PENGARUH KANDUNGAN ZAT ORGANIK TERHADAP KONSENTRASI PLUTONIUM PADA SEDIMEN PANTAI DEPOK YOGYAKARTA

GALANG ARIF WASKITO, Dr. Akhmad Syoufian

2014 | Skripsi | KIMIA

Kajian mengenai pengaruh kandungan zat organik terhadap konsentrasi plutonium di sedimen Pantai Depok Yogyakarta telah dilakukan untuk mendapatkan hubungan antara keduanya sekaligus sebagai nilai acuan untuk konsentrasi plutonium di sekitar Pantai Depok, Yogyakarta. Sampel sedimen muara diambil pada tiap lapisan pada kedalaman 0 – 30 cm dan dipisahkan berdasarkan kedalaman setiap 5 cm menjadi enam lapisan. Setiap lapisan dianalisis kandungan plutoniumnya melalui tiga tahap utama, yaitu tahap pelarutan (digestion), tahap pemurnian melalui kromatografi penukar ion, dan tahap elektrodeposisi plutonium ke pelat logam. Hasil elektrodeposisi kemudian dicacah dengan menggunakan spektrometer alfa. Sebelumnya dilakukan optimasi kromatografi penukar ion dan elektrodeposisi melalui variasi laju alir kromatografi dan variasi kuat arus. Penentuan kandungan zat organik dilakukan dengan membakar sejumlah sampel dan kemudian membandingkan massa sebelum dan sesudah pembakaran untuk mengetahui persentase zat organik yang hilang. Hasil yang diperoleh menunjukkan bahwa aktivitas 239,240Pu paling tinggi terekam pada lapisan sedimen dengan kedalaman 0 – 5 cm sebesar 3,26 Bq/kg. Aktivitas 238Pu paling tinggi pada kedalaman 0 – 5 cm sebesar 0,148 Bq/kg. Aktivitas kedua radionuklida plutonium tersebut cenderung menurun dengan semakin dalamnya lapisan sedimen. Sebaliknya kandungan zat organik menunjukkan kecenderungan peningkatan dengan semakin dalamnya lapisan sedimen. Kandungan zat organik paling rendah terdapat pada lapisan sedimen dengan kedalaman 0 – 5 cm sebesar 3,85 %, dan yang paling tinggi terdapat pada lapisan sedimen dengan kedalaman 25 - 30 cm sebesar 17,18 %.

Study about organic matter influence to plutonium concentration in Depok Beach’s sediment has been done in order to get their correlation and also as reference value of plutonium concentration in the south coastal of Java Island, especially, Yogyakarta. Sediment sample within 0 – 30 cm depth was separated into six layers which has 5 cm thickness each. Plutonium radionuclide of each layer was analyzed through three steps, digestion, ion exchange chromatography and electrodeposition into metal plate. The sample were then counted with Alpha Spectrometry. Some experiments involving flow rate variation and current variation were conducted to determine the optimum condition of ion exchange chromatography and electrodeposition before that. Organic content mass determined by burning some samples into high temperature. The after burn mass of sample were then compared to before burn mass of sample. This was the organic content mass in percent. The result showed that the highest 239,240Pu activity was recorded within 0 – 5 cm layer of sediment, which was 3,26 Bq/kg. While the highest 238Pu activity was recorded within 0 – 5 layer of sediment which was 0,148 Bq/kg. Generally, plutonium radionuclide activity were decreased by the deeper layer of sediment. On the contrary, organic matters were increased by the deeper layer of sediment. The lowest organic matter content was recorded within 0 – 5 cm sediment with 3,85 % content mass, and the highest organic matter content was recorded within 25 – 30 cm sediment which was 17,18 % organic content mass.

Kata Kunci : Plutonium, zat organik, kromatografi, elektrodeposisi