Amini Horri B, Chong MN, Chen XD, Wang HT (2014) Modelling of Solar Evaporation Assisted by Floating Light-Absorbing Porous Materials, Current Environmental Engineering1(2)pp. 73-81
Solar energy is one of the promising renewable energy sources for desalination of saline and brackish waters. The solar evaporation rate could be enhanced by placing light-absorbing agents on the surface or bottom of the solar ponds. So far, different materials such as various dyes, blackened wet jute cloth, black plastic bubble sheets, black rubber, floating porous plates, etc. were used to induce the solar evaporation rate, but the evaporation results showed that the water evaporation enhancement using those materials was quite limited. We have recently reported the use of solar lightabsorbing carbon-Fe3O4 particles and achieved a 230% increase in solar evaporation rate. This paper focuses on mathematical modeling of the solar evaporation process assisted by this kind of floating light-absorbing material. The proposed model was used to predict the evaporation rate of the experimental tests and results showed an acceptable compatibility between the experimental and calculated evaporation rates by an error lower than 13%.
Amini Horri B, Selomulya C, Wang HT (2012) Characteristics of Ni/YSZ ceramic anode prepared using carbon microspheres as a pore former, International Journal of Hydrogen Energy37(20)pp. 15311-15319
Microstructural features and physical properties of the anodes crucially affect the electrochemical performance of anode-supported solid oxide fuel cells (SOFCs). This paper evaluated the microstructural characteristics and properties including porosity, pore size distribution, sintering shrinkage, mechanical strength, and electrical conductivity of the SOFC anode using carbon microspheres (CMSs) as the pore-former in the fabrication of Ni/YSZ ceramic anode. CMSs with different average particle sizes (CMS1: 11.54 ¼m, CMS2: 4.39 ¼m, and CMS3: 0.27 ¼m) were synthesized, and then incorporated into NiO/YSZ at various volumetric blend ratios ranging from 4.4 to 44.6 vol.%. SOFC anode cermets with a desirable range of porosity (30?40%), shrinkage (15.9?17.3%), flexural strength (75.4?157.8 N), and electrical conductivity (253.5?510.7 S/cm) were obtained using approximately 4?10 vol% of CMS1, 4?20 vol.% of CMS2, and 10?34 vol.% of CMS3. In addition, the use of CMS as the pore former reduced the amount of closed pores in the anode disks from 2.05% to <1%.
Montazer-Rahmati MM, Amini Horri B (2005) From laboratory experiments to design of a conveyor-belt dryer via mathematical modeling, Drying technology23(12)pp. 2389-2420 Taylor & Francis
A conveyor-belt dryer for picrite has been modeled mathematically in this work. The necessary parameters for the system of equations were obtained from regression analysis of thin-layer drying data. The convective drying experiments were carried out at temperatures of 40, 60, 80, and 100°C and air velocities of 0.5 and 1.5 m/sec. To analyze the drying behavior, the drying curves were fitted to different semi-theoretical drying kinetics models such as those of Lewis, Page, Henderson and Pabis, Wang and Singh, and the decay models. The decay function (for second order reactions) gives better results and describes the thin layer drying curves quite well. The effective diffusivity was also determined from the integrated Fick's second law equation and correlated with temperature using an Arrhenius-type model. External heat and mass transfer coefficients were refitted to the empirical correlation using dimensionless numbers (J h , J D = m · Re n ) and their new coefficients were optimized as a function of temperature. The internal mass transfer coefficient was also correlated as a function of moisture content, air temperature, and velocity.
Choo CK, Vivek YS, Salamatinia B, Horri BA, Amini Horri B (2017) Green Synthesis of ZnO Nanoparticles by an Alginate Mediated Ion-Exchange Process and a case study for Photocatalysis of Methylene Blue Dye, Journal of Physics: Conference Series829(1) IOPscience
n this study, zinc oxide (ZnO) was prepared via extrusion-dripping method through an ion exchange mediated process using sodium alginate. The samples were synthesized at 500 °C and 600 °C to study the effect of calcination temperature. The morphology, microstructure and optical activity of the calcined ZnO nanoparticles were analyzed by TGA, FESEM and XRD. It was found that ZnO nanoparticles synthesized at 600 °C was of higher purity with high crystallinity. To enhance the photocatalytic efficiency of zinc oxide, ZnO/NCC films were synthesized at varying ZnO loading fractions of 10 wt%, 15 wt%, 20 wt% and 25 wt% and were evaluated by photodegradation of Methylene blue dye and the highest dye percentage removal is found to be 96% which is obtained at ZnO loadings of 25 wt%. The usage of ion-exchange process has shown promising results in producing ZnO of desirable characteristics.
Choo CK, Kong XY, Goh TL, Amini Horri B, Salamatinia B (2016) Chitosan/halloysite beads fabricated by ultrasonic-assisted extrusion-dripping and a case study application for copper ion removal, Carbohydrate Polymers138pp. 16-26
Development of new materials for different applications especially as bio-composites has received great attention. This study concentrates on development of a biopolymer based on chitosan (CT) and halloysite nanotubes (HNT) and evaluates the copper removal intake as a potential application of this bio-composite. In this study, CT/HNT beads were prepared by ultrasonic-assisted extrusion-dripping method for the first time. Two sources of HNTs (i.e. Dragonite and Matauri Bay) were added into a chitosan solution (2 wt.%) at various loading fractions (25, 50, 75 wt.%). The effect of ultrasound as a mixing device was also studied by varying the amplitude at constant frequency of 25%, 50% and 75%. Characteristics and physical properties of the prepared CT/HNT beads were also analyzed by SEM, FTIR, TGA and BET the results show that introducing HNT to chitosan increases the adsorption capacity toward copper ions; however HNT loading fraction above 50 wt.% resulted in a decrease in adsorption capacity attributed to limited accessibility of the amino groups. The adsorption capacity of the CT/HNT beads prepared from Dragonite source had a larger adsorption capacity of 14.2 mg/g as compared to that of Matauri Bay, 10.55 mg/g. It was observed that the adsorption capacity of the beads toward copper ions decreased when the loading fraction of HNT is increased at constant ultrasound amplitude. The result of this study helps to understand the links between the characteristics and adsorption abilities of CT/HNT beads.
