Showing papers by "Karna Wijaya published in 2017"

Synthesis and characterization of sulfated zirconia mesopore and its application on lauric acid esterification

Abstract: Sulfated zirconia mesopore has been successfully prepared from zirconyl oxychloride using structure directing agent cetyl trimethyl ammonium bromide (CTAB) and (NH4)2SO4. The preparation involved calcination at four different temperatures denoted as MZS (400, 500, 600, and 700 °C) and three different zirconyl-to-CTAB ratios (1:1, 3:1, and 9:1). Characterization of resulting zirconia was carried out using XRD method, TEM, gas sorption analyzer, and FTIR. The acidity of zirconia evaluated by ammonia adsorption. Calcination temperatures conducted at 500, 600, and 700 °C lead to crystalline structure and tetragonal phase. MZS-600 prepared at ratio 3:1 showed optimum specific surface area, pore diameter, and pore volume: 147.5 m2/g, 6.6 nm, and 0.396 cc/g, respectively. CTAB assisted larger pore size formation in zirconia along with higher surface area. The catalytic activity of sulfated zirconia mesopore was tested on lauric acid esterification. All sulfated zirconia mesopores prepared were able to give 99–100% conversion. The highest yield of methyl lauric 89.8% was achieved by MZS-600 prepared using CTAB to zirconyl ratio 9:1.

Effect of Sulfuric Acid Treatment and Calcination on Commercial