Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 4214

Search results for: chemical activation

4214 The Adsorption of Zinc Metal in Waste Water Using ZnCl2 Activated Pomegranate Peel

Authors: S. N. Turkmen, A. S. Kipcak, N. Tugrul, E. M. Derun, S. Piskin

Abstract:

Activated carbon is an amorphous carbon chain which has extremely extended surface area. High surface area of activated carbon is due to the porous structure. Activated carbon, using a variety of materials such as coal and cellulosic materials; can be obtained by both physical and chemical methods. The prepared activated carbon can be used for decolorize, deodorize and also can be used for removal of organic and non-organic pollution. In this study, pomegranate peel was subjected to 800W microwave power for 1 to 4 minutes. Also fresh pomegranate peel was used for the reference material. Then ZnCl2 was used for the chemical activation purpose. After the activation process, activated pomegranate peels were used for the adsorption of Zn metal (40 ppm) in the waste water. As a result of the adsorption experiments, removal of heavy metals ranged from 89% to 85%.

Keywords: activated carbon, adsorption, chemical activation, microwave, pomegranate peel

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4213 The Utilization of Tea Residues for Activated Carbon Preparation

Authors: Jiazhen Zhou, Youcai Zhao

Abstract:

Waste tea is commonly generated in certain areas of China and its utilization has drawn a lot of concern nowadays. In this paper, highly microporous and mesoporous activated carbons were produced from waste tea by physical activation in the presence of water vapor in a tubular furnace. The effect of activation temperature on yield and pore properties of produced activated carbon are studied. The yield decreased with the increase of activation temperature. According to the Nitrogen adsorption isotherms, the micropore and mesopore are both developed in the activated carbon. The specific surface area and the mesopore volume fractions of the activated carbon increased with the raise of activation temperature. The maximum specific surface area attained 756 m²/g produced at activation temperature 900°C. The results showed that the activation temperature had a significant effect on the micro and mesopore volumes as well as the specific surface area.

Keywords: activated carbon, nitrogen adsorption isotherm, physical activation, waste tea

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4212 Research of the Activation Energy of Conductivity in P-I-N SiC Structures Fabricated by Doping with Aluminum Using the Low-Temperature Diffusion Method

Authors: Ilkham Gafurovich Atabaev, Khimmatali Nomozovich Juraev

Abstract:

The activation energy of conductivity in p-i-n SiC structures fabricated by doping with Aluminum using the new low-temperature diffusion method is investigated. In this method, diffusion is stimulated by the flux of carbon and silicon vacancies created by surface oxidation. The activation energy of conductivity in the p - layer is 0.25 eV and it is close to the ionization energy of Aluminum in 4H-SiC from 0.21 to 0.27 eV for the hexagonal and cubic positions of aluminum in the silicon sublattice for weakly doped crystals. The conductivity of the i-layer (measured in the reverse biased diode) shows 2 activation energies: 0.02 eV and 0.62 eV. Apparently, the 0.62 eV level is a deep trap level and it is a complex of Aluminum with a vacancy. According to the published data, an analogous level system (with activation energies of 0.05, 0.07, 0.09 and 0.67 eV) was observed in the ion Aluminum doped 4H-SiC samples.

Keywords: activation energy, aluminum, low temperature diffusion, SiC

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4211 Kinetic Parameter Estimation from Thermogravimetry and Microscale Combustion Calorimetry

Authors: Rhoda Afriyie Mensah, Lin Jiang, Solomon Asante-Okyere, Xu Qiang, Cong Jin

Abstract:

Flammability analysis of extruded polystyrene (XPS) has become crucial due to its utilization as insulation material for energy efficient buildings. Using the Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa methods, the degradation kinetics of two pure XPS from the local market, red and grey ones, were obtained from the results of thermogravity analysis (TG) and microscale combustion calorimetry (MCC) experiments performed under the same heating rates. From the experiments, it was discovered that red XPS released more heat than grey XPS and both materials showed two mass loss stages. Consequently, the kinetic parameters for red XPS were higher than grey XPS. A comparative evaluation of activation energies from MCC and TG showed an insignificant degree of deviation signifying an equivalent apparent activation energy from both methods. However, different activation energy profiles as a result of the different chemical pathways were presented when the dependencies of the activation energies on extent of conversion for TG and MCC were compared.

Keywords: flammability, microscale combustion calorimetry, thermogravity analysis, thermal degradation, kinetic analysis

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4210 Improving Cyclability and Capacity of Lithium Oxygen Batteries via Low Rate Pre-Activation

Authors: Zhihong Luo, Guangbin Zhu, Lulu Guo, Zhujun Lyu, Kun Luo

Abstract:

Cycling life has become the threshold for the prospective application of Li-O₂ batteries, and the protection of Li anode has recently regarded as the key factor to the performance. Herein, a simple low rate pre-activation (20 cycles at 0.5 Ag⁻¹ and a capacity of 200 mAh g⁻¹) was employed to effectively improve the performance and cyclability of Li-O₂ batteries. The charge/discharge cycles at 1 A g⁻¹ with a capacity of 1000 mAh g⁻¹ were maintained for up to 290 times versus 55 times for the cell without pre-activation. The ultimate battery capacity and high rate discharge property were also largely enhanced. Morphology, XRD and XPS analyses reveal that the performance improvement is in close association with the formation of the smooth and compact surface layer formed on the Li anode after low rate pre-activation, which apparently alleviated the corrosion of Li anode and the passivation of cathode during battery cycling, and the corresponding mechanism was also discussed.

Keywords: lithium oxygen battery, pre-activation, cyclability, capacity

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4209 A Study on the Strategy for Domestic Space Industry Activation

Authors: Hangil Park, Hwayeon Song, Jingyung Sim

Abstract:

In this study, a business ecosystem of a domestic space industry is comprehensively analyzed to derive the influence factors. The priority level of each element as well as the disparity between the ideal and reality are investigated through a literature review and an expert survey. The three major influence factors determined are: (a) investment scale and approach, (b) propulsion system, and (c) industrialization with overseas expansion. Related issues based on the current status are evaluated, followed by a proposed activation strategy. This research's findings offer a direction for R&D budget allocation and law system maintenance for the activation of the domestic space industry.

Keywords: space industry, activation, strategy, business ecosystem

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4208 The Effect of Deformation Activation Volume, Strain Rate Sensitivity and Processing Temperature of Grain Size Variants

Authors: P. B. Sob, A. A. Alugongo, T. B. Tengen

Abstract:

The activation volume of 6082T6 aluminum is investigated at different temperatures on grain size variants. The deformation activation volume was computed on the basis of the relationship between the Boltzmann’s constant k, the testing temperatures, the material strain rate sensitivity and the material yield stress of grain size variants. The material strain rate sensitivity is computed as a function of yield stress and strain rate of grain size variants. The effect of the material strain rate sensitivity and the deformation activation volume of 6082T6 aluminum at different temperatures of 3-D grain are discussed. It is shown that the strain rate sensitivities and activation volume are negative for the grain size variants during the deformation of nanostructured materials. It is also observed that the activation volume vary in different ways with the equivalent radius, semi minor axis radius, semi major axis radius and major axis radius. From the obtained results it is shown that the variation of activation volume increased and decreased with the testing temperature. It was revealed that, increased in strain rate sensitivity led to decrease in activation volume whereas increased in activation volume led to decrease in strain rate sensitivity.

Keywords: nanostructured materials, grain size variants, temperature, yield stress, strain rate sensitivity, activation volume

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4207 Thermodynamics of Water Condensation on an Aqueous Organic-Coated Aerosol Aging via Chemical Mechanism

Authors: Yuri S. Djikaev

Abstract:

A large subset of aqueous aerosols can be initially (immediately upon formation) coated with various organic amphiphilic compounds whereof the hydrophilic moieties are attached to the aqueous aerosol core while the hydrophobic moieties are exposed to the air thus forming a hydrophobic coating thereupon. We study the thermodynamics of water condensation on such an aerosol whereof the hydrophobic organic coating is being concomitantly processed by chemical reactions with atmospheric reactive species. Such processing (chemical aging) enables the initially inert aerosol to serve as a nucleating center for water condensation. The most probable pathway of such aging involves atmospheric hydroxyl radicals that abstract hydrogen atoms from hydrophobic moieties of surface organics (first step), the resulting radicals being quickly oxidized by ubiquitous atmospheric oxygen molecules to produce surface-bound peroxyl radicals (second step). Taking these two reactions into account, we derive an expression for the free energy of formation of an aqueous droplet on an organic-coated aerosol. The model is illustrated by numerical calculations. The results suggest that the formation of aqueous cloud droplets on such aerosols is most likely to occur via Kohler activation rather than via nucleation. The model allows one to determine the threshold parameters necessary for their Kohler activation. Numerical results also corroborate previous suggestions that one can neglect some details of aerosol chemical composition in investigating aerosol effects on climate.

Keywords: aqueous aerosols, organic coating, chemical aging, cloud condensation nuclei, Kohler activation, cloud droplets

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4206 Zinc Adsorption Determination of H2SO4 Activated Pomegranate Peel

Authors: S. N. Turkmen Koc, A. S. Kipcak, M. B. Piskin, E. Moroydor Derun, N. Tugrul

Abstract:

Active carbon can be obtained from agricultural sources. Due to the high surface area, the production of activated carbon from cheap resources is very important. Since the surface area of 1 g activated carbon is approximately between 300 and 2000 m2, it can be used to remove both organic and inorganic impurities. In this study, the adsorption of Zn metal was studied with the product of activated carbon, which is obtained from pomegranate peel by microwave and chemical activation methods. The microwave process of pomegranate peel was carried out under constant microwave power of 800 W and 1 to 4 minutes. After the microwave process, samples were treated with H2SO4 for 3 h. Then prepared product was used in synthetic waste water including 40 ppm Zn metal. As a result, removal of waste Zn in waste water ranged from 91% to 93%.

Keywords: activated carbon, chemical activation, H₂SO₄, microwave, pomegranate peel

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4205 Saturation Misbehavior and Field Activation of the Mobility in Polymer-Based OTFTs

Authors: L. Giraudet, O. Simonetti, G. de Tournadre, N. Dumelié, B. Clarenc, F. Reisdorffer

Abstract:

In this paper we intend to give a comprehensive view of the saturation misbehavior of thin film transistors (TFTs) based on disordered semiconductors, such as most organic TFTs, and its link to the field activation of the mobility. Experimental evidence of the field activation of the mobility is given for disordered semiconductor based TFTs, when reducing the gate length. Saturation misbehavior is observed simultaneously. Advanced transport models have been implemented in a quasi-2D numerical TFT simulation software. From the numerical simulations it is clearly established that field activation of the mobility alone cannot explain the saturation misbehavior. Evidence is given that high longitudinal field gradient at the drain end of the channel is responsible for an excess charge accumulation, preventing saturation. The two combined effects allow reproducing the experimental output characteristics of short channel TFTs, with S-shaped characteristics and saturation failure.

Keywords: mobility field activation, numerical simulation, OTFT, saturation failure

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4204 Study of the Microstructural Evolution and Precipitation Kinetic in AZ91 Alloys

Authors: A. Azizi, M. Toubane, L. Chetibi

Abstract:

Differential scanning calorimetry (DSC) is a widely used technique for the study of phase transformations, particularly in the study of precipitation. The kinetic of the precipitation and dissolution is always related to the concept of activation energy Ea. The determination of the activation energy gives important information about the kinetic of the precipitation reaction. In this work, we were interested in the study of the isothermal and non-isothermal treatments on the decomposition of the supersaturated solid solution in the alloy AZ91 (Mg-9 Al-Zn 1-0.2 Mn. mass fraction %), using Differential Calorimetric method. Through this method, the samples were heat treated up to 425° C, using different rates. To calculate the apparent activation energies associated with the formation of precipitated phases, we used different isoconversional methods. This study was supported by other analysis: X-ray diffraction and microhardness measurements.

Keywords: calorimetric, activation energy, AZ91 alloys, microstructural evolution

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4203 An Experimental Approach of the Reuse of Dredged Sediments in a Cement Matrix by Physical and Heat Treatment

Authors: Mahfoud Benzerzour, Mouhamadou Amar, Nor-edine Abriak

Abstract:

In this study, a sediment was used as a secondary raw material in cement substitution with prior treatment. The treatment adopted is a physical treatment involving grinding and separation to obtain different fractions, using a dry method (1 mm, 250µm, 120µm) and washing method (250µm and 120µm). They were subsequently heat treated at temperatures of 650°C, 750°C and 850°C for 1 hour and 3 hours, in order to enable chemical activation by decarbonation or by pozzolanic activation of the material. Different characterization techniques were performed. The determination of main physical and chemical characteristics was obtained through multiple tests: particle size distribution, specific density, the BET surface area, the initial setting time and hydration heat calorimetry Langavant. The chemical tests include: ATG analysis, X-ray diffractometry (XRD) and X-ray fluorescence (XRF) which were used to quantify the fractions, phases and chemical elements present. Compression tests were performed conforming NF EN 196-1 French standard, over terms of 7 days - 14 days - 28 days and 60 days on all formulated mortars: reference mortar based on 100% CEM I 52.5N binder and cement substituted mortars with 8% and 15% by treated sediment. This clearly evidenced contribution due to the chemical activity which was confirmed by calorimetry monitoring and strength investigation.

Keywords: sediment, characterization, grinding, heat treatment, substitution

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4202 Integration of the Electro-Activation Technology for Soy Meal Valorization

Authors: Natela Gerliani, Mohammed Aider

Abstract:

Nowadays, the interest of using sustainable technologies for protein extraction from underutilized oilseeds is growing. Currently, a major disposal problem for the oil industry is by-products of plant food processing such as soybean meal. That is why valorization of soybean meal is important for the oil industry since it contains high-quality proteins and other valuable components. Generally, soybean meal is used in livestock and poultry feed but is rarely used in human feed. Though chemical composition of this meal compensate nutritional deficiency and can be used to balance protein in human food. Regarding the efficiency of soybean meal valorization, extraction is a key process for obtaining enriched protein ingredient, which can be incorporated into the food matrix. However, most of the food components such as proteins extracted from oilseeds by-products imply the utilization of organic and inorganic chemicals (e.g. acids, bases, TCA-acetone) having a significant environmental impact. In a context of sustainable production, the use of an electro-activation technology seems to be a good alternative. Indeed, the electro-activation technology requires only water, food grade salt and electricity as main materials. Moreover, this innovative technology helps to avoid special equipment and trainings for workers safety as well as transport and storage of hazardous materials. Electro-activation is a technology based on applied electrochemistry for the generation of acidic and alkaline solutions on the basis of the oxidation-reduction reactions that occur at the vicinity electrode/solution interfaces. It is an eco-friendly process that can be used to replace the conventional acidic and alkaline extraction. In this research, the electro-activation technology for protein extraction from soybean meal was carried out in the electro-activation reactor. This reactor consists of three compartments separated by cation and anion exchange membranes that allow creating non-contacting acidic and basic solutions. Different current intensities (150 mA, 300 mA and 450 mA) and treatment durations (10 min, 30 min and 50 min) were tested. The results showed that the extracts obtained by the electro-activation method have good quality in comparison to conventional extracts. For instance, extractability obtained with electro-activation method was 55% whereas with the conventional method it was only 36%. Moreover, a maximum protein quantity of 48 % in the extract was obtained with the electro-activation technology comparing to the maximum amount of protein obtained by conventional extraction of 41 %. Hence, the environmentally sustainable electro-activation technology seems to be a promising type of protein extraction that can replace conventional extraction technology.

Keywords: by-products, eco-friendly technology, electro-activation, soybean meal

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4201 Preparation and Chemical Characterization of Eco-Friendly Activated Carbon Produced from Apricot Stones

Authors: Sabolč Pap, Srđana Kolaković, Jelena Radonić, Ivana Mihajlović, Dragan Adamović, Mirjana Vojinović Miloradov, Maja Turk Sekulić

Abstract:

Activated carbon is one of the most used and tested adsorbents in the removal of industrial organic compounds, heavy metals, pharmaceuticals and dyes. Different types of lignocellulosic materials were used as potential precursors in the production of low cost activated carbon. There are, two different processes for the preparation and production of activated carbon: physical and chemical. Chemical activation includes impregnating the lignocellulosic raw materials with chemical agents (H3PO4, HNO3, H2SO4 and NaOH). After impregnation, the materials are carbonized and washed to eliminate the residues. The chemical activation, which was used in this study, has two important advantages when compared to the physical activation. The first advantage is the lower temperature at which the process is conducted, and the second is that the yield (mass efficiency of activation) of the chemical activation tends to be greater. Preparation of activated carbon included the following steps: apricot stones were crushed in a mill and washed with distilled water. Later, the fruit stones were impregnated with a solution of 50% H3PO4. After impregnation, the solution was filtered to remove the residual acid. Subsequently impregnated samples were air dried at room temperature. The samples were placed in a furnace and heated (10 °C/min) to the final carbonization temperature of 500 °C for 2 h without the use of nitrogen. After cooling, the adsorbent was washed with distilled water to achieve acid free conditions and its pH was monitored until the filtrate pH value exceeded 4. Chemical characterizations of the prepared activated carbon were analyzed by FTIR spectroscopy. FTIR spectra were recorded with a (Thermo Nicolet Nexus 670 FTIR) spectrometer, from 400 to 4000 cm-1 wavenumbers, identifying the functional groups on the surface of the activated carbon. The FTIR spectra of adsorbent showed a broad band at 3405.91 cm-1 due to O–H stretching vibration and a peak at 489.00 cm-1 due to O–H bending vibration. Peaks between the range of 3700 and 3200 cm−1 represent the overlapping peaks of stretching vibrations of O–H and N–H groups. The distinct absorption peaks at 2919.86 cm−1 and 2848.24 cm−1 could be assigned to -CH stretching vibrations of –CH2 and –CH3 functional groups. The adsorption peak at 1566.38 cm−1 could be characterized by primary and secondary amide bands. The sharp bond within 1164.76 – 987.86 cm−1 is attributed to the C–O groups, which confirms the lignin structure of the activated carbon. The present study has shown that the activated carbons prepared from apricot stone have a functional group on their surface, which can positively affect the adsorption characteristics with this material.

Keywords: activated carbon, FTIR, H3PO4, lignocellulosic raw materials

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4200 Activation Parameters of the Low Temperature Creep Controlling Mechanism in Martensitic Steels

Authors: M. Münch, R. Brandt

Abstract:

Martensitic steels with an ultimate tensile strength beyond 2000 MPa are applied in the powertrain of vehicles due to their excellent fatigue strength and high creep resistance. However, the creep controlling mechanism in martensitic steels at ambient temperatures up to 423 K is not evident. The purpose of this study is to review the low temperature creep (LTC) behavior of martensitic steels at temperatures from 363 K to 523 K. Thus, the validity of a logarithmic creep law is reviewed and the stress and temperature dependence of the creep parameters α and β are revealed. Furthermore, creep tests are carried out, which include stepped changes in temperature or stress, respectively. On one hand, the change of the creep rate due to a temperature step provides information on the magnitude of the activation energy of the LTC controlling mechanism and on the other hand, the stress step approach provides information on the magnitude of the activation volume. The magnitude, the temperature dependency, and the stress dependency of both material specific activation parameters may deliver a significant contribution to the disclosure of the nature of the LTC rate controlling mechanism.

Keywords: activation parameters, creep mechanisms, high strength steels, low temperature creep

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4199 Preparation of Activated Carbon Fibers (ACF) Impregnated with Ionic Silver Particles from Cotton Woven Waste and Its Performance as Antibacterial Agent

Authors: Jonathan Andres Pullas Navarrete, Ernesto Hale de la Torre Chauvin

Abstract:

In this work, the antibacterial effect of activated carbon fibers (ACF) impregnated with ionic silver particles was studied. ACF were prepared from samples of cotton woven wastes (cotton based fabrics 5x10 cm) by applying a chemical activation procedure with H3PO4. This treatment was performed using several H3PO4: Cotton based fabrics weight ratios (1:2–2:1), temperatures (600–900 ºC) and activation times (0.5–2 h). The ACF obtained under the best activation conditions showed BET surface area of 1103 m2/g; this result along with iodine index demonstrated the microporous nature of the fibers herein obtained. Then, the obtained fibers were impregnated with ionic silver particles by immersion in 0.1 and 0.5 M AgNO3 solutions followed by drying and thermal decomposition in order to fix the silver particles in the structure of ACF. It was determined that the presence of Ag ions lowered the BET surface area of the ACF in approximately 17 % due to the obstruction of the porosities along the carbonized structure. Finally, the antibacterial effect of the ACF impregnated with silver was studied through direct counting method for coliforms. The antibacterial activity of the impregnated fibers was demonstrated, and it was attributed to the strongly inhibition of bacteria growth because of chemical properties of the particles of silver inside the ACF. This behavior was demonstrated at concentrations of silver as low as 0.035 % w/w.

Keywords: activated carbon, adsorption, antibacterial activity, coliforms, surface area

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4198 Inhibitory Effects of PPARγ Ligand, KR-62980, on Collagen-Stimulated Platelet Activation

Authors: Su Bin Wang, Jin Hee Ahn, Tong-Shin Chang

Abstract:

The peroxisome proliferator-activated receptors (PPARs) are member of nuclear receptor superfamily that act as a ligand-activated transcription factors. Although platelets lack a nucleus, previous studies have shown that PPARγ agonists, rosiglitazone, inhibited platelet activation induced by collagen. In this study, we investigated the inhibitory effects of KR-62980, a newly synthesized PPARγ agonist, on collagen receptor-stimulated platelet activation. The specific tyrosine phosphorylations of key components (Syk, Vav1, Btk and PLCγ2) for collagen receptor signaling pathways were suppressed by KR-62980. KR-62980 also attenuated downstream responses including cytosolic calcium elevation, P-selectin surface exposure, and integrin αIIbβ3 activation. PPARγ was found to associate with multiple proteins within the LAT signaling complex in collagen-stimulated platelets. This association was prevented by KR-62980, indicating a potential mechanism for PPARγ function in collagen-stimulated platelet activation. Furthermore, KR-62980 inhibited platelet aggregation and adhesion in response to collagen in vitro and prolonged in vivo thrombotic response in carotid arteries of mice. Collectively, these data suggest that KR-62980 inhibits collagen-stimulated platelet activation and thrombus formation through modulating the collagen receptor signaling pathways.

Keywords: KR-62980, PPARγ, antiplatelet, thrombosis

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4197 Removal of Polycyclic Aromatic Hydrocarbons (PAHS) and the Response of Indigenous Bacteria in Highly Contaminated Aged Soil after Persulfate Oxidation

Authors: Yaling Gou, Sucai Yang, Pengwei Qiao

Abstract:

Integrated chemical-biological treatment is an attractive alternative to remove polycyclic aromatic hydrocarbons (PAHs) from contaminated soil; wherein indigenous bacteria is the key factor for the biodegradation of residual PAHs concentrations after the application of chemical oxidation. However, the systematical study on the impact of persulfate (PS) oxidation on indigenous bacteria as well as PAHs removal is still scarce. In this study, the influences of different PS dosages (1%, 3%, 6%, and 10% [w/w]), as well as various activation methods (native iron, H2O2, alkaline, ferrous iron, and heat) on PAHs removal and indigenous bacteria in highly contaminated aged soil were investigated. Apparent degradation of PAHs in the soil treated with PS oxidation was observed, and the removal efficiency of total PAHs in the soil ranged from 38.28% to 79.97%. The removal efficiency of total PAHs in the soil increased with increasing consumption of PS. However, the bacterial abundance in soil was negatively affected following oxidation for all of the treatments added with PS, with bacterial abundance in the soil decreased by 0.89~2.88 orders of magnitude compared to the untreated soil. Moreover, the number of total bacteria in the soil decreased as PS consumption increased. Different PS activation methods and PS dosages exhibited different influences on the bacterial community composition. Bacteria capable of degrading PAHs under anoxic conditions were composed predominantly by Proteobacteria and Firmicutes. The total amount of Proteobacteria and Firmicutes also decreased with increasing consumption of PS. The results of this study provide important insight into the design of PAHs contaminated soil remediation projects.

Keywords: activation method, chemical oxidation, indigenous bacteria, polycyclic aromatic hydrocarbon

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4196 Organic Contaminant Degradation Using H₂O₂ Activated Biochar with Enhanced Persistent Free Radicals

Authors: Kalyani Mer

Abstract:

Hydrogen peroxide (H₂O₂) is one of the most efficient and commonly used oxidants in in-situ chemical oxidation (ISCO) of organic contaminants. In the present study, we investigated the activation of H₂O₂ by heavy metal (nickel and lead metal ions) loaded biochar for phenol degradation in an aqueous solution (concentration = 100 mg/L). It was found that H₂O₂ can be effectively activated by biochar, which produces hydroxyl (•OH) radicals owing to an increase in the formation of persistent free radicals (PFRs) on biochar surface. Ultrasound treated (30s duration) biochar, chemically activated by 30% phosphoric acid and functionalized by diethanolamine (DEA) was used for the adsorption of heavy metal ions from aqueous solutions. It was found that modified biochar could remove almost 60% of nickel in eight hours; however, for lead, the removal efficiency reached up to 95% for the same time duration. The heavy metal loaded biochar was further used for the degradation of phenol in the absence and presence of H₂O₂ (20 mM), within 4 hours of reaction time. The removal efficiency values for phenol in the presence of H₂O₂ were 80.3% and 61.9%, respectively, by modified biochar loaded with nickel and lead metal ions. These results suggested that the biochar loaded with nickel exhibits a better removal capacity towards phenol than the lead loaded biochar when used in H₂O₂ based oxidation systems. Meanwhile, control experiments were set in the absence of any activating biochar, and the removal efficiency was found to be 19.1% when only H₂O₂ was added in the reaction solution. Overall, the proposed approach serves a dual purpose of using biochar for heavy metal ion removal and treatment of organic contaminants by further using the metal loaded biochar for H₂O₂ activation in ISCO processes.

Keywords: biochar, ultrasound, heavy metals, in-situ chemical oxidation, chemical activation

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4195 Usage of Biosorbent Material for the Removal of Nitrate from Wastewater

Authors: M. Abouleish, R. Umer, Z. Sara

Abstract:

Nitrate can cause serious environmental and human health problems. Effluent from different industries and excessive use of fertilizers have increased the level of nitrate in ground and surface water. Nitrate can convert to nitrite in the body, and as a result, can lead to Methemoglobinemia and cancer. Therefore, different organizations have set standard limits for nitrate and nitrite. The United States Environmental Protection Agency (USEPA) has set a Maximum Contaminant Level Goal (MCLG) of 10 mg N/L for nitrate and 1 mg N/L for nitrite. The removal of nitrate from water and wastewater is very important to ensure the availability of clean water. Different plant materials such as banana peel, rice hull, coconut and bamboo shells, have been studied as biosorbents for the removal of nitrates from water. The use of abundantly existing plant material as an adsorbent material and the lack of energy requirement for the adsorption process makes biosorption a sustainable approach. Therefore, in this research, the fruit of the plant was investigated for its ability to act as a biosorbent to remove the nitrate from wastewater. The effect of pH on nitrate removal was studied using both the raw and chemically activated fruit (adsorbent). Results demonstrated that the adsorbent needs to be chemically activated before usage to remove the nitrate from wastewater. pH did not have a significant effect on the adsorption process, with maximum adsorption of nitrate occurring at pH 4. SEM/EDX results demonstrated that there is no change in the surface of the adsorbent as a result of the chemical activation. Chemical activation of the adsorbent using NaOH increased the removal of nitrate by 6%; therefore, various methods of activation of the adsorbent will be investigated to increase the removal of nitrate.

Keywords: biosorption, nitrates, plant material, water, and wastewater treatment

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4194 Removal of Heavy Metal Using Continous Mode

Authors: M. Abd elfattah, M. Ossman, Nahla A. Taha

Abstract:

The present work explored the use of Egyptian rice straw, an agricultural waste that leads to global warming problem through brown cloud, as a potential feedstock for the preparation of activated carbon by physical and chemical activation. The results of this study showed that it is feasible to prepare activated carbons with relatively high surface areas and pore volumes from the Egyptian rice straw by direct chemical and physical activation. The produced activated carbon from the two methods (AC1 and AC2) could be used as potential adsorbent for the removal of Fe(III) from aqueous solution contains heavy metals and polluted water. The adsorption of Fe(III) was depended on the pH of the solution. The optimal Fe(III) removal efficiency occurs at pH 5. Based on the results, the optimum contact time is 60 minutes and adsorbent dosage is 3 g/L. The adsorption breakthrough curves obtained at different bed depths indicated increase of breakthrough time with increase in bed depths. A rise in inlet Fe(III) concentration reduces the throughput volume before the packed bed gets saturated. AC1 showed higher affinity for Fe(III) as compared to Raw rice husk.

