Degradation of Furfural by UV/O3 Technology

Furfural in aqueous solution was treated by UV/O3 method.The results show that the removal rate of furfural is severely enhanced and the synergism phenomenon appears when ultraviolet and ozone are present together.The influences of experimental parameters such as pH,the intensity of light and the negative-positive ions on furfural degradation were investigated.The results indicate that furfural(300 mg/L) is almost completely degraded after 3 h under the optimum conditions.The intermediate in the furfural de...     

Retrieval of ozone profile from ground-based measurements with polarization: A synthetic study

We perform a retrieval based on optimal estimation theory to retrieve the vertical distribution of ozone from simulated spectra in the Huggins bands. The model atmosphere includes scattering by aerosol as well as Rayleigh scattering. The virtual instrument is ground-based and zenith-viewing. Using this algorithm, we show that it is possible to retrieve the ozone profile provided that the spectral resolution is at least 0.2 nm and the signal to noise ratio greater than 500. Our synthetic retrievals suggest that if we are able to measure the Stokes parameters Q, U and V with accuracy comparable to that of the intensity, the information contained in the measurements, and therefore the inversion, will improve. Furthermore, we find that the measurement of the full Stokes vector from the ground-based instrument will especially enhance the retrieval of tropospheric ozone. Utilizing concepts from information theory, our arguments are confirmed by increases in the degrees of freedom and the Shannon information content in the simulated measurements.     

Interaction of ozone with gold nanoparticles

Gold nanoparticles interact with aqueous ozone to produce a surface plasmon resonance shift without aggregation of the nanoparticles. Given ozone's destructive nature, the surprising finding was that the gold nanoparticles returned to their original color and were able to cycle between the wavelengths as ozone was introduced and removed. Gold islands were made and tested for a gaseous ozone response. Similarly to the aqueous system, the gold islands show a cycling effect. Potentially, this system would be useful as a sensor that identifies the presence of ozone in gaseous media.     

Ozone profiles and total column amounts derived at Izaña, Tenerife Island, from FTIR solar absorption spectra, and its validation by an intercomparison to ECC-sonde and Brewer spectrometer measurements

Since February 1999 high-resolution Fourier transform infrared (FTIR) solar absorption spectra are recorded at the Izaña Observatory (, 2370 m a.s.l.), which forms part of the network for detection of stratospheric change (NDSC). The vertical distribution of the ozone amount was deduced from the spectra by using the retrieval code PROFFIT. Two microwindows at 782.5 and are used whereby an individually and regularly determined instrumental line shape (ILS) was applied. A detailed error analysis of the ozone retrieval is performed, i.e. the height-dependent impact of all important error sources on the retrieved profiles is estimated. The retrieved total column amounts and profiles as well as their estimated error budgets are verified by comparisons with column amounts and profiles derived from Brewer spectrometer and ECC-sonde measurements performed simultaneously at the same location. Whereas the mean difference of 1.9% of the FTIR total column amounts and the Brewer data lies within the precision of the instruments, systematic differences of up to 9% between FTIR and ECC-sonde profile are observed above . The assumed precisions of the experiments are consistent with the experimental results, which demonstrates the excellent characterization of the FTIR data. The analysis of systematic errors allows to conclude that the systematic differences are mainly due to the sonde data since the systematic errors in the FTIR profile can only explain a small part of them.     

Long-term evolution in the tropospheric concentration of chlorofluorocarbon 12 (CCl2F2) derived from high-spectral resolution infrared solar absorption spectra: retrieval and comparison with in situ surface measurements

The average tropospheric volume mixing ratios of chlorofluorocarbon 12 (CCl₂F₂) have been retrieved from high-spectral resolution ground-based infrared solar-absorption spectra recorded from March 1982 to October 2003 with the McMath Fourier transform spectrometer at the US National Solar Observatory facility on Kitt Peak in southern Arizona (31.9°N, 111.6°W, 2.09 km altitude). The retrievals are based on fits to the unresolved ν₈ band Q-branches near using the SFIT2 retrieval algorithm. The annual increase rate was equal to (16.88±1.37) parts per trillion (10^-12) by volume at the beginning of the time series, March 1982, or (4.77±0.04)%, 1 sigma, declining progressively to (2.49±1.24) parts per trillion, by volume at the end, October 2003, or (0.46±0.24)%, 1 sigma. Average tropospheric mixing ratios from the solar spectra have been compared with average surface flask and in situ sampling measurements from the Climate Monitoring and Diagnostics Laboratory (CMDL) station at Niwot Ridge, CO, (USA) (40.0°N, 105.5°W, 3013 m altitude). The average ratio and standard deviation of the monthly means of the retrieved tropospheric mixing ratios relative to the CMDL surface mixing ratios is (1.01±0.03) for the overlapping time period. Both datasets demonstrate the progressive impact of the Montreal protocol and its strengthening amendments on the trend of CCl₂F₂, though a tropospheric decrease has yet to be observed.     

Residual aqueous ozone determination by gas diffusion reverse flow injection analysis

A novel system based on reverse flow injection analysis with a gaseous diffusion step (GD-r-FIA) has been developed for the analysis of ozone. It includes an automatic microburet injection system. The ozone diffuses through a microporous membrane of polyvinylidene difluoride (PVDF) from the donor stream to the acceptor stream containing nitrite ions. The nitrite concentration in the acceptor solution decreases due to the ozone reduction reaction. In this way, a simple indirect measurement of the ozone concentration can be performed using the Griess–Ilosvay reaction for the nitrite ion. This correlates with the decrease in absorbance of the azoic dye formed with the ozone concentration in the donor stream. The system has been optimised by investigating the effect of the nitrite concentration in the acceptor stream on the diffusion flow. The optimum nitrite concentration was set at 0.250 ppm with a flow rate of 1.5 ml/min. The efficiency of the ozone diffusion through the membrane was only 4.4%. This affects the average sensitivity, which is low (0.0092±0.0012 AU/ppm), although the detection limit is similar to that obtained with other reported methods (0.03 ppm). The main advantage of the system reported here is that it has a linear range that is an order of magnitude broader than those observed for other GD-FIA systems. This is especially useful for continuous monitoring systems, since the residual ozone concentration is normally between 0.05 and 5.0 ppm. Additionally, using the reverse flow injection analysis (FIA) technique minimises chemical consumption and residue generation. Finally, the stability of the ozone solution and the repeatability and reproducibility of the method have been studied.     

Crucial role of the magnetic field in the evolution of life

The formation of a steady ozone layer in the earth’s atmosphere is the most significant event in the evolutionary cycle of the earth which, in turn, has been responsible for the development of life with an oxygen metabolism. In addition to protecting biological life from exposure to ultraviolet radiation the ozone layer has also been responsible for maintaining the water and oxygen balance in the atmosphere. It is argued that the magnetic field of the earth is really responsible for the formation of this steady ozone layer in the earth’s atmosphere. Because of the earth’s magnetic field and associated trapped charge particle belts and the magnetosphere, the earth’s atmosphere does not directly interact with the interplanetary space. Without such a shielding, the free oxygen atoms could have been depleted considerably causing a severe depletion in the ozone concentration to start with. The impact of charged particles from galactic and solar cosmic rays over the entire earth’s atmosphere and the consequent production of NO _x would have given rise to a major ozone sink, if earth were devoid of a magnetic field. The net result would have been the absence of a steady ozone layer and the absence of life with an oxygen metabolism, as in the case of the atmospheres of Venus and Mars, if the earth did not have a magnetic field.     

Effect of complexones and tensides on selectivity of nitrogen dioxide determination in air with a chemiluminescence aerosol detector

Modification of the luminol solution by means of addition of various complexones and surfactants has been investigated to eliminate interferences from gaseous co-pollutants in the determination of ambient nitrogen dioxide using a chemiluminescence aerosol detector. The simultaneous presence of EDTA and triton X-100 or X-405 together with sulphite and iodide in the luminol solution suppressed interferences from ozone and peroxyacetyl nitrate to a negligible level and no scrubbers or corrections of the NO₂ measurements were needed.

In general, the best composition of the reagent solution included luminol, KOH, Na₂SO₃, KI, Na₂EDTA and triton X-100. From the point of view of selectivity of NO₂ determination, an optimum reagent solution consisted of luminol (0.002 M), KOH (0.5 M), Na₂SO₃ (0.2 M), KI (0.1 M), Na₂EDTA (0.05 M) and triton X-100 (0.5 vol.%). Interferences from ozone (170 ppb (v/v)) and peroxyacetyl nitrate (81 ppb (v/v)) were 0.2 and 1.2%, respectively, for nitrogen dioxide at a concentration of 50 ppb (v/v) and 0.25 and 1.7%, respectively, for 0.5 ppb (v/v) NO₂. The calibration graph was linear for NO₂ concentrations ranging from 3 to 665 ppb (v/v). Below 3 ppb (v/v) NO₂ the detector response to nitrogen dioxide can be fitted with a linear equation of the third order.     

利用紫外和荧光光谱指示臭氧降解典型内分泌干扰物的研究

污水处理和再生回用是缓解我国水污染严重和水资源紧张的有效途径。二级出水水量大、稳定且水质相对良好，是污水再生回用的良好水源。然而，二级出水中广泛存在内分泌干扰物(endocrine disrupting compounds, EDCs)，对其再生回用形成了潜在的安全风险。臭氧氧化是去除EDCs的有效方法，但二级出水中存在着多种有机质，臭氧降解EDCs的过程中同时和有机质中的活性基团发生反应，引起一定程度的臭氧衰减，从而对EDCs的臭氧氧化造成影响。有机质中与臭氧反应的活性基团变化可反映为特征紫外和荧光光谱的变化。因此，可以采用特征紫外和荧光光谱变化来指示臭氧对EDCs的降解效果。本研究通过考察二级出水中主要的三类有机质代表(腐殖酸、牛血清蛋白和海藻酸钠)对臭氧衰减动力学的影响，进一步解析有机质对5种典型EDCs臭氧降解规律的影响，在此基础上考察特征紫外和荧光光谱与EDCs臭氧降解效果的关系，以期筛选出二级出水中EDCs臭氧降解效果的指示参数，并建立其与EDCs降解效率之间的定量关系，从而以这些指示参数来预测EDCs的臭氧化降解情况，简化EDCs检测。该研究中五种目标EDCs(雌酮(E1)、雌二醇(E2)、雌三醇(E3)、17α-乙炔基雌二醇(EE2)和双酚A(BPA))采用超高效液相色谱-双质谱联用技术同时分析定量。通过考察不同种类二级出水有机质对臭氧衰减动力学和EDCs降解效果的影响发现三种有机质均可促进臭氧衰减，对EDCs的臭氧化降解效率均有抑制作用，顺序依次是腐殖酸>牛血清蛋白>海藻酸钠；三种有机质的紫外-可见光谱特征谱图表明有机质中能与臭氧反应的活性基团在紫外-可见光有特定的响应特征；三种有机质的三维荧光光谱特征谱图表明富里酸类腐殖质及喹啉类结构对臭氧消耗均有显著的贡献；腐殖酸在254，258和280 nm的紫外吸光度及激发波长/发射波长(Ex/Em)=240/396 nm，Ex/Em=345/436 nm的荧光吸光度去除率与臭氧投加量显著相关；其中280 nm处的特征紫外吸光度UVA₂₈₀，特征荧光吸光度Ex/Em=240/396 nm可作为臭氧降解EDCs的指示参数，具体为UVA₂₈₀去除率大于18%或者Ex/Em=240/396 nm去除率大于35%时，1 μmol·L-1的5种EDCs几乎被完全降解。此研究对污水处理厂臭氧去除EDCs过程中臭氧剂量的优化及EDCs去除效果具有指导作用，且可避免复杂的EDCs检测。     

Intensified recovery of lipids,proteins, and carbohydrates from wastewater-grown microalgae Desmodesmus sp. by using ultrasound or ozone

This study evaluates the effect of ultrasound and ozone pretreatments for the subsequent recovery of Desmodesmus sp. biocomponents—lipids, proteins, and carbohydrates—using a response surface methodology. Both pretreatments impact on the recovered lipids quality, solvent waste production and extraction time is analysed for process intensification purposes. For ultrasound pretreatment, independent parameters were energy applied (50–200 kWh/kg dry biomass), biomass concentration (25–75 g/L), and ultrasonic intensity (0.32 and 0.53 W/mL). While for ozone pretreatment, independent parameters were ozone concentration (3–9 mg O₃/L), biomass concentration (25–75 g/L), and contact time (5–15 min). In the case of ultrasound pretreatment, recovery yield reached 97 ± 0.4%, 89 ± 3%, and 73 ± 0.6% for proteins, carbohydrates and lipids respectively. Given process required: energy applied of 50 kWh/kg dry biomass, 75 g/L of biomass concentration, 0.32 W/mL of ultrasonic intensity, and 56 min of time process. Ultrasound caused high cell disruption releasing all proteins, thereby obviating downstream processing for its recovery. Ozone pretreatment recovery yield was 85 ± 2%, 48 ± 1.4%, and 25 ± 1.3%, for carbohydrates, lipids and proteins respectively, under the following conditions: 9 mg O₃/L of ozone concentration, 25 g/L of biomass concentration, and 5 min of contact time that depicts an energy consumption of 30.64 kWh/kg dry biomass. It was found that ultrasound and ozone pretreatments intensified the lysis and biocomponents recovery process by reducing solvent consumption by at least 92% and extraction time between 80% and 90% compared with extraction of untreated biomass biocomponents. Both pretreatments improve the composition of the recovered lipids. It was noted that the yield of neutral lipids increased from 28% to 67% for ultrasound pretreatment while for ozone pretreatment from 49% to 63%. The method used for lipid extraction may also have an effect but here it was kept constant.