Fenton高级氧化工艺降解苯酚模拟废水的动力学实验研究

针对Fenton高级氧化反应动力学过程进行了精细研究和深入探讨,结果表明:Fenton氧化法降解苯酚模拟废水的过程并不是单纯地符合一级动力学过程,其降解过程符合公式的形式。实验还研究了过氧化氢、亚铁离子、pH值等反应参数与反应进程的关系,为其实际应用提供了数据积累和理论依据。     

合肥市水环境承载力评估

从经济、人口、资源和技术管理等角度分析了影响水环境承载力的因素,结合研究区的特点确定了评价的指标体系.采用向量模法对合肥市2000年-2007年的水环境承载力进行评估.结果表明:合肥市的水环境承载力水平较低,但总体呈逐年上升趋势,评价值由2000年的0.027增加到2007年的0.077.在主要的水资源支持因素中,经济发展和技术管理因素对水环境的贡献增长速度最快,而自然资源因素则是主要的不稳定因素.为了协调经济发展和环境保护,提高水环境承载力,开源节流,提高水资源量是维持水环境承载力的重要途径之一.     

Effect of crystalline structure on terbuthylazine degradation by H2O2-assisted TiO2 photocatalysis under visible irradiation

Various methods for shifting the optical response of TiO₂ into the visible (Vis) range have been reported. Herein, we reported the application of a TiO₂/H₂O₂/Vis process and the effects of TiO2 crystalline structure on the degradation of terbuthylazine. The results indicated that TiO₂ crystalline structure and H₂O₂ addition had significant effects on terbuthylazine degradation: its degradation rate could be increased from 7% to 70% with H₂O₂ addition after 180?min of reaction, the synergistic degradation of terbuthylazine by TiO₂-Fe^{3 +} was substantially accelerated, with the degradation rate reaching up to 100% after 20?min of reaction, and rutile TiO₂ showed better photocatalytic activity and a more obvious synergistic effect than anatase TiO₂. The addition of free-radical scavengers (tert-butyl alcohol or methanol) inhibited the degradation efficiency of rutile TiO₂, but had a relatively minor effect on anatase TiO₂. Fluorescence spectrophotometry analysis indicated that hydroxyl free radicals could be continuously produced when using rutile TiO₂ as the photocatalyst. Degradation of terbuthylazine catalyzed by rutile TiO₂ occurred mainly in solution, but occurred on the particle surface of the photocatalyst when catalyzed by anatase TiO₂. This study provides new insight into the role of TiO₂ crystalline structure on the degradation of terbuthylazine and its photocatalytic degradation mechanism.     

Characterization of value-added chemicals derived from the thermal hydrolysis and wet oxidation of sewage sludge

• Hydrothermal treatment can greatly improve resource recovery from sewage sludge. • tCOD removal during WO was ~55% compared with ~23% after TH. • TOC solubilization during hydrothermal treatment followed first-order kinetics. • Solids and carbon balance confirmed loss of organics during thermal hydrolysis. • Reaction pathways for thermal hydrolysis and wet oxidation are proposed. We evaluated the effect of hydrothermal pretreatments, i.e., thermal hydrolysis (TH) and wet oxidation (WO) on sewage sludge to promote resource recovery. The hydrothermal processes were performed under mild temperature conditions (140°C–180°C) in a high pressure reactor. The reaction in acidic environment (pH= 3.3) suppressed the formation of the color imparting undesirable Maillard’s compounds. The oxidative conditions resulted in higher volatile suspended solids (VSS) reduction (~90%) and chemical oxygen demand (COD) removal (~55%) whereas TH caused VSS and COD removals of ~65% and ~27%, respectively at a temperature of 180°C. During TH, the concentrations of carbohydrates and proteins in treated sludge were 400–1000 mg/L and 1500–2500 mg/L, respectively. Whereas, WO resulted in solids solubilization followed by oxidative degradation of organics into smaller molecular weight carboxylic acids such as acetic acid (~400–500 mg/L). Based on sludge transformation products generated during the hydrothermal pretreatments, simplified reaction pathways are predicted. Finally, the application of macromolecules (such as proteins), VFAs and nutrients present in the treated sludge are also discussed. The future study should focus on the development of economic recovery methods for various value-added compounds.     

诱导剂对白腐真菌降解难降解有机物的作用

近年来，许多研究者就白腐真菌对难降解有机物的降解能力和降解效果进行了研究。结果发现，某些诱导剂的添加可有效地提高白腐真菌的酶活性，进而提高白腐真菌的降解效果。该文着重介绍了几种常用的诱导剂，如吐温80、藜芦醇等，并就它们对白腐真菌降解有机物的作用机理和最终降解效果进行了探讨。     

Simultaneous adsorption and degradation of γ-HCH by nZVI/Cu bimetallic nanoparticles with activated carbon support

Cu amended zero valent iron bimetallic nanoparticles were synthesized by doping Cu on the surface of iron. They were incorporated with granular activated carbon (AC) to prepare supported particles (AC-Fe⁰-Cu), which were used to remove γ-HCH. Cu on the surface of iron enhanced the dechlorination activity of Fe⁰. The dechlorination rate constant (k_obs) increased with the Cu loading on the surface of iron and the maximum was achieved with 6.073% Cu. AC as a support was effective for increasing the dispersion of the nanoparticles and avoiding the agglomeration of the metallic nanoparticles. The simultaneous adsorption of γ-HCH on AC accelerated the degradation rate of γ-HCH by the bimetals. After reaction for 165 min, around 99% of γ-HCH was removed by the solids of AC-Fe⁰-Cu. In addition, AC could adsorb the degradation products. The degradation of γ-HCH was mainly through dehydrochlorination and dichloroelmination based on the intermediate products detected by GC/MS.     

零价铁与过硫酸盐异相芬顿降解活性艳橙X-GN

采用零价铁(Fe~0)与过硫酸盐构建异相类芬顿体系,由Fe0腐蚀释放Fe~(2+)催化S_2 O_8~(2-)产生硫酸根自由基快速降解偶氮染料活性艳橙,考察了初始p H值、Fe~0投加量、过硫酸盐投加量和温度对降解过程的影响。结果表明,当活性艳橙初始浓度为100 mg/L、pH值为7、Fe~0投加量为0.5 g/L、过硫酸盐投加量为1 mmol/L和反应温度为30℃时,反应60 min后活性艳橙降解率达到92.6%。酸性条件和提高反应温度均有利反应的进行,而且活性艳橙的降解率在初始pH值为9时也高于90%。反应过程符合准一级动力学,表观反应速率常数k为0.0513 min~(-1)(30℃)。UV-Vis扫描显示,活性艳橙的发色基团在反应过程中被破坏。由Fe~0与S_2O_8~(2-)构成的异相Fenton体系可作为一种高效手段用于染料废水的处理。     

Catalytic performance and reaction mechanisms of NO removal with NH3 at low and medium temperatures on Mn-W-Sb modified siderite catalysts

Iron-based catalysts have been explored for selective catalytic reduction (SCR) of NO due to environmentally benign characters and good SCR activity. Mn-W-Sb modified siderite catalysts were prepared by impregnation method based on siderite ore, and SCR performance of the catalysts was investigated. The catalysts were analyzed by X-ray diffraction, H₂-temperature-programmed reduction, Brunauer-Emmett-Teller, Thermogravimetry-derivative thermogravimetry and in-situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The modified siderite catalysts calcined at 450°C mainly consist of Fe₂O₃, and added Mn, W and Sb species are amorphous. 3Mn-5W-1.5Sb-siderite catalyst has a wide temperature window of 180-360°C and good N₂ selectivity at low temperatures. In-situ DRIFTS results show NH₄⁺, coordinated NH₃, NH₂, NO₃⁻ species (bidentate), NO₂⁻ species (nitro, nitro-nitrito, monodentate), and adsorbed NO₂ can be discovered on the surface of Mn-W-Sb modified siderite catalysts, and doping of Mn will enhance adsorbed NO₂ formation by synergistic catalysis with Fe³⁺. In addition, the addition of Sb can inhibit sulfates formation on the surface of the catalyst in the presence of SO₂ and H₂O. Time-dependent in-situ DRIFTS studies also indicate that both of Lewis and Brønsted acid sites play a role in SCR of NO by ammonia at low temperatures. The mechanism of NO removal on the 3Mn-5W-1.5Sb-siderite catalyst can be discovered as a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms with three reaction pathways. The mechanism of NO, oxidized by synergistic catalysis of Fe³⁺ and Mn^4+/3+ to form NO₂ among three pathways, reveals the reason of high NO_x conversion of the catalyst at medium and low temperatures.

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Prediction of the self-ignition temperature in lagging fires by means of isothermal calorimetry

Under certain circumstances, contamination of a porous insulation material by a combustible liquid may result in a lagging/insulation fire. In the current study, a method based on isothermal calorimetry and modelling to estimate the risk of a lagging fire, or a maximum insulation thickness for a certain system temperature, is presented. The studied system was a combination of mineral wool and rapeseed oil. Full-scale tests were performed to determine suitable ignition criteria and to validate the results from the isothermal calorimetry tests and modelling. We contaminated the lagging using two methods – a direct method and a solvent method. These methods were evaluated in the full-scale tests. The solvent method resulted in more repeatable results than the direct method, where the contaminant was poured on the insulation. Using the calorimetric measurements, we estimated the parameters for the kinetic equation. This result was used to estimate the self-ignition temperature of contaminated lagging installed on a pipe. We found that a temperature increase of 40 °C was a reasonable ignition criterion when modelling.