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: Penggunaan ZnCl2 sebagai Aktivator Karbon Aktif dari Limbah Padat Agar dan Aplikasinya sebagai Adsorben pada Limbah Cair Industri Tahu
Abstrak: Agar solid waste is a material that has the potential as a raw material for activated carbon. This waste contains high value of cellulose, hemicellulose and lignin. The study aims to determine the best concentration of ZnCl2 and best activation time on activation step and to determine the effectiveness of the using of activated carbon as adsorbent for tofu wastewater treatment. The activation step was carried out with ZnCl2 concentration of 10; 20; 30% and activation time of 15; 20; 25 hours. The best activation treatment was obtained from the treatment of 10% ZnCl2 concentration and 25 hours of activation time with activated carbon’s yield 96.24%, moisture content 1.12%, ash 85.68%, volatile matter 10.16%, carbon yield 4.25% and absorption of iodine 579.12 mg/g. Activated carbon from the best treatment applied to tofu wastewater treatment with activated carbon levels of 0; 1; 2; 3% and contact period of 0.5; 1; 1.5; 2 hours. Application treatment with activated carbon level of 3% and 1 hour contact period decreased the value of BOD, TSS and pH from 3485.77 mg/L, 4249.38 mg/L, 681.33 mg/L and 4.68 to 1269.82 mg/L, 72 mg/L dan 4.09 significantly, however it did not affect the COD value.
Keyword: ZnCl2, agar solid waste, tofu wastewater, activated carbon, adsorbent

Judul: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix