Photocatalytic degradation of VOCs from air stream using Mo:TiO2/GAC nanocomposites

Modification of TiO2 is one of the techniques used to enhance its photodegradation efficiency and to make it visible-light-active. In this study, Mo-doped TiO2 nanoparticles were synthesized using a fast sol-gel technique, and then coated on granular activated carbon (GAC) as both substrate and adsorbent to obtain Mo:TiO2/GAC composite. The fabricated composite was characterized using powder XRD, SEM, EDAX, FTIR, and BET analysis. Then the composite was applied to photodegrade volatile organic compounds (VOCs) under both UV and visible light irradiation. The characterization results showed high crystallinity and purity. Mo:TiO2/GAC composite had higher photodegradation efficiency compared with bare TiO2 and bare GAC. Moreover, studying operational parameters showed that the optimum condition for photodegradation efficiency of VOCs was at flowrate of 1 l/min, VOCs concentration of 20 ppm, and light intensity of 400 and 600 W/m2 for UV and visible light respectively. The results suggest that Mo:TiO2/GAC is a visible-light-active composite and can be acceptably used to decompose VOCs under visible light with adequate efficiency and without the generation of harmful by-products such as O3 as compared with UV.

Effect of an Electric Field on an Optical Breakdown in the Air Stream

Experimental data on the effect of an electric field on the plasma of an optical discharge in an air flow have been obtained. Two configurations of an external electric field under the action of an optical discharge on the plasma are considered. To create an electric field, flat (the field along the beam and across the flow) and ring electrodes (the field across the laser beam and along the flow) were used. It was found that there are two modes of combined discharge (optical and electrical). When the field was created symmetrically with respect to the flow axis, an electrical breakdown was observed from the nozzle exit (positively charged electrode) to the focusing point of the laser beam, while no streamers were observed in the optical discharge wake. In another case, an electric discharge is realized between flat electrodes simultaneously with optical breakdown. In a field of constant strength above 3 kV/cm, the presence of an optical discharge plasma promoted electrical breakdown of the medium. In this case, the parameters of the electrical breakdown depended on the shape of the electrodes, the polarity of the applied voltage, and the air flow rate.

Determination of The Physical, Physio-Chemical and Chemical Properties of Gilaburu Fruits (Viburnum opulus) Dried by Convectional Drying Technique

Our country has many species in fruit and vegetable cultivation. One of them is Gilaburu fruit (Viburnum Opulus), which has spread to different regions, especially in Kayseri. Longer preservation of products in fruits and vegetables; Drying process has been applied since ancient times to prevent deterioration caused by microbial and/or biochemical changes. One of them and the most common one is convectional drying in other words drying in a drying chamber under controlled hot air stream. In this study, Gilaburu fruits were obtained from a local producer in Kayseri. Drying processes were carried out in a convectional oven at 60, 70 and 80℃ in three repetitions. The effects of different drying conditions on the drying characteristics of Gilaburu fruits were examined. Drying time for Gilaburu fruits decreased with increasing temperature. As a color parameter total color change with respective to fresh fruit (ΔΕ) was investigated. The results indicated that it remained almost identical with temperature change. Similar trend was observed for rehydration rate. Titration acidity and pH values showed compatible changes. With temperature increase, titration acidity increased, as pH decreased. As textural properties, skin-hardness and elasticity of dried fruits were measured. As hardness increased, elasticity decreased with temperature elevation. Total phenolic content and antioxidant activity of dried samples were also examined. The results showed that there were increases in both of them with an increase in temperature.

Uji Spesifikasi Pengukuran PM10 Dengan EPAM5000 dan BAM 1020 Terhadap Kelembaban Udara

PM10 merupakan salah satu aerosol yang merupakan bagian dari partikel pencemar. Keberadaannya menempati volume ruang di atmosfer dengan konsentrasi yang selalu tergabung dengan materi lainnya dan dipengaruhi oleh kondisi atmosfer setempat. Pengukuran PM10 pada periode waktu siang dan malam dengan menggunakan EPAM5000 dan BAM1020 telah dilakukan untuk mengetahui specifikasi alat terhadap hasil pengukuran pada responnya terhadap unsur cuaca (kelembaban). Data hasil pengukuran dan analisis korelasi menunjukkan bahwa terdapat perbedaan pada hasil ukur konsentrasi PM10 pada periode malam pada EPAM5000 dan BAM1020 yang disebabkan oleh perbedaan pendukung instrument pada aliran udara masuk. Adanya smart heather pada BAM1020 berfungsi untuk mengontrol kadar uap air dari aliran udara yang dihisap sedangan pada EPAM5000 udara yang dihisap langsung diukur kosentrasinya sehingga hasil ukur konsentrasi PM10 pada EPAM5000 lebih tinggi karena masih mengandung banyak uap air (aerosol hidroskopis). Adanya menu Manual Zero atau Auto Zero pada EPAM5000 untuk membersihkan optic sensor dan mereset menjadi 0 mg/m3. Pada periode malam, partikulat PM10 akan bergabung dengan uap air menyebabkan konsentrsi yang terukur pada EPAM5000 tinggi. Hal ini diperkuat oleh hasil korelasi menunjukkan bahwa nilai PM10 berkorelasi kuat terhadap kelembaban data pengukuran EPAM5000. Untuk ini perlu adanya metode untuk memisahkan PM10 dan materi lainnya (uap air) agar didapatkan nilai konsentarsi yang sebenarnya untuk menentukan kebijakan terkait kondisi udara yang terjadi.ABSTRACTPM10 is one of the aerosols which is part of polluting particles. Its existence occupies a volume of space in the atmosphere with a concentration that is always combined with other materials and is influenced by local atmospheric conditions. Measurement of PM10 in the time period of day and night using EPAM5000 and BAM1020 has been carried out to determine the specifications of the instrument on the measurement results in response to weather elements (humidity). Measurement data and correlation analysis indicate that there are differences in the results of measuring PM10 concentrations in the night period on EPAM5000 and BAM1020 due to differences in instrument support in the intake air flow. The presence of a smart heather on the BAM1020 functions to control the water vapor content of the sucked air stream, while on the EPAM5000 the air that is sucked is directly measured so that the concentration of PM10 on EPAM5000 is higher because it still contains a lot of water vapor (hydroscopic aerosol). There is a Manual Zero or Auto Zero menu on the EPAM5000 to clean the optical sensor and reset it to 0 mg/m3. During the night period, PM10 particulates will combine with water vapor causing concentrations measured at high EPAM5000. This is confirmed by the correlation results showing that the PM10 value has a strong correlation to the humidity of the EPAM5000 measurement data. For this, it is necessary to have a method for separating PM10 and other materials (water vapor) in order to obtain the actual concentration value to determine policies related to air conditions that occur.

Statistical Analysis of SO2 and NO2 with Respect to Meteorological Parameters (Gwalior, India)

The present study is carried out in Gwalior to know the level of pollutants viz sulphur dioxide (SO2) and nitrogen dioxide (NO2). In this study, both NO2 and SO2 were collected during different seasons, and estimation was done using chemical methods. The methods used for the determination of SO2 and NO2 in the ambient air of Gwalior was (Modified West and Geake method) and (Modified Jacob and Hochheisier). The SO2 from the air stream was absorbed in a sodium tetramer curate solution. NO2 was collected by bubbling air through a sodium hydroxide solution to form a stable solution of sodium nitrate. Meteorological parameters like temperature, relative humidity were recorded by thermometers and hygrometry during the sampling. Rainfall data was taken from Indian Meteorological Department, New Delhi, for four sampling years. The statistical analysis was carried out between the level of pollutants SO2 and NO2 measured and meteorological parameters recorded during the sampling. This study observed that pollutants were very high in winter and summer compared to monsoon and post-monsoon periods due to the heavy transport movement and favourable meteorological conditions like temperature, humidity, rainfall, and wind speed and directions.

Stability of an air–water mixing layer: focus on the confinement effect

The shear instability occurring at the interface between a slow water layer and a fast air stream is a complex phenomenon driven by momentum and viscosity differences across the interface, velocity gradients as well as by injector geometries. Simulating such an instability under experimental conditions is numerically challenging and few studies exist in the literature. This work aims at filling a part of this gap by presenting a study of the convergence between two-dimensional simulations, linear theory and experiments, in regimes where the instability is triggered by the confinement, i.e. finite thicknesses of gas and liquid streams. It is found that very good agreement between the three approaches is obtained. Moreover, using simulations and linear theory, we explore in detail the effects of confinement on the stability of the flow and on the transition between absolute and convective instability regimes, which is shown to depend on the length scale of the confinement as well as on the dynamic pressure ratio. In the absolute regime under study, the interfacial wave frequency is found to be inversely proportional to the smallest injector size (liquid or gas).

Large scale aspects of the monsoon-2011 Relevant to the objectives of the CTCZ

Hkkjr esa xzh"edkyhu ekulwu ds nkSjku flukWfIVd vkSj mi&ekSleh mrkj p<+koksa dks le>us ds fy, o"kZ 2011 esa egk}hih; m".kdfVca/kh; vfHklj.k {ks= ¼lh-Vh-lh-tsM-½ ds uke ls Hkkjrh; ok;qeaMyh;&leqnzh foKku leqnk; us ,d QhYM dk;Zdze vk;ksftr fd;kA bl dk;Zdze dk ,d mís'; ekulwu ds flukWfIVd vkSj varjk&ekSleh mrkj&p<+koksa ls lacaf/kr c`greku ifjlapj.k ds dzfed fodkl ds ckjs esa tkudkjh izkIr djuk Hkh jgk gSA bl 'kks/k i= esa ekulwu 2011 ds le; cM+s iSekus ij gq, mrkj&Pk<+koksa ds ckjs esa Hkh crk;k x;k gSA o"kZ 2011 esa ekuwlu esa ekSle dh yxHkx lkekU; o"kkZ gqbZ rFkkfi mi&ekSleh eku ij twu ekg esa vPNh o"kkZ gqbZ] rRi'pkr tqykbZ ekg esa de o"kkZ gqbZ vksj fQj vxLr ekg ds vkjaHk ls ysdj flracj ekg ds var rd fQj ls vPNh o"kkZ gqbZA ekSle ds iwokZ)Z esa djhc&djhc U;wVªy yk&fuuk fLFkfr;k¡ cuhA rFkkfi vxLr ekg ls ysdj flracj ekg ds var rd Hkwe/;js[kh; iwohZ iz'kkar egklkxj esa leqnz lrg rkieku ¼,l-,l-Vh-½ lkekU; ls de ¼yk&fuuk fLFkfr;k¡½ esa ifjofrZr gks x,A gkykafd xaxk ds eSnkuh Hkkxksa esa fuEu {kksHkeaMy ij leqnz dh rjQ ls vkus okyh ok;q dk izokg cuk] ij iwjh _rq esa ok;q foy; yksM lkekU; ls cgqr de cus jgsA bl 'kks/k i= esa flukWfIVd ds fofHkUu igyq] iz'kkar egklkxj esa ,l-,l-Vh ds lqnwj izHkko ls lacaf/kr ekulwu ds miekSleh mrkj&p<+koksa rFkk Hkkjrh; leqnzh f}/zkqo ¼vkbZ-vks-Mh-½ ds LFkkuh; izHkko ij fopkj&foe'kZ fd;k x;kA blds lkFk&lkFk izpkyukRed lkaf[;dh; ekSle izkxqfDr ¼,u-MCY;w-ih-½ fun'kksZa] ;wjksih; e/; vof/k ekSle iwokZuqeku dsUnz ¼bZ-lh-,e-MCY;w-,Q-½] HkweaMyh; iwokZuqeku iz.kkyh ¼th-,Q-,l-½ vkSj ekSle vuqla/kku vkSj iwokZuqeku ¼MCY;w-vkj-,Q-½ ds fu"iknu ij Hkh fopkj&foe'kZ fd;k x;kA lh-Vh-lh-tsM- vkadM+ksa dk mi;ksx djrs gq, ekulwu 2011 ds fu"iknu ds vk/kj ij vkxs fd, tkus okys vuqla/kku ds dbZ {ks=ksa ds fo"k; esa Hkh lq>ko j[ks x,A Indian atmosphere-ocean science community organised a field programme known as Continental Tropical Convergence Zone (CTCZ) during 2011 to understand the synoptic and sub-seasonal fluctuations of summer monsoon over India. One of the objectives of the programme was to understand the evolution of the large scale circulation in relation to synoptic & intra-seasonal fluctuations of the monsoon. The paper addresses the large scale fluctuations of Monsoon-2011. The Monsoon-2011 performed very close to the normal rainfall of the season. However, on the sub-seasonal scale its performance was good during June, became deficient during July and it recovered from the beginning of August to the end of September. The early part of the season was accompanied by near neutral La-Nina conditions. However, sea surface temperatures (SSTs) in the Equatorial Eastern Pacific Ocean shifted to below normal (La-Nina conditions) from August to the end of September. As the Gangetic Plain was swept by marine origin air stream in the lower troposphere, the aerosol load remained much below the normal during the entire season. The paper discusses different aspect of synoptic, sub-seasonal fluctuations of monsoon in relation to remote forcing of the SSTs in the Pacific and the local forcing of the Indian Ocean Dipole (IOD). Also the performance of the operational numerical weather prediction (NWP) models: European Centre for Medium-Range Weather Forecasts (ECMWF), Global Forecast System (GFS) and Weather Research and Forecasting (WRF) is discussed. Several areas of further research using CTCZ data are also suggested based on the performance of the Monsoon-2011.

Theoretical and Experimental Studies of Uneven Dust Suction from a Multi-Cyclone Settling Tank in a Two-Stage Air Filter

In this paper, the uneven air stream distribution problem of individual cyclones is studied in the multi-cyclones of intake air filters in special vehicles’ engines. This problem increases in multi-cyclones, in which several dozen cyclones have a common dust trap from which the collected dust is continuously removed by ejection suction. The aim of this study is the recognition of the theoretical and experimental possibility of reducing the streams’ unevenness, which should result in an efficiency increase in multi-cyclone separation. The methods that led to obtaining a relative stream uniformity from the suction of individual cyclones was analyzed. The method for creating equal pressure drops between the suction streams in the channels was used to achieve this goal. For this purpose, the internal structure of the multi-cyclone settler was changed. The multi-cyclone settling tank space was divided by vertical partitions into independent segments. The settling tank segment was then divided with horizontal shelves into suction channels of different heights, which were assigned a specific number of individual cyclones. The suction channels’ height was theoretically selected in terms of the equal resistance to air stream flow through the channels. For this purpose, the multi-cyclone dust settler segment model was developed. The theoretically determined suction channel’s height was verified by performing experimental flow tests in four (A, B, C, D) dust settler variants. Suction streams of satisfactory uniformity from the cyclones of the variant D settling tank were obtained at a level of 5%. In the next stage, experimental tests of the segment cyclones were carried out with dust before and after the division into suction channels of variant D for the settling tank. A significant increase was achieved from 93.73% to 96.08% in the cyclones’ separation efficiency, which were located as far away from the suction stub as possible and led to a reduction in the non-uniformity of cyclone efficiency in the segment. It follows that the multi-cyclone dust settling segment’s internal structure change gave the expected results.

Assessment of the efficiency of the use of activating turbulent jets to eliminate the risk of the formation of unventilated zones in large premises

Strict requirements for microclimate parameters are imposed on food storage premises, which are equipped with artificial cooling systems. The experience of operating the refrigerated premises revealed the following disadvantages: uneven distribution and significant fluctuations in temperature and relative humidity; periodic precipitation of condensate in low-temperature sections. Elimination of the noted disadvantages is effectively achieved by using axial fans that form a swirling air stream that induces the ambient air. Swirling jets used to intensify the process of air circulation in a room in order to eliminate unventilated zones will be called activating jets. To assess the efficiency of the application of activating turbulent jets, an integral method based on the energy balance was used. Using the example of a representative object, it is shown that the distance of the effective application of an activating turbulent jet should be calculated taking into account the influence of environmental turbulence, which is determined by the amount of energy introduced and dissipated in the room.