Judul: Pembuatan komposit magnet oksida besi-karbon aktif sebagai adsorben Cs dan Sr
Abstrak: Iron oxide and iron oxide-activated carbon magnetic composites have been prepared by co-precipitation method at temperature 70oC. The magnetic composite were prepared with ratios of 1:1, 1:2, and 1:3 by weight. The magnetic composites were made to obtain adsorbent which can be responsive to magnetic field so that it can be separated by simple magnetic procedure. The result from X-ray diffraction characterization showed a similarity of diffraction peak of iron oxide and magnet composite with specific peak in PCDFWIN program data base no 11-0614, which is iron oxide of magnetite (Fe3O4). Magnetization value of iron oxide and magnetic composites measured by vibrating sample magnetometer were 76.59, 25.6, 18.9, and 11 emu/g, respectively. Magnetization value decreased due to the lowering iron oxide fraction in the sample. Characterization using scanning electron microscope showed little particle of iron oxide. Microstructure of activated carbon showed large pores, while magnetic composite revealed iron oxide particles that cover and surround on the pores of the activated carbon. Surface area measured by Brunauer, Emmett, and Teller equipment showed decreasing surface areas of the activated carbon after composited with iron oxide. Adsorption experiment showed that higher Cs and Sr adsorption capacity occured at adsorbent 0.0125 g and initial concentration 200 ppm. Optimum pH for Cs adsorption occured at pH 7, while that of Sr adsorption was lower at pH 6.
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Judul: Komposit Oksida Besi Magnetit-Zeolit Cikembar Sebagai Adsorben Cr(III) dan Cr(VI)
Abstrak: Iron oxide and iron oxide-zeolite magnetite composites have been prepared by co-precipitation method at temperature 70 ˚C. The magnetite composite were prepared with ratios of 1:1, 1:2, and 1:3 by weight. The magnetite composites were made to obtain an adsorbent that can be responsive to magnetic field so that it can be separated by simple magnetic procedure. The result from X-ray diffraction characterization showed a similarity of diffraction peak of zeolite with specific peak in PCDFWIN program database no 29-1257, which was mordenit. In addition, iron oxide and magnetite composites had a same peak with specific peak in PCDFWIN program database no 19-0629, which was iron oxide of magnetite (Fe3O4). Characterization using scanning electron microscope showed microstructure of zeolite that have small pores, while magnetite composite revealed iron oxide particles that cover and surrounded the pores of the zeolite. Adsorption experiment using surface response method showed that adsorption capacity of Cr(III) and Cr(VI) with composite did not increase significantly. However, the composite samples were capable in separating the composite adsorbent from the adsorbate medium using permanent magnet. The optimum capacity of adsorption occurred in 0.5 g of adsorbent, adsorption time of 12 hours, and initial concentration of 60 ppm
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Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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