Judul: The utilization of activated carbon as micro nutrients carrier in slow release fertilizer formulation
Abstrak: In many plantations, fertilizers were often added in high dosage and applied several times in order to get maximum productivity. Actually, some processes in soil caused not all nutrients in fertilizer could be uptaken by plants. Besides, high dosage can be toxic to plants. The use of slow release fertilizer can overcome this case. Slow release fertilizers (SRF) were fertilizers coated within a substance that enables a slow release time and had higher efficiency rate than soluble fertilizers. This research was aimed to: 1) identify the characteristics of bamboo and coconut shell activated charcoal that were activated in 600oC or 700oC temperature and steamed for 90 minutes, 2) obtain the data of adsorptive capacity of activated charcoal to the nutrients mixed, 3) gathering the information about nutrients release rate of fertilizer produced, and 4) determine the influence of slow release fertilizer addition to nutrient uptake in Acacia crassicarpa. The study was conducted by converting materials into charcoal. The charcoal was then activated in 600oC and 700oC temperature and steamed for 90 minutes. The activated charcoal was ground and analyzed based on SNI 06-3730-1995. SRF was formulated by soaking fine activated charcoal in 1N or 2N of CuSO4, FeSO4 or ZnSO4 solution for 24 hours. Analysis conducted were observation of surface topography by SEM, qualitative analysis using EDX, calculation of chrystallinity, width, length and number of aromatic layer, and determination of total Cu, Fe and Zn in SRF. The optimal treatment was chosen to determine its release rate by extracting fertilizer with distilled water and 2% citric acid during 0, 15, 30, 45, and 60 minutes. The influence of SRF addition to nutrients uptake was determined by observing nutrients content in root. The results showed that the activated charcoal produced met SNI 06-3730-1995 except for its adsorptive capacity to iodine and blue methylene. Nevertheless, the activated charcoal could be used to adsorb nutrients mixed as shown by SEM and EDX results. The adsorption of Cu, Fe and Zn increased the activated charcoal chrystallinity and influence its width and length of aromatic layer. The highest nutrients concentration obtained were 11,443 ppm Cu, 5,476 ppm Fe, and 6,603 ppm Zn for bamboo activated charcoal and 10,775 ppm Cu, 7,611 ppm Fe, and 6,343 ppm Zn for coconut shell activated charcoal. Nutrients in the charcoal could be released slowly and could not be easily leached out.
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Judul: Effectivity of activated charcoal as adsorbent for wastewater treatment
Abstrak: The main purpose of this research was to study the optimum condition for production activated charcoal in a retort with 100 kg capacity and to apply the best activated charcoal as adsorbent for wastewater treatment. The raw materials used in this research were wood sawdust, mangium wood (Acacia mangium) and coconut shell. The charcoal was activated using the condition : activating temperature at 700 ºC continued by steaming with H2O for 1, 2, 3 hours and without steaming as a control. In Order to improve the qualities of the activated charcoal, further activation was conducted using H3PO4 solution at 5 % concentration. The possible changes in structure were evaluated using Infrared Spectrophotometry, X-ray Difraction and Scanning Electron Microscope. The results showed that the best quality of activated charcoal was achieved by Acacia mangium by soaking in H3PO4 5 % solution without steaming. The yield of activated charcoal was 40,54 %; moisture content 5,25 %; ash content 2,31 %; volatile matter 7,01 %; fixed carbon 90,69 %. Adsorptive capacity of iodine was 657,20 mg/g; metanol 7,13 %; CCl4 8,39 %; CHCl3 13,24 %; formaldehida 6,57 % and benzene 7,13 %. Degree of crystalinity 58,23 %; height of aromatic layers (Lc) 4,02 nm; width of aromatic layers (La) 4,22 nm; number of aromatic layers (N) 10,84 and distance of aromatic layers (d) 0,21 nm with pore diameter of 0,14 – 0,35 μm. The best concentration of activated charcoal as adsorbent for domestic wastewater treatment was 1 % concentration. It decreased Biological Oxygen Demand (BOD) 98,03 %; Total Suspended Solid 97,66 %; oil and grease 76,92 % and pH value increased 6,15 %. For hospital wastewater treatment, the best condition was achieved using activated charcoal at 2 % concentration. It could decreased pH value 17,50 %; Total Suspended Solid 93,06 %; ammonia 76,09 %, phosphat 33,06 % and coliform bacteri 90 %. BOD and Chemical Oxygen Demand (COD) increased 330,79 % and 135,91 %. The best concentration of activated charcoal as adsorbent for nicel coated industry wastewater treatment was 1 % concentration. It decrease Total Suspended Solid 84,72 %; Cr 39,50 %; Cu 66,67 %; Zn 91,50 %; Ni 73,75 % and Cd 71,43 %. pH value increase 242,84 %, but Pb value was not changed.
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Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix