Dioxide Oxide Research Articles

Features of degradation and recovery of the optical properties of coatings based on ZnO powder modified with nanoparticles after irradiation

ABSTRACTThe effect of electron irradiation with energy of 30 keV and fluence up to 7 × 1016 cm−2 on diffuse reflection spectra in situ of coatings based on ZnO powders unmodified and modified with zirconium dioxide and aluminum oxide nanopowders was investigated. The higher radiation stability of coatings based on modified pigments in comparison to unmodified pigments has been established. A significant recovery of the reflection spectra of irradiated coatings after exposure to residual vacuum and air was shown.

Effects of emulsifying agents on the safety of titanium dioxide and zinc oxide nanoparticles in sunscreens

ABSTRACTThe use of titanium oxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) in sunscreen formulations has increased considerably, and might pose a serious health hazard worldwide. A thorough investigation into the toxicity induced by such components is highly necessary. In this study, the effects of TiO2 and ZnO NPs on HaCaT cells were tested in the presence and absence of emulsifiers (cyclopentasiloxane, jojoba ester, and lecithin). Cell viability results revealed that the toxicity of NPs was highly dose dependent and influenced by the emulsifier type. The emulsifiers themselves are minimally toxic. However, when used in combination with TiO2 and ZnO, they were highly toxic to HaCaT cells. Transmission electron microscopy revealed that the cells showed least permeability to NPs dispersed in lecithin compared to other emulsifiers. In conclusion, the toxicity of NPs may be highly dependent on the emulsifier type and be varied. In particular, lecithin can be used as a potential alternative emulsifier in sunscreens.

Suppression of parasitic modes in a YAG:Nd slab laser using selective coating

The use of selective coating for suppression of parasitic modes in a slab laser with a YAG:Nd active element is investigated. Various designs of selective coatings are analyzed and optimized, based on the phenomenon of total internal reflection. The possibility of implementing a selective coating based on thin-film materials titanium, silicon dioxide, and aluminum oxide is demonstrated.

Analysis of Technogenic Loading on the Natural Environment of the Zaporozhye Region

Purpose. To assess the level of pollution of the atmospheric air and the surface waters of the Zaporozhye region, as well as assessing the technogenic loading on the natural environment of the region. Methods. Statistical. Results. The obtained results indicate that the highest values of the atmospheric pollution index are defined in such substances as formaldehyde, phenol, nitrogen dioxide and nitrogen oxide. The surface waters quality of the Zaporozhye region was characterized as "poorly polluted", class I – "polluted", class II. The assessment of the loading on the air basin showed a gradual decrease in the level of loading. The contribution of mobile sources is about 50 % of the total emissions. For the surface water, there is also a significant decrease in a loading module index. With the amount of accumulated waste, a loading level increases. For a generated waste amount, a maximum amount is solid household waste. The overall assessment of a technogenic loading on the region shows that in 2010 – 2012, the maximum values of a man-caused load module were characterized. A slight decrease in an anthropogenic pressure level is noted. This is due to the reduction of pollutants emissions into the atmosphere and the generation of waste in 2013 – 2015. Conclusion. Zaporozhye region belongs to the technogenically stressed regions. Priorities for improving the state of the environment are activities related to reducing the amount of pollutant emissions into the atmosphere and the generation of waste.

Bio-drying Technology of Solid Waste to Reduce Greenhouse Gas

Bio-drying technology is a solid waste treatment with a decentralized system, in which solid waste will undergo biological-mechanical bioconversion. The heat generated from the aerobic decomposition process of organic compounds combined with excess air serves to drain solid waste. The bio-drying process will emit VOCs and other gases that potentially cause global warmings such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) gases. The research method used variation of airflow from 0, 2, 3, 4, 5, and 6 l/m. N2O gases were analyzed using Chromatography gas. The results showed that the bio-drying process was able to reduce the water content from 69% to 40% by the thirtieth day. N2O concentration difference between control (no aeration) and waste with bio-drying processing is 534.69 ppb and 175.48 ppb respectively at 1st day. N2O concentration are known when the bio drying process uses a 4 l / m discharge.

Hydrogen peroxide-assisted photocatalytic degradation of textile wastewater using titanium dioxide and zinc oxide

ABSTRACTThe present work investigated the degradation of a dyeing factory effluent by advanced oxidative process under UV irradiation. TiO2 and ZnO were used as catalysts and the influence of different concentrations of H2O2 added to the system was studied. The catalysts were characterized in terms of crystal structure (X-ray diffraction), textural properties (Brunauer–Emmett–Teller area and pore volume) and point of zero charge, which indicated the semiconductors had a positively charged surface in an acidic medium. After 8 h of irradiation at pH 3.0 and catalyst concentration of 0.0625 g L−1, the effect of H2O2 was evaluated by means of kinetic efficiency (rate constants), absorbance reduction (at 284, 621 e 669 nm), total organic carbon reduction and mineralization (in terms of the formation of ions such as and ). Adding H2O2 to the photocatalytic system significantly increased pollutants’ removal, highlighting tests with 1.0 × 10−2 mol L−1, showing higher absorbance reduction and rate constants at 621 and 669 nm for TiO2 and best mineralization rates for ZnO. Ecotoxicity bioassays using Artemia salina L confirmed the treatment efficacy, with effluent lethal concentration (LC50) increasing from 65.68% (in natura) to over 100% after photocatalysis treatment.

Development and characterization of clay facial mask containing turmeric extract solid dispersion

Objective: To develop clay facial mask containing turmeric extract solid dispersion (TESD) for enhancing curcumin water solubility and permeability and to determine suitable clay based facial mask.Methods: The TESD were prepared by solvent and melting solvent method with various TE to polyvinylpyrrolidone (PVP) K30 mass ratios. The physicochemical properties, water solubility, and permeability were examined. The effects of clay types on physical stability of TESD, water adsorption, and curcumin adsorption capacity were evaluated.Results: The TESD prepared by solvent method with a TE to PVP K30 mass ratio of 1:2 showed physically stable, dry powders, when mixed with clay. When TESD was dissolved in water, the obtained TESD micelles showed spherical shape with mean size of ∼100 nm resulting in a substantial enhancement of curcumin water solubility, ∼5 mg/ml. Bentonite (Bent) and mica (M) showed the highest water adsorption capacity. The TESD’s color was altered when mixed with Bent, titanium dioxide (TiO2) and zinc oxide (ZnO) indicating curcumin instability. Talcum (Talc) showed the greatest curcumin adsorption followed by M and kaolin (K), respectively. Consequently, in vitro permeation studies of the TESD mixed with Talc showed lowest curcumin permeation, while TESD mixed with M or K showed similar permeation profile as free TESD solutions. The developed TESD-based clay facial mask showed lower curcumin permeation as compared to those formulations with Tween 80.Conclusion: The water solubility and permeability of curcumin in clay based facial mask could be improved using solid dispersion technique and suitable clay base composed of K, M, and Talc.

Cold End Corrosion Avoiding by Using a New Type of Air Combustion Pre-Heater

This paper analyzes the possibility of reducing the cold end corrosion in boilers and furnaces by using a new type of air combustion pre-heater. Cold end corrosion appears due to catalytic oxidation of the sulfur dioxide to sulfur trioxide and then due to the sulfuric acid condensation at dew point. Calculating dew points of various acid gases and options for reducing cold end corrosion of heat recovery exchangers are presented. For avoiding the cold end corrosion we design a new type of air combustion pre-heater for boilers and furnaces. Also, the tube skin temperature of the first row of pipes of the actual air pre-heater was simulated with this computer program, in order to determine whether this temperature is lower than acid dew point of flue gas. With the simulation for this configuration of the actual combustion air pre-heater, the skin temperature for the first row (for the combustion air flow) of tubes from the upper bundle was TS = 134 °C. A way to reduce the cold end corrosion in the combustion air pre-heaters is raising the temperature of the combustion air at the air pre-heater entrance. This solution involves taking a quantity of preheated air, recirculation and then reintroducing it in the air pre-heater. In the same time, this solution avoiding to use the steam radiator, mounted after the fan, for pre-heating the combustion air from 1°C to 45°C. Thus, the furnaces equipped with the new combustion air pre-heater and modern low NOx burners made a fuel economy about 3%.

The Characterisations of Airborne Particulates Soiling Defect Towards Museum Artefacts

The conservation of museum artefact and its preservation against possible damage from air pollution is of increasing concern. Soiling is harmful to the inorganic artefact as it happened when the airborne particulates deposited onto the surface of objects and then the chemical compounds catalyse the oxidation of sulphur dioxide (SO2) to form sulfuric acid which presence as the black crust. The deposited airborne material can attack museum collections chemically. Therefore, museum environment should have low particle concentrations. This paper present current literature studies on the relationship of chemical characteristics of airborne particulates with the soiling defect of the inorganic artefact. The aim of this article is to provide a better understanding of the origin of particulates pollutants within the built environment. This research employs a qualitative method which encompasses the technique of case studies and content analysis of reports on physical and chemical properties of airborne particulates and soiling defect of museum artefact. A significant finding of this paper is the in-depth understanding of the various chemical characterization of airborne particulate that reacts with the artefact surface to form a black crust or soiling defect. The results will assist future research to come up with a variety of solution and techniques to control the rate of particle depositing to the surfaces of an artefact as many of the techniques are cost saving. So, to protect and conserve the relics of human history, it is important to apprehend the interaction of atmospheric pollutants, airborne particulates and heritage material towards the conservation of built environment.

Ozone Measurements at Some Work Places for Environment Protection and Career Health Care

ABSTRACTAir pollution has become one of the top issues in China. The Chinese government has launched a national program to reduce emissions of particulate matter (PM2.5), carbon dioxide, sulfur dioxide and nitrogen oxide during its “Twelfth Five-Year Plan” (2011–2015). In the following decade (2016–2025) emphases will be placed on control of volatile organic compounds (VOCs) emissions and ground-level ozone. Before that, a lot of background knowledge has to be known such as source apportionments of VOCs and ozone in air environment, which is so far very limited in China. In this work, concentrations of ozone and its precursors were measured at work places like petroleum factory, coal-fired power plant, shipbuilding factory (welding site) and heavy traffic road. The major aim of this article is to investigate the presence of those point sources in ozone formation in the area. Although the measurements were rough, results met the needs of China’s strategy on environment protection and career health care, and may serve as reference data for basic research work.

PREPARATION AND CHARACTERIZATION OF SUPERHYDROPHILIC NANOCOMPOSITE ULTRAFILTRATION MEMBRANES FOR TREATMENT OF HIGHLY CONCENTRATED OIL-IN-WATER EMULSION

In oily wastewater treatment using membrane technology, surface fouling is the major issue that could deteriorate membrane flux and shorten its lifespan. Therefore, nanocomposite membranes were developed in this study by incorporating titanium dioxide (TiO2) and hydrous manganese oxide (HMO) nanoparticles into polymeric membrane matrix. Three different types of membranes were fabricated. They were pristine PES and membrane incorporated with TiO2 or HMO. With respect to pure water flux, TiO2- and HMO-incorporated membranes showed value of 57 and 40 L/m2.h, respectively. These values were 33-90% higher than that of control PES membrane. In treating 500 ppm oily solution, TiO2 membrane exhibited the highest water flux. However, the membrane’s oil removal rate was slightly compromised. When tested with higher concentration of oily solution (5,000 or 10,000 ppm), TiO2- and HMO-incorporated membranes still showed promising water flux with 94.5-99.6% oil removal rate. This proved that ultrafiltration membrane incorporated with suitable nanomaterials could improve the water flux of pristine PES membrane and is of more practical for industrial applications.

Experimental Investigation of Performance and Emissions of a Stratified Charge CNG Direct Injection Engine with Turbocharger

This paper presents the results from 1.6 litre, 4 cylinders stratified charge compressed natural gas (CNG) direct injection engine with boosting device. A turbocharger with compressor trim of 40 was used to increase engine output. The engine was tested at wide open throttle (WOT) and speed ranging from 1000 to 5000 rpm. Engine performance and emissions data were recorded under steady state condition. Results show turbocharged CNG engine produced an average of 26% increment in brake power and 24% additional maximum brake torque as compared with natural aspirated (NA) CNG engine. Turbocharged CNG engine improved brake specific fuel consumption (BSFC) and yielded higher fuel conversion efficiency (FCE). Relatively turbocharged CNG engine showed lower emission of hydrocarbon (HC) and carbon monoxide (CO) throughout tested engine speed. Conversely, the carbon dioxide (CO 2 ) and nitrogen oxide (NO x ) emission produced were slightly higher compared with NA CNG engine.

