) effect on the zero valent iron (ZVI) induced oxidative reaction was investigated for the first time. The degradation of 4-chlorophenol (4-CP) in the ZVI system was employed as the test oxidative reaction. MF markedly enhanced the degradation of 4-CP with the concurrent production of chlorides. The consumption of dissolved O₂ by ZVI reaction was also enhanced in the presence of MF whereas the competing reaction of H₂ production from proton reduction was retarded. Since the ZVI-induced oxidation is mainly driven by the in situ generated hydroxyl radicals, the production of OH radicals was monitored by the spin trap method using electron spin resonance (ESR) spectroscopy. It was confirmed that the concentration of trapped OH radicals was enhanced in the presence of MF. Since both O₂ and Fe⁰ are paramagnetic, the diffusion of O₂ onto the iron surface might be accelerated under MF. The magnetized iron can attract oxygen on itself, which makes the mass transfer process faster. As a result, the surface electrochemical reaction between Fe⁰ and O₂ can be accelerated with the enhanced production of OH radicals. MF might retard the recombination of OH radicals as well.     

Rapid degradation of biomedical magnesium induced by zinc ion implantation

The degradation rate is important to biodegradable magnesium materials. In this study, Zn is implanted using a cathodic arc source into pure magnesium at an accelerating voltage of 35 kV. The nominal ion implant fluence is 2.5 × 10¹⁷ ions cm⁻². After Zn implantation, the degradation rate in simulated body fluids is increased significantly. It is postulated that because Zn exists in the metallic state in the implanted layer, the galvanic effect between the Zn rich surface region and magnesium matrix induces the observed accelerated degradation.     

Anodic oxidation of wastewater containing the Reactive Orange 16 Dye using heavily boron-doped diamond electrodes

Boron-doped diamond (BDD) films grown on the titanium substrate were used to study the electrochemical degradation of Reactive Orange (RO) 16 Dye. The films were produced by hot filament chemical vapor deposition (HFCVD) technique using two different boron concentrations. The growth parameters were controlled to obtain heavily doped diamond films. They were named as E1 and E2 electrodes, with acceptor concentrations of 4.0 and 8.0 × 10²¹ atoms cm⁻³, respectively. The boron levels were evaluated from Mott-Schottky plots also corroborated by Raman's spectra, which characterized the film quality as well as its physical property. Scanning Electron Microscopy showed well-defined microcrystalline grain morphologies with crystal orientation mixtures of (1 1 1) and (1 0 0). The electrode efficiencies were studied from the advanced oxidation process (AOP) to degrade electrochemically the Reactive Orange 16 azo-dye (RO16). The results were analyzed by UV/VIS spectroscopy, total organic carbon (TOC) and high-performance liquid chromatography (HPLC) techniques. From UV/VIS spectra the highest doped electrode (E2) showed the best efficiency for both, the aromaticity reduction and the azo group fracture. These tendencies were confirmed by the TOC and chromatographic measurements. Besides, the results showed a direct relationship among the BDD morphology, physical property, and its performance during the degradation process.     

Comparison of various advanced oxidation processes for the degradation of 4-chloro-2 nitrophenol

In the present study an attempt is made efficiently to degrade USEPA listed 4-chloro-2-nitrophenol (4C-2-NP), widely available in bulk drug and pesticide wastes using various advanced oxidation processes (AOPs). A comparative assessment using various AOPs (UV, H(2)O(2,) UV/H(2)O(2), Fenton, UV/Fenton and UV/TiO(2)) was attempted after initial optimization studies, viz., varying pH, peroxide concentration, iron concentration, and TiO(2) loading. The degradation of the study compound was estimated using chemical oxygen demand (COD) reduction and compound reduction using spectrophotometric methods and further validated with high performance liquid chromatography (HPLC). The degradation trends followed the order: UV/Fenton > UV/TiO(2) > UV/H(2)O(2) > Fenton > H(2)O(2) > UV(.) It can be inferred from the studies that UV/Fenton was the most effective in partial mineralization of 4C-2-NP. However, lower costs were obtained with H(2)O(2). Kinetic constants were evaluated using first order equations to determine the rate constant K.     

国内外地震滑坡研究综述

滑坡监测及滑后稳定过程,是理解滑坡机理及进行滑坡预警的关键。该文基于微芯桩监测系统监测四川省雅安市泸定县黄草坪滑后边坡得到的倾角数据,分析边坡稳定过程和监测结果的影响因素。监测结果表明,边坡失稳后的稳定过程,在不同的区域呈现出不同倾角发展特征,这表明同一滑坡事件中,不同区域发展机理的不同。但是,各区域滑后稳定过程有一个共同的特征,即均存在两个典型阶段,即失稳滑动后的倾角快速发展阶段,但是该阶段呈现减速发展特征;随后,随着倾角发展速度逐渐减小,并趋向于一个近似于零速度的稳定阶段,即第Ⅱ阶段。进一步地数据分析结果表明,该滑坡稳定过程可以用伯格斯蠕变模型来很好地描述。这表明滑后边坡稳定过程实际是一种蠕变稳定过程。该文监测结果显示,在这类昼夜温差较大的区域,监测结果受设备温度差影响较大,这也是导致测量结果呈现规律性日较大涨落的关键因素。     

面向现代制造的先进测试技术及其发展趋势

先进测试技术与仪器对于现代制造系统的发展具有重要支撑作用。在分析现代制造系统与先进测试技术同步发展特征的基础上,探讨现代制造系统与先进测试技术相互关系和协同发展的问题,分析论述了现代制造系统中的精密测试、在线检测、数字化测试、计算机视觉测试、三坐标测试机等关键技术的应用和发展概况,介绍了在工业机器人视觉检测、超声波在线探伤系统以及基于Web的智能远程无损评估系统等方面的研究工作成果。针对先进测试技术的研究要紧紧围绕现代制造业的发展需要,分析论述了先进测试技术领域的一些值得关注、重点研究和应用的技术发展方向。     

A kinetic model for the degradation of benzothiazole by Fe3+-photo-assisted Fenton process in a completely mixed batch reactor

The degradation of benzothiazole in aqueous solution by a photo-assisted Fenton reaction has been studied in a batch reactor in the pH range 2.0–3.2 and for H₂O₂ and Fe(III) concentrations respectively between 1.0×10⁻³–1.5×10⁻¹ and 1.0×10⁻⁶–4.0×10⁻⁶ M.

A kinetic model has been developed to predict the decay of benzothiazole at varying reaction conditions. The use of kinetic constants from the literature in the model allows to simulate the system behavior by taking into account the influence of pH, hydrogen peroxide, Fe(III) and sulfate concentrations and the ionic strength.     

Studies on the in vitro and in vivo degradation behavior of amino acid derivative-based organogels

The in vitro degradation behavior of organogel with different gelators based on amino acid was investigated in detail. Two methods were applied in this research: weighting method and high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) method, which was established for the first time. Their degradation behaviors in vivo were investigated by varying the kind and concentration of gelators via subcutaneous implantation. The results showed that the stronger the gelation ability or the higher the gelator concentration, the slower the degradation rate of organogel. Moreover, the organogel prepared by oils with longer alkyl length degraded slower than that of the shorter ones, which also decreased in thermal stability and mechanical strength. The investigation on degradation process showed that the degradation rate was mainly controlled by the collapse of network structure formed by gelators. In conclusion, organogel had a tunable degradation rate through altering the gelator type, oil type and the gelator concentration. It remains a promising candidate for subcutaneous in-situ implant as drug delivery vehicle.     

Photocatalytic degradation of 2,4-dinitrophenol

Contamination of the food supply from agricultural waste is an increasing concern worldwide. Numerous hazardous chemicals enter the environment from various industrial sources daily. Many of these pollutants, including 2,4-dinitrophenol (2,4-DNP), are water soluble, toxic, and not easily biodegradable. The solar photocatalytic degradation of 2,4-DNP was investigated in a solution of titanium dioxide (TiO(2)) that was prepared to be an optically clear aqueous solution of nanosized particles of TiO(2). In order to achieve optimal efficiency of the photodegradation, the effects of light intensity and pH were conducted. All experiments were carried out in a batch mode. At a pH of 8, maximum removal of 70% of 2,4-DNP was achieved within 7h of irradiation time. The nearly homogeneous solution of 5.8nm TiO(2) particles, size determined by XDS, were very effective in the photocatalytic degradation of 2,4-DNP.     

