Rice Husk Silica-Coated Magnetic Particles As A Low Cost Support Material For Crude Pseudomonas Aeruginosa Lipase Immobilization

In this research, lipase produced from the bacteria Pseudomonas aeruginosa was immobilized on rice husk silica-coated Fe3O4 nanoparticles. The process included the following steps: preparation of magnetic ferrosoferric oxide nanoparticles (NP), coating NP with silica from rice husk ash, activation with glutaraldehyde and covalent immobilization of lipase on the support. The synthesis of the nanoparticle was followed by characterization through FT-IR, XRD, and FE-SEM. The hydrolysis kinetics (using 4-Nitrophenyl palmitate as a substrate) of the immobilized lipase followed Michaelis-Menten model with a Vmax and a Km value of 4.0 mM.s-1 and 0.63 mM, respectively. The immobilized lipase showed better tolerance to extreme temperature and pH compared to free lipase. About 60% of enzyme remained immobilized after ten cycles of reuse and 68.13% of it were stable until 49 days. Thus the silica-coated Fe3O4 nanoparticles appeared to be a potential support material for lipase immobilization applications

ISOLATION OF STEROID COMPOUNDS IN THE n-HEKSANA FRACTION FROM JARUM TUJUH BILAH LEAVES EXTRACT (Leuenbergeria bleo (Kunth) D.C.)

This study aims to find secondary metabolites isolated from the leaves of the Jarum Tujuh Bilah (Leuenbergeria bleo (Kunth) D.C.). The method used was maceration, fractionation and column chromatography and was identified using Fourier Transformra Infra Red (FT-IR). The phytochemical preliminary test of the n-hexane fraction contains the steroid secondary metabolite compound. The results of column chromatography produced 75 vial bottles which were then identified by thin layer chromatography and produced 8 combined fractions (A-H fraction) based on the similarity of characterization, from the 8 fractions D and E forming yellow crystals. The yellow crystals formed are then cleaned and recrystallized to produce 11.7 mg white amorphous crystals. Compounds are characterized by FTIR spectrometers. Based on FTIR analysis, isolates showed IR spectrum λ max cm-1: 3375; 2927,98; 2852,18; 1680; 1462,51; 1376.81; 1329.74; 1043,92; 1022.02 and 956.27. Based on the results obtained by isolates, it is suspected that the compound is a steroid sterol

PEMBUATAN KOMPOSIT WO3-ZnO MELALUI REAKSI PADAT-PADAT DAN KARAKTERISASINYA

Pembuatan komposit WO3-ZnO melalui reaksi padat-padat telah dilakukan. Tahapan penelitian meliputi pencampuran padatan WO3 dan ZnO dengan penambahan polivinil alkohol, pengeringan, pengayakan dan pemanasan. Padatan WO3 dan  ZnO sebelum dikompositkan serta komposit WO3-ZnO dikarakterisasi menggunakan instrumen X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), dan uji luas permukaan menggunakan larutan methylene blue. Hasil karakterisasi XRD menunjukkan bahwa pada sampel mengandung WO3 dan ZnO juga adanya puncak difraksi ZnWO4. Pada analisa SEM dapat diamati bahwa terdapat ukuran dan bentuk partikel yang tidak homogen. Komposit WO3-ZnO memiliki luas permukaan sebesar 110,7596 m2/g.The preparation of WO3-ZnO composites through the solid state reaction has been conducted. The research stages included mixing WO3 and ZnO solids with the addition of polyvinyl alcohol, drying, sieving and heating. WO3 and ZnO solids before being composited and WO3-ZnO composites were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) instrument, and  test  the  surface  area using methylene blue solution. The results of XRD characterization showed that the samples containing WO3 and ZnO also contained ZnWO4 diffraction peaks. In SEM analysis, it can be observed that the size and shape of the particles was not homogeneous. WO3-ZnO composite has a surface area of 110.7596 m2/g

Rice Husk Silica Supported Oil Palm Fruit Ash as a Catalyst in the Transesterification of Waste Frying Oil

An investigation was conducted on palm oil palm fruit ash (OPFA), OPFA supported by rice husk silica (RHS), and potassium-OPFA-RHS as catalysts for methyl esters production through transesterification process using waste frying oil. The catalysts showed longer lasting activity than the traditional alkali catalysts. The optimum conditions for the process were: OPFA and K-OPFA-RHS catalyst amount 3 %; OPFA-RHS catalyst amount 5 %; methanol to oil molar ratio 9:1; and a reaction duration is 2 h. The process was able to transesterify oil to methyl esters at 96.6–98.2 % conversion at 65 °C for all series. The catalysts were easily separated from the reaction mixture by filtration and able to be reused. Reusability up to 5 cycles is feasible with ME content above 83 %. The final product met selected biodiesel fuel properties in accordance with European Standard EN 14214

SYNTHESIS AND CHARACTERIZATION OF ZnO NANOPARTICLES: MINI REVIEW

This mini review will explore the manufacture of ZnO nanomaterials. ZnO material has the advantages of high electron mobility, wide bandgap, high temperature resistance, and good UV absorption. ZnO has many applications in everyday life such as for photocatalysts, antibacterials, edible coatings, and others. Based on the literature review, ZnO material can be synthesized using sol-gel, hydrothermal, solvothermal, precipitation and coprecipitation methods. The resulting synthesis results are 7.4 nm-170 nm in size, have a hexagonal wurtzite crystal structure, have a bandgap of 3.23 eV-3.50 eV, and produce a surface area of 91.87 m2/g-113.37 m2/g. Based on the review conducted, it can be concluded that the method that produces ZnO nanoparticles with the smallest size and the largest surface area is synthesis using the solvothermal method.   Keywords: Nano materials, Semiconductors, Nanoparticles

Daya Antibakteri Ekstrak Metanol Buah Okra (Abelmoschus esculentus (L.) Moench)

ABSTRACT Phytochemical test and antibacterial activity of methanol extract of Okra (Abelmoschus esculentus (L.) Moench) fruit have been carried out. Extraction using maceration method. The methanol extract of Okra fruit contains phenolic secondary metabolites, alkaloids and steroids. Antibacterial activity opposes the agar diffusion method against the bacteria Salmonella typhi and Steprococcus mutans. The Minimum Inhibitory Concentration Value of Okra fruit methanol extract against Salmonella typhi bacteria at a concentration of 0.625-1.25% and against Streptococcus mutans bacteria 1.25% -2.5%. Okra fruit methanol extract has antibacterial activity with wide variations. Keywords : Abelmoschus esculentus (L.) Moench, antibacterial activity, secondary metabolites, Minimum Inhibitory Concentration (MIC)

Adsorption of Methylene Blue using Composite Fe3o4-Activated Charcoal Cassava Skin (Manihot esculenta C.)

Preparation of Fe3O4 activated cassava shell charcoal composite (Fe3O4-AAKS) by coprecipitation method, namely mixing activated cassava shell charcoal (AAKS) with FeCl3.6H2O and FeSO4.7H2O solutions using a mole ratio of 3:2 in alkaline conditions with the addition of 25% NH4OH has been carried out. The Fe3O4-AAKS composite was characterized using Fourier Transform Infra-Red (FTIR) and X-Ray Diffraction (XRD) instruments, then the composite material was applied to adsorb methylene blue with variations in the influence of contact time, optimum concentration and optimum adsorbent mass and determined the adsorption isotherm model. The results of the characterization of Fe3O4-AAKS with FTIR showed that a composite had been formed which was marked by the appearance of absorption at wave number 1033,85 cm-1 indicating the presence of a C-O group and the appearance of a typical absorption of Fe-O groups at 540,07 cm-1. Fe3O4-AAKS XRD results show an amorphous charcoal diffraction pattern at an angle of 20º-30º and a magnetic phase iron oxide diffraction pattern of Fe3O4 at 2 θ at angles of 18.59º, 30.38º, 35.62º, 43.56º, 53.85º, 57.30º, 62.90º and 74.62º. Methylene blue adsorption application using Fe3O4-AAKS composite showed optimum conditions at contact time of 30 minutes, optimum concentration at 60 mg/L with optimum adsorbent mass of 0.05 gram. The adsorption pattern of the composite material follows the Langmuir isotherm with a maximum adsorption capacity of 25.38 mg/g