Degradation of Organic Compounds by Active Species Sprayed in a Dielectric Barrier Corona Discharge System

Investigation was made into the degradation of organic compounds by a dielectric barrier corona discharge （DBCD） system. The DBCD, consisting of a quartz tube, a concentric high voltage electrode and a net wrapped to the external wall （used as ground electrode）, was introduced to generate active species which were sprayed into the organic solution through an aerator fixed on the bottom of the tube. The effect of four factors-the discharge voltage, gas flow rate, solution conductivity, and pH of wastewater, on the degradation efficiency of phenol was assessed. The obtained results demonstrated that this process was an effective method for phenol degradation. The degradation rate was enhanced with the increase in power supplied. The degradation efficiency in alkaline conditions was higher than those in acid and neutral conditions. The optimal gas flow rate for phenol degradation in the system was 1.6 L/min, while the solution conductivity had little effect on the degradation.

Fast inactivation of microbes and degradation of organic compounds dissolved in water by thermal plasma

The multifunctionality and the advantages of thermal plasma for the fast inactivation of viable cells and degradation of organic compounds dissolved in waste water are presented.A complete bacterial inactivation process was observed and studied using a thermal plasma treatment source with very short application times,in particular for Staphylococcus aureus bundle spore survival.The survival curves and analyses of the experimental data of the initial and final densities of S.aureus bacteria show a dramatic inhibitory effect of the plasma discharge on the residual bacteria survival ratio.As the exposure time increased,the inactivation process rate increased for direct exposure more than it did for indirect exposure.The evaluation of direct and indirect exposure was based on the analysis of the ultraviolet spectrum from the absorbance spectra of the organic compound dye called benzene sulfonate（C（16）H（11）N2Na O4S）and of viable cells called S.aureus.Organic compounds were degraded and viable cells were killed in a short time by thermal plasma.Moreover,analyses of total carbon,total organic carbon,and total inorganic carbon showed a fast decrease in organically bound carbon,however,this was not as fast as the absorbance spectra revealed by the exposure time increasing more for direct exposure than indirect exposure.After 100 s of exposure to the organic compound dye the removal had a maximun of 40%for samples with indirect exposure to the plasma and a maximum of 90%for samples with the direct exposure.For both samples,where some organic contaminants still remained in treated water,four electrolytes（KCl,Na Cl,Na2SO4,and CH3COONa）were added to be effective for complete sterilization,reaching a purity of 100%.A proposal is made for an optimized thermal plasma water purification system（TPWPS）to improve fast inactivation of microbes and the degradation of organic compounds dissolved in water（especially for direct exposure rather than indirect exposure）using a hybrid plasma torch with an electrical power of 125 kW（500 V–250 A）producing a high-temperature（10 000 K–19 000 K）plasma jet with a maximum gas consumption of 28 mg s^-1.

Role of oxygen vacancies and Sr sites in SrCo_(0.8)Fe_(0.2)O_3 perovskite on efficient activation of peroxymonosulfate towards the degradation of aqueous organic pollutants

Metal-based perovskite oxides have contributed significantly to the advanced oxidation processes(AOPs)due to their diverse active sites and excellent compositional/structural flexibility.In this study,we specially designed a perovskite oxide with abundant oxygen vacancies,SrCo_(0.8)Fe_(0.2)O_(3)(SCF),and firstly applied it as a catalyst in peroxymonosulfate(PMS) activation towards organic pollutants degradation.The result revealed that the prepared SCF catalyst exhibited excellent performance on organic compounds degradation.Besides,SCF showed much better activity than La_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3)(LSCF) in terms of reaction rate and stability for the degradation of the organic compounds.Based on the analysis of scanning electron microscope,transmission electron microscope,X-ray diffraction,N_(2) adsorption-desorption,X-ray photoelectron spectroscopy and electron paramagnetic resonance,it was confirmed that the perovskite catalysts with high content of Sr doping at A-site could effectively create a defect-rich surface and optimize its physicochemical properties,which was responsible for the excellent heterogeneous catalytic activity of SCF.SCF can generate three highly active species:~1 O_(2),SO_(4)^(-)· and ·OH in PMS activation,revealing the degradation process of organic compounds was a coupled multiple active species in both radical and nonradical pathway.Moreover,it was mainly in a radical pathway in the degradation through PMS activation on SCF and SO_(4)^(-)· radicals produced were the dominant species in SCF/PMS system.This study demonstrated that perovskite-type catalysts could enrich OVs efficiently by doping strategy and regulate the PMS activation towards sulfate radical-based AOPs.

CO₂Absorption Solvent Degradation Compound Identification Using Liquid Chromatography-Mass Spectrometry Quadrapole-Time of Flight (LCMSQTOF)

The degradation of the alkanolamine solvent used in the removal of acid gases from natural gas streams due to exposure to contaminants, thermal degradation and presence of oxygen or oxygen containing compounds will change the solvent properties, such as heat transfer coefficient, diffusion coefficient, and mass transfer coefficient of the solvent. Therefore, characterization and quantification of amine degradation product becomes one of the important analyses to determine alkanolamine solvent’s health. In order to identify degradation products of alkanolamine solvent, analytical strategies by using mass spectrometry (MS) as detector have been studied extensively. In this work, due to the low concentration of the amine degradation product, a method was developed for identification of alkanolamine degradation products using LCMS-QTOF technique. A strategy for identification of trace degradation products has been identified. Six (6) alkanolamine degradation products had been identified by using LCMS-QTOF targeted analysis in the blended alkanolamine solvent used in natural gas processing plant. Another fifteen (15) molecular formulas having similarity in chemical structure to alkanolamine degradation products were identified using untargeted analysis strategy, as possible compounds related to degradation products. Using LCMS-QTOF via targeted and untargeted analysis strategy, without tedious column separation and reference standard, enables laboratory to provide a quick and indicative information for alkanolamine solvent’s organic degradation compounds identification in CO2 adsorption, within reasonable analysis time.

Efficiency and mechanism of degradation of alachlor in water by O_3/H_2O_2 catalyst system

Alachlor is used widely as a herbicide,but is an environmental endocrine disruptor. O 3/H 2O 2 system is used as catalyst to delve on the degradation efficiency of alachlor. The amount of the catalyst H 2O 2,the pH value of the soluble, the temperature and quality of water sample are changed to investigate the effect of these factors on the degradation of alachlor. The degradation of alachlor is qualitatively analyzed through their GS MS spectra and the possible mechanism of the degradation of alachlor is discussed as well.

Enhanced photocatalytic performance of tungsten-based photocatalysts for degradation of volatile organic compounds: a review

Photocatalytic oxidation process for the degradation of volatile organic compounds(VOCs)contaminants is a promising technology.But until now,the low photocatalytic activity of the conventional TiO_(2) photocatalyst under visible-light irradia-tion hinders the deployment of this technique for VOCs degradation.WO_(3) has been proved to be a suitable photocatalytic material for degradation of various VOCs as its appropriate band-gap,high stability and great capability.Nevertheless,the actual implementation of WO_(3) is still restricted by short lifetime of photoexcited charge carriers and low light energy conver-sion efficiency:its photocatalytic performance is needed to be improved.This review discusses the process of tungsten-based photocatalyst for removal of VOCs and summarizes a variety of strategies to improve the VOCs oxidation performances of WO_(3),such as controlling the morphology structure,engendering chemical defects,coupling heterojunction,doping suitable dopants and loading a co-catalyst.In addition,the practical application of tungsten-based photocatalyst is discussed.

Ozonation of o-phenylenediamine in the presence of hydrogen peroxide by high-gravity technology

The study herein investigated the effectiveness of simultaneous use of ozone and hydrogen peroxide(O_3/H_2O_2 process) to degrade o-phenylenediamine(o-PDA) in a simulated wastewater. A rotor–stator reactor(RSR) was employed to create a high-gravity environment in order to enhance ozone-liquid mass transfer rate and possibly improve the degradation rate of o-PDA. The degradation efficiency of o-PDA(η) as well as the overall gas-phase volumetric mass transfer coefficient(KGa) were determined under different operating conditions of H_2O_2 concentration, initial o-PDA concentration, temperature of reaction, initial p H and rotation speed of RSR in attempt to establish the optimal conditions. Chemical oxygen demand reduction rate(rCOD) of wastewater treated at a particular set of conditions was also analyzed. Additionally, the intermediate products of degradation were identified using a gas chromatography-mass spectrometer(GC/MS) to further evaluate the extent of o-PDA degradation as well as establish its possible degradation pathway. Results were validated by comparison with those of sole use of ozone(O_3 process), and it was noted that η, KGa and rCODachieved by O_3/H_2O_2 process was 24.4%,31.6% and 25.2% respectively higher than those of O_3 process, indicating that H_2O_2 can greatly enhance ozonation of o-PDA. This work further demonstrates that an RSR can significantly intensify ozone-liquid mass transfer rate and thus provides a feasible intensification means for the ozonation of o-PDA as well as other recalcitrant organics.

Widespread and active piezotolerant microorganisms mediate phenolic compound degradation under high hydrostatic pressure in hadal trenches

Phenolic compounds,as well as other aromatic compounds,have been reported to be abundant in hadal trenches.Although high-throughput sequencing studies have hinted at the potential of hadal microbes to degrade these compounds,direct microbiological,genetic and biochemical evidence under in situ pressures remain absent.Here,a microbial consortium and a pure culture of Pseudomonas,newly isolated from Mariana Trench sediments,efficiently degraded phenol under pressures up to 70 and 60 MPa,respectively,with concomitant increase in biomass.By analyzing a high-pressure(70 MPa)culture metatranscriptome,not only was the entire range of metabolic processes under high pressure generated,but also genes encod-ing complete phenol degradation via ortho-and meta-cleavage pathways were revealed.The isolate of Pseudomonas also contained genes encoding the complete degradation pathway.Six transcribed genes(dmpKLMNOP_(sed))were functionally identified to encode a multicomponent hydroxylase catalyzing the hydroxylation of phenol and its methylated derivatives by heterogeneous expression.In addition,key catabolic genes identified in the metatranscriptome of the high-pressure cultures and genomes of bacterial isolates were found to be all widely distributed in 22 published hadal microbial metagenomes.At microbiological,genetic,bioinformatics,and biochemical levels,this study found that microorganisms widely found in hadal trenches were able to effectively drive phenolic compound degradation under high hydrostatic pressures.This information will bridge a knowledge gap concerning the microbial aromatics degradation within hadal trenches.

Characteristics of ozone and ozone precursors(VOCs and NOx) around a petroleum refinery in Beijing, China

A field measurement campaign for ozone and ozone precursors （VOCs and NOx） was conducted in summer 2011 around a petroleum refinery in the Beijing rural region. Three observation sites were arranged, one at southwest of the refinery as the background, and two at northeast of the refinery as the downwind receptors. Monitoring data revealed the presence of serious surface 03 pollution with the characteristics of high average daily mean and maximum concentrations （64.0 and 145.4 ppbV in no-rain days, respectively） and multi-peak diurnal variation. For NOx, the average hourly concentrations of NO2 and NO were in the range of 20.546.1 and 1.8-6.4 ppbV, respectively. For VOC measurement, a total of 51 compounds were detected. Normally, TVOCs at the background site was only dozens of ppbC, while TVOCs at the downwind sites reached several hundreds of ppbC. By subtracting the VOC concentrations at background, chemical profiles of VOC emission from the refinery were obtained, mainly including alkanes （60.0% ± 4.3%）, alkenes （21.1% ± 5.5%） and aromatics （18.9% ±3.9%）. Moreover, some differences in chemical profiles for the same measurement hours were observed between the downwind sites; the volume ratios of alkanes with low reactivity and those of alkenes with high reactivity respectively showed an increasing trend and a decreasing trend. Finally, based on temporal and spatial variations of VOC mixing ratios, their photochemical degradations and dispersion degradations were estimated to be 0.15-0.27 and 0.42-0.62, respectively, by the photochemical age calculation method, indicating stronger photochemical reactions around the refinery.

自噬小体绑定化合物(ATTEC)靶向降解线粒体及其潜在治疗效果

功能异常的线粒体的累积会诱发多种神经退化相关疾病,如帕金森氏病(PD)和唐氏综合征(DS).借助小分子化合物促进线粒体的降解被认为可以缓解这类疾病的进程.然而,目前尚缺乏这样一类高效、安全的靶向降解线粒体的小分子化合物.本研究借助一种名为自噬小体绑定化合物(ATTEC)的新型靶向降解技术,创造性地合成一种能同时结合自噬关键分子LC3B以及线粒体外膜蛋白TSPO的小分子化合物—mT1,并发现该化合物能够有效地降解细胞中的线粒体.借助分子生物学及细胞生物学手段,作者证明mT1能够促进LC3B和TSPO结合,从而将线粒体靶向自噬小体,并进一步与溶酶体融合而降解.此外,在PD的细胞模型和DS的类器官模型中证明mT1能够通过促进线粒体的清除而改善相应的病理学表型.该研究将ATTEC技术的应用范畴拓展到亚细胞器的层面,并为以PD和DS为代表的一类线粒体异常引起的疾病提供了一种潜在的新治疗策略.