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N. M. Surdia
Departemen Kimia, FMIPA Institut Teknologi Bandung
Mathematics

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Uji Selektivitas dan Penentuan Rekoveri Akhir pada Pemisahan Logam Emas dengan Metode Agregasi Hidrofobik Suharta Suharta; N. M. Surdia; Buchari Buchari; Djulia Onggo
Jurnal Matematika & Sains Vol 5, No 1 (2000)
Publisher : Institut Teknologi Bandung

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STUDI APLIKASI METODE POTENSIOMETRI PADA PENENTUAN KANDUNGAN KARBON ORGANIK TOTAL TANAH The separation of substance by hydrophobic aggregation method is always started from colloidal particles. The flaws of this technique are especially in the selectivity and recovery. This research was developing of gold separation by hydrophobic aggregation method where it was started from solution system. Complex of [AuCl4]- was chosen in this solution system. The gold selectivity from cations {Ag(I), Cu (II), Fe (III), Zn (II), Pb(II)}, and anions {SO4 2-, NO3-, Br-, I-} was studied. As a result, this method can be separated of gold with height selectivity. The selectivity is restrained by pH, and the optimum pH is 2,0. The recovery of gold with DTMAB, TTMAB, and HTMAB surfactant is 92,60 ± 0,89 %; 90,30 ± 1,32 %; and 89,40 ± 1,51 % respectively.
Pengaruh Variasi Konsentrasi Asam Sulfat pada Proses Hidroksilasi Minyak Jarak (Castor Oil) Marlina Marlina; N. M. Surdia; Cythia Linaya Radiman; S. Achmad
Jurnal Matematika & Sains Vol 9, No 2 (2004)
Publisher : Institut Teknologi Bandung

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Castor oil is derived from the bean of castor plant Ricinus communis L., belonging to Euphorbiaceae family from Nangroe Aceh Darussalam. Oil rendement per gram of castor bean is 45 – 52% with high purity and better than the standard oil given by AOAC. Acetylation and methylation protective process occurs on hydroxyl group of castor oil, indicated by decreasing of hydroxyl number, and also changing the structure of oil. Hydration process is more efective on acetylation-protective oil than that on non-protective and methylation-protective oil. Optimum condition reached when acid (H2SO4) concentration was 5% for non protective, 20% for acetylation protective and 15% for methylation protective oil. At those conditions, iodine and hidroxy values for non-protective, acetylation-protective, and methylation protective oil were 56.0 and 730.3; 23.3 and 664.5; and 38.5 and 649.8 mg/g, respectively.
Konstruksi Diagram Potensial-pH untuk Baja Karbon dalam Buffer Asetat secara Potensiodinamik Eksperimental Bunbun Bundjali; N. M. Surdia; Oei Ban Liang; Bambang Ariwahjoedi
Jurnal Matematika & Sains Vol 9, No 4 (2004)
Publisher : Institut Teknologi Bandung

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The pH-potential, or the so called Pourbaix, diagram for the system Fe - H2O is normally been constructed by using thermodynamic data. In this work the diagram was constructed experimentally based on potentiodynamic measurements of carbon steel in acetic acid - acetate ion buffer solutions at a temperature range of 25-85 0C. Due to the limited pH trajectory of buffer acetate solutions the resulted diagrams were not as wide pH as those of thermodynamic Pourbaix diagrams, but they are more useful for analysing carbon steel corrosion in acetate environment systems at that temperature range. In Addition the effects of pH and temperature on the primary passive potential (Epp) and Fladge potential (EF) relationship could also be obtained.
Pengaruh Variasi Komposisi Amilosa terhadap Kemudahan Biodegradasi Poliuretan Eli Rohaeti; N. M. Surdia; Cynthia L. Radiman; E. Ratnaningsih
Jurnal Matematika & Sains Vol 8, No 4 (2003)
Publisher : Institut Teknologi Bandung

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Amylose had been used to synthesize polyurethanes. A mixture of polyethylene glycol (PEG) with a molecular weight 400 with amylose was reacted with diphenylmethane-4,4’-diisocyanate (MDI) at room temperature to produce polyurethanes. The precured polyurethanes were heat-pressed and PU sheets were obtained. Characterization of functional groups was determined by FTIR spectrophotometry and crystallinity was analyzed by using XRD. The hydrogen bonding index (HBI) of polyurethane samples increased with an increasing of amylose content. The addition of 15% (w/w) amylose decreased the degree of crystallinity of polyurethane. The films of polyurethanes were biodegraded by Pseudomonas aeruginosa in an liquid of Luria Bertani (LB) media at 37oC for 5, 10, 15, 20, 25, and 30 days, with the changing of media every 5 days. The result of weight loss percentace showed that all polymers may be biodegraded, with different biodegradation rate. The biodegradability (rate of weight loss) of polyurethanes by Pseudomonas aeruginosa increased when the amylose content in the polyurethane increased. The polyurethane product with 15% amylose – PEG400 – MDI had the highest biodegradability.
Co-Authors Bambang Ariwahjoedi Buchari Buchari Bunbun Bundjali Cynthia L. Radiman Cynthia Linaya Radiman Djulia Onggo E. Ratnaningsih Eli Rohaeti Marlina Marlina Oei Ban Liang S. Achmad Suharta Suharta