Choo CK, Amini Horri B, Salamatinia B (2016) Synthesis and Characterization of Nickel (II) Oxide/Gadolinium-Doped Ceria (NiO/GDC) Nanocomposites As a Potential Material for Anode Supported LT-SOFCs, Proceedings of the World Congress on Engineering and Computer ScienceII
In this study, Ni-GDC Nano-powder was synthesized via ion-exchange technique using sodium alginate as the templating material. Nanoparticles were obtained by controlling the calcination temperature. FE-SEM showed that the particle size of the grain decreased with the increase in the calcination temperature. Furthermore, pure NiO-GDC structure was obtained at the calcination temperature of 500 C with no secondary phase present which is evident through the compositional characterization performed including XRD, FTIR and TGA analysis. The usage of ion-exchange sol gel technique has shown promising results to overcome high polarization observed at low operating temperature.
Izadi N, Amini Horri B, Rashidi A, Mosoudi MR, Bozorgzadeh HR, Zeraatkar A (2011) Growth of single-walled carbon nanotubes on a Co?Mo?MgO supported catalyst by the CVD of methane in a fixed bed reactor: Model setting and parameter estimation, Solid State Sciences13(6)pp. 1242-1250 Elsevier
In this work methane was decomposed to hydrogen and carbon to determine its kinetic behavior during reaction over a Co?Mo?MgO supported catalyst using the CVD (Chemical Vapor Deposition) technique. Decomposition of methane molecules was performed in a continuous fixed bed reactor to obtain data to simulate methane decomposition in a gas phase heterogeneous media. The products and reactants of reaction were analyzed by molecular sieve column followed by GC-analysis of the fractions to determine the amount of product converted or reactant consumed. The synthesis of single-walled carbon nanotubes was performed at atmospheric pressure, different temperatures and reactant concentrations. The experimental data analyzed to suggest the formula for calculation of the initial specific reaction rate of the carbon nanotubes synthesis, were fitted by several mathematical models derived from different mechanisms based on Longmuir-hinshelwood expression. The suggested mechanism according to dissociation adsorption of methane seems to explain the catalytic performance in the range of operating conditions studied. The apparent activation energy for the growth of SWNTs was estimated according to Arrhenius equation. The as grown SWNTs products were characterized by SEM, TEM and Raman spectroscopy after purification. The catalyst deactivation was found to be dependent on the time, reaction temperature and partial pressure of methane and indicated that the reaction of deactivation can be modeled by a simple apparent second order of reaction.
Amini Horri B, Selomulya C, Wang HT (2012) Electrochemical characteristics and performance of anode-supported SOFCs fabricated using carbon microspheres as a pore-former, International Journal of Hydrogen Energy37(24)pp. 19045-19054
This paper evaluates the influence of carbon microspheres (CMSs) as an electrode pore-former on the fabrication and electrochemical properties of the anode-supported solid oxide fuel cells (SOFCs). The anode supports are fabricated by dry-pressing of CMS and NiO/YSZ (nickel-oxide/yttria-stabilized zirconia) composite powder, and the YSZ electrolyte layer is prepared by the electrophoretic deposition technique. The ohmic and polarization resistances for NiO/YSZ?YSZ half cells at different testing temperatures (650?850 °C) are analyzed by electrochemical impedance spectroscopy (EIS). The polarization ASR (area specific resistance) for the fabricated half cells increases from 0.583 © cm2 to 3.047 © cm2 when the temperature decreases from 850 °C to 650 °C. The electrochemical performance of single cells is measured at different temperatures (700?850 °C) and the results indicate that the cells fabricated using CMS as the pore-former exhibit much higher electrochemical performance than those without using CMS. A maximum power density of 207.7 mW cm?2, 431.2 mW cm?2, and 571.6 mW cm?2 is recorded at 850 °C for the cells fabricated by adding 0 wt. %, 2.5 wt. % and 5 wt. % of CMS, respectively. The maximum fuel utilization efficiency is also found to increase from 26.5% for the cell prepared without CMS to 47.0% and 59.6% for the cells prepared with 2.5 wt. % and 5 wt. % of CMS, respectively. The increase in the electrochemical performance by adding CMS as pore-former to anode-supports is attributed to higher porosity and pore size of the electrode.
Amini Horri B, Dong D, Selomulya C, Wang HT (2012) Rheological behaviour of NiO/YSZ slurries for drying-free casting, Powder Technology223pp. 116-122 Elsevier
We have recently developed a new drying-free casting method for shape forming of ceramics, in which a polymerizable solvent such as furfuryl alcohol (FA) is used to disperse the ceramic powders, and then polymerized into a poly (furfuryl alcohol) (PFA) binder during the casting process. Compared with conventional casting processes, this method offers more flexibility in controlling the microstructure of ceramics and eliminates defects that are likely to arise from the drying step. Controlling the rheological behaviour of ceramic slurries is an important step in the casting process to achieve improved microstructural properties. In this study, the viscosity of slurries comprising NiO/YSZ (yttria stabilized zirconia) powders and FA as solvent was investigated over a wide range of shear rates (1 s? 1?1000 s? 1) and at different volumetric solid concentrations (from 20% to 70%), while the effects of dispersant were quantified by adding different amounts of PVP (polyvinyl pyrrolidone) between 1 wt.% and 4 wt.%. The minimum viscosity of NiO/YSZ/FA slurries could be achieved with 2 wt.% dispersant. The experimental data relating the changes in viscosity to the volumetric solid concentration were modeled using different viscosity models, with Liu's equation showing the best fit for NiO/YSZ/FA slurries with and without dispersant. The slurries showed a highly pseudoplastic behaviour without dispersant, while adding PVP as dispersant effectively modified the rheological behaviour toward Newtonian fluids.
Lam WH, Chong MN, Amini Horri B, Tey BT, Chan ES (2017) Physicochemical stability of calcium-alginate beads immobilizing TiO2 nanoparticles for removal of cationic dye under UV irradiation, Journal of Applied Polymer Science
Recently, there have been considerable interests to immobilize photocatalyst in alginate beads for removing pollutants from water sources. However, the feasibility of using alginate beads in industry largely depends on its long-term stability during operation. This study investigated the physicochemical stability of alginate/titanium dioxide beads (Alg/TiO2) when exposed to UV irradiation in aqueous environment. The degradation of Alg/TiO2 beads was evident because the diameter and mass of the beads was reduced by 12% and 40%, respectively, after 120 h of irradiation. A substantial amount of TiO2 was leached into the external medium. Consequently, the removal efficiency of model cationic dye was found to reduce after every process cycle. Morphological analysis showed the formation of cavities on the surface of the Alg/TiO2 beads. Interestingly, the blank alginate beads degraded more rapidly than the Alg/TiO2 beads, confirming the UV shielding effect of TiO2. Nevertheless, this study reveals the need to improve the UV stability of alginate-based beads before they can be considered for practical application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 133, 45002.
Pezeshkpour S, Abdullah AZ, Salamatinia B, Amini Horri B (2017) Ionic?gelation synthesis of gadolinium doped ceria (Ce0.8Gd0.2O1.90) nanocomposite powder using sodium-alginate, Ceramics International43(9)pp. 7123-7135 Elsevier
Nanocomposite powders of gadolinium-doped ceria (GDC, Ce0.8Gd0.2O1.9) were synthesized via thermal treatment of the gel formed by contacting ionic solutions of sodium alginate as the jelling template and metal (gadolinium/cerium) nitrates as the starting material. The influence of calcination temperature and sodium alginate loading fraction on the properties of the synthesized GDC nanocomposite powders was investigated. Characterization was performed by energy dispersive X-ray spectroscopy, powder X-ray diffraction, thermogravimetric analysis, Field Emission Scanning Electron Microscopy, Fourier transformed infrared spectroscopy and nitrogen adsorption/desorption analysis. It was observed that the particle size and the surface area of the produced GDC nanocomposite powders are dominantly controlled by the calcination temperature, while the effect of sodium alginate loading fraction is limited by the range of the calcination temperature. In this study, the smallest mesoporous GDC nanocomposite powder with cubic fluorite structure (8 nm crystallite size and 3.05 ± 0.005 m2/g surface area) was synthesized using 2 wt. % of sodium alginate at a calcination temperature of 550 °C (for 4 h).The results of this study could help to perceive the influence of the basic processing variables on the particle size and the other physiochemical properties of GDC nanocomposite powders produced by the ionic-gelation method.
Tan KB, Vakili M, Poh PE, Abdullah AZ, Amini Horri B, Salamatinia B (2015) Adsorption of dyes by nanomaterials: Recent developments and adsorption mechanisms, Separation and Purification Technology150pp. 229-242
Application of nanomaterials in dye wastewater treatment has received wide attention in recent years. This review highlights recent developments in the use of nanomaterials for the adsorption of dyes from wastewater. Specific adsorption mechanisms, improvements, particularly for increasing adsorption capacities, and toxicity are discussed for each nanomaterial. The accumulated data indicate that nanomaterials can be effectively used for treating dye wastewater. Nanochitosan, in particular, has a huge potential for commercial application due to its sustainability with respect to excellent adsorption performance, non-toxicity and low cost. Although the applications using nanomaterials have been developing rapidly, the technology is still far from achieving the ultimate goal of commercialization. Other considerations, such as regeneration methods and treatment of actual commercial textile dye wastewater, have not been sufficiently researched.
Amini Horri B, Selomulya C, Wang HT (2012) Modeling the influence of carbon spheres on the porosity of SOFC anode materials, J American Ceramic Society95(4)pp. 1261-1268
The influence of fabrication pressure and other ceramic processing variables, including volumetric loading fraction and the particle size ratio of pore-forming agents, on the porosity of fabricated ceramic anodes, was investigated using an integrated experimental approach with mathematical modeling to differentiate the impacts of each parameter. Despite historic observation of the properties of ceramic bodies, to date, there is a lack of available models to accurately interpret the ceramic properties as a function of the processing variables. Herein, we focus on the open porosity of the solid oxide fuel cell anode prepared from NiO/YSZ (nickel oxide/yttria stabilized zirconia) as the ceramic powder and using CMS (carbon microspheres) as a pore-forming agent. A range of pore-former volumetric blend ratios (4.4%?44.6%) and different particle size ratios between NiO/YSZ and CMS (11.27, 4.29, and 0.26) were used, whereas the influence of the applied uni-axial fabrication pressure on the open porosity of sintered anode was studied in a range of atmospheric pressure up to 40 MPa. A good agreement was observed between the proposed model and the experimental data, implying that the approach could be used to determine the significant processing parameters to fabricate ceramics with desired porosity. The model could also be used to interpret the physical basis of pore formation when using a pore-forming agent in a fabricated porous ceramic body.
Lim HH, Sulistya E, Salamatinia B, Wong MY, Amini Horri B (2016) Ceramic Nanocomposites for Solid Oxide Fuel Cells, In: Mishra AK (eds.), Sol-gel Based Nanoceramic Materials: Preparation, Properties and Applications6pp. 157-183 Springer
This book summarizes recent research and development in the field of nanostructured ceramics and their composites.
Choo CK, Goh TL, Shahcheraghi L, Ngoh GC, Abdullah AZ, Amini Horri B, Salamatinia B (2016) Synthesis and Characterization of NiO Nano-Spheres by Templating on Chitosan as a Green Precursor, Journal of the American Ceramic Society99(12)pp. 3874-3882 Wiley
In this study, nickel oxide was prepared through the calcination of extrusion dripped chitosan/nickel nitrate beads. The morphology and structural properties of the products were studied using various characterization techniques. Uniformly distributed nickel oxide was formed as observed from the studies of surface morphology where the processing parameters play a huge role on the resulting morphology. TEM results have shown that nickel oxide with crystallite sizes of 10?30 nm was obtained. The Fourier-transform infrared spectra studies show an intense peak at 525 cm?1, which is attributed to the vibration of Ni?O bond. Furthermore, the XRD results show NiO diffraction peaks correspond to (111), (200), (220), (311), and (222) which indicates that a bunsenite structure with a face-centered cubic phase was produced in this study. The usage of 500°C as the lower limit in this study is justified due to the complete removal of the templating material as seen in the thermalgravimetric analysis studies. Furthermore, it was obtained that the largest surface area of nickel oxide synthesized using this technique is 48.024 m2/g with pore sizes of 19.843 nm. The usage of chitosan as a green template for the synthesis of nanoparticles has shown promising results which allows a more economical and sustainable approach for the fabrication of nanomaterials.
Amouzgar P, Wong MY, Amini Horri B, Salamatinia B (2016) Advanced Material for Pharmaceutical Removal from Wastewater, In: Mishra AK (eds.), Smart Materials for Waste Water ApplicationsChapter 7pp. 179-212 John Wiley & Sons
The 15 state-of-the-art review chapters contained in this book cover the recent advancements in the area of waste water, as well as the prospects about the future research and development of smart materials for the waste water applications ...
Khakdaman HR, Amini Horri B, Manafi Varklani H, Sadraei Noori S Continuous Catalyst/Wax Separation Method,
An improved Method for the separation of catalyst particles and the wax product from the output slurry of a Fischer-Tropsch bubble column reactor comprising the contact of a hydrocarbon solvent from a cyclic solvent stream with the slurry, wherein the solvent is a hydrocarbon fraction which is pressurized and heated to its supercritical state and the temperature and the pressure of the solvent at the supercritical state are similar to those of the F-T reactor. After the separating of the catalyst from the hydrocarbon mixture of the solvent and the slurry in a catalyst separation section the hydrocarbon solvent and the wax product are separated, whereby the recovered solvent phase is lead to the cyclic solvent stream; which is used after re-pressurizing and re-heating in a supercritical solvent supply module to recycling the hydrocarbon solvent for the contact step. A system for carrying out the method is also disclosed.
Rashidi AM, Mohajeri A, Jafari Jozani K, Khorami P, Amini Horri B, Parviz D, Kalbasi M Hydrodesulphurization Nanocatalyst, Its Use and a Process for Its Production,
A nano-supported hydrodesulphurization (HDS) catalyst is prepared for hydrodesulphurization of hydrocarbonaceous feed stock. The catalyst can be prepared through different methods and also used under milder conditions than those required for conventionally used HDS catalysts, but can also function under other hydrodesulphurization operating conditions
Zeng Y, Wang K, Amini Horri B, Yao J, Wu Y, Li D, Want HT (2011) Solar evaporation enhancement using floating light-absorbing magnetic particles, Energy & Environmental Science4(10)pp. 4074-4078 Royal Society of Chemistry
We have demonstrated a new strategy for enhancing solar evaporation by using floating light-absorbing materials. Floating Fe3O4/C magnetic particles with an average size of 500 nm were synthesized by carbonization of poly(furfuryl alcohol) (PFA) incorporated with Fe3O4 nanoparticles. The Fe3O4/C particles had a BET surface area of 429 m2 g?1, and a density of 1.44 g cm?3. Because of their hydrophobicity and a bulk packing density of 0.53 g cm?3, Fe3O4/C particles were floatable on water. Our results indicated that these Fe3O4/C particles enhanced the water evaporation rate by as much as a factor of 2.3 in the solar evaporation of 3.5% salt water. In addition, Fe3O4/C particles were easily recycled using a magnet, and stable after being recycled three times. Our work provides a low-cost and highly effective way for accelerating solar evaporation for industrial applications such as solar desalination, salt production, brine management and wastewater treatment.
Amini Horri B, Ranganathan P, Selomulya S, Wang HT (2011) A new empirical viscosity model for ceramic suspensions, Chemical Engineering Science66(12)pp. 2798-2806
This paper presents a new predictive viscosity model for ceramic suspensions. Starting from Einstein's model (1906), various theoretical, empirical, and phenomenological models have been proposed for different suspension systems. However, there is still a lack of reliable model for ceramic suspensions used in colloidal ceramic shape-forming methods. Here, the rheological properties of ceramic suspensions comprising NiO/YSZ (nickel oxide/yttria stabilized zirconia) as the ceramic powder, and furfuryl alcohol as the suspending media were measured over a range of shear-rates (between 1 and 1000 s?1) and different solid volume fractions from 0 to 0.4010. An empirical equation was then developed for the ceramic suspensions using the mobility parameter (Õ/(Õm?Õ)), which links Einstein's model with the more recent relative viscosity models. The proposed model was used to predict the relative viscosity data, showing excellent agreement to the experimental data from this study and with reported data in literature for other ceramic systems. The model was also used to estimate the maximum solid volume fraction for the ceramic suspensions (Õm=0.571), with better accuracy than those estimated by existing models.
Tan KB, Abdullah AZ, Amini Horri B, Salamatinia B (2016) Adsorption Mechanism of Microcrystalline Cellulose as Green Adsorbent for the Removal of Cationic Methylene Blue Dye, JOURNAL OF THE CHEMICAL SOCIETY OF PAKISTAN38(4)pp. 651-664 The Chemical Society of Pakistan
The adsorption mechanism of pure cellulose is yet to be explored. Thus, in this study, the adsorption mechanism of Microcrystalline Cellulose (MCC), a polysaccharide which is renewable, low cost and non-toxic, was studied on the adsorption of model dye Methylene blue (MB). It was found that the main adsorption mechanism of MB on MCC was due to the electrostatic attraction between the positively charged MB dye and negatively charged MCC. Thus, physical adsorption was the dominant effect, since electrostatic attraction is categorized as physical adsorption. This was verified by Dubinin-Radushkevich isotherm, whereby mean free energy adsorption value was found to be less than 8 kJ/mol. The values of Gibbs free energy for thermodynamics studies were found to be within the range of -20 kJ/mol and 0 kJ/mol, which also indicated physical adsorption. It was due to the electrostatic attraction as adsorption mechanism of this adsorption process which resulted rapid adsorption of MB dye. It was found that equilibrium dye concentration was achieved between 1-3 minutes, depending on the adsorption temperature. The rapid adsorption, as compared to a lot of materials, showed the potential of MCC as the future of green adsorbent. The adsorption of Methylene Blue on MCC fitted well in Langmuir Isotherm, with R2 values of higher than 0.99, while fitted moderately in Freundlich Isotherm, with R2 values between 0.9224 and 0.9223. Comparatively, the adsorption of MB on MCC fitted best Langmuir Isotherm as compared to Freundlich Isotherm which monolayer adsorption occurred at the homogenous surface of MCC. This also indicated adsorbed MB molecules do not interact with each other at neighboring adsorption sites. The maximum adsorption capacity calculated from Langmuir Isotherm was found to be 4.95 mg/g. Despite the potential of MCC as green adsorbent, the challenge of low adsorption capacity has to be addressed in the future.
Rashidi AM, Amini Horri B, Mohajeri A, Sadraei Noori S, Jafari Jozani K, Nakhaeipor A Continuous Process for Producing Carbon Nanotubes,
The present invention relates to a continuous process for producing carbon nanotubes (herein after also referred to as ?CNTs?) of single, double and/or multi-wall type, with any possible desired diameter and with high purity. The preferred embodiment provides means for continuous supply of a catalyst during the process for producing the carbon nanotubes, according to which one can achieve the advantageous continuity of the process.
Chitosan is a linear polysaccharide that can be synthesized through the deacetylation of chitin, a naturally abundant biopolymer found in the exoskeleton of crustaceans. It has received a lot of attention because of important features such as biodegradability, biocompatibility and antibacterial and regenerative properties. These features render it useful as the basic building block in important applications such as adsorptive wastewater treatment, sustained drug delivery, gene therapy, and electrosensors. Grafting this polymer with different types of moieties enhances its properties in different ways, e.g., grafting polyethylene glycol (PEG) to chitosan increases its solubility, and subsequently tuning the percent content of PEG imparts thermoresponsivity to the hydrogel. In this chapter, different applications of grafted chitosan are outlined with respect to different types of moieties, cross-linking reagents, grafting techniques, and experimental parameters such as the pH and the percent concentration of polymers.
This paper has described the application of nickel-doped catalytic constituents based on gadolinium-doped ceria (GDC) for fabrication of the solid-oxide fuel cell (SOFC) anode layer integrated with an in-situ methane-reforming layer (MRL). Nanocrystalline powders of Ni1-xCo3xO1+3x/GDC and Ni1-xCuxO/GDC with various compositions (x = 0.3, 0.5, 0.7) were synthesised using an ultrasound-assisted method followed by a thermal treatment to be applied for fabrication of the integrated MRL and the SOFC anode layer, respectively. Thermogravimetric analysis showed that the synthesized powders should be optimally calcined at 700 °C to exhibit improved crystallinity and catalytic activity. The morphological analysis showed the formation of nanocrystalline powders with particle size ranging from 4-86 nm that was confirmed by the crystal size analysis using XRD results. The elemental analysis by EDX indicated a successful distribution of the constituent ceramic and bimetallic phases after the addition of a sonication stage. The results of FT-IR and Raman spectroscopy confirmed lack of solvents residual after calcination that was in agreement with residual moisture content values obtained from TGA data. The fabricated anode-MRL bilayers had an adequate porosity (36.7%) and shrinkage (33.5%) after adding carbon particles as a pore former (at a loading fraction of 5.9 wt.%). The catalytic performance measurements of the MRL showed a methane conversion of 13% at maximum activity with a weight hour space velocity (WHSV) of 60 L/gh that was mainly due to carbon deposition in the reaction condition.
In this study, nanocrystalline nickel oxide gadolinium-doped ceria (NiO-GDC) powder was synthesized using an ionic sol-gel method. The effects of calcination time and temperature on the particle size and the physiochemical properties of nanocrystalline NiO-GDC are presented in this paper. Using this method, gel beads were formed by contacting sodium alginate solution as the gelling template and metal (gadolinium/cerium/Ni) nitrates as the precursor. The obtained nanocrystallites were characterized using Field Emission Scanning Electron Microscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, thermo gravimetric analysis, nitrogen adsorption/desorption analysis, and Fourier transform infrared spectroscopy. It was observed that the increasing calcination temperature had affected both the particle size and the surface area of the NiO-GDC, whereas the increasing calcination time had only impacted the size of the particles. The smallest mesoporous nanocrystalline NiO-GDC powder (12.1225 ± 0.005 m2/g surface area), composed of cubic GDC (5.18 nm crystallite size) and cubic NiO (7.99 nm crystallite size) were synthesized at a calcination temperature of 500 °C for 2 hours. This study hopes to inspire more researches on the ionic-gelation method for synthesizing other metal nanostructures as well as other reaction parameters.
In this study, nanosized nickel oxide (NiO) and nickel (Ni) powders were synthesised via glycine-nitrate (GN) combustion process, assisted by nanocrystalline cellulose (NCC) as a template. Despite the unique morphology of NCC, it has yet to be applied as a sacrificial bio-template for GN combustion process. In addition, NiO and Ni nanoparticles were obtained at relatively low temperatures in this study, whereby the calcination temperatures were varied from 400 °C to 600 °C, with calcination durations of 2, 4, and 6 h. The morphological analysis of the resulting products were conducted using FESEM, which showed uniformly dispersed NiO and Ni particles with average crystallite size of 25 nm and 27 nm, respectively. These results were confirmed using X-ray diffraction (XRD) technique. The Raman and Fourier transform infrared (FTIR) spectra revealed that the molecular fingerprints of the samples were in agreement with each other. Further analyses revealed that samples calcined at 600 °C for 4 h showed the lowest particle size for pure NiO, whereas the lowest particle size for pure Ni was obtained at 400 °C for 4 h. The TGA results were also consistent with the XRD analysis, whereby pure Ni was initially formed and upon heating, had gradually converted into NiO.
Alkaline water electrolysis is a well-established conventional technique for hydrogen production.
However, due to its relatively high energy consumption, the cost of hydrogen produced by this
technique is still high. Here in this work, we report for the first time the application of alkaline zinc
hydroxide solution (composed of sodium zincate and potassium zincate in NaOH and KOH
solutions, respectively) as an efficient, simple and recursive electrolyte for producing clean hydrogen
through a continuous dual-step electrolysis process. The ionic conductivity, electrodes current
density, and hydrogen evolution rate were measured in a wide range of the electrolyte concentrations
(0.1-0.59 M). Also, the cell efficiency was studied at different ranges of current density (0.09-0.25
A/cm2) and applied potential (1.8-2.2 V). Results indicated that the application of alkaline zinc
hydroxide solution at the optimum electrolyte concentration can enhance the hydrogen evolution rate
minimally by a factor of 2.74 (using sodium zincate) and 1.47 (using potassium zincate) compared to
the conventional alkaline water electrolysers. The results of this study could be helpful to better
understand the electrochemical behaviour of the alkaline water electrolysers when sodium zincate
and potassium zincate are used as ionic activators for enhancing hydrogen evolution.
Nanocrystalline gadolinium-doped ceria (GDC) was synthesized by a single step, low cost and environmentally friendly method using ammonium tartrate as an inexpensive, green and novel precipitant. The precipitate obtained during the process was calcined at 400 and 600/°C and the effect on the final microstructural properties of the powders of differing process variables were studied. The synthesized GDC samples were analysed using a range of different techniques, including XRD, TG/DSC, FESEM, STEM, and FT-IR and Raman spectroscopies. The thermal (TG/DSC), XRD and Raman spectroscopic analyses confirm the formation of a single crystalline phase with a cubic (fluorite) unit cell and formed at a low calcination temperature (400/°C). XRD profiles permitted estimation of crystallite sizes as 20/nm, which was further confirmed by STEM and FESEM micrographs indicating the formation of quasi-spherical particles with uniform particle sizes in the range 10?30/nm. This study will aid understanding of effects of process variables on the properties of doped metal-oxide powders prepared using the carboxylate route
This study is focused on nanocrystalline cellulose (NCC) flakes for methylene blue (MB) removal via adsorption. NCC flakes exhibit a high adsorption capacity (188.7/mg/g fixed at 0.7/g/L adsorbent dosage, 25/°C and pH 6) compared to other nanomaterials, such as carbon nanotube and other cellulosic materials, such as coffee husks. Unlike NCC powder, it was observed that NCC flakes can be easily separated from wastewater containing MB. Further adsorption studies were conducted on NCC flakes, and it was found that 0.7/g/L was the optimum adsorbent dosage, which fitted well with the Langmuir Isotherm. The mean free energy value from Dubinin-Radushkevich isotherm was less than 8/kJ/mol. Go values at different temperatures were within the -20/kJ/mol to 0/kJ/mol range. In conclusion, NCC flakes is a promising and practical ?green? nanomaterial that can be further developed for industrial applications.
Co-precipitation method has been used for the synthesis of single crystalline Nickel (II) Oxide sub-micro rods. A two-step method was used to synthesise NiO sub-micro rods, in which the first step was the co-precipitation process Nickel (II) Nitrate with Ammonium Oxalate to form Nickel (II) Oxalate (NiC2O4), which is the precursor for the precipitates. The precipitate precursor then underwent the calcination process to form NiO sub-micro rods. Synthesized materials undergo Field Emission Scanning Electron Microscope (FESEM), particle size measurement via Zetasizer, elemental analysis via Energy-Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FT-IR) and Thermogravimetric Analysis (TGA). The morphology of NiO is found to have uniform rod- like crystals with mean z-diameter between 1600 nm to 2600 nm using Zetasizer.
Pure cubic phase yttrium oxide or yttria (Y2O3) nanoparticles were successfully synthesised via the co-precipitation method in a distillate pack, followed by calcination of the precursor, yttrium oxalate (Y2(C2O4)3) in a furnace. The co-precipitation reaction temperature was varied between room temperature and 100/°C for various reaction durations ranging between 0.5 and 3/h. The as-synthesised precursor was characterised using a thermogravimetric analyser (TGA) and Fourier transform infrared spectrometer (FTIR). The Y2O3 nanoparticles obtained from the calcination of the precursor at various calcination conditions (temperature ranged from 500 to 800/°C for 2?8/h) were characterised using a field emission scanning electron microscope (FESEM), a transmission electron microscope (TEM), X-ray diffraction (XRD), FTIR, a Raman spectrometer, and Brunauer?Emmett?Teller analyser (BET). It was concluded from these characterisations that the optimum processing parameters for pure Y2O3 nanoparticles are co-precipitation reaction at 40/°C for 1/h, followed by calcination at 650/°C for 4/h. This method yielded semispherical Y2O3 nanoparticles with crystallite size ranging between 7 and 21/nm and a large specific surface area of 7.40/m2/g.
Multiwall carbon nanotubes are modified by urea (MWCNTs-U), as an amide group, through a simple amination method to be used as support for Pt nanoparticles in methanol electrooxidation reaction (MOR). The amination method involves a covalent grafting of urea molecules onto the surface of acid treated multiwall carbon nanotubes (MWCNTs-A) using O-(7-azabenzotriazol-1-yl)-N,N,N2,N2-tetramethyluronium hexafluorophosphate (HATU) as the coupling agent. Platinum nanoparticles are impregnated on the surface of MWCNTs-U using NaBH4. Pt/MWCNTs-U shows an enhanced electrocatalytic activity and durability with exposing larger accessible surface area and 27% higher active surface area compared to Pt/MWCNTs-A. In addition, urea incorporation can improve the electrocatalyst tolerance against CO-poisoning, due to the enhanced formation kinetics of the chemisorbed hydroxyl groups. The onset potential of COads oxidation indicates a decrease from 553/mV to 530/mV for Pt/MWCNTs-A and Pt/MWCNTs-U, respectively. It is observed that in the presence of amide group the forward peak current density and exchange current density, in CV and LSV experiments, respectively increase from 378 to 515/mA/mgPt and 1.59/×/10?8/A/cm2 to 2.12/×/10?8/A/cm2. These results are also in a good agreement with the theoretical activation energies obtained from Arrhenius plots, indicating a decrease from 41.7 to 38.8/kJ/mol methanol in the case of Pt/MWCNTs-A and Pt/MWCNTs-U, respectively.
The impacts of co-precipitation reaction temperature and duration, as well as calcination temperature and duration, on the particle morphology and properties of gadolinia (Gd2O3) nanopowders were investigated. Thermogravimetric curve of thermally treated gadolinium oxalate (Gd2(C2O4)3) showed that pure stable cubic phase Gd2O3 nanopowders could be obtained by calcining at 640/°C and higher. This finding was also supported by results obtained from Fourier Transform Infrared Spectrometry (FTIR) and Raman spectrometry. This study also shows that uniform spherules of Gd2O3 nanopowders could be obtained under controlled synthesis conditions. However, with an increase in both the co-precipitation reaction temperature and duration, the extent of agglomeration of Gd2O3 nanopowders increased, as observed under a Field Emission Scanning Electron Microscope (FESEM). The FESEM images and X-ray Diffraction (XRD) patterns also revealed accelerated grain growth and increased average crystallite size at high calcination temperatures and holding times. It was determined that the most favourable Gd2O3 particle morphology was achieved when Gd2(C2O4)3 was co-precipitated at 40/°C, then thermally degraded at 650/°C, for 1/h and 4/h, respectively. Estimated Scherrer's average crystallite size of the resulting Gd2O3 nanopowders was 16.54/nm, which was further affirmed with the transmission electron microscope (TEM) image, where crystallite sizes of 3?27.5/nm were observed in the Gd2O3 sample. This specimen also demonstrated a considerably large specific surface area of 9.16/m2/g, as measured using a Brunauer?Emmett?Teller (BET) analyser.
Biogas is a renewable, as well as abundant, fuel source which can be utilised in the production of heat and electricity as an alternative to fossil fuels. Biogas can additionally be upgraded via the dry reforming reactions into high value syngas. Nickel-based catalysts are well studied for this purpose but have shown little resilience to deactivation caused by carbon deposition. The use of bi-metallic formulations, as well as the introduction of promoters, are hence required to improve catalytic performance. In this study, the effect of varying compositions of model biogas (CH4/CO2 mixtures) on a promising multicomponent Ni-Sn/CeO2-Al2O3 catalyst was investigated. For intermediate temperatures (650 °C), the catalyst displayed good levels of conversions in a surrogate sewage biogas (CH4/CO2 molar ratio of 1.5). Little deactivation was observed over a 20 h stability run, and greater coke resistance was achieved, related to a reference catalyst. Hence, this research confirms that biogas can suitably be used to generate H2-rich syngas at intermediate temperatures provided a suitable catalyst is employed in the reaction.
In this study, high quality monodispersed nanocrystalline cupric oxide (CuO) nanopowder was prepared through novel sol-gel green synthesis method, assisted by sodium alginate (Na-ALG) as the green ionic exchange material. The morphology and structural properties of CuO nanopowders synthesized with and without the incorporation of extrusion dripping, at different Na-ALG solution concentrations and calcination temperatures, were studied using thermalgravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. Optimum synthesis conditions were identified, resulting in high-purity, monodispersed nanocrystalline CuO powder in the range of 9.92 ? 12.4 nm, which could have a promising future in various applications.
Transition metal oxides have various interesting properties, especially nanostructures of the Copper (II) Oxides (CuO) have special magnetic properties and larger surface area which enhance the applications of the CuO in various fields. In this study, CuO nanoparticles supported on Halloysite Nanotubes (HNTs) via an in-situ glycine nitrate process was successfully synthesized by templating on chitosan. Effects of calcination time and temperature are fully elaborated by detail charactrizations including, FESEM, FTIR, TGA, EDX, BET and Raman Spectroscopy. The best calcination condition was found to be at 600 C for 5 h of calcination duration. Charactrizations confirmed the presence of both HNT and CuO within the particles confirming that the in-situ synthesis of metal-oxides by supporting them on HNTs is very much feasible.
Zirconia (ZrO) nanoparticles were successfully synthesised from zirconyl chloride and ammonium oxalate via co-precipitation (CP), followed by calcination of the resulting co-precipitated precursor. CP and calcination processing parameters showed considerable effects on the surface morphology, average crystallite size, and phase purity of the resulting ZrO particles. In this work, field emission scanning and transmission electron microscopy (FESEM and TEM) confirmed the existence of spherical and uniformly shaped ZrO particles, with crystallite size ranging between 6 and 35/nm. Pure ZrO nanoparticles synthesised through calcination at 650/°C had a strained monoclinic phase structure. On the other hand, ZrO particles prepared through calcination at 600/°C revealed presence of a transitional phase from tetragonal to monoclinic phase in its X-ray diffraction (XRD) patterns. The FESEM images and XRD results also revealed that the degree of particle agglomeration and average crystallite size had increased with increasing processing temperatures and durations. Henceforth, precursor was co-precipitated at 40/°C for 1/h, then calcined at 650/°C for 4/h for optimum production of ZrO nanoparticles with an average crystallite size of 12.85/nm and large Brunauer?Emmett?Teller (BET) surface area of 18.06/m²/g.
This paper deals with the development and potential application of a novel mixed ionic-electronic conductive anode composite comprised of copper and iron oxide based on gadolinium-doped ceria (CuO?Fe2O3/GDC) for solid-oxide fuel cell (SOFC). Synthesis of the nanocrystalline CuO?Fe2O3/GDC powders was carried out using a novel co-precipitation method based on ammonium tartrate as the precipitant in a mixed-cationic solution composed of Cu2+, Fe3+, Gd3+, and Ce3+. Thermal decomposition of the resultant precipitate after drying (at 55 °C) was investigated in a wide range of temperature (25?900 °C) using simultaneous DSC/TGA technique in air. The DSC/TGA results suggested the optimal calcination temperature of 500 °C for obtaining the nanocrystalline anode composite from the resultant precipitate. The synthesised CuO?Fe2O3/GDC samples were further characterised using XRD, dilatometry, FESEM, and EDX. Several single cells of SOFCs were fabricated in the anode-supported geometry using the synthesised CuO?Fe2O3/GDC composite as the anode, GDC/CuO composite as the electrolyte, and LSCF/GDC composite as the cathode layer. The fabricated cells were analysed using FESEM imaging and EIS analysis, where an equivalent circuit containing five R-CPE terms was used to interpret the EIS data. The module fitted well the impedance data and allowed for a detailed deconvolution of the total impedance spectra. The catalytic activity and uniformity of the synthesised nanocomposites was further evaluated using TPR analysis, demonstrating excellent activity at temperatures as low as 200 °C.
The production of size-tunable Carbon microspheres (CMSs) from cheaply available materials
using an environmentally friendly technique is highly appreciated. In this study, size-tunable
CMSs were hydrothermally synthesized at 190°C using sucrose as carbon source, and citric acid
as a catalyst. The effect of varying citric acid concentration on the size of the microspheres was
investigated. Results indicated that under similar hydrothermal conditions, variation in the concentration
of citric acid between 0 and 5 wt.% increased the size of CMSs ranging from 3.12 to
11.2 ¼m, as evidenced by SEM and particle size analyzer. TGA confirmed the purity of the carbonaceous
particles in a single-step degradation with the presence of D-band and G-band in
Raman spectra. FTIR and elemental analyzer confirmed the presence of hydrophilic oxygen functionalities
such as ?OH, ?C=O, and COOH on the surface of CMSs. This study opens a novel and
straightforward approach to produce size-tunable CMSs with functional groups.