Judul: Pembuatan Karbon Aktif Dari Jerami Padi Menggunakan Activating Agent H3po4.
Abstrak: Melimpahnya jerami padi di Indonesia dapat dimanfaatkan sebagai bahan baku untuk pembuatan karbon aktif dan diaplikasikan pada penjernihan air limbah. Tujuan penelitian ini adalah membuat, menguji dan mengaplikasikan karbon aktif dari jerami padi. Pembuatan karbon aktif dilakukan dengan tiga tahap yaitu pengarangan, aktivasi fisika dengan variasi suhu 500, 600, 700 dan 800 °C, kemudian masing-masing sample tersebut di aktivasi secara kimia menggunakan H3PO4. Hasil pengujian karbon aktif menunjukan bahwa karbon aktif yang mempunyai sifat fisik terbaik adalah karbon aktif yang diaktivasi pada suhu 800 ºC. Hasil XRD menunjukan bahwa kenaikan suhu meningkatkan derajat kristalinitas. Hasil FTIR Arang aktif yang dihasilkan memiliki pola serapan dengan jenis ikatan OH, C-H, C-O, dan C=C. Pengujian karbon aktif pada penjernihan air menunjukkan hasil parameter perubahan fisik air yaitu warna air menjadi jernih, tidak berbau dan pH 8.08 - 8.84.
Keyword: aktivasi fisika, aktivasi kimia, jerami padi, karbon aktif

Judul: Pemanfaatan Karbon Aktif dengan Aktivator H3PO4 dari Limbah Padat Agar sebagai Penjerap pada Limbah Cair Industri Penyamakan Kulit
Abstrak: Agar solid waste can be used as an adsorbent in the form of activated carbon. The study aims were to determine the best concentration of H3PO4 and activation time on the processing of activated carbon and the effectiveness of activated carbon as an adsorbent in the tanning industry wastewater. The activation step of activated carbon was carried out with H3PO4 concentration of 10; 20; 30% and the time activation of 15; 20; 25 hours. The best activation treatment was obtained on 10% H3PO4 concentration and 15 hours activation time with activated carbons yield of 93.42%, moisture content of 10.59%, ash content of 65.91%, absorption of iodine of 1090.80 mg/g, volatile matter of 21.60% dan fixed carbon of 12.35%. The best activated carbon was applied to the tanning industry wastewater with contact time of 0.5; 1; 1.5; 2 hours and activated carbon concentrations of 0; 1; 2; 3%. Application treatment with contact time of 0.5 hours and 3% activated carbon concentration decreased the value of Cr from 4371.21 ppm to 3572.76 ppm, treatment with contact time of 1 hours and 3% activated carbon concentration decreased the value of BOD, COD from 1216.10 mg/L, 17753.33 mg/L to 438.21 mg/L, 11770.00 mg/L respectively, however it did not affect the pH value.
Keyword: adsorbent, agar solid waste, wastewater, activated carbon, H3PO4

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology