Abstract. Zirconium oxide (zirconia, ZrO2) is the most common material used for electrolyte of solid oxide fuel cells (SOFCs). Zirconia has attracted attention for applications in optical coatings, buffer layers for growing superconductors, thermal-shield, corrosion resistant coatings, ionic conductors, and oxygen sensors, and for potential applications including transparent optical devices and electrochemical capacitor electrodes, fuel cells, catalysts, and advanced ceramics. In this work, zirconia particles were synthesized from ZrCl4 precursor with hydrothermal treatment in a batch reactor. Hydrothermal treatment may allow obtaining nanoparticles and sintered materials with controlled chemical and structural characteristics. Hydrothermal treatment was carried out at temperatures of 150 -200 o C with precursor concentration of 0.1 -0.5 M. Zirconia particles obtained from this treatment were analyzed by using SEM, PSD and XRD to characterize the morphology, particle size distribution, and crystallinity, respectively. Based on the analysis, the size of zirconia particles were around 200 nm and it became smaller with decreasing precursor concentration. The increasing temperature caused the particles formed having uniform size. Zirconia particles formed by hydrothermal treatment were monoclinic, tetragonal and cubic crystal.

Energi listrik adalah energi yang berasal dari muatan listrik yang menimbulkan medan listrik statis atau bergeraknya elektron pada konduktor (pengantar listrik) atau ion (positif atau negatif) pada zat cair atau gas. Energi listrik dibutuhkan oleh masyarakat untuk menghidupkan lampu penerangan, memanaskan, mendinginkan ataupun untuk menggerakkan kembali suatu peralatan mekanik untuk menghasilkan bentuk energi yang lain. Untuk memenuhi kebutuhan tersebut dilakukan berbagai upaya pembaharuan energi salah satunya memanfaatkan campuran pasir laut dan air laut. Pemanfaatan air laut sudah diketahui bahwa memang bisa menghasilkan arus listrik. Penelitian ini merupakan studi awal untuk mengkombinasi air laut dan pasir laut sebagai bahan baku. Tujuan dari penelitian ini adalah menganalisis komposisi optimal antara air laut dan pasir laut dalam menghasilkan energi listrik. Sumber air laut dan pasir laut berasal dari Pantai Kenjeran Surabaya Indonesia. Metode penelitian berupa pencampuran air laut dan pasir laut dengan komposisi perbandingan persen berat pasir laut di dalam campuran sebesar 0%, 25%, 50%, 75%, dan 100%. Energi listrik yang dihasilkan ditunjukkan dengan mengamati aliran arus dan daya yang terlihat pada multimeter. Berdasarkan hasil pengukuran arus dan tegangan didapatkan berturut-turut sebesar 2,4 V; 2,3 V; 2,3 V; 1,8 V; dan 0,9 V. Sehingga hasil analisis dari kandungan air laut dan pasir laut berpotensial untuk dimanfaatkan sebagai sumber energi listrik, meskipun pasir laut berperan sebagai hambatan.Electrical energy is energy derived from electric charge that causes static electric field or the movement of electrons in a conductor (conductor of electricity) or ions (positive or negative) in a liquid or gas. The electrical energy needed by society to lighting, heating, cooling, or to move back in mechanical equipment to produce other forms of energy. Utilization of a mixture of sand and sea water is one of the methods of renewable energy. In other hand, utilization of sea water is known that it can generate electricity. This study is a preliminary study to combine sea water and sea sand as raw materials. The purpose of this study was to analyze the optimal composition of sea water and sea sand in generating electrical energy. Source of sea water and sea sand comes from Kenjeran Beach Surabaya Indonesia. Research methods such as mixing sea water and sea sand with a weight percent ratio sea sand in the mixture of 0%, 25%, 50%, 75%, and 100%. The electrical energy generated is determined by observing the current flow and power are seen on the multi meter. Based on the results of current and voltage measurements obtained respectively 2,4 V; 2,3 V; 2,3 V; 1,8 V; and 0,9 V. So the results of the analysis of the composition of sea water and sea sand can potentially be used as a source of electrical energy, although sea sand as agent of resistant.

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Textile waste is produced in the starch process, a starch removal process, coloring, and printing. The use of banana peel (Musa Paradisiaca) was an alternative that was being developed as an absorbent to remove the color content and metal ions in textile waste. The purpose of this study was to analyze the workings and effectiveness of heavy metal adsorption and textile dyes with banana peel waste. Banana peel particles that were ready to be used as adsorbents were characterized using Scanning Electron Microscopy (SEM) to obtain particle morphology. Absorbance curve of Cu2+ dan Cr6+ can be obtained using spectrophotometric UV-Vis analysis with a wavelength of 635 nm for copper (Cu) and 469 nm for chromium (Cr). The activated carbon of banana peel was applied to 50 ml industrial waste solution and observed changes in absorbance for 120 minutes. The activated carbon was directly in contact with the solution of metal ions but the adsorption power was still not seen effectively so that the Atomic Absorption Spectroscopy (AAS) test was performed. The results of AAS analysis, namely activated carbon can reduce copper and chromium ion content respectively by 55.5% and 61%. If this activated carbon was used as an adsorbent for dyes in textile waste, the average absorption capacity of dye ion was 12.21% during the contact time of adsorption 120 minutes.

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An alternative wound dressing based on nanofiber mats have been developed recently. The antioxidant and antibacterial activity play an important role in wound healing process. This study aims to combine the properties of Bassela rubra linn extract (BRLE) and Alginate from brown macroalgae into Polivynil Pyrrolidone (PVP) nanofiber using electrospinning method. Firstly, the optimization step was conducted to obtain the best operation voltage and distance. Afterwards, the nanofiber composites of PVP/BRLE/Alginate were injected into electrospinning tool in various Alginate concentrations of 1%, 2%, and 3% (w/w) respectively. The morphology of PVP nanofiber observed by Scanning Electron Microscopy (SEM) conveys that the closest distance and the highest voltage were the best. Meanwhile, the in vitro analysis through 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and antibacterial activity to S. aureus and E. choli bacteria show a quite strong radical scavenging ability around 60% and adequate antibacterial property as good as reference a well-known material consecutively.

Nanofiber through electrospinning process has been developed as a promising material for wound dressing due to its large porosity and high surface area. This characteristic of nanofiber provides an adequate gas permeability surrounding the wound which prevents the healing failure. The best wound dressing not only maintain a wound to have a good gas permeability but also to have an active agent giving an antibacterial and antiinflammation property. This research aims to combine a synthetic polymer and active agent, polyvinylpyrrolidone (PVP) and Bassela rubra linn leaf extract (BRLE), become nanofibrous material. The electrospinning process was conducted in two steps. The first step is to obtain the best voltage of PVP electrospinning by using the voltage of 10, 12, 15, 17 kV. The other step is combining PVP to 2%, 5%, 8% of BRLE. The first step shows the best operation condition is using 12 kV. Hence, it is used to obtain nanofiber with different BRLE percentage. Based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the result indicates that increase the BRLE composition will rise the antioxidant activity because of the smaller diameter size.

The purpose of this work was to investigate the mechanism of macroporous zirconia particles formation by hydrothermal synthesis. Hydrothermal synthesis of zirconia was prepared from precursor solution of Zr(NO3)2 with a concentration of 0.3 M at temperatures of 300 and 200°C carried out in a batch and a continuous reactor, respectively. Hydrothermally synthesized colloid subsequently was mixed with polystyrene template to form macroporous zirconia particles, and then was synthesized hydrothermally for 1 hour at temperature of 150°C and 200°C. Once the synthesis was complete, the particles were then dried at temperature of 60°C for 6 hours. In order to eliminate polystyrene template from the particles, the dried particles were calcined at temperature of 600°C and 900°C for 6 hours. The morphology of particles formed were characterized by scanning electron microscope (SEM) and Particle Size Analyzer (PSA). The analytical result showed that macroporous particles were formed at all experimental condition, and the mechanism of macroporous particles formation could be observed clearly. Based on the XRD analysis, the crystal zirconia consisted of monoclinic and tetragonal phase.