Carbon Footprint Analyses of Wastewater Treatment Systems in Puducherry

Carbon footprint analysis is a method to quantify the life cycle Greenhouse Gases (GHGs) emissions and identify the measure to reduce climate change impacts. The Intergovernmental Panel on Climate Change (IPCC) has identified that the global warming and climate change which is one of the most important issues in the domain of environment are caused by the excessive emission of Greenhouse Gases (GHG) mainly constituting Carbon dioxide (CO2), Methane (CH4) and Nitrous oxide (N2O). The municipal wastewater treatment plant receives wastewater for treatment and finally discharges the treated effluent. The emissions of GHG during the treatment of wastewater as well as during the treatment process of sludge and also for energy generation are known to be on-site GHG emissions. Off-site GHG emissions are generated due to transportation and disposal of sludge, off-site energy and chemical production. In Puducherry, the municipal wastewater is being treated using oxidation ponds, Upflow Anaerobic Sludge Blanket (UASB) and Sequencing Batch Reactor (SBR). Wastewater treatment using Sequencing Batch Reactor (SBR) technology is one of the state-of-the art wastewater management systems. In this technology equalization, biological treatment and secondary clarification are performed in a single reactor in a time control sequence. The emissions of GHG from the Oxidation ponds of 12.5 MLD, UASB reactor of 2.5 MLD and SBR of 17 MLD were assessed based on the IPCC guidelines and the total emissions of GHG in terms of equivalent of CO2 were compared. The performance of the SBR is more efficient and the emissions of GHG are less than the emissions in the UASB as well as in oxidation ponds. The emission of GHG in SBR is about 60% of the existing treatment systems of oxidation ponds and UASB thus a reduction of 40% GHG emission could be achieved.

TiO2: ZnO nanocomposites in treatment of dental plaques

Dental caries is a major concern effecting most of the individuals today. Statistics show that 69% of adults aged 35 to 44 years have lost permanent tooth due to accident, gum disease failed root canal or tooth decay. Dental plaque is a general term for the diverse microbial community found on tooth surface, embedded in matrix of polymers of bacteria. Nanoparticles considered being of a size not greater than 100 nm have unique properties to combat infection. Nanocomposite is a matrix to which nanoparticles have been added to improve a particular property of the material. The present study deals with the antimicrobial studies of nanocomposite preparations of Titanium dioxide and Zinc oxide. Titanium dioxide and Zinc oxide nanocomposites are found to be effective in inhibiting the growth of bacteria. The present work is to prepare different proportions of nanocomposites of these oxides and find out if the effectivity is more when compared to using the nanoparticle alone. Some nanocomposite materials have been shown to be 1000 times tougher than the bulk component materials. The study carried out shows that the antimicrobial activity of nanocomposites is more effective than the nanoparticle alone providing best alternative to dental implant surgery.

Simultaneously Photoacoustic Measurement of Carbon Dioxide and Nitrous Oxide Using a Quantum Cascade Laser

In this paper a photoacoustic senor for carbon dioxide and nitrous oxide detection is described which uses a quantum cascade laser. The sensor relies on a 4.43 μm continuous-wave room temperature quantum-cascade laser source and a homemade photoacoustic cell based on a cylindrical acoustic resonator. Primary laboratory tests have been performed for estimation of the achievable detection limits and possible applications for in situ and real time atmosphere measurements. It is demonstrated that the minimum detectable concentration of 13CO2 and N2O under laboratory conditions is 8 ppbv and 0.45 ppbv, respectively.

Anatase TiO2 (101) and wurtzite ZnO (001) modified polymer for visible light-photocatalytic efficiency enhancement

ABSTRACTPhotocatalytic property of titanium dioxide and zinc oxide was used in several of application in the environmental field due to their high oxidation power and a self-sensitized degradation in a wide range of organic compound. Unfortunately, the large band gap of these metal oxides absorbs only UV radiation and limits the photocatalytic efficiency results in high cost of photocatalytic degradation of environmental pollutant. To be used under visible light irradiation, time-dependent density functional theory was applied to study anatase titanium dioxide (101) and wurtzite zinc oxide (001) with modified organic materials. Four modified structures, including polyisoprene ring, polyisoprene chain, polyacethylene, and polyphenylenevinylene, were investigated. The electronic structure and simulated UV-Vis spectra were analyzed.

