Table of contents

This volume of the Journal of Physics: Conference Series contains papers presented at the Tunisia-Japan Symposium: R&D of Energy and Material Sciences for Sustainable Society (TJS 2014) held at Gammarth, Republic of Tunisia on November 28-30, 2014. The TJS 2014 is based on the network of the Tunisia-Japan Symposium on Science, Society and Technology (TJASSST) which has been regularly organized since 2000. The symposium was focused on the technological developments of energy and materials for the realization of sustainable society. To generate technological breakthrough and innovation, it seems to be effective to discuss with various fields of researchers such as solid-state physicists, chemists, surface scientists, process engineers and so on. In this symposium, there were as many as 109 attendees from a wide variety of research fields. The technical session consisted of 106 contributed presentations including 3 plenary talks and 7 key-note talks. We hope the Conference Series and publications like this volume will contribute to the progress in research and development in the field of energy and material sciences for sustainable society and in its turn contribute to the creation of cultural life and peaceful society.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Dye-sensitized solar cells (DSC or DSSC) have been widely investigated because of their potentially high cost performance compared with Si-based solar cells and of their fascinating appearance. DSC with photoelectric conversion efficiency of >10 % (or even 12 %) have been reported, where porous TiO₂ films are generally used as semi-conductor electrodes. Such porous TiO₂ films usually have high specific surface area, and thus, they adsorb plenty of dye molecules, resulting in high photocurrent density. Recently, some double oxides have been examined as alternative photoanode materials, mainly in order to improve photovoltage. Here, studies on DSC using double-oxide electrodes, i.e., perovskite, spinel, ilmenite, wolframite, scheelite and pseudobrookite-types, are briefly reviewed.

Plasmonics is a new light trapping method used in photovoltaic (PV) solar cells. A significant enhancement of the scattered and absorbed incident light due to the use of silver nanoparticles (Ag-NPs) was observed, which yield to the exaltation of the electromagnetic field in the vicinity of these NPs. In this context, we investigate optically and morphologically the effect of the NPs size dependence on the localized surface plasmon resonance. Extinction, absorption and scattering cross sections are calculated using Mie theory.

The industries related to the ceramics such as construction bricks, pottery and tile are the important sectors that cover the large part of the working population in Tunisia. The raw materials, clay or silt are excavated from opencast site of limestone clay stratum. The opencast site give the negative impact on landscape and environment, risks of landslide, soil erosion etc. On the other hand, a most serious problem in water resource management, especially in arid land such as Tunisia, is sedimentation in reservoirs. Sediment accumulation in the reservoirs reduces the water storage capacity. The authors proposed the exploitation of the sediment as raw material for the ceramics industries in the previous studies because the sediment in Tunisia is fine silt. In this study, the potential of the water reservoirs in Tunisia as the resource of the raw material for the ceramics industries is estimated from the sedimentation ratio in the water reservoirs.

This study deals with the performance of the ejector-vapour compression cycle assisted by solar. The effect of operating conditions on the combined cycle performance is examined. Also, a comparison of the system performance with environment friendly refrigerants (R134a, R600, R123, R141b, R142b, R152a, R290, and R245fa) is made. This performance is calculated using an empirical correlation. Thermodynamic properties of functioning fluids are obtained with package REFPROP 8. Using the typical meteorological year file containing the weather data of the city of Tunis, the system performance is computed for three collector types. The theoretical results show that the R290 offers the highest coefficient of performance, COP=3.75, for generator temperature T_B = 78°C, condenser temperature T_c = 30°C and the intercooler temperature T_e = 15°C.

We grow BaSi₂ epitaxial films on Si(111) substrates by molecular beam epitaxy, and investigate their optical properties such as optical absorption coefficients, minority-carrier diffusion length, and minority-carrier lifetime. These are key parameters which determine the solar cell performance. The band gap of BaSi₂ is measured to be approximately 1.3 eV. The absorption coefficient reaches approximately 3×10⁴ cm⁻¹ at 1.5 eV. The minority-carrier diffusion length and minority-carrier lifetime are found to be about 10 μm and 8 μs, respectively. These values are sufficiently large for thin-film solar cell applications. Internal photoresponse spectra are deduced from data obtained experimentally.

A 3D CFD (Computational fluid dynamics) model of a Solar Chimney Power Plant (SCPP) was developed and validated through comparison with the experimental data of the Manzanares plant. Then, it was employed to study the SCPP performance for locations throughout Tunisia.

Hollow silica (SiO₂) nanoparticles with tunable shell microstructures were synthesized in ethanol solvent by using a polyelectrolyte as template. The polyelectrolyte template was composed of poly (acrylic acid) (PAA) with small amount of ammonia solution (NH₄OH) and prepared by dispersion of the PAA-NH₄OH mixture in ethanol. Upon the addition of silica precursor, tetraethoxysilane (TEOS), into the PAA-NH₄OH/ethanol suspension, a certain thickness of SiO₂ shell could be gradually formed outside the template through+the sol-gel reaction of TEOS, which was supposed to be driven by the catalytic effect of NH₄ ions suspended on the surface of the template. By varying the NH₄OH amount in reaction solution, it was found that the hollow SiO₂ nanoparticles could be obtained only in the case of NH₄OH amount below a critical value. Furthermore, it was found that the water amount in reaction solution had a significant influence on the shell microstructure of hollow SiO₂. The shells formed in water-free solution were thick, rough and rich of mesopores, which became relatively thinner, smoother and richer of micropores if the water amount was gradually increased within a limited range. Therefore, it was thought to be possible for the controllable synthesis and shell structure design of hollow SiO₂ nanoparticles by optimizing the NH₄OH and water amount in reaction solution.

There is a small quantity of participants in the global market of silicon, mainly from the developed countries. It should be noticed also that production of metallurgical silicon Mg-Si is among the most important steps to produce solar grade silicon and photovoltaic panels. Therefore, in this paper we focused on the growth of Mg-Si by carbothermal reduction of silica. An investigation was made using FT-IR characterization to study the effect of process conditions (temperature, atmosphere, duration) in Mg-Si production. Raman spectroscopy was used to investigate the produced Mg-Si. Based on these results, we established a pilot line production of metallurgical silicon at the "CRTEn" in Tunisia.

Brushite (Dicalcium phosphate dihydrate, (DCPD), CaHPO₄·2H₂O) is one of key components in calcium phosphate system due to wide attractive material not only as bioceramics but also environmental materials. Morphology of DCPD crystals is important factor when one uses its functionality with chemical reaction; because its surface crystal face, shape and size rule the chemical reactivity, responsiveness. Moreover, physical properties are also changed the morphology; such as cohesion, dispersiveness, permeability and so on. If one uses DCPD crystals as environmental renovation materials to catch the fluoride ions, their shape require 020 crystal surfaces; which usually restricts their shape as plate-like structure. After the chemical reaction, the shape of sludge is not good for handling due to their agglutinate property. Therefore searching an effective parameter and developing the method to control the morphology of DCPD crystals is required. In past, we reported that initial concentration and pH value of starting solution, prepared by dissolving calcium nitrate, Ca(NO₃)₂ and ammonium dihydrogen phosphate, NH₄H₂PO₄, changes the morphology of DCPD crystals and phase diagram of morphology of DCPD crystal depend on those parameter. The DCPD crystallization shows unique behaviour; products obtained higher initial concentration form single crystal-like structure and under lower condition, they form agglomerate crystal-like structure. These results contradict usual crystallization. Here we report that the effect of mixing process of two solutions. The morphology of DCPD crystals is changed from plate structure to petal structure by the arrangement. Our result suggests that morphology of DCPD crystals strongly depends at incipient crystallization condition and growth form is controllable by setting initial crystallization condition.

This paper proposes a stand-alone photovoltaic (PV) system study in domestic applications. Because of the decrease in power of photovoltaic module as a consequence of changes in solar radiation and temperature which affect the photovoltaic module performance, the design and control of DC-DC buck converter was proposed for providing power to the load from a photovoltaic source.In fact, the control of this converter is carried out with integrated MPPT (Maximum Power Point Tracking) algorithm which ensures a maximum energy generated by the PV arrays. Moreover, the output stage is composed by a battery energy storage system, dc-ac inverter, LCL filter which enables higher efficiency, low distortion ac waveforms and low leakage currents. The control strategy adopted is cascade control composed by two regulation loops.Simulations performed with PSIM software were able to validate the control system.The realization and testing of the photovoltaic system were achieved in the Photovoltaic laboratory of the Centre for Research and Energy Technologies at the Technopark Borj Cedria. Experimental results verify the effeciency of the proposed system.

Dissolution rate of various chemical gypsums in the water was investigated by using batch experiment. The rate of the dissolution of the gypsum had good agreement for explanation of dissolution of plate particle. The rate constants of the experimental formula were different with particle morphology of the gypsums. When morphology of the particle was sheet-liked, the dissolution rate was 10 timed large than it of block-shaped particle. From result of observation of dissolution phenomena of the in the water, it was find that dissolution of the gypsum was preceded on long axis. From these results, particle morphology is seems to be important parameter for using chemical gypsums.

Nanostructured titanium dioxide (TiO₂) thin films were prepared with one and two layers on glass substrates (ITO) using sol gel-spin coating technique and annealed at temperature ranging from 300°C to 600°C. X-ray diffraction (XRD) and UV-Vis transmittance spectroscopy were used to study the effects of annealing temperature on the structural and optical properties. X-ray diffraction studies showed that the as-deposited films were amorphous and at first changed to anatase phase with increase of annealing temperature. Optical constants of these films were derived from the transmission and reflection spectra subjected to annealing at different temperatures. The results indicate that an anatase phase structure TiO₂ thin film with nanocrystallite size of about 10.72 nm can be observed at 400°C. The optical gap decreases from 3.82 eV to 3.74.eV for one layer and from 3.64 eV to 3.5 eV for two layers when the annealing temperature increases from 300 °C to 600°C. The refractive index is low compared to a pore free anatase TiO₂ and it increases contrary to the porosity which is reduced with the raising of the annealing temperature.

One of the biggest problems of the 21st century is the global water shortage. Therefore it is difficult to increase the quantity of conventional water resources such as surface water and groundwater for agriculture and industry in arid area. Technical advancement in water treatment membrane technology including RO membrane has been remarkable especially in recent years. As the pore size of RO membrane is less than one nanometer, it is possible to produce the fresh water, which satisfies the drinking water quality standards, with utilizing RO membrane. In this report a new fresh water resource from municipal waste water is studied to apply to the plant factory which is the water saving type agriculture and industry in arid area.

A simple and sensitive electroanalytical method was developed to determine the Endocrine Disrupting chemical 4-tert-octylphenol on clay modified carbon paste electrode (Clay/CPE). The electrochemical response of the proposed electrode was studied by means of cyclic and square wave voltammetry. It has found that the oxidation of 4-tert-octylphenol on the clay/CPE displayed a well-defined oxidation peak. Under these optimal conditions, a linear relation between concentrations of 4-tert-octylphenol current response was obtained over range of 7.26×10⁻⁶ to 3.87×10⁻⁷ with a detection and quantification limit of 9.2×10⁻⁷ M and 3.06×10⁻⁶ M, respectively. The correlation coefficient is 0.9963. The modified electrode showed suitable sensitivity, high stability and an accurate detection of 4-tert-octylphenol. The modified electrode also relevant suitable selectivity for various phenolic estrogenic compounds.

The shortage of silicon for solar cells has much attract in research and development of the low cost mass production process of solar grade Silicon (SOG-Si). The key of the strategy to silicon for solar cells in long terms is the efficiency in reduction. We developed a new concept reduction furnace using the combinatorial method in order to investigate the metallurgical process for silicon reduction. The production of reduced Si shows purity with less 2ppm level.

The comparison between the experimental and theoretical simulations of a desiccant cooling system under various climatic conditions (outdoor temperature and relative humidity) on the system performance has been presented. The performance of the system is evaluated using Cooling Capacity (CC) parameter. The system under a typical summer day of hot and humid climate was tested. A remarkable decrease about 40-65% in the specific humidity and with a supply air temperature lower than 25°C of the proposed system was observed. The study is important and helpful to improve the effectiveness of this kind of liquid desiccant system in hot and humid places.

Biodiesel fuel is a replacement for diesel as a fuel produced from biomass resources. It is usually defined as a fatty acid methyl ester (FAME) derived from vegetable oil or animal fat. In European countries, such as Germany and France, biodiesel fuel is commercially produced mainly from rapeseed oil, whereas in the United States and Argentina, soybean oil is more frequently used. In many other countries such as Japan and countries in Southeast Asia, lipids that cannot be used as a food source could be more suitable materials for the production of biodiesel fuel because its production from edible oils could result in an increase in the price of edible oils, thereby increasing the cost of some foodstuffs. Therefore, used edible oil, lipids contained in waste effluent from the oil milling process, byproducts from oil refining process and crude oils from industrial crops such as jatropha could be more promising materials in these countries. The materials available in Japan and Southeast Asia for the production of biodiesel fuel have common characteristics; they contain considerable amount of impurities and are high in free fatty acids (FFA). Superheated methanol vapor (SMV) reactor might be a promising method for biodiesel fuel production utilizing oil feedstock containing FFA such as waste vegetable oil and crude vegetable oil. In the conventional method using alkaline catalyst, FFA contained in waste vegetable oil is known to react with alkaline catalyst such as NaOH and KOH generating saponification products and to inactivate it. Therefore, the FFA needs to be removed from the feedstock prior to the reaction. Removal of the alkaline catalyst after the reaction is also required. In the case of the SMV reactor, the processes for removing FFA prior to the reaction and catalyst after the reaction can be omitted because it requires no catalyst. Nevertheless, detailed study on the productivity of biodiesel fuel produced from waste vegetable oils and other non-edible lipids by use of the SMV reactor has not been examined yet. Therefore, this study aims to investigate the productivity of biodiesel produced from waste vegetable oils using the SMV reactor. Biodiesel fuel is a replacement for diesel as a fuel produced from biomass resources. It is generally produced as a FAME derived from vegetable oil by using alkaline catalyzed alcoholysis process. This alkaline method requires deacidification process prior to the reaction process and the alkaline catalyst removal process after the reaction. Those process increases the total cost of biodiesel fuel production. In order to solve the problems in the conventional alkaline catalyzed alcoholysis process, the authors proposed a non-catalytic alcoholysis process called the Superheated Methanol Vapor (SMV) method with bubble column reactor. So, this study aims to investigate the productivity of biodiesel produced from vegetable oils and other lipids using the SMV method with bubble column reactor.

The central receiver technology for electricity generation consists of concentrating solar radiation coming from the solar tracker field into a central receiver surface located on the top of the tower. The heliostat field is constituted of a big number of reflective mirrors; each heliostat tracks the sun individually and reflects the sunlight to a focal point. Therefore, the heliostat should be positioned with high precision in order to minimize optical losses. In the current work, a mathematical model for the analysis of the optical efficiency of solar tower field power plant is proposed. The impact of the different factors which influence the optical efficiency is analyzed. These parameters are mainly, the shading and blocking losses, the cosine effect, the atmospheric attenuation and the spillage losses. A new method for the calculation of blocking and shadowing efficiency is introduced and validated by open literature.

Cu₂ZnSn(S,Se)₄ (CZTSSe) thin films with various Cu/Sn ratio in the films have been investigated to study the effect of compositional variation over the electrical, optical, and structural properties of the film. Surface morphology and grain size were found to be significantly influenced by the Cu/Sn ratio in the films and grain size was found better for the samples with moderate Cu/Sn ratio of 1.75. Irrespective of the growth condition and compositional variation, all the CZTSSe crystals show that grains are oriented along (112) direction as evident from the room temperature XRD data. Dark current-voltage (I-V) curve reveals that that sample with Cu/Sn = 1.75 exhibits lowest leakage current, while sample with Cu/Sn = 1.85 has the highest leakage current along with larger ideality factor indicating larger recombination centers in this film. Series resistance was also found to be higher in the sample with higher Cu-content. An anomaly in the optical band-gap has been explained with the presences of impurity phases and compositional inhomogeneities in the CZTSSe materials.