Judul: Characterization and Modification of Natural Zeolites as Media Material Detection, Case Studies: Hexavalent Chromium
Abstrak: Zeolites are widely used for various agricultural applications and industrial catalysts. An abundant amount of natural zeolite has not been widely utilized. So this study aims to characterize and to modify surface of natural zeolite samples from Indonesia. The zeolite samples contain some impurities, chraracterized by X-ray diffraction (XRD) pattern. Acid and alkaline modification do not alter the structure of the the zeolite significantly, for samples from Bayah and Cikalong. Modification both samples using barium cation do not increase the adsorption capacity of Cr(VI), although adsorption of barium cation occurs on to zeolite surface. Surface modification using iron ion yield significant adsorption of anion Cr (VI) on to the zeolite. This is characterized by the change of XRD peak patterns
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Judul: Adsorpsi dan desorpsi kromium (VI) pada zeolit alam asal Lampung termodifikasi Heksadesiltrimetilamonium bromida
Abstrak: Zeolite is a mineral that is able to adsorp chromium. Chromium has three stable forms in nature,i.e. metal chromium, trivalent chromium, and hexavalent chromium. Among these forms, hexavalent chromium are the most toxic and generally obtained in its anion form as chromat (CrO4 2-) and dichromat (Cr2O7 2-). Therefore, it is very important to decrease content in environment. The function of negative zeolite structure were cation exchange and their somewhat for anion exchange. Therefore, modified zeolite with hexadeciltrimethylammonium bromide (HDTMABr) was attempted to increase anion adsorption capacity of zeolite in solution. Modified zeolite with HDTMABr at 50% dosage of its cation exchange capacity, caused an increase the adsorption capacity of zeolite to chromium(VI) from 0.74 to 1.40 mg/g. Adsorption was carried out by varying adsorption time, solution acidity, and initial concentration of chromium(VI). The optimum adsorption time, solution acidity, and initial concentration of chromium(VI) for unmodified-zeolite were 20 hours, 3.5, and 350 ppm, respectively. On the other hand, the optimum adsorption for modified-zeolite were 23 hours, 5, and 350 ppm, respectively. Isotherm type for both of adsorbent followed Freundlich isotherm. Desorption of chromium(VI) on unmodifiedzeolite and modified-zeolite a lot off obtained using aquadest at level 30.56 and 0.33%, respectively.
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Judul: Nilai Wajar Asuransi Endowmen Murni dengan Partisipasi  untuk Tiga Skema Pemberian Bonus
Abstrak: Asuransi Endowmen Murni adalah asuransi yang memberikan benefit pada pemegang polis jika dan hanya jika pemegang polis masih dalam keadaan hidup setelah melewati waktu jatuh tempo. Jika pemegang polis meninggal sebelum melewati waktu jatuh tempo, maka benefit tidak akan diberikan. Dalam kontrak partisipasi, perusahaan asuransi diwajibkan memberikan benefit (manfaat) dan profit (bonus) setelah waktu jatuh tempo. Benefit diberikan sebagai nilai jaminan dari pertanggungan yang telah disepakati antara perusahaan asuransi dan pemegang polis. Sedangkan profit diberikan sebagai imbal hasil (rate of return) dari hasil investasi yang dilakukan oleh perusahaan asuransi dalam pasar bursa. Besar kecilnya profit ditentukan oleh imbal hasil secara finansial yang diperoleh perusahaan asuransi.
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