Conversion of a gasoline engine-generator set to a bi-fuel (hydrogen/gasoline) electronic fuel-injected power unit

The modifications performed to convert a gasoline carbureted engine-generator set to a bi-fuel (hydrogen/gasoline) electronic fuel-injected power unit are described. Main changes affected the gasoline and gas injectors, the injector seats on the existing inlet manifold, camshaft and crankshaft wheels with their corresponding Hall sensors, throttle position and oil temperature sensors as well as the electronic management unit. When working on gasoline, the engine-generator set was able to provide up to 8 kW of continuous electric power (10 kW peak power), whereas working on hydrogen it provided up to 5 kW of electric power at an engine speed of 3000 rpm. The air-to-fuel equivalence ratio (λ) was adjusted to stoichiometric (λ = 1) for gasoline. In contrast, when using hydrogen the engine worked ultra-lean (λ = 3) in the absence of connected electric load and richer as the load increased. Comparisons of the fuel consumptions and pollutant emissions running on gasoline and hydrogen were performed at the same engine speed and electric loads between 1 and 5 kW. The specific fuel consumption was much lower with the engine running on hydrogen than on gasoline. At 5 kW of load up to 26% of thermal efficiency was reached with hydrogen whereas only 20% was achieved with the engine running on gasoline. Regarding the NO_x emissions, they were low, of the order of 30 ppm for loads below 4 kW for the engine-generator set working on hydrogen. The bi-fuel engine is very reliable and the required modifications can be performed without excessive difficulties thus allowing taking advantage of the well-established existing fabrication processes of internal combustion engines looking to speed up the implementation of the energetic uses of hydrogen.     

Porous g-C3N4-encapsulated TiO2 hollow sphere as a high-performance Z-scheme hybrid for solar-induced photocatalytic abatement of environmentally toxic pharmaceuticals

Herein,we rationally constructed a hybrid heterostructure comprising porous g-C3N4(CN)-encapsulated anatase TiO2 hollow spheres(TOHS)via a synthesis method that involves hydrothermal and calcination treatments.The fabricated hybrid,termed CN/TOHS,demonstrated extraordinary activity toward the degradation of environmentally toxic pharmaceutical substances(acetaminophen and ciprofloxacin)in aqueous solutions under simulated sunlight irradiation;the activity of CN/TOHS was superior to that attained for individual TOHS and CN counterparts.In particular,the CN/TOHS hybrid containing 13.3 wt.％of CN on TOHS displayed the optimum degradation activity among the tested catalysts used in this study,and it also possessed exceptional recyclability and stability during consecutive degradation tests.The remarkable photocatalytic activity and stability of the hybrid were predominantly ascribed to the large solid interfacial contact between constituents,TOHS and CN,induced by effective hybrid structure,which boosted the interfacial charge transfer and impeded with the direct recombination of photo-induced charges.Notably,the results of the liquid chromatography-mass spectrometry analysis corroborated the effective mineralization of model pharmaceutical pollutants in the presence of the CN/TOHS hybrid.The simple interfacial engineering strategy presented in this study offers a potential route for the rational design of novel catalysts for application in environmental remediation and solar energy conversion.     

Influence of hydrogen enriched gas injection upon polluting emissions from pulverized coal combustion

This paper presents the experimental results on the pollutant emission of a 2 MW thermal pilot furnace with the injection of hydrogen enriched gas (HRG) into the primary jet (coal dust and primary air). An experimental method to study the effects of this procedure on the thermal pilot furnace, which was specially designed to burn pulverized solid fuel, was conducted. The hydrogen enriched gas used in the study is dried and was produced by an electrolytic system still under patent by the authors. The primary conclusions from the results are focused on the quick diffusion of hydrogen, unlike oxygen, within the coal particles and that the hydrogen forms stable compounds with the sulfur and other elements the sterile content. A primary chemical analysis of the ash/sludge components is also presented within the paper.     

Chlorine doped graphitic carbon nitride nanorings as an efficient photoresponsive catalyst for water oxidation and organic decomposition

Rationally engineering the microstructure and electronic structure of catalysts to induce high activity for versatile applications remains a challenge. Herein, chlorine doped graphitic carbon nitride (Cl-doped g-C₃N₄) nanorings have been designed as a superior photocatalyst for pollutant degradation and oxygen evolution reaction (OER). Remarkably, Cl-doped g-C₃N₄ nanorings display enhanced OER performance with a small overpotential of approximately 290 mV at current density of 10 mA cm⁻² and Tafel slope of 83 mV dec^-1, possessing comparable OER activity to precious metal oxides RuO₂ and IrO₂/C. The excellent catalytic performance of Cl-doped g-C₃N₄ nanorings originates from the strong oxidation capability, abundant active sites exposed and efficient charge transfer. More importantly, visible light irradiation gives rise to a prominent improvement of the OER performance, reducing the OER overpotential and Tafel slope by 140 mV and 28 mV dec^-1, respectively, demonstrating the striking photo-responsive OER activity of Cl-doped g-C₃N₄ nanorings. The great photo-induced improvement in OER activity would be related to the efficient charge transfer and the OH radicals arising spontaneously on CN-Cl₁₀₀ catalyst upon light irradiation. This work establishes Cl-doped g-C₃N₄ nanorings as a highly competitive metal-free candidate for photoelectrochemical energy conversion and environmental cleaning application.     

Nitrogen-containing TiO2 photocatalysts: Part 2. Photocatalytic behavior under sunlight excitation

A series of nanosized N-containing TiO₂-based materials with Anatase-type structure and synthesized by a microemulsion method were tested in the photocatalytic degradation of methylcyclohexene, a representative example of volatile organic compound (VOC) present in urban atmospheres. A combined diffuse reflectance infrared (DRIFTS) and X-ray absorption (XAS) spectroscopic study allows to analyze the nature and number of N-containing species and other defects (particularly oxygen vacancies) present in the solid catalysts. The structural characterization was used to interpret the UV–vis spectra of the solids and the resulting joint information allows to rationalize the photocatalytic activity differences observed through the samples under sunlight-type excitation. We founded that our samples contain substitutional and interstitial N-containing impurities and a significant number of oxygen vacancies. Photocatalytic activity is correlated with an optimum of oxygen vacancies, above and below which a decrease of the steady state reaction rate is observed. The physico-chemical bases of this behavior are discussed on the light of the above mentioned experimental results.     

Application of the colloidal stability of TiO2 particles for recovery and reuse in solar photocatalysis

TiO2-catalyst suspensions work efficiently in photocatalysis for wastewater treatment. Nevertheless, once photocatalysis is complete, separation of the catalyst from solution becomes the main problem. Catalyst recovery has been enhanced through charge neutralisation and coagulation with electrolytes at lab and pilot-plant scale (40 L) to evaluate the potential for its separation after photocatalytic degradation of pollutants. Zeta-potential analysis showed that the isoelectric point (IEP) of TiO2 suspensions is near pH 7. Settling rates and hydrodynamic diameter of TiO2 particles are maximum at the IEP. However, suspensions are stable at different pH. TiO2 was reused in solar photocatalysis pilot-plant (40 L) for treatment of tetrachloroethylene (C2Cl4) comparing two procedures: reuse of the entire suspension after destruction of the organics without separation of the catalyst, and reuse of the catalyst after it had settled to the bottom and clear water had been removed. Photocatalytic efficiency worsens with successive runs when catalyst and water are reused without separation, whereas, when TiO2 is separated, the photocatalyst is not deactivated.     

Organic micropollutant removal in a full-scale surface flow constructed wetland fed with secondary effluent

The mass emission rate of 12 pollutants from a wastewater treatment plant (WWTP) secondary effluent into a small tributary of the River Besòs (northeastern Spain) was determined. The pollutants tested included pharmaceutical and personal care products (PPCPs) and herbicides. Furthermore, a 1-ha surface flow constructed wetland (SFCW) was evaluated for pollution removal. Whereas the low concentration values (ngL(-1)) of PPCP discharge into the tributary was comparable to inter- and intra-campaigns, herbicides and a veterinary drug (flunixin) exhibited a high variability in concentrations (microgL(-1)). Moreover, removal efficiencies were often higher than 90% for all compounds, with the exception of carbamazepine and clofibric acid (ca. 30-47%). As expected, a seasonal trend of pollutant removal in the wetland was observed for compounds with low biodegradation and moderate photodegradation rates (i.e. naproxen and diclofenac).     

含风电的发电资源优化调度与仿真研究

风电大规模集群接入电网给电力系统的调度带来巨大挑战.基于对风功率波动特性的分析,将风电作为负的负荷,构建了以污染物排放最小为目标的含风电的电力系统优化调度模型.根据次日风功率和负荷功率的预测值,安排火电机组的发电调度计划.把目标函数作为适应度函数,利用遗传算法迭代优化蚁群算法的参数,得到两者融合后的改进算法,最后求得最优解.实例仿真表明,本文提出的运行调度模型及改进求解方法能够用于计划机组出力,可有效减小污染物的排放.     

涤纶织物碱减量处理废液中对苯二甲酸的回收

涤纶碱减量废液由于其碱度大、有机物含量高,治理起来相当困难。本课题研究了用酸析法从废液中 回收对苯二甲酸的可行性及影响因素。采用适当的工艺可以从碱减量废液中回收纯度为99.8％的对 苯二甲酸,回收率为83％左右,同时CODer的去除率为82％,实现了资源化治污。     

Photocatalytic degradation of organic pollutants catalyzed by layered iron(II) bipyridine complex–clay hybrid under visible irradiation

An organic–inorganic layered hybrid was prepared by intercalation of Fe(bpy)₃²⁺ into laponite clay. UV–vis diffuse reflectance, X-Ray diffraction, and SEM confirmed the intercalation and the strong host–guest interaction of Fe(bpy)₃²⁺ molecules with the clay matrix. Compared with laponite, the hybrid formed a solid layered structure due to the linking of laponite platelets by Fe(bpy)₃²⁺ molecules. Upon visible light irradiation (λ > 420 nm), the hybrid was found to be highly effective for the degradation of nonbiodegradable cationic organic pollutants such as Rhodamine B (RhB) and N,N-dimethylaniline by activating H₂O₂ at neutral pH values, but inactive toward anionic organic compounds such as Orange II and Sulforhodamine-B. The adsorption and degradation of organics on the hybrid could be controlled by changing the pH value of the suspension. The total organic carbon (TOC) removal yield of RhB was 41%. pH effect trials and the final degraded products further indicate that unless the target is adsorbed onto the clay layers the reaction could not occur. Neither OH nor OOH/O₂⁻ EPR signals were detected during the reaction. The solid support of laponite not only alters the photochemical properties of Fe(bpy)₃²⁺ but also provides a rigid microenvironment for the enrichment of local substrate molecules and thus enhances the interaction of the active center with the substrate.