Hidroksiapatit (HAp) merupakan salah satu senyawa biokeramik yang digunakan dalam berbagai aplikasi.  Pada penelitian ini telah dilakukan sintesis hidroksiapatit (HAp) dengan metode pengendapan menggunakan cangkang lokan (Geloina coaxans) dan H3PO4  sebagai prekursor. Analisis menggunakan X-Ray Flourocence (XRF) menunjukkan bahwa komposisi kimia utama pada cangkang lokan (Geloina coaxans) adalah CaO.  Produk terbaik diperoleh melalui waktu kalsinasi pada suhu 900 oC selama 180 menit yang ditunjukkan dengan puncak yang memiliki intensitas tertinggi pada 2θ = 31,7o dan puncak spesifik lainnya untuk hidroksiapatit pada 2θ = 32,89o, 32, 17o, 25,86o dan 49,46o. Difraktogram dibandingkan dengan JCPDS (No 09-0432). Berdasarkan perhitungan menggunakan persamaan Scherrer, didapatkan ukuran kristal dari hidroksiapatit (HAp) adalah 26,62 nm. Analisis menggunakan FTIR juga telah dilakukan untuk mengidentifikasi gugus fungsi pada hidroksiapatit yang diperoleh. Dari spektrum FTIR menunjukkan adanya pita serapan yang khas untuk gugus  OH‒, CO32- dan PO43-pada hidroksiapatit. Morfologi partikel berbentuk granular seperti bola dan gumpalan yang tidak seragam diperoleh melalui analisis menggunakan SEM.. ABSTRACT  Hydroxyapatite (HAp) is a bioceramic compound that is used in various applications. In this research, hydroxyapatite (HAp) synthesis has been carried out by precipitation method using Geloina coaxans shell and H3PO4 as precursors. Analysis using X-Ray Flourocence (XRF) showed that the main chemical composition of Geloina coaxans shell was CaO. The best product was obtained by calcination at 900 oC for 180 minutes indicated by a peak having the highest intensity at 2θ = 31.7o and other specific peaks for hydroxyapatite at 2θ = 32.89o, 32 ,17o, 25.86o and 49.46o. The difractogram was compared to JCPDS (No 09-0432). Based on calculations using the Scherrer equation, the crystallite size of hydroxyapatite was 26.62 nm. Analysis using FTIR has also been carried out to identify the functional groups of the hydroxyapatite obtained. The FTIR spectrum showed that there were unique absorption bands  for OH‒, CO32- and PO43- groups on hydroxyapatite. Analysis using SEM showed that the morphology was granular like balls and non-uniform aggregate

Dahlia is a floriculture plant with tuber that rich of inulin. Inulin is soluble in hot water and it will settle on cool temperature in alcohol. Extraction of result from 100 g dahlia tuber taken from Bukittinggi, West Sumatra is 4% inulin (w/w dahlia tuber). Inulin flour produced is white gray. Qualitative tests with Seliwanoff and Nelson-Somogyi methods shows that inulin positive contained of fructose and reducing sugar. Extracted result of inulin can be converted into levulinic acid using acid catalyst at high temperature. In this experiment, production of levulinic acid will bundle with variate temperature, reaction time and catalyst concentration of hydrochloride acid. The reaction of inulin convertion was done in ampul that burned in oven. Conversion result of 5% inulin to be levulinic acid on heating 150 o C hydrochloride acid concentration 0,1 M about 25 minutes was 12,33% (w/w inulin). On heating 170 o C hydrochloride acid concentration 0,1 M about 15 minutes is 26,25% (w/w inulin), while on heating 150 o C hydrochloride acid concentration 1 M about 15 minutes is 32,28% (w/w inulin). Experiment result showed that concentration of glucose, levulinic acid and formiat acid increase with increasing in reaction reaction temperature while fructose concentration decrease from 55,14 mg/mL to be 0,12 mg/mL. The longer time reaction and the higher concentration of catalyst hydrochloride acid, the lower concentration of glucose and fructose and the larger concentration of levulinic acid and formic acid.

Composite banana peel activated carbon-TiO2 is a photocatalyst used to degrade complex compound. In this research, peel of banana was activated using NaOH activator. The aims of this study was to compose biomass wastes (banana peels) with TiO2 catalyst using photocatalytic process to solve Methylene Blue and Methyl Orange dye waste problems. Sample were calcined at 300°C and activator concentration of NaOH varied (1:0; 1:1; 1:2; and 1:3) to obtain optimal results. The quality of activated carbon of banana peel was compared to SNI 06-3730-1995. There parameter measured were moisture content, ash content, adsorption of iodine, adsorption capacity of Methylene Blue and surface area of activated carbon. The results showed that the highest banana peel activated carbon compares to NaOH concentration of 1: 3 were 0.65%; 4.88%; 774.09 mg/g; 24.90 mg/g and 92.43 m2/g, respectively. It indicates that the optimal results are obtained in the preparation of activated carbon with 1:3 of activator composition. This activated carbon banana peel was combined with titanium dioxide P25. The composites were characterized by FTIR (Fourier Transform Infrared) and SEM (Scanning Electron Microscopy). FTIR spectrum showed that the absorption appeared in the region of Ti-O-C at wave number 1009 cm−1 and C=C at wave number 1620 cm−1. SEM showed that TiO2 spread on activated carbon surfaces. Based on analysis of Infrared presents the functional group of Ti-O and C=O of the composite. Morphology of the composite banana peel activated carbon-TiO2 showed that TiO2 spreads on active carbon surfaces. Based on analysis which have done showed that the composite activated carbon of banana peel-TiO2 formed. Optimum Methylene Blue and Methyl Orange degraded were 94.61% and 84.30%, respectively.

In this study, the synthesize of hydroxyapatite-chitosan composites has carried out using the microwave-assisted method. The hydroxyapatite-chitosan composite is interesting to develop based on the application in many fields. Porous hydroxyapatite is very useful for reconstructing damaged bones because it will stimulate the growth of new bone cells. The synthesize of hydroxyapatite utilized waste of Geloina coaxans shells as the calcium source both phosphate sources are ammonium dihydrogen phosphate NH4H2PO4 and KH2PO4 while for synthesis hydroxyapatite-chitosan composites will be carried out using the waste of Scylla olivacea shell as a source of chitosan. The rapid pathway synthesis is very crucial for producing composites. Synthesis has done using the microwave 450 W with a retention time of 20 minutes. Based on the results, the hydroxyapatite powder can be produced with specific peaks of hydroxyapatite at 31.7°. Mass of chitosan influenced pore of the hydroxyapatite-chitosan composite increased the pore diameter of hydroxyapatite-chitosan composite 0.28 to 5.0308 nm and 4.3182 and 7.0268 using KH2PO4 and NH4H2PO4. The functional group also shows the specific bands of hydroxyapatite.

Synthesis of Co3O4 has been done using Co(NH3)4.6H2O and KOH as precursors with molar ratio 1:1 M with precipitation method. Several of calcination temperature were done to learn type of mineral phase and crystalinity of Co3O4 synthesized. The XRD analysis revealed that calcination temperature influence crystalinity and mineral phase of Co3O4 prepared and calcination temperature at 700 oC has highest intensity and crystalinity that others. Analysis of particle size was examined using Schererr equation, and the results showed that particle size decrease with calcination temperature. The particle size at  700 oC was = 32.387 nm. Analysis morphology of Co3O4 was examined using SEM technique, and the result revelaed Co3O4 have nearly spherical.DOI :http://dx.doi.org/10.15408/jkv.v0i0.3176.