This paper describes the synthesis of graphene-based activated carbon from carbonaceous rice straw fly ash in an electrical furnace and the subsequent potassium hydroxide extraction. The produced graphene has a proper morphological structure; flakes and a rough surface can be observed. The average size of the graphene was defined as up to 2000 nm and clarification was provided by high-resolution microscopes (FESEM and FETEM). Crystallinity was confirmed by surface area electron diffraction. The chemical bonding from the graphene was clearly observed, with -C=C- and O-H stretching at peaks of 1644 cm-1 and 3435 cm-1, respectively. Impurities in the graphene were found using X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The measured size, according to zeta-potential analysis, was 8722.2 ± 25 nm, and the average polydispersity index was 0.576. The stability of the mass reduction was analyzed by a thermogravimetric at 100 °C, with a final reduction of ~ 11%.
This paper introduces a new spark plasma sintering technique that is able to order crystalline anisotropy by in-series/in situ DC electric coupled magnetic field. The process control parameters have been investigated on the production of anisotropic BaFe12O19 magnets based on resulted remanence (Mr). Sintering holding time (H.T.), cooling rate (C.R.), pressure (P), and sintering temperature (S.T.) are optimized by Taguchi with L9 orthogonal array (OA). The remanent magnetization of nanocrystalline BaFe12O19 in parallel (Mrǁ) and perpendicular (MrꞱ) to the applied magnetic field was regarded as a measure of performance. The Taguchi study calculated optimum process parameters, which significantly improved the sintering process based on the confirmation tests of BaFe12O19 anisotropy. The magnetic properties in terms of Mrǁ and MrꞱ were greatly affected by sintering temperature and pressure according to ANOVA results. In addition, regression models were developed for predicting the Mrǁ as well as MrꞱ respectively.
In the present paper, the potentiality of integrating microbial fuel cells (MFCs) with a photocatalytic reactor to maximize the wastewater treatment efficiency with concurrent power generation was explored. Dimethyl phthalate (DMP) and acetic acid (AA) were the employed substrate and the co-substrate, respectively, using Pseudomonas aeruginosa as a biocatalyst. MFCs operated by single substrate showed the maximum power generation of 0.75-3.84 W m-3 whereas an addition of AA as the co-substrate yielded 3-12 fold higher power generation. Pseudomonas aeruginosa produced phenazine-1-carboxylic acid in DMP-fed MFC as the metabolite whereas AA along with DMP yielded pyocyanin which reduced the charge transfer resistance. Chemical oxygen demand (COD) removal efficiency in the MFCs was circa 62% after 11 days of operation. Thereafter, it further increased albeit with a drastic reduction in power generation. Subsequently, the MFC anolyte was treated in a photocatalytic reactor under visible light irradiation and catalyzed by CuO-gC3N4. The performance of photocatalytic reactor was evaluated, with COD and total organic carbon (TOC) removal efficiency of 88% and 86% after 200 min of light irradiation. The present work suggests that the MFC can be integrated with photocatalysis as a sustainable wastewater treatment method with concurrent power generation.
This paper addresses the growth of nano-structured MgZnO thin films by sol-gel spin coating method which will be used as a template layer to grow carbon nanotubes. The nano-structured MgZnO films were deposited on platinized (100) silicon substrates. In this work, we focused on the effect of aging and Mg content on the film structure and resistivity. Sols with Mg content of 10, 30 and 50 at.% were subjected to aging times of between 3 to 240 hours. Results from scanning (SEM) and field emission scanning electron (FESEM) microscopes and surface profiler (SP) showed that the sol aging increased the thickness, grain size and surface roughness for aging up to 240 hours. The energy dispersive analysis by X-ray (EDAX) confirmed the element of Mg in the ZnO films. The electrical resistivity also increased with aging time as confirmed by four point probe method. The results suggest that appropriate aging of the sol is important for improving physical quality and electrical performance of MgZnO thin films derived from sol-gel technique.
Electromagnetic (EM) waves transmitted by Horizontal Electric Dipole (HED) source to detect contrasts in subsurface resistivity termed Seabed Logging (SBL) is now an established method for hydrocarbon exploration. However, currently used EM wave detectors for SBL have several challenges including the sensitivity and its bulk size. This work exploits the benefit of superconductor technology in developing a magnetometer termed Superconducting Quantum Interference Device (SQUID) which can potentially be used for SBL. A SQUID magnetometer was fabricated using hexagon shape-niobium wire with YBa2Cu37O, (YBCO) as a barrier. The YBa2Cu37O, samples were synthesized by sol-gel method and were sintered using a furnace and conventional microwave oven. The YBCO gel was dried at 120 degrees C in air for 72 hours. It was then ground and divided into 12 parts. Four samples were sintered at 750 degrees C, 850 degrees C, 900 degrees C, and 950 degrees C for 12 hours in a furnace to find the optimum temperature. The other eight samples were sintered in a microwave with 1100 Watt (W) with a different sintering time, 5, 15, 45 minutes, 1 hour, 1 hour 15 minutes, 1 hour 30 minutes, 1 hour 45 minutes and 2 hours. A DEWAR container was designed and fabricated using fiberglass material. It was filled with liquid nitrogen (LN2) to ensure the superconducting state of the magnetometer. XRD results showed that the optimum sintering temperature for the formation of orthorhombic Y-123 phase was at 950 degrees C with the crystallite size of 67 nm. The morphology results from Field Emission Scanning Electron Microscopy (FESEM) showed that the grains had formed a rod shape with an average diameter of 60 nm. The fabricated SQUID magnetometer was able to show an increment of approximately 249% in the intensity of the EM waves when the source receiver offset was one meter apart.
Transparent nanostructured ZnO thin films were successfully deposited using sol-gel spin coating method on a quartz substrate. The 0.4 M ZnO solution gel was prepared using zinc acetate dihydrate (Zn(CH3COO)22H2O) as the precursor, 2-methoxyethanol as the solvent and monoethanolamine (MEA) as the stabilizer. The electrical and optical properties dependencies on the annealing temperature of the nanostructured ZnO thin films were investigated. It was found that as the annealing temperature increased, the particle size, conductivity and the peak of the UV emission also increased.
Xylene, a recalcitrant compound present in wastewater from activities of petrochemical and chemical industries causes chronic problems for living organisms and the environment. Xylene contaminated wastewater may be biodegraded through a benthic microbial fuel cell (BMFC) as seen in this study. Xylene was oxidized into intermediate 3-methyl benzoic acid and entirely converted into non-toxic carbon dioxide. The highest voltage of the BMFC reactor was generated at 410 mV between 23 and 90 days when cell potential was 1 kΩ. The reactor achieved a maximum power density of about 63 mW/m2, and a current of 0.4 mA which was optimized from variable resistance (20 Ω - 1 kΩ). However, the maximum biodegradation efficiency of the BMFC was at 87.8%. The cyclic voltammetry curve helped to determine that the specific capacitance was 0.124 F/g after 30 days of the BMFC operation. Furthermore, the fitting equivalent circuit was observed with the help of Nyquist plot for calculating overall internal resistance of 65.82 Ω on 30th day and 124.5 Ω on 80th day. Staphylococcus edaphicus and Staphylococcus sparophiticus were identified by 16S rRNA sequencing as the dominant species in the control and BMFC electrode, presumably associated with xylene biodegradation.
Synthesis of 2,5-bisarylthiophenes was accomplished by sequential Suzuki cross coupling reaction of 2-bromo-5-chloro thiophenes. Density functional theory (DFT) studies were carried out at the B3LYP/6-31G(d, p) level of theory to compare the geometric parameters of 2,5-bisarylthiophenes with those from X-ray diffraction results. The synthesized compounds are screened for in vitro bacteria scavenging abilities. At the concentration of 50 and 100 μg/mL, compounds 2b, 2c, 2d, 3c, and 3f with IC50-values of 51.4, 52.10, 58.0, 56.2, and 56.5 μg/mL respectively, were found most potent against E. coli. Among all the synthesized compounds 2a, 2d, 3c, and 3e with the least values of IC50 77, 76.26, 79.13 μg/mL respectively showed significant antioxidant activities. Almost all of the compounds showed good antibacterial activity against Escherichia coli, whereas 2-chloro-5-(4-methoxyphenyl) thiophene (2b) was found most active among all synthesized compound with an IC50 value of 51.4 μg/mL. All of the synthesized compounds were screened for nitric oxide scavenging activity as well. Frontier molecular orbitals (FMOs) and molecular electrostatic potentials of the target compounds were also studied theoretically to account for their relative reactivity.
Thermo-Electrochemical cells (Thermocells/TECs) transform thermal energy into electricity by means of electrochemical potential disequilibrium between electrodes induced by a temperature gradient (ΔT). Heat conduction across the terminals of the cell is one of the primary reasons for device inefficiency. Herein, we embed Poly(Vinylidene Fluoride) (PVDF) membrane in thermocells to mitigate the heat transfer effects - we refer to these membrane-thermocells as MTECs. At a ΔT of 12 K, an improvement in the open circuit voltage (Voc) of the TEC from 1.3 mV to 2.8 mV is obtained by employment of the membrane. The PVDF membrane is employed at three different locations between the electrodes i.e. x = 2 mm, 5 mm, and 8 mm where 'x' defines the distance between the cathode and PVDF membrane. We found that the membrane position at x = 5 mm achieves the closest internal ∆T (i.e. 8.8 K) to the externally applied ΔT of 10 K and corresponding power density is 254 nWcm(-2); 78% higher than the conventional TEC. Finally, a thermal resistivity model based on infrared thermography explains mass and heat transfer within the thermocells.
In industrial plants such as electricity generating, petroleum, chemical and petrochemical plants, pipelines are used extensively to transport liquid from one location to another. In radiation vulcanization of natural rubber latex (RVNRL) plants, pipelines are also used to transport latex to storage tank. During one of its maintenance activities, a pipeline intelligent gauge (PIG) that was used to monitor pipe integrity jammed inside the pipe causing interruption to its operation or loading activities. Sealed source technology was utilized to determine the location of jammed PIG in the pipeline. Fast neutrons from a 50 mCi Americium Beryllium (AmBe241), with energy range between 0.5 to11 MeV, were used for the study. Helium 3 (He3) detector was used to detect slow neutrons having a range of energy of 30 eV- 0.5 MeV. The investigation was carried out using neutron backscatter technique scanner. By adopting back-scattered technique, the location of jammed PIG in the pipeline has been successfully determined.
Industrial heat pumps are heat-recovery systems that allow the temperature of waste-heat stream to be increased to a higher, more efficient temperature. Consequently, heat pumps can improve energy efficiency in industrial processes as well as energy savings when conventional passive-heat recovery is not possible. In this paper, possible ways of saving energy in the chemical industry are considered, the objective is to reduce the primary energy (such as coal) consumption of power plant. Particularly the thermodynamic analyses of integrating backpressure turbine of a power plant with distillation units have been considered. Some practical examples such as conventional distillation unit and heat pump are used as a means of reducing primary energy consumption with tangible indications of energy savings. The heat pump distillation is operated via electrical power from the power plant. The exergy efficiency of the primary fuel is calculated for different operating range of the heat pump distillation. This is then compared with a conventional distillation unit that depends on saturated steam from a power plant as the source of energy. The results obtained show that heat pump distillation is an economic way to save energy if the temperature difference between the overhead and the bottom is small. Based on the result, the energy saved by the application of a heat pump distillation is improved compared to conventional distillation unit.
Therapies with magnetic/electromagnetic field are employed to relieve pains or, to accelerate flow of blood-particles, particularly during the surgery. In this paper, a theoretical study of the blood flow along with particles suspension through capillary was made by the electro-magneto-hydrodynamic approach. Analytical solutions to the non-dimensional blood velocity and non-dimensional particles velocity are obtained by means of the Laplace transform with respect to the time variable and the finite Hankel transform with respect to the radial coordinate. The study of thermally transfer characteristics is based on the energy equation for two-phase thermal transport of blood and particles suspension with viscous dissipation, the volumetric heat generation due to Joule heating effect and electromagnetic couple effect. The solution of the nonlinear heat transfer problem is derived by using the velocity field and the integral transform method. The influence of dimensionless system parameters like the electrokinetic width, the Hartman number, Prandtl number, the coefficient of heat generation due to Joule heating and Eckert number on the velocity and temperature fields was studied using the Mathcad software. Results are presented by graphical illustrations.
Microbial electrochemical systems (MESs) are an attracting technology for the disposal of wastewater treatment and simultaneous energy production. In MESs, at the anode microorganisms through the catalytic activity generates electrons that can be converted into electricity or other valuable chemical compounds. Microorganisms those having ability to donate and accept electrons to and from anode and cathode electrodes, respectively are recognized as 'exoelectrogens'. In the MESs, it renders an important function for its performance. In the present mini-review, we have discussed the role of microbiome including pure culture, enriched culture and mixed culture in different BESs application. The effects of operational and biological factors on microbiome development have been discussed. Further discussion about the molecular techniques for the evaluation of microbial community analysis is addressed. In addition different electrochemical techniques for extracellular electron transfer (EET) mechanism of electroactive biofilms have been discussed. This review highlights the importance of microbiome in the development of MESs, effective operational factors for exo-electrogens activities as well their key challenges and future technological aspects are also briefly discussed.
An experimental study of the field emission from nitrogen doped Diamond-Like-Carbon (DLC) thin films prepared by plasma Chemical Vapor Deposition (CVD) was carried out for the purpose of investigating the characteristic of field electron emission from the surface of nitrogen doped DLC thin film. Thin DLC film was deposited on silicon using the plasma CVD method, from a mixture of Methane (CH4), Helium (He) and Nitrogen (N2) at room temperature. Emission current was measured while high volume of voltage was applied between the cathode-anode diode structures. Barrier height was obtained by current density-electric field (J-E) characteristic in the relation of Fowler-Nordheim equation. The value of barrier height in range of 0.03eV to 0.06eV was obtained and considered as low barrier.
Thermoelectric nanostructures hold great promise for capturing and directly converting into electricity some vast amount of low-grade waste heats now being lost to the environment (e.g. from nuclear power plant, fossil fuel burning, automotives and household appliances). In this study, large-area vertically-aligned silicon nanowire (SiNW) arrays were synthesized in an aqueous solution containing AgN•i and HF on p-type Si (100) substrate by self-selective electroless etching process. The etching conditions were systematically varied in order to achieve different stages of nanowire formation. Diameters of the SiNWs obtained varied from approximately 50 to 200 nm and their lengths ranged from several to a few tens of um. Te/Bi2Tex.Si thermoelectric core-shell nanostructures were subsequently obtained via galvanic displacement of SiNWs in acidic HF electrolytes containing HTe02+ and 139' /HTe02+ ions. The reactions were basically a nano-electrochemical process due to the difference in redox potentials between the materials. The surface-modified SiNWs of core-shell structures had roughened surface morphologies and, therefore, higher surface-to-bulk ratios compared to unmodified SiNWs. They have potential applications in sensors, photovoltaic and thermoelectric nanodevices. Growth study on the SiNWs and core-shell nanostructures produced is presented using various microscopy, diffraction and probe-based techniques for microstructural, morphological and chemical characterizations.
CaCu3Ti4O12 (CCTO) has attracted a great attention for electronic devices miniaturization due to its
very high dielectric constant properties at a wide range of frequency and nearly constant over broad temperature range. The origins of the giant dielectric constant have been speculated from electrical heterogeneous of interior elements of the CCTO ceramics. Four origins were suggested contributed to the electrical heterogeneous. In this study heat treatment were done with the electrode contact in Argon gas environment and the electrical properties over very wide frequency of CCTO ceramics were investigated. Cylindrical CCTO pellets samples were prepared by solid state reaction method and single phase of XRD pattern was obtained after sintering processes. Electrical impedance responds were measured at frequency from 100 Hz to 1 GHz for the samples for untreated and heat treated at 200ºC, 250ºC, 300ºC, 350ºC and 400ºC of CCTO. Improvement to the dielectric constant can be seen for 350ºC and 400ºC samples and dielectric loss were improved for 200ºC and 300ºC samples for overall frequency. The variations were discussed based on oxygen deficiency content and resistivity of the elements inside of CCTO structure.
In this study, we propose an innovative, bio-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes using clove buds. This approach is innovative because we do not use toxic and hazardous acids which are typically used in common carbon nanomaterial functionalization procedures. The MWCNTs are functionalized in one pot using a free radical grafting reaction. The clove-functionalized MWCNTs (CMWCNTs) are then dispersed in distilled water (DI water), producing a highly stable CMWCNT aqueous suspension. The CMWCNTs are characterized using Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The electrostatic interactions between the CMWCNT colloidal particles in DI water are verified via zeta potential measurements. UV-vis spectroscopy is also used to examine the stability of the CMWCNTs in the base fluid. The thermo-physical properties of the CMWCNT nano-fluids are examined experimentally and indeed, this nano-fluid shows remarkably improved thermo-physical properties, indicating its superb potential for various thermal applications.
In the last 10 years, the microbial fuel cell (MFC) has been extensively studied worldwide to extract energy from wastewater via electricity generation. More recently, a merged technique of embedding MFC into a constructed wetland (CW) has been developed and appears to be increasingly investigated. The driving force to integrate these two technologies lies in the fact that CWs naturally possess a redox gradient (depending on flow direction and wetland depth), which is required by MFCs as anaerobic anode and aerobic cathode chambers. No doubt, the integration of MFC with a CW will upgrade the CW to allow it to be used for wastewater treatment and, simultaneously, electricity generation, making CWs more sustainable and environmentally friendly. Currently, published work shows that India, China, Ireland, Spain, Germany and Malaysia are involved in the development of this technology although it is in its infant stage and many technical issues are faced on system configuration, operation and maximisation of electricity production. This paper aims to provide an updated review and analysis of the CW-MFC development. Focuses are placed on the experience gained so far from different researchers in the literature and further research directions and proposals are discussed in great detail.
Electricity has become one of the necessities for human daily activities. The presence of electric
current produces electromagnetic fields (EMF) at extremely low frequency (ELF). The problem arises
when scientists suggests a possible connection between ELF exposure to human health and safety.
Concerned about the safety and health of students and staff, Universiti Kebangsaan Malaysia (UKM)
took the initiative to identify possible ELF sources and measure their exposure in various locations
around the UKM main campus in Bangi. This paper reports the results obtained from the monitoring
of the magnetic flux density at three identified locations in the vicinity of the overhead high-voltage
transmission line which transverses the university compound and compare the maximum value results
with the exposure limit suggested by the International Committee on Non Ionising Radiation
Protection (ICNIRP) for ELF. Measurements were done with an (Extech) Three Axis
Electromagnetic Field (EMF) Meter (Model 430826) to determine the magnetic flux density. The
lateral profile method was applied as the standard measurement methodology. Results showed that the
maximum value of the magnetic flux density was 12.5 mG, which is below the suggested ICNIRP
public exposure limit of 1000 mG, or in percentage ratio, 1.25% of ICNIRP public exposure limit.
Results from the statistical Kruskal-Wallis test showed that there is a significant difference in the
distributions of the magnetic flux densities at the different locations (P < 0.05). In conclusion, the
measured locations are still safe for people in short-term exposure. However, long-term exposure
measurements still need to be done to provide concrete data on the ELF-emission levels in UKM.
Thorium is a fertile material that can undergo transmutation for it to become a fissile material,
uranium-233. The fissile material can go through a fission process in order to generate heat energy
and eventually electricity. Most nuclear reactors use uranium as their fission source. The use of
thorium as nuclear fuel has been only investigated for few types of reactors such as a high, temperature
gas reactor (HTGR), fast breeder reactor, light water reactor (LWR) and heavy water reactor
(HWR). For research reactors specifically, there are limited academic publications related to the
la,test u.se of thorium. Hence, the main, interest, of this work is to compile and review the latest
academic publications related to the active use of thorium, for research reactors in particular. The
reviewed studies have been, divided into two categories which are experimented and simulation projects.
The experimental projects are a,bold the ongoing thorium fuel tests that have been carried out. in an
actual, research reactor. On the hand, the simulation work: is related to the computational analysis
performed in predicting the neutronic behaviour of thorium based fuel in research reactors. The
experimented study of thorium is currently active for the KAMINI research reactor. Additionally, most,
simulation works focus on finding criticality and neutron spectra.