Keywords: rice straw, activated carbon, Fe(III), fixed bed column, pyrolysis

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4193 Kinetic Studies on CO₂ Gasification of Low and High Ash Indian Coals in Context of Underground Coal Gasification

Authors: Geeta Kumari, Prabu Vairakannu

Abstract:

Underground coal gasification (UCG) technology is an efficient and an economic in-situ clean coal technology, which converts unmineable coals into calorific valuable gases. This technology avoids ash disposal, coal mining, and storage problems. CO₂ gas can be a potential gasifying medium for UCG. CO₂ is a greenhouse gas and, the liberation of this gas to the atmosphere from thermal power plant industries leads to global warming. Hence, the capture and reutilization of CO₂ gas are crucial for clean energy production. However, the reactivity of high ash Indian coals with CO₂ needs to be assessed. In the present study, two varieties of Indian coals (low ash and high ash) are used for thermogravimetric analyses (TGA). Two low ash north east Indian coals (LAC) and a typical high ash Indian coal (HAC) are procured from the coal mines of India. Low ash coal with 9% ash (LAC-1) and 4% ash (LAC-2) and high ash coal (HAC) with 42% ash are used for the study. TGA studies are carried out to evaluate the activation energy for pyrolysis and gasification of coal under N₂ and CO₂ atmosphere. Coats and Redfern method is used to estimate the activation energy of coal under different temperature regimes. Volumetric model is assumed for the estimation of the activation energy. The activation energy estimated under different temperature range. The inherent properties of coals play a major role in their reactivity. The results show that the activation energy decreases with the decrease in the inherent percentage of coal ash due to the ash layer hindrance. A reverse trend was observed with volatile matter. High volatile matter of coal leads to the estimation of low activation energy. It was observed that the activation energy under CO₂ atmosphere at 400-600°C is less as compared to N₂ inert atmosphere. At this temperature range, it is estimated that 15-23% reduction in the activation energy under CO₂ atmosphere. This shows the reactivity of CO₂ gas with higher hydrocarbons of the coal volatile matters. The reactivity of CO₂ with the volatile matter of coal might occur through dry reforming reaction in which CO₂ reacts with higher hydrocarbon, aromatics of the tar content. The observed trend of Ea in the temperature range of 150-200˚C and 400-600˚C is HAC > LAC-1 >LAC-2 in both N₂ and CO₂ atmosphere. At the temperature range of 850-1000˚C, higher activation energy is estimated when compared to those values in the temperature range of 400-600°C. Above 800°C, char gasification through Boudouard reaction progressed under CO₂ atmosphere. It was observed that 8-20 kJ/mol of activation energy is increased during char gasification above 800°C compared to volatile matter pyrolysis between the temperature ranges of 400-600°C. The overall activation energy of the coals in the temperature range of 30-1000˚C is higher in N₂ atmosphere than CO₂ atmosphere. It can be concluded that higher hydrocarbons such as tar effectively undergoes cracking and reforming reactions in presence of CO₂. Thus, CO₂ gas is beneficial for the production of high calorific value syngas using high ash Indian coals.

Keywords: clean coal technology, CO₂ gasification, activation energy, underground coal gasification

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4192 The Retinoprotective Effects and Mechanisms of Fungal Ingredient 3,4-Dihydroxybenzalacetone through Inhibition of Retinal Müller and Microglial Activation

Authors: Yu-Wen Cheng, Jau-Der Ho, Liang-Huan Wu, Fan-Li Lin, Li-Huei Chen, Hung-Ming Chang, Yueh-Hsiung Kuo, George Hsiao

Abstract:

Retina glial activation and neuroinflammation have been confirmed to cause devastating responses in retinodegenerative diseases. The expression and activation of matrix metalloproteinase (MMP)-9 and inducible nitric oxide synthase (iNOS) could be exerted as the crucial pathological factors in glaucoma- and blue light-induced retinal injuries. The present study aimed to investigate the retinoprotective effects and mechanisms of fungal ingredient 3,4-dihydroxybenzalacetone (DBL) isolated from Phellinus linteus in the retinal glial activation and retinodegenerative animal models. According to the cellular studies, DBL significantly and concentration-dependently abrogated MMP-9 activation and expression in TNFα-stimulated retinal Müller (rMC-1) cells. We found the inhibitory activities of DBL were strongly through the STAT- and ERK-dependent pathways. Furthermore, DBL dramatically attenuated MMP-9 activation in the stimulated Müller cells exposed to conditioned media from LPS-stimulated microglia BV-2 cells. On the other hand, DBL strongly suppressed LPS-induced production of NO and ROS and expression of iNOS in microglia BV-2 cells. Consistently, the phosphorylation of STAT was substantially blocked by DBL in LPS-stimulated microglia BV-2 cells. In the evaluation of retinoprotective functions, the high IOP-induced scotopic electroretinographic (ERG) deficit and blue light-induced abnormal pupillary light response (PLR) were assessed. The deficit scotopic ERG responses markedly recovered by DBL in a rat model of glaucoma-like ischemia/reperfusion (I/R)-injury. DBL also reduced the aqueous gelatinolytic activity and retinal MMP-9 expression in high IOP-injured conditions. Additionally, DBL could restore the abnormal PLR and reduce retinal MMP-9 activation. In summary, DBL could ameliorate retinal neuroinflammation and MMP-9 activation by predominantly inhibiting STAT3 activation in the retinal Müller cells and microglia, which exhibits therapeutic potential for glaucoma and other retinal degenerative diseases.