Catalytic Synthesis of Propylene Carbonate from CO2 and Propylene Oxide on Fixed Bed

An efficient catalytic system is developed for propylene carbonate synthesis from carbon dioxide and propylene oxide on fixed bed reactor. The active component screening results make sure that the efficient catalyst is composed of methyl imidazole onium salt, zinc bromide and phenol formaldehyde resin. The prepared catalyst proves 72 h long running with 96 % yield and 98 % selectivity of propylene carbonate. The novel extruded catalyst for PC synthesis used in fixed bed is developed. PR, MimCl and ZnBr2 have the catalytic synergy for the reaction. The catalyst composition is optimized.

ENGINE PERFORMANCE AND EXHAUST EMISSION OF DIESEL DUAL FUEL ENGINE FUELLED BY BIODIESEL, DIESEL AND NATURAL GAS

The performance and exhaust emission of 6 cylinder four stroke direct injection diesel dual fuel (DDF) engine were investigated, the duel fuel used is corn oil methyl esters consist of 5%, 10%, 15% and 20% blends with diesel and compressed natural gas (CNG). Experiment was conducted at a fixed compression ratio of 17.5:1 with variance of engine speed 1400, 1800, 2400 and 2600 rpm. Combination of Biodiesel and CNG showed a better result on engine performance in terms of horse power and engine torque compared to other types of tested fuel. The substantial decrease of 25.6 % in exhaust emission flue was observed, giving lower value of UHC and nitrogen oxide (NOx). However, when the fuel is blended with CNG, a poor performance on exhaust emission was recorded, which include carbon dioxide (CO2), carbon monoxide (CO), unburned hydrocarbon (UHC) and nitrogen oxide (NOx) due to presence of CNG in fuel.

Soil Carbon and Nitrogen Fractions of a Grassland in Central Missouri, USA

ABSTRACTQuantification of soil carbon (C) and nitrogen (N) fractions in grasslands is vital for estimating C sequestration and climate change studies. We quantified background soil total carbon (TOC) status, recalcitrant carbon (RC), acid hydrolysable labile carbon (AHC), hot- and cold-water extractable carbon (HWC and CWC, respectively) fractions in the grassland in this study. Soil C fractions were as follows: TOC (11,633 to 15,525 mg C kg−1); RC (11,500 to 15,357 mg C kg−1); AHC (132 to 168 mg C kg−1); HWC (57 to 70 mg C kg−1); and CWC (27 to 33 mg C kg−1). Labile C fractions contributed at most 1.2% to total C. Concentrations of total N ranged from 1072 to 1230 g N kg−1. Recalcitrant C contributed higher amounts (>90%) to total C, indicating the incorporation of C into the stable C fraction. Carbon dioxide (CO2) and nitrous oxide (N2O) fluxes were not significantly correlated with total C.

Experimental and numerical investigation on natural convection heat transfer in nanofluids

Abstract An experimental study has been undertaken concerning natural convection heat transfer of nanofluids over a cylindrical heater with a constant wall heat flux condition. The cylindrical heater having 7.1 mm O. D. and 0.5 mm thickness with 100 mm heated length was used as heater surface. The heat flux was varied from 0 to 50 000 W/m2 and the corresponding Rayleigh number range is varied from 3 × 104 to 1.65 × 105. Different Nanofluids were used i. e. Aluminium oxide, Titanium dioxide, Silicon dioxide and Copper oxide with concentration varying from 0.0005 % to 0.05 % by weight. Results show that there was a reduction in natural convection heat transfer coefficient of nanofluids as compared to water. Experimental results were compared with existing models for similar geometry. However, the available correlation was found to be unable to predict experimental data as it does not take into account the effect of particle concentration. A new empirical model was developed based on the experimental data including the effect of nanoparticles concentration which predicts the experimental data satisfactorily.