Effect of Different Pluronic P123 Triblock Copolymer Surfactant Concentrations on SBA-15 Pore Formation

Santa Barbara Amorphous-15 (SBA-15) is an interesting mesoporous silica material with highly ordered nanopores and a large surface area. Due to its unique properties, this material has been widely employed in many areas. This study aimed to predict the number of nanopores per gram of SBA-15 material based on an optimum value of surfactant addition at the desired number of nanopores. For this purpose, SBA-15 was synthesized via a sol-gel process using tetraethyl orthosilicate (TEOS, Si(OC2H5)4) as a precursor and pluronic P123 triblock copolymer surfactant (EO20PO70EO20, EO = ethylene oxide, PO = propylene oxide) as a template. There were five different surfactant concentrations, namely 0.35, 2.50, 2.70, 3.00, and 3.30 millimoles, used with a fixed concentration of TEOS. The characterization was performed using small-angle x-ray scattering (SAXS), adsorption-desorption (BET), and transmission electron microscopy (TEM). The results showed that the surfactant concentration did not affect the crystal structure, although an increase in the surfactant concentration linearly correlated with an increase in the surface area. The shape and size of the pore diameter tends to be approximately 3 nm, as characterized using BET adsorption-desorption. The optimum concentration of surfactant for the formation of mesoporous SBA-15 material was 2.70 millimoles. The value obtained in this study was in accordance with the calculated value, indicating that the theoretical calculations can be used to experimentally predict the number of pores

Exploring Potential Materials, Science, and Technology for Improvements in Reusing Energy and Waste

Exploring the science and engineering of new approaches to energy and waste reuse is both a very important and very interesting issue. There have been great efforts made to find potential materials, science, and technology for improvements in the reuse of energy and waste, to ensure energy sustainability and to increase the effectiveness and efficiency of engineering processes to achieve optimum energy production. Most of the efforts have been devoted to materials for photovoltaics, hydrogen production, batteries, and green energy. The range of materials of interest is very wide, from polymers to quantum dots. However, the engineering and environmental issues still present limitations, such as high energy demands, catalyst costs, and insufficient reuse or regeneration of spent adsorbents and catalysts. These challenges have opened new exploration of, for example, cheaper precursors, regeneration of spent adsorbents or catalysts, extraction of useful elements from waste, and overall optimization of engineering processes. More recently, multifunctional and advanced materials have started to show promise for future applications. Integration of economical precursors, high performance materials, efficient methods, easy-to-use designs, and cost-effective manufacturing are always required for competitive energy production, and one would therefore expect clean energy that could address global warming to remain a major issue for many years. Development of alternative uses and reuses of by-products (waste) has also been of interest, not only to reduce the production of carbon dioxide, but also to achieve zero-waste policies. Overall, efforts are being made toward achieving high efficiency, economical or low-cost, renewable, and eco-friendly energy production. Adsorption processes utilizing agro-waste as a simple method for removing heavy metals, pollutants, and odor from wastewater, are another important thread for environmental and industrial applications. Exploring new alternative adsorption processes and low-cost, highly efficient, and abundant adsorbents from agro-waste are being pursued for the further development of environmental applications that could remove or reduce a diverse range of hazardous pollutants and facilitate minimization methods for the management of waste on large a scale. To address the above issues, the 3rd International Tropical Renewable Energy Conference (i?TREC) 2018, with the main theme of “Sustainable Development of Tropical Renewable Energy,” was held on September 6–8, 2018, at the Discovery Kartika Plaza, Bali, Indonesia. This conference was   proudly organized by the Tropical Renewable Energy Center, Faculty of Engineering, Universitas Indonesia. The conference consisted of four symposia, including Smart Grids and Regulation, Bioenergy, Multifunctional and Advanced Materials, and Eco Tropical Built Environment. The current edition consists of 21 peer-reviewed papers, out of 313 papers submitted to the 3rd International Tropical Renewable Energy Conference (i?TREC) 2018, which are divided based on the symposia topics. The 21 presented and selected papers come from various countries, including the USA, UK, Canada, Brunei Darussalam, Malaysia, and Indonesia. At the conference, the participants updated the current trends in new materials and approaches to reuse of energy and waste, providing a space for discussion focusing on the methodology, technology, and empirical work of tropical renewable energy. Publishing information on the conference via traditional printed media, however, takes time and, for several reasons, the discussion presented therein might remain unknown to a wider audience.   In this special issue of the International Journal of Technology, we would therefore like to present the discussions in the form of research papers, and thereby make it available to a wider readership and, with the inclusion of these published materials, enrich and extend the i-TREC conference reports

Characteristics of Vanadium Doped and Bamboo Activated Carbon Coated LiFePO4 and Its Performance for Lithium Ion Battery Cathode

Vanadium doped and bamboo activated carbon coated lithium iron phosphate (LiFePO4) used for lithium ion battery cathode has been successfully prepared. Lithium iron phosphate was prepared through a wet chemical method followed by a hydrothermal process from the starting materials of LiOH, NH4H2PO4, and FeSO4.7H2O. The dopant variations of 0 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% of vanadium and a fixed 3 wt.% of bamboo activated carbon were carried out via a solid-state reaction process each by using NH4VO3 as a source of vanadium and carbon pyrolyzed from bamboo tree, respectively. The characterization was carried out using X-ray Diffraction (XRD) for the phase formed and its crystal structure, Scanning Electron Microscope (SEM) for the surface morphology, Electrochemical Impedance Spectroscopy (EIS) for the conductivity, and battery analyzer for the performance of lithium ion battery cathode. The XRD results show that the phase formed has an olivine based structure with an orthorhombic space group. Morphology examination revealed that the particle agglomeration decreased with the increasing level of vanadium concentrations. Conductivity test showed that the impedance of solid electrolyte interface decreased with the increase of vanadium concentration indicated by increasing conductivity of 1.25 x 10-5 S/cm, 2.02 x 10-5 S/cm, 4.37 x 10-5 S/cm, and 5.69 x 10-5 S/cm, each for 0 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% vanadium, respectively. Vanadium doping and bamboo activated carbon coating are promising candidate for improving lithium ion battery cathode as the initial charge and discharge capacity at 0.5C for LiFePO4/C at 7 wt.% vanadium is in the range of 8.0 mAh/g

Optimization of Silicon Extraction from Tanjung Tiram Asahan Natural Sand through Magnesiothermic Reduction

We carried out silicon extraction from the natural resources of Tanjung Tiram Asahan, Batu Bara Regency, North Sumatra through variation of heating temperatures and magnesiothermic reduction. Prior to the extraction, the sand from the natural resource was refined until the solid white silica powder was separated. The reaction conditions were performed at various heating temperatures in a furnace, as follows: at 750 (2 hours), 800 (3 hours), 850 (3 hours), 900 (3 hours), and 950 (3 hours). Optimization of the extraction reaction conditions was then performed using magnesiothermic reduction at several silica and magnesium ratios, i.e. 1:1.125, 1:1.50, 1:1.75, 1:1.20, and 1:1.25. The refined silica, together with all of the silicon products from the extraction, was characterized using XRD and analyzed. The morphology of the reaction product was characterized using an electron microscope. The results showed that changes to the silicon products after extraction varied, depending on temperature. Optimization of silicon extraction from silica was obtained at 800°C for 3 hours, with a silica and magnesium ratio of 1:1.75

Characteristics of Nano Rosette TiO2 Hydrothermally Grown on a Glass Substrate at Different Reaction Time and Acid Concentration

The characteristics of nano rosette TiO2 hydrothermally grown on a glass substrate at different reaction times and acid concentrations has been examined. The hydrothermal reaction was performed at 170°C for 3, 4, 5, and 6 hours whereas the crystallization was achieved through calcination at 450°C for 90 minutes. The growth mechanism was observed by employing the hydrothermal reaction under different acid concentrations: 0%, 12.5%, 25%, and 50% v/v HCl. The morphology, formation, crystallization, and growth mechanism of the nano rosette TiO2 were characterized using a field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). The electron images showed that after 3 hours of hydrothermal reaction time, the nucleation process has just taken place; the formation of the nano rosette was completed after 6 hours. The results also showed that the acid environment plays a dominant role in determining the three-dimensional (3D) architecture of the nano rosette TiO2. Structural studies from XRD showed that different acid concentrations resulted in different crystalline formations. The nano rosette rutile TiO2 crystal structure was formed after 6 hours of hydrothermal reaction under 1:1 distilled water and HCl with a structure indexed to rutile P42/mnm with lattice parameters of a = 4.557(6) Å and c = 2.940(5) Å

