Judul: Pemanfaatan biji alpukat untuk pembuatan arang aktif sebagai adsorben alternatif zat warna pada limbah cair batik
Abstrak: Avocado seeds are agricultural waste containing starch that is potential to be used as raw materials for activated carbon. The purpose of this experiment is to produce an activated carbon from avocado seeds and to be applied for adsorbing remazol dyes on batik effluent. This study performed 2 types of activation, i.e. chemical and physical activations. Chemical activation was performed by submerging the charcoal in KOH 30% and H3PO4 30%, while physical activation performed by steaming at 700 oC for 60 and 90 minutes. The activated carbon with the highest iodine number (AB60) was used to adsorb dyes in batik effluent. The result showed that activated carbon from avocado seeds have a relatively low ability to adsorb dye, as evaluated from the lowering color concentration of remazol dye by 42% in the batik effluent.
Keyword: Bogor Agricultural University (IPB), remazol, batik effluent, avocado seeds, adsorption, active carbon

Judul: Arang Aktif Berbasis Kulit Buah Malapari (Pongamia pinnata) sebagai Adsorben dalam Penangan Limbah Batik
Abstrak: Vegetable oil production of malapari (Pongamia pinnata) fruit leaving unprocessed waste. The purpose of this study was to use malapari fruit peel as raw material for preparing activated charcoal, characterizing, and applying the best quality activated charcoal produced as adsorbent for dyes of batik industry waste water. Some samples treated through carbonization at temperature of 450 ℃ and continued activation with phosphoric acid 2% and physical activation at 750 ℃ with flow steam for 60 minutes resulted the best quality of activated charcoal with methylene blue adsorptivity of 120 mg/g. Leaching with HCl 10% was able to increase methylene blue adsorptivity up to 193 mg/g which meet SNI 06-3730- 1995 requrement with specific surface area and pore surface area of 715 m2/g and 138 μm2,respectively. Indigosol dye adsorption by the best quality charcoal followed the Freundlich isotherm. The activated charcoal was able to reduce intensity of the dye in the waste water and the chemical oxygen demand of 98.51% and 97.43%, respectively.
Keyword: Bogor Agricultural University (IPB), malapari, batik dye waste water, activated charcoal

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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