Keywords: glaucoma, blue light, DBL, retinal Müller cell, MMP-9, STAT, Microglia, iNOS, ERG, PLR

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4191 The Role of a Novel DEAD-Box Containing Protein in NLRP3 Inflammasome Activation

Authors: Yi-Hui Lai, Chih-Hsiang Yang, Li-Chung Hsu

Abstract:

The inflammasome is a protein complex that modulates caspase-1 activity, resulting in proteolytic cleavage of proinflammatory cytokines such as IL-1β and IL-18, into their bioactive forms. It has been shown that the inflammasomes play a crucial role in the clearance of pathogenic infection and tissue repair. However, dysregulated inflammasome activation contributes to a wide range of human diseases such as cancers and auto-inflammatory diseases. Yet, regulation of NLRP3 inflammasome activation remains largely unknown. We discovered a novel DEAD box protein, whose biological function has not been reported, not only negatively regulates NLRP3 inflammasome activation by interfering NLRP3 inflammasome assembly and cellular localization but also mitigate pyroptosis upon pathogen evasion. The DEAD-box protein is the first DEAD-box protein gets involved in modulation of the inflammasome activation. In our study, we found that caspase-1 activation and mature IL-1β production were largely enhanced upon LPS challenge in the DEAD box-containing protein- deleted THP-1 macrophages and bone marrow-derived macrophages (BMDMs). In addition, this DEAD box-containing protein migrates from the nucleus to the cytoplasm upon LPS stimulation, which is required for its inhibitory role in NLRP3 inflammasome activation. The DEAD box-containing protein specifically interacted with the LRR motif of NLRP3 via its DEAD domain. Furthermore, due to the crucial role of the NLRP3 LRR domain in the recruitment of NLRP3 to mitochondria and binding to its adaptor ASC, we found that the interaction of NLRP3 and ASC was downregulated in the presence of the DEAD box-containing protein. In addition to the mechanical study, we also found that this DEAD box protein protects host cells from inflammasome-triggered cell death in response to broad-ranging pathogens such as Candida albicans, Streptococcus pneumoniae, etc., involved in nosocomial infections and severe fever shock. Collectively, our results suggest that this novel DEAD box molecule might be a key therapeutic strategy for various infectious diseases.

Keywords: inflammasome, inflammation, innate immunity, pyroptosis

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4190 Effect of TPA and HTLV-1 Tax on BRCA-1 and ERE Controlled Genes Expression

Authors: Azhar Jabareen, Mahmoud Huleihel

Abstract:

BRCA-1 is a multifunctional tumor suppressor, whose expression is activated by the estrogen (E2)-liganded ERα receptor. The activated ERα is a transcriptional factor which activates various genes either by direct binding to the DNA at E2-responsive elements (EREs) and indirectly associated with a range of alternative non-ERE elements. Interference with BRCA-1 expression and/or functions leads to high risk of breast or/and ovarian cancer. Our lab investigated the involvement of Human T-cell leukemia Virus Type 1 (HTLV-1) in breast cancer, since HTLV-1 Tax was found to strongly inhibit BRCA-1 expression. In addition, long exposure of 12-O-tetradecanoylphorbol-13-acetate (TPA), which is one of the stress-inducing agents activated the HTLV-1 promoter. So here the involvement of TPA in breast cancer had been examined by testing the effect of TPA on BRCA-1 and ERE expression. The results showed that TPA activated both BRCA-1 and ERE expression. In the 12 hours TPA activated the tow promoters more than others time, and after 24 hours the level of the tow promoters was decreased. Tax inhibited BRCA-1 expression but did not succeed to inhibit the effect of TPA. Then the activation of the two promoters was not through ERα pathway because TPA had no effect on ERα binding to the two promoters of the BRCA-1 and ERE. Also, the activation was not via nuclear factor kappa B (NF-κB) pathway because when the inhibitory of NF-κB had been added to the TPA, it still activated the tow promoters. However, it seems that 53BP1 may be involved in TPA activation of these promoters because ectopic high expression of 53BP1 significantly reduced the TPA activity. In addition, in the presence of Bisindolylmaleimide-I (BI)- the inhibitor of Protein Kinase C (PKC)- there was no activation for the two promoters, so the PKC is agonized BRCA-1 and ERE activation.

Keywords: BRCA-1, ERE, HTLV-1, TPA

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4189 Investigations on Enhancement of Fly Ash in Cement Manufacturing through Optimization of Clinker Quality and Fly Ash Fineness

Authors: Suresh Vanguri, Suresh Palla, K. V. Kalyani, S. K. Chaturvedi, B. N. Mohapatra

Abstract:

Enhancing the fly ash utilization in the manufacture of cement is identified as one of the key areas to mitigate the Green House Gas emissions from the cement industry. Though increasing the fly ash content in cement has economic and environmental benefits, it results in a decrease in the compressive strength values, particularly at early ages. Quality of clinker and fly ash were identified as predominant factors that govern the extent of absorption of fly ash in the manufacturing of cement. This paper presents systematic investigations on the effect of clinker and fly ash quality on the properties of resultant cement. Since mechanical activation alters the physicochemical properties such as particle size distribution, surface area, phase morphology, understanding the variation of these properties with activation is required for its applications. The effect of mechanical activation on fly ash surface area, specific gravity, flow properties, lime reactivity, comparative compressive strength (CCS), reactive silica and mineralogical properties were also studied. The fineness of fly ash was determined by Blaine’s method, specific gravity, lime reactivity, CCS were determined as per the method IS 1727-1967. The phase composition of fly ash was studied using the X-ray Diffraction technique. The changes in the microstructure and morphology with activation were examined using the scanning electron microscope. The studies presented in this paper also include evaluation of Portland Pozzolana Cement (PPC), prepared using high volume fly ash. Studies are being carried out using clinker from cement plants located in different regions/clusters in India. Blends of PPC containing higher contents of activated fly ash have been prepared and investigated for their chemical and physical properties, as per Indian Standard procedures. Changes in the microstructure of fly ash with activation and mechanical properties of resultant cement containing high volumes of fly ash indicated the significance of optimization of the quality of clinker and fly ash fineness for better techno-economical benefits.

Keywords: flow properties, fly ash enhancement, lime reactivity, microstructure, mineralogy

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4188 Effects of Strain-Induced Melt Activation Process on the Structure and Morphology Mg₂Si in Al-15%Mg₂Si Composite

Authors: Reza Eslami-Farsani, Mohammad Alipour

Abstract:

The effect of deformation on the semisolid microstructure and degree of globularity of Al–15%Mg₂Si composite produced by the strain induced melt activation (SIMA) process was studied. Deformation of 25% was used. After deformation, the samples were heated to a temperature above the solidus and below the liquidus point and maintained in the isothermal conditions at three different temperatures (560, 580 and 595 °C) for varying time (5, 10, 20 and 40 min). The microstructural study was carried out on the alloy by the use of optical microscopy. It was observed that strain induced deformation and subsequently melt activation has caused the globular morphology of Mg₂Si particles. The results showed that for the desired microstructures of the alloy during SIMA process, the optimum temperature and time are 595 °C and 40 min respectively.

Keywords: deformation, semisolid, SIMA, Mg₂Si phase, modification

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4187 Fabrication of Activated Carbon from Palm Trunksfor Removal of Harmful Dyes

Authors: Eman Alzahrani

Abstract:

Date palm trees are abundant and cheap natural resources in Saudi Arabia. In this study, an activated carbon was prepared from palm trunks by chemical processes. The chemical activation was performed by impregnation of the raw materials after grinding with H3PO4 solution (63%), followed by placing of the sample solution on a muffle furnace at 400ºC for 30 min, and then at 800ºC for 10 min. The morphology of the fabricated material was checked using scanning electron microscopy that showed the rough surfaces on the carbon samples. The use of fabricated activated carbon for removal of eosin dye from aqueous solutions at different contact time, initial dye concentration, pH and adsorbent doses was investigated. The experimental results show that the adsorption process attains equilibrium within 20 min. The adsorption isotherm equilibrium was studied by means of the Langmuir and Freundlich isotherms, and it was found that the data fit the Langmuir isotherm equation with maximum monolayer adsorption capacity of 126.58 mg g-1. The results indicated that the home made activated carbon prepared from palm trunks has the ability to remove eosin dye from aqueous solution and it will be a promising adsorbent for the removal of harmful dyes from waste water.

Keywords: activated carbon, date palm trunks, H3PO4 activation, adsorption, dye removal, eosin dye, isotherm

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4186 Energy Consumption in Biodiesel Production at Various Kinetic Reaction of Transesterification

Authors: Sariah Abang, S. M. Anisuzzaman, Awang Bono, D. Krishnaiah, S. Rasmih

Abstract:

Biodiesel is a potential renewable energy due to biodegradable and non-toxic. The challenge of its commercialization is associated with high production cost due to its feedstock also useful in various food products. Non-competitive feedstock such as waste cooking oils normally contains a large amount of free fatty acids (FFAs). Large amount of fatty acid degrades the alkaline catalyst in the biodiesel production, thereby decreasing the biodiesel production rate. Generally, biodiesel production processes including esterification and trans-esterification are conducting in a mixed system, in which the hydrodynamic effect on the reaction could not be completely defined. The aim of this study was to investigate the effect of variation rate constant and activation energy on energy consumption of biodiesel production. Usually, the changes of rate constant and activation energy depend on the operating temperature and the degradation of catalyst. By varying the activation energy and kinetic rate constant, the effects can be seen on the energy consumption of biodiesel production. The result showed that the energy consumption of biodiesel is dependent on the changes of rate constant and activation energy. Furthermore, this study was simulated using Aspen HYSYS.

Keywords: methanol, palm oil, simulation, transesterification, triolein

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4185 The Occurrence of Sporeformers in Processed Milk from Household Refrigerators and The Effect of Heat Treatment on Bacillus Spores Activation

Authors: Sarisha Devnath, Oluwatosin A. Ijabadeniyi

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In recent years milk contamination has become a major problem in households; due to the likely occurrence of bacteria, even after the milk has been processed. One such genus of bacteria causing unwanted growth is Bacillus. This research project looks at the presence of spore formers in processed milk from household refrigerators and the effect of pasteurization and high temperature on Bacillus spores activation. 24 samples each of UHT milk and pasteurised milk from 24 households were sampled for the presence of spore formers. While anaerobic spore formers were not found in any of the samples, the average aerobic spore formers in UHT milk and pasteurized milk however were 5.77 cfu/ml and 5.88 cfu/ml respectively. After sequencing, it was detected that the mixed culture contained Bacillus cereus, for both pasteurised and UHT milk samples. For the activation study, raw milk samples were collected and subjected to four different temperatures; 65˚C, 72˚C, 80˚C, 100˚C respectively. Samples were stored for 7 days at 5˚C and 10˚C and analysed daily. The average aerobic spore formers in raw milk for samples stored at 5˚C range between 4.67-6.00 cfu/ml while it ranges between 4.84-6.00 cfu/ml at 10˚C, signifying that the high temperatures could have resulted in germination of dominant spores. Statistical analysis conducted on these results indicated a significant difference between the numbers of colonies present at the different treatment temperatures the bacterium was exposed to. This work showed that household milk may constitute public health risk furthermore; pasteurization and higher temperatures may not be effective to remove aerobic spore formers because of Bacillus spores activation.

Keywords: sporeformers, bacillus, spores, activation, milk

Procedia PDF Downloads 341