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: Pemanfaatan Arang Aktif Tempurung Kelapa Sawit dan Tongkol Jagung sebagai Adsorben Logam Berat pada Limbah Batik
Abstrak: Heavy metals in wastewater of batik industry dumped into the environment can cause pollution and decrease the quality of waters. Using activated carbon as the adsorbent is one way to reduce the heavy metals level in the wastewater. In this study, the activated carbons were prepared from palm shell and corn cobs. The activation was done through 2 methods, i.e. chemical activation (KOH 30% immersion) and physical activation (steamed). The result showed that the best activated carbon was prepared using KOH 30% treatment, giving 10.7% moisture content, 14.6% volatile matter, 18.1% ash, 67.1%bound carbon, 20.9% benzene adsorption, 121.0 mg/g methylene blue adsorption, and 584.5 mg/g iodine adsorption. The optimum adsorption of heavy metal was obtained in 90 minutes contact time using 1.0 g adsorbent. The activated carbon originated from corncob with KOH 30% treatment was capable to reduce iron and copper up to 63.32% and 79.25%, respectively.
Keyword: palm oil shell, heavy metal, corn cob, activated carbon

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.
Keyword: