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This paper describes a method to synthesize a graphene oxide sand composites (GSC) as filter media (absorbent) for water purification. Graphene oxides is synthesized from graphite using modification of Hummer's method. The graphene oxide sand composites is prepared through solution method at 100 °C. The graphene oxide is analyzed using XRD, FTIR to confirm its formation. The FTIR spectrum and XRD diffraction pattern confirmed that the graphene oxide synthesized by this method is able to convert graphite into graphene oxide. Performance tests were conducted using a column to purify contaminated water which was mimicked using dyes such as rhodamine B, methylene blue and methyl orange.The initial concentration for all dyes were set for 5, 10, 25, 50 and 100 ppm. The color removal for methylene blue was 100% at all concentrations. However, for the rhodamine B and methyl orange, the color removal achieved 100% for the first three concentration 5, 10 and 25 ppm. The higher concentration of 50 and 100 ppm, the removal were slightly reduced. For the 50 ppm, the color removal of rhodamine B was 98% and for methyl orange 87% respectively. At 100 ppm, the color removal for rhodamine B drops to 92% and for the methyl orange was only 77% respectively. The GSC was very effective to remove methylene blue dyes at any concentration followed by rhodamine B and methyl orange. This GSC composite material is potential to be applied for water purification.

This study is to see the effect of edible coating such as chitosan to prevent fruits from ripening and to extend their shelf-life. Grape and tomato were used as samples and those were treated with chitosan solution at different concentration 1, 2 and 3%. The combination of 3% chitosan solution with polyphenol and ascorbic acid at different concentration were also studied. The shelf-life of the grape and tomato was improved almost 2.5 to 3 times longer using 3% chitosan solution compared to the uncoated grape used as blank. The shelf-life of grape is increased from 6 days to 16 days and tomato is enhanced from 4 days to 18 days by coating it with 3 % chitosan solution. The addition of polyphenol to the chitosan solution was slightly extending their shelf-life although it is not very significant. The results proved that the chitosan treatment into grape and tomato enhanced their shelf-life quite significantly and this material has potential to extend the shelf-life for other fruits and it can benefit for farmer.

Abstract. The oleic acid solubility in methanol is low due to two phase separation, and this causes a slow reaction time in biodiesel production. Tetrahydrofuran as co-solvent can decrease the interfacial surface tension between methanol and oleic acid. The objective of this study was to investigate the effect of co-solvent, methanol to oleic acid molar ratio, catalyst amount, and temperature of the reaction to the free fatty acid conversion. Oleic acid esterification was conducted by mixing oleic acid, methanol, tetrahydrofuran and Amberlyst 15 as a solid acid catalyst in a batch reactor. The Amberlyst 15 used had an exchange capacity of 2.57 meq/g. Significant free fatty acid conversion increments occur on biodiesel production using co-solvent compared without co-solvent. The highest free fatty acid conversion was obtained over methanol to the oleic acid molar ratio of 25:1, catalyst use of 10%, the co-solvent concentration of 8%, and a reaction temperature of 60 o C. The highest FFA conversion was found at 28.6 %, and the steady state was reached after 60 minutes. In addition, the use of Amberlyst 15 oleic acid esterification shows an excellent performance as a solid acid catalyst. Catalytic activity was maintained after 4 times repeated use and reduced slightly in the fifth use.

Batteries and supercapacitors are one of the energy storage devices that had been used for a practical application most electronic devices such as mobile phone. The development of these energy storage devices is faced by the poor performance of (the) electrode. Electrode commonly used for batteries and supercapacitors is derived from nonrenewable carbon resources such as graphite. However, the availability of this material is becoming a long-term problem for the development of batteries and supercapacitors. Biomass from (the) waste plant as a green source for battery electrode is one of alternative carbon which has great potential, due to the low price, easy to process and has high stability. This paper reports the study of the biomass conversion into carbon electrode material having high electrical conductivity or low electrical resistivity using carbonization and pyrolysis process. The process involved FeCl3 as an activating agent to reduce the electrical resistivity of the material as low as possible. The research was studying the effect of biomass sources and the processing method on the electrical resistivity of the electrode produced. The biomasses used in the study were corncob, water hyacinth, rice straw, and coconut husk. The material is the waste plant which is available in abundant. The morphological analysis of the carbon surface was conducted using Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX). The lowest electrical resistivity was produced from corncob material through the carbonization process at 300°C for 2 h, activated by 4 M FeCl3 solution and followed by pyrolysis process at 800°C for 6 h. The FeCl3 is suspected responsible for the decreasing of the carbon resistivity or increasing the electrical conductivity produced, this correlates with the increase of the surface area of the material. The lowest electrical resistivity (highest electrical conductivity) produced from corncob has a value of 1 Ω with the surface area of 601 m2/g. This is considered better than graphite in term of electrical resistivity in which graphite has electrical resistivity between 10 - 30 Ω. The result of SEM images shows that the carbon surface activated by FeCl3 has more pores compared to the carbon without activation.

ABSTRAK  Perkembangan baterai tak luput dari kebutuhan energi yang kian meningkat. Meskipun sumber energi tidak terpaku pada baterai, namun baterai banyak diminati karena dapat menampung cukup banyak energi, relatif aman, dan bersifat portable. Penelitian ini bertujuan untuk mensintesa dan mengetahui karakteristik salah satu jenis katoda baterai lithium-ion yaitu Lithium Iron Phosphate (LiFePO4) dengan variasi mol reagent berdasarkan perbandingan stoikiometri dan suhu proses kalsinasi 600°C, 700°C, dan 800°C selama 3x3 jam menggunakan metode solid state reaction dengan Li2SO4.H2O, FeSO4.7H2O, dan KH2PO4 sebagai reagent. Produk hasil kalsinasi 800°C dengan variasi 0.1 mol dijadikan sampel untuk dianalisa dan dikarakterisasi karena memiliki penurunan berat endapan BaSO4 tertinggi. Hasil karakterisasi menggunakan FTIR menunjukan gugus fungsi P-O yang cukup kuat, sementara hasil karakterisasi menggunakan SEM/EDX menunjukan partikel yang terbentuk memiliki ukuran sekitar 160nm hingga 14µm dan terdapat atom S yang merupakan impurities dalam produk. Pola difraksi hasil uji XRD menunjukan terbentuknya sejumlah fasa seperti LiFePO4, LiFeP2O7, dan Li3PO4.   ABSTRACT  The development of batteries is inseparable from the increasing energy needs. Although energy sources are not available for batteries, batteries are in great demand because they can store a lot of energy, are relatively safe, and are portable. This study aims to synthesize and determine the characteristics of one type of lithium-ion battery cathode, namely Lithium Iron Phosphate (LiFePO4) with various mole reagents based on stoichiometric ratios and calcination process temperatures of 600oC, 700oC, and 800oC for 3x3 hours using the solidstate reaction method with Li2SO4.H2O, FeSO4.7H2O, and KH2PO4 as reagents. The 800oC calcined product with 0.1 mol variation was sampled for analysis and characterization because it had the highest weight loss of BaSO4 deposits. The results of characterization using FTIR showed that the functional group P-O are quite strong, while the results of characterization using SEM/EDX showed that the particles formed had a size of about 160nm to 14µm and contained S atoms which were impurities in the product. The diffraction pattern of XRD test results shows the formation of phase numbers such as LiFePO4, LiFeP2O7, dan Li3PO4.

ABSTRAK Dengan meningkatnya kebutuhan akan konsumsi energi, maka semakin meningkat pula kebutuhan akan peralatan  untuk mengkonversi energi dan menyimpannya, seperti baterai lithium. Lithium-ion batteries (LIBs) menjadi salah satu alat yang paling mendapat perhatian karena dianggap memiliki densitas energi yang tinggi. Senyawa LiFePO4 (LIPO) mulai dilirik sebagai alternatif yang paling cocok menggantikan LiCoO2 sebagai katoda pada baterai lihium karena memiliki stabilitas termal yang tinggi.  Pada penelitian ini, dipelajari pengaruh  kondisi reaksi sintesis LiFePO4 menggunakan metode solid state reaction yang dioptimasi dengan memvariasikan  suhu kalsinasi. Bahan baku yang digunakan adalah  Li2SO4. H2O , FeSO4. 4H2O dan NH4PO4 dengan ratio molar 1:1:0,5. Sintesis dengan metode solid state reaction ini dilakukan dengan memvariasikan suhu kalsinasi  600o, 650o dan 700 oC selama 5 jam untuk membentuk fase kristalin  LiFePO4. Difraktogram LiFePO4 hasil sintesis dibandingkan dengan difraktogram standar LiFePO4 - JCPDS 40-1499. Ketiga variasi suhu ini menghasilkan  difraktogram yang sangat identik dengan standar LiFePO4, namun demikian pada suhu 700 oC dianggap menjadi  kondisi yang optimum untuk menghasilkan LiFePO4 dengan tingkat kemiripan yang lebih baik dengan LiFePO4 rujukan atau standar. Li2SO4 adapat dijadikan precursor sumber lithium dalam sintesis material LiFePO4. ABSTRACT The increasing for energy consumption, the need for electrical devices to convert energy and store it also increases, such as lithium ion battery.  Lithium-ion batteries (LIBs) have received the wide attention because they are considered to have high energy density. LiFePO4 (LIPO) compounds are starting to be regarded as the most suitable alternative to replace LiCoO2 as a cathode in lithium ion batteries because it has high thermal stability. In this study, the reaction conditions for the synthesis of LiFePO4 utilized the solid state reaction method which was optimized by varying the calcination temperature was examined. The raw material used in this synthesis is Li2SO4. H2O, FeSO4. 4H2O and NH4PO4 with a molar ratio of 1:1:0.5. The synthesis method was carried out at high temperature calcination of 600o, 650o and 700oC for 10 hours to form a crystalline LiFePO4 phase. The synthesized LiFePO4 diffractogram was compared with the diffractogram standard of LiFePO4 - JCPDS 40-1499. These three temperature variations resulted in diffractogram that was very identical to the standard LiFePO4, however at 700oC it was considered to be the optimum condition to produce LiFePO4 with a better similarity to the reference LiFePO4. The Li2SO4 can be utilized as a precursor of ion sources in the synthesis of cathode material LiFePO4.