Porous SnIn4S8 microspheres in a new polymorph that promotes dyes degradation under visible light irradiation

Porous SnIn(4)S(8) microspheres were initially synthesized through a facile solvothermal approach and were investigated as visible-light driven photocatalysts for dyes degradation in polluted water. The photocatalysts were characterized by XRD, SEM, TEM, N(2) adsorption-desorption, and UV-vis diffuse reflectance techniques. Results demonstrated that the as-synthesized SnIn(4)S(8) was of a new tetragonal polymorph, showing a band-gap of 2.5 eV, a specific surface area of 197 m(2) g(-1), and an accessible porous structure as well. The photocatalytic activity of the porous SnIn(4)S(8) was evaluated by decomposition of several typical organic dyes including methyl orange, rhodamine B, and methylene blue in aqueous solution under visible light irradiation. It is demonstrated that porous SnIn(4)S(8) was highly photoactive and stable for dyes degradation, showing photocatalytic activity much higher than binary constituent sulfides like In(2)S(3), SnS(2), or even ternary chalcogenide ZnIn(2)S(4) photocatalyst. The excellent photocatalytic performance of porous SnIn(4)S(8) is the consequence of its high surface area, well-defined porous texture, and large amount of hydroxyl radicals.     

Detection and localization of degradation damaged regions in 1.3 μm laser diodes on InP using low-coherence reflectometry

We report here on the high potential of low-coherence reflectometry, a basically nondestructive technique, to detect and to localize spatially the degradation damaged regions in 1.3 μm laser diodes on InP. Using 1.3 μm low-coherence probe, three Fabry–Perot lasers with identical active regions (compressively strained multi-quantum wells) and exhibiting different degradation behaviors are investigated. The degradation induced modifications in the optical and electrical activity of the laser cavities are monitored by recording reflectograms both with and without carrier injection. This methodology gave precise information to detect and spatially localize the damaged regions in the cavities of degraded lasers.     

An overview of the damage approach of durability modelling at elevated temperature

Lifetime prediction techniques for components working at elevated temperature are revisited. Two damage approaches in which time effects at high temperature are introduced in different ways are discussed in greater detail. First, a creep–fatigue damage model considers the interaction of the two processes during the whole life before macrocrack initiation; and second, a creep–fatigue–oxidation model separates the fatigue life into two periods: during initiation the environment-assisted processes interact with fatigue, although bulk creep damage only interacts during the micropropagation period. The second model is illustrated by its application to a coated single-crystal superalloy used in aerojet turbine blades. Its capabilities are illustrated in a number of isothermal and thermomechanical fatigue tests. Anisotropy effects are also briefly discussed and a special test, introducing cyclic thermal gradients through the wall thickness of a tubular component, demonstrates the predictive capabilities for actual engine conditions.     

Dynamic degradation behavior of MgZn alloy in circulating m-SBF

A test platform was designed to mimic the conditions that an implanted coronary stent encounters in coronary arteries, and the degradation behavior of a biodegradable MgZn alloy in the circulating modified simulated body fluid (m-SBF) was investigated on the platform. Results indicated that the presence of circulating solution over the surface of the specimen increased its corrosion rate compared to that in static immersion test, and the diffusion of Mg²⁺ and other ions dominated the corrosion mechanism of the alloy. A corrosion layer with randomly scattering particles conglomerated to clusters on its surface was observed after 168 h of measurement. While the amount of Mg decreased from the matrix to the corrosion layer, the concentration ratio of Zn did not have a significant change. The concentrations of calcium and phosphor seemed to be gradually increased with the extension of distance from MgZn matrix to the degradation layer.     

医院放射科空调系统的辐射防护问题

介绍了医院放射科产生射线的设备及射线的种类,介绍了空调风管穿越放射科房间墙壁时的处理措施,并着重介绍了包裹在风管外的辐射防护材料的屏蔽厚度的计算问题.     

Decontamination of soil washing wastewater using solar driven advanced oxidation processes

Decontamination of soil washing wastewater was performed using two different solar driven advanced oxidation processes (AOPs): the photo-Fenton reaction and the cobalt/peroxymonosulfate/ultraviolet (Co/PMS/UV) process. Complete sodium dodecyl sulphate (SDS), the surfactant agent used to enhance soil washing process, degradation was achieved when the Co/PMS/UV process was used. In the case of photo-Fenton reaction, almost complete SDS degradation was achieved after the use of almost four times the actual energy amount required by the Co/PMS/UV process. Initial reaction rate in the first 15 min (IR₁₅) was determined for each process in order to compare them. Highest IR₁₅ value was determined for the Co/PMS/UV process (0.011 mmol/min) followed by the photo-Fenton reaction (0.0072 mmol/min) and the dark Co/PMS and Fenton processes (IR₁₅ = 0.002 mmol/min in both cases). Organic matter depletion in the wastewater, as the sum of surfactant and total petroleum hydrocarbons present (measured as chemical oxygen demand, COD), was also determined for both solar driven processes. It was found that, for the case of COD, the highest removal (69%) was achieved when photo-Fenton reaction was used whereas Co/PMS/UV process yielded a slightly lower removal (51%). In both cases, organic matter removal achieved was over 50%, which can be consider proper for the coupling of the tested AOPs with conventional wastewater treatment processes such as biodegradation.     

An overview of discrete event simulation methodologies and implementation

Discrete event simulation has been widely used to model and evaluate computer and engineering systems and has been an on-going area of research and development. This paper presents an overview of the field. It covers specifications of discrete event systems, simulation methodology, simulation languages, data structures for event management, and front and backend support in simulation packages including random number generation and resource management. The emphasis of the survey is on simulation methodology and event scheduling, which forms the core of any simulation package or environment.     

Study of the degradation behaviour of dimethoate under microwave irradiation

In this work, the degradation of dimethoate under microwave irradiation assisted advanced oxidation processes (MW/oxidants) were studied. The efficiencies of the degradation of dimethoate in dilute aqueous solutions for a variety of oxidants with or without MW irradiation were compared. The results showed that the synergistic effects between MW and K(2)S(2)O(8) had high degradation efficiency for dimethoate. Simultaneously, UV/TiO(2)/K(2)S(2)O(8) photocatalytic oxidation degradation of dimethoate was investigated. The experimental results indicated that the method of microwave degradation of organic pollutants in the presence of oxidant could reduce reaction time and improve product yield. Microwave irradiation was an advisable choice for treating organic wastewaters and has a widely application perspective for non- or low-transparent and fuscous dye wastewaters.     

An efficient chemical precipitation route to fabricate 3D flower-like CuO and 2D leaf-like CuO for degradation of methylene blue

A facile and eco-friendly way for fabrication of CuO is developed based on an one-step chemical precipitation route without calcination procedure or use of surfactant. The structure features of as-prepared CuO are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N₂ adsorption-desorption experiment. X-ray diffraction analysis shows that CuO with particle size of 13.5–19.2 nm and crystallinity of 67.0–72.9% can be fabricated by the transformation of Cu(OH)₂ precursor at bath temperature above 50 °C. By adjusting the oil bath temperature and the content of ammonium hydroxide, we demonstrate a formation mechanism to control CuO to be 2D leaf-like structure with large specific surface area of 33.4 m²/g and pore volume of 0.226 cm³/g, or 3D flower-like ones with specific surface area of 7.45–18.7 m²/g and pore volume of 0.0249–0.0850 cm³/g. The catalytic performances of as-prepared CuO are evaluated by monitoring degradation of methylene blue in the presence of hydrogen peroxide. Almost 100% methylene blue degradation rate can be reached after reaction for 210 min on 3D flower-like CuO synthesized with 10 mL ammonia content in oil bath of 50 °C. The high activity can be correlated with the morphology and pore volume of CuO. The present synthetic strategy is an inexpensive and convenient way suitable for large-scale fabrication of copper oxides, which are potential catalysts for organic compounds degradation.