Kurniawan, Yehezkiel Steven
Universitas Gadjah Mada

Published : 3 Documents

Found 3 Documents

Synthesis of 1,4-Dioxaspiro[4.4] and 1,4-Dioxaspiro[4.5] Novel Compounds from Oleic Acid as Potential Biolubricant Kurniawan, Yehezkiel Steven; Ramanda, Yudha; Thomas, Kevin; Hendra, Hendra; Wahyuningsih, Tutik Dwi
Indonesian Journal of Chemistry Vol 17, No 2 (2017)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (381.558 KB) | DOI: 10.22146/ijc.24891


Two 1,4-dioxaspiro novel compounds which derivated from methyl 9,10-dihydroxyoctadecanoate (MDHO) with cyclopentanone and cyclohexanone had been synthesized by a sonochemical method in the presence of montmorillonite KSF catalyst. The MDHO compound had been prepared from 9,10-dihydroxyoctadecanoic acid (DHOA) and methanol. Meanwhile, DHOA was synthesized by hydroxylation of oleic acid with the solution of 1% KMnO4 under basic condition. The structures of the products were confirmed by FTIR, GC-MS, 1H-NMR, and 13C-NMR spectrometers. Hydroxylation reaction of oleic acid gave DHOA as a white solid powder in 46.52% yield (m.p. 131-132 °C). On the other side, esterification reaction via sonochemical method between DHOA and methanol gave MDHO as a white powder in 93.80% yield (m.p. 80-81 °C). The use of cyclopentanone in 45 min sonochemical method gave methyl 8-(3-octyl-1,4-dioxaspiro[4.4]nonan-2-yl)octanoate as a yellow viscous liquid in 50.51% yield. The other compound, methyl 8-(3-octyl-1,4-dioxaspiro[4.5]decan-2-yl)octanoate as yellow viscous liquid had been synthesized by similar method with cyclohexanone via the sonochemical method in 45.12% yield. From physicochemical properties, i.e. density, total acid number, total base number, and iodine value, gave the conclusion that these novel compounds are potential biolubricant candidates to be developed.
Synthesis and Kinetic Study of the Urea Controlled Release Composite Material: Sodium Lignosulfonate from Isolation of Wood Sawdust-Sodium Alginate-Tapioca Imawan, Arif Cahyo; Kurniawan, Yehezkiel Steven; Lukman, Muhammad Fernadi; Jumina, Jumina; Triyono, Triyono; Siswanta, Dwi
Indonesian Journal of Chemistry Vol 18, No 1 (2018)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (422.693 KB) | DOI: 10.22146/ijc.26597


A synthesis and kinetic study of the urea controlled-release composite material based on isolated Na-lignosulfonate, Na-alginate and tapioca was carried out. This experiment’s aims were to isolate Na-lignosulfonate from wood sawdust and to applicate this isolated Na-lignosulfonate, along with tapioca and Na-alginate as urea control release composite material. A kinetic study of urea released from the composite materials was also conducted. Na-lignosulfonate was isolated by Kraft lignin method to give a brown solid yield of 16.92% and was characterized by FT-IR spectrophotometer and SEM-EDX. The composite materials were synthesized by blending urea as the active compound with composite material as the carrier compound. Three types of material were prepared: complete material (A), low-concentration Na-lignosulfonate material (B) and material without tapioca (C). The composite material had a spherical form with 0.79 mm radius and 2.16 mm swollen radius. Urea content inside material was 40.425 mg urea/g material. The urea diffusivity coefficient for material A, B, and C were 7.27 x 10–6; 15.50 x 10–6 and 0.94 x 10–6 m2 h–1, respectively. Modelling analysis showed the experiment obeyed around only 15% of the Korsmeyer–Peppas model, but there was good correlation (80%) with the unsteady-state diffusion model.
Separation of Pb(II) Ion with Tetraacetic Acid Derivative of Calix[4]arene by Using Droplet-based Microreactor System Kurniawan, Yehezkiel Steven; Ryu, Mizuki; Sathuluri, Ramachandra Rao; Iwasaki, Wataru; Morisada, Shintaro; Kawakita, Hidetaka; Ohto, Keisuke; Maeki, Masatoshi; Miyazaki, Masaya; Jumina, Jumina
Indonesian Journal of Chemistry Article in press
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (207.762 KB) | DOI: 10.22146/ijc.34387


In this study, the microreactor system was investigated and compared with the batch-wise system as rapid and effective extractive Pb(II) separation over Fe(III), Cu(II) and Zn(II) with tetraacetic acid calix[4]arene. By using a microreactor system, the Pb(II) extraction percentages reached the maximum of 73, 89 and 100% in 8 sec residence time at equilibrium pH of 2.00, 2.25 and 2.50, respectively. The stripping percentage was 92% at 8 sec residence time by using a microreactor system with 2.0 M HNO3 as a stripping reagent. Complete separation of Pb(II) over Fe(III), Cu(II) and Zn(II) ions with the tetraacetic acid calix[4]arene in a competitive metal system was achieved at pH 2.00. However, the batch system required 24 h to reach the equilibrium for both extraction and stripping processes. The results suggested that the microreactor system enhanced the Pb(II) extraction and stripping rate up to 104 times faster than the batch-wise system.