Dedi Setiabudidaya

Synthesis and Properties of Fe3O4 Nanoparticles by Co-precipitation Method to Removal Procion Dye

Fe3O4 (magnetite) nanoparticles were synthesized by chemical co-precipitation method. The structure, morphology and magnetic properties of as-prepared were characterized by X Ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X Ray Spectrometry (SEM-EDS), Transmission Electron Microscope (TEM) and Vibrating Sample Magnetometer (VSM). The result of XRD characterization was indicated Fe3O4 as the product. SEM and TEM image of the Fe3O4 showed nanoparticles Fe3O4 have the mean diameter 5-20 nm. The EDS spectra showed strong peaks of Fe and O. Magnetic characteristic of Fe3O4 nanoparticles was indicated super paramagnetic properties. The saturation magnetic was 89.46 emu g-1. Therefore, the nanoparticles Fe3O4 is suitabe to remove dye in the water by a simple magnetic separation process. The optimum adsorption occurred at initial concentration of procion dye 100 mg L-1, pH solution 6, dosage of Fe3O4 0.8 g L-1 and contact time 30 minutes under room temperature with color removal 24.40 % and adsorption capacity was 30.503 mg g-1

Coherent intraseasonal oceanic variations in the eastern equatorial Indian Ocean and in the Lombok and Ombai Straits from observations and a high‐resolution OGCM

Ongoing acoustic Doppler current profilers (ADCP) observation in the eastern equatorial Indian Ocean and a recent International Nusantara Stratification and Transport (INSTANT) experiment in the Indonesian Throughflow (ITF) straits have shown coherent intraseasonal oceanic variations in this region. The intraseasonal variations are dominated by 30–70 day variations, with a tendency for the observed currents in the eastern equatorial Indian Ocean to lead those at the Lombok and Ombai Straits. Phase speed of these eastward propagating signals estimated using lag correlation analysis does not correspond to one particular baroclinic mode, though it is in the range expected for the first two baroclinic modes. In this study, the dynamics underlying this intraseasonal coherency is evaluated using output from a high-resolution ocean general circulation model developed for the Earth Simulator (OFES). The results from model simulation of January 2001 through December 2007 show that the first two baroclinic modes dominate the intraseasonal variations in this region. While the first and second baroclinic modes have comparable contribution to the intraseasonal oceanic variations in the eastern equatorial Indian Ocean and in the Ombai Strait, the intraseasonal oceanic variations in the Lombok Strait are dominated by the first baroclinic mode. Moreover, the analysis reveals that the intraseasonal variability at all mooring sites is mostly confined in the upper layer above ∼100 m depth. Both equatorial wind from the Indian Ocean and alongshore winds off Sumatra and Java play important roles in generating intraseasonal variations in the Lombok and Ombai Straits.

Characteristics of Leachate at Sukawinatan Landfill, Palembang, Indonesia

Landfill (TPA) Sukawinatan Palembang is an open dumping system which covers an area of 25 hectares. This system may bring an environmental damage to the surrounding area because it does not provide leachate treatment. Leachate is the landfill waste that dissolves many compounds that contain pollutants from both organic substances and heavy metal origin. This paper presents the results of laboratory analysis on samples of leachate as well as shallow groundwater from the surrounding area. The results were compared to established quality standards to evaluate whether the leachate has influenced the quality of the shallow groundwater in the surrounding area. The results show that there are some indications that the quality of groundwater has been polluted by the leachate of both organic substances and heavy metals produced by the Sukawinatan landfill.

Spatio-temporal variations of sea surface temperature in the Banda Sea during the period of 2002-2008

Spatial and temporal variations of sea surface (SST) in the Banda Sea are studied for the period of June 2002 – May 2008. An empirical orthogonal function (EOF) analysis has been applied to an optimum interpolation SST (OISST) having spatial resolution of 0.25° and temporal resolution of 1 day. The results revealed that the four EOF modes account for 53.1% of the total SST variance. The first EOF mode, which accounts for 33.2% of the total variance, revealed the east-west SST pattern in the Banda Sea. This indicates 180° out of phase temporal variability between the eastern and the western parts of the Banda Sea. The second and the fourth modes explain 9.6% and 4.6% of the total variance respectively. Both two modes show the southeast-northwest spatial pattern. Meanwhile, the third mode accounting for 5.4% of the total variance indicates that the high SST variation is concentrated in the central Banda Sea. In addition, the corresponding principal component time series of the first mode revealed robust sea...

Characterization of Activated Carbon from Oil Palm Shell Prepared by H3PO4 for Procion Red Dye Removal

Characterization of activated carbon from oil palm shell prepared by H3PO4 and application for the removal of procion red dye was investigated. Oil palm shell was carbonized at 500°C and prepared by H3PO4 5 % with ratio of 1:3. Characterized activated carbon by Fourier Transform Infra Red Spectroscopy (FTIR), Brunauer Emmet Teller (BET) surface area, Scanning Electron Microscope-Energy Dispersive X Ray Spectrometry (SEM-EDS). The result indicated that functional groups on the activated carbon surface were influenced by acidic treatment. The activated carbon have surface area 385.991 m2g-1 and volume of micro porous 0.201 cm3g-1. The SEM-EDS image showed that activated carbon have many porous structure and the strong peak of C was 92.7 %. Adsorption capacity of activated carbon prepared by H3PO4 5 % was 278.197 mg g-1 which is higher than not chemical activation was 216.456 mg g-1 at equilibrium time 5 h.

How strong was the 2015/2016 El Niño event?

On the interannual timescale, the Indonesian climate is strongly influenced by a coupled ocean-atmosphere modes in the tropical Pacific Ocean. During a warm phase (El Nino event), negative sea surface temperature anomalies (SSTA) in the western tropical Pacific lead to suppress convection activities causing reduce precipitation over the maritime continent. The situation is reverse during the cold season(La Nina event). In this study, the evolution of 2015/2016 El Nino event is evaluated based on the collected data by the Tropical Atmosphere Ocean/Triangle Trans-Ocean Buoy Network (TAO/TRITON) buoys. The results show that the evolution of the event has started in boreal spring (April – May 2015). It came to thepeak in boreal fall/winter (October – December 2015). The event lasted until boreal spring before it terminated in April/May 2016. In addition, the intensity of the event is classified as a strong event, and it is one of the strongest El Nino events during the last three decades.

Effect of Sintering Temperature to Physical, Magnetic Properties and Crystal Structure on Permanent Magnet BaFe12O19 Prepared From Mill Scale

Permanent magnet of Barium hexa Ferrite with formula BaFe12O19 has been made by metallurgy powder method from raw materials : Barium carbonate (BaCO3 E-merck) and Iron Oxide (Fe2O3 from mill scale). Both of raw materials have been mixed with stoichiometry composition by using a ball mill for 24 hours. The fine powder obtained from milling process was formed by using a hydraulic press at pressure 50 MPa and continued with sintering process. The sintering temperature was varied : 1150°C, 1200°C, 1250°C and 1300°C with holding time for 1 hour. The sintered samples were characterized such as : physical properties (bulk density, porosity and shrinkage), magnetic properties (flux density, remanence, coercivity and magnetic saturation) by using VSM and crystal structure by using XRD. According characterization results show that the crystal structure of BaFe12O19 does not change after sintering process, but the grain size tends to increase. The optimum condition is achieved at temperature 1250°C, and at this condition, the sample has characterization such as : bulk density = 4.35 g/cm3, porosity = 1.03% and firing shrinkage = 11.63%, flux density = 681.1 Gauss, remanence (σr) = 20.78 emu/g, coercivity (Hc) = 2058 Oe and magnetic saturation (σs) 45.16 emu/g.

Burnscar analysis using normalized burning ratio (NBR) index during 2015 forest fire at Merang-Kepahyang peat forest, South Sumatra, Indonesia

Forest fire, classified as a natural hazard or human-induced hazard, has negative impacts on humans. These negative impacts are including economic loss, health problems, transportation disruption and land degradation or even biodiversity loss. During 2015, forest fire had occurred at the Merang-Kepahyang peat forest that has a total area of about 69.837,00 ha. In order to set a rehabilitation plan for recovering the impact of forest fire, information on the total burnscar area and severity level is required. In this study, the total burnscar area and severity level is evaluated using a calculation on the Normalized Burning Ratio (NBR) Index. The calculation is based on the Near Infra Red (NIR) and Short Wave Infra Red (SWIR) of the satellite imageries from LANDSAT. The images of pre-and post-fire are used to evaluate the severity level, which is defined as a difference in NBR Index of pre- and post-fire. It is found that about 42.906,00 ha of the total area of Merang-Kepahyang peat area have been fired in...

Evolution of 2015/2016 El Niño and its impact on Indonesia

A coupled ocean-atmosphere mode, namely the El Nino event, took place in the tropical Pacific during 2015 – 2016. The event developed in spring (April – May 2015), peaked in late fall to early winter (November – December 2015) and terminated in spring (April – May 2016). The intensity of the event, indicated by the Nino3.4 index, is classified as a strong event. Compare to the previous events, the 2015/2016 El Nino event is one of the strongest event during the last two decades. This study examined the evolution of the event and highlighted some of the important aspects of its influence on the Indonesian climate.A coupled ocean-atmosphere mode, namely the El Nino event, took place in the tropical Pacific during 2015 – 2016. The event developed in spring (April – May 2015), peaked in late fall to early winter (November – December 2015) and terminated in spring (April – May 2016). The intensity of the event, indicated by the Nino3.4 index, is classified as a strong event. Compare to the previous events, the 2015/2016 El Nino event is one of the strongest event during the last two decades. This study examined the evolution of the event and highlighted some of the important aspects of its influence on the Indonesian climate.

Crystal structure and magnetic properties of Nd2Fe14B powder prepared by using high energy milling from elements metal Nd,Fe,B powders

The Nd2Fe14B powder has been made by using High Energy Milling (HEM) from mixed metal powders Iron (Fe), Neodymium (Nd) and Boron (B). The Nd, Fe and B powders were mixed according stoichiometric composition (atomic ratio Nd:Fe:B = 2: 14: 1) and milled and milling time was varied in 10, 20, and 40 hours by using HEM. Toluene liquid was used as milling media to protect of metal powders from oxygen. The measurement result of x- ray diffraction show that the optimum Nd2Fe14B phase already formed about 69,46% after milling 40 hours with crystallite size about 25.64 nm. The magnetic properties of milled powders were measured by using VSM at room temperature. The highest value of magnetic properties are obtained at powder milled in 40 hours, at this condition, it is obtained Ms = 122 emu/g, Mr = 81 emu/g, Hc = 5.54 kOe and BHmax = 11.01 MGOe.