Modelling of Magma Density and Viscocity Changes and Their Influences Towards the Characteristic of Kelud Volcano Eruption

DOI: 10.17014/ijog.v6i4.129The effusive eruption of Kelud Volcano in 2007 was different from the previous ones, which in general were more explosive. Among others, density and viscosity are factors that determine the type of eruption. Therefore, the study on the difference of the recent eruption style based on the density and viscosity of magma was carried out. The method used in this study was based on geochemical analysis of the rock and then a modeling was established by using the above parameter. The study on the explosive eruption was emphasized on the data of 1990 eruption, whereas the effusive eruption was based on the data of 2007 eruption. The result shows that the magma viscosity of Kelud Volcano depend on the H O concentration as one of the volatile compound in magma, and temperature which gives the exponential equation. The higher the increase of H O content the smaller the value of its viscosity as well as the higher the temperature. The H O content in silica fluid can break the polymer bond of the silica fluid, because a shorter polymer will produce a lower viscosity. The density of the silica content of Kelud Volcano ranges between andesitic and basaltic types, but andesite is more likely. The fluid density of the material of 1990 eruption is different from 2007 eruption. Compared to the 2007, the 1990 eruption material gave a lower density value in its silica fluid than that of the 2007 one. The low density value of the silica fluid of the 1990 eruption material was reflecting a more acid magma. The level of density value of silica fluid depends on its temperature. At the temperature of 1073 K the density of the 1990 Kelud magma is 2810 kg/m3 and the 2007 magma is 2818 kg/m3, whereas at a temperature of 1673 K, the density is 2672 kg/m3 and 2682 kg/m3 of the 1990 and 2007 eruptions respectively. A modeling by using an ideal gas law of Henry's Law illustrated that the ascent of Kelud's magma to the surface may cause changes in it's physical properties. The evolution of the flow pressure in the conduit is characterized by three different areas; based of the conduit until the pressure is saturated, then at the level between release and fragmentation, and then the level above the fragmentation, that implicates the decrease in the wall friction

Isolasi Dan Karakterisasi Lesitin Kelapa Dan Wijen

Lecithin is a natural amphiphilic substance which has unique structures. Lecithin molecules are able to aggregate to form a carrier structure known as liposom which is useful for carrying active substances in drug, food and cosmetics. Lecithin is generally derived from soybeans and eggs. Research efforts have been made to seek new sources of lecithin such as from coconut and sesame seeds. This study aimed to determine the character of plant lecithin derived from coconut and sesame seeds. Isolation of lecithin was done by solvent extraction using a mixture of chloroform-methanol (2:1) and characterization was conducted using TLC, FTIR and GCMS. The results indicated that lecithins from coconut and sesame seeds were from cephalin class with hydrophilic group consisted of ethanolamin. The lipophilic parts of coconut lecithin were C12 and C8 and those of sesame seeds lecithin were C18:1 and C18:0

Aktivitas Gamma Dan Adsorpsi Radionuklida Perairan Kali Code, YOGYAKARTA

AKTIVITAS GAMMA DAN ADSORPSI RADIONUKLIDA PERAIRAN KALI CODE YOGYAKARTA. Telah dilakukan penelitian mengenai hubungan antara aktivitas Gamma dan adsorpsi radionuklida perairan Kali Code, Yogyakarta. Tujuan dari penelitian ini untuk mengetahui model adsorpsi yang mengendalikan distribusi radionuklida Ra-226, Pb-212, Pb-214, dan Ac-228 dan mengestimasi distribusi radionuklida dalam air dan sedimen berdasarkan pengukuran radioaktivitas gamma dan padatan tersuspensi. Pengambilan sampel berupa air dan sedimen dilakukan 11 titik lokasi dari hulu hingga hilir Kali Code, dimulai dari Turgo, Boyong, Ngentak, Ring Road Utara, Sardjito, Tukangan, Tungkak, Karangkajen, Ring Road Selatan, Ngoto, dan Pacar. Radionuklida dianalisis dengan menggunakan metode Spektrometri Gamma. Hasil analisis menunjukkan bahwa adsorpsi Ra-226 dan Ac-228 mengikuti model adsorpsi Freundlich, Pb-212 model adsorpsi partisi, dan Pb-214 mengikuti model adsorpsi Langmuir. Tidak adanya korelasi yang signifikan antara aktivitas radionuklida dan padatan tersuspensi, mengindikasikan bahwa radionuklida yang diteliti tidak dalam bentuk kationik melainkan dalam bentuk senyawa dengan polaritas rendah dan terdapat di dalam sedimen dalam jangka waktu yang cukup lama

Adsorption of Mg(ii) Ion From Aqueous Solution on Chitosan Beads and Chitosan Powder

A basic investigation on the removal of Mg(II) ion from aqueous solution by chitosan beads was conducted in a batch adsorption system. The influence of different experimental parameters; pH, agitation period and different concentration of Mg(II) ion was evaluated. A pH 7.0 was found to be an optimum pH for Mg(II) adsorption onto chitosan powder and chitosan beads. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherms and isotherm constants for the adsorption of Mg(II) onto chitosan powder and chitosan beads. Results indicated that Mg(II) uptake could be described by the Langmuir adsorption model. The maximum adsorption capacities of Mg(II) ion onto chitosan powder and chitosan beads were 7.20 and 17.39 mol gâ^\u271, respectively. The rate of adsorption Mg(II) on chitosan powder and chitosan beads were 16.0.10-4 min-1 and 48.00 . 10-4 min-1, respectively