Characteristics of Vanadium Doped And Bamboo Activated Carbon Coated LiFePO4 And Its Performance For Lithium Ion Battery Cathode

Vanadium doped and bamboo activated carbon coated lithium iron phosphate (LiFePO4) used for lithium ion battery cathode has been successfully prepared. Lithium iron phosphate was prepared through a wet chemical method followed by a hydrothermal process from the starting materials of LiOH, NH4H2PO4, and FeSO4.7H2O. The dopant variations of 0 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% of vanadium and a fixed 3 wt.% of bamboo activated carbon were carried out via a solid-state reaction process each by using NH4VO3 as a source of vanadium and carbon pyrolyzed from bamboo tree, respectively. The characterization was carried out using X-ray Diffraction (XRD) for the phase formed and its crystal structure, Scanning Electron Microscope (SEM) for the surface morphology, Electrochemical Impedance Spectroscopy (EIS) for the conductivity, and battery analyzer for the performance of lithium ion battery cathode. The XRD results show that the phase formed has an olivine based structure with an orthorhombic space group. Morphology examination revealed that the particle agglomeration decreased with the increasing level of vanadium concentrations. Conductivity test showed that the impedance of solid electrolyte interface decreased with the increase of vanadium concentration indicated by increasing conductivity of 1.25 x 10-5 S/cm, 2.02 x 10-5 S/cm, 4.37 x 10-5 S/cm, and 5.69 x 10-5 S/cm, each for 0 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% vanadium, respectively. Vanadium doping and bamboo activated carbon coating are promising candidate for improving lithium ion battery cathode as the initial charge and discharge capacity at 0.5C for LiFePO4/C at 7 wt.% vanadium is in the range of 8.0 mAh/g

Innovation of Renewable Energy, CO2 Capture and Storage Materials for Better Applications

The 15th International Conference on Quality in Research (QiR) was held in Nusa Dua, Bali, Indonesia on July 24–27, 2017. The main theme was “Science, Technology and Innovation for Sustainable World.” This third book of special edition of International Journal of Technology (IJTech) present 18 papers in the research areas of chemical and metallurgy & materials engineering. The International Symposium on Chemical Engineering, QiR, covered various topics such as renewable energy business and economics, biomass conversion technologies, modeling and simulation, advanced thermal and chemical processes, waste to energy, advanced biofuel technology, catalysts, composites, photocatalysis, and adsorption. We have selected 10 papers from the 80 submitted for publication in the IJTech. The International Symposium on Materials and Metallurgy, QiR, covered topics such as carbon, graphene, oxides, nanocomposites, mesostructured materials, advanced superconducting, electrochemical water splitting, extraction, hydrometallurgy, and energy storage devices. We selected 8 papers from the 111 fullpapers for publication in the IJTech. The eighteen papers, from both symposia, are summarized below

Characteristics of Carbon Pyrolyzed from Table Sugar and Sucrose for Pt-less DSSC Counter Electrode

Platinum is the most effective counter electrode for use in dye-sensitized solar cells (DSSC). However, as platinum is very expensive, its price impedes its broad use as a DSSC counter electrode. As an alternative, carbon has been used for this purpose. In this study, carbon has been successfully pyrolyzed from the precursors of table sugar and sucrose through a chemical process, i.e. the dehydration of the precursors with sulfate acid followed by a pyrolysis process, and used as Pt-less counter electrode in a DSSC device. The as-synthesized carbon was characterized using X-ray diffraction (XRD) to obtain crystal structure information and a scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX) was employed to carry out morphological and compositional examination. The material activity and performance of the counter electrode in the DSSC device were analyzed using a semiconductor parameter analyzer through current–voltage characteristic curves (I-V). The results show that the precursors of table sugar without the addition of a metal catalyst and with initial heat treatment at 300°C for 1 hour, and of sucrose with a catalyst could produce carbon with a particle size of around 600–900 nm. The I-V curve characteristic of the DSSC device assembled using carbon produced from sucrose as a counter electrode resulted in a power conversion efficiency (PCE) of only 0.041%, whereas the DSSC device assembled using carbon produced from table sugar as a counter electrode exhibited a good performance with a PCE of 3.239%, almost equivalent to that of platinum paste with a PCE of 4.024%. This result is promising in terms of using a cheap source of carbon for the Pt-less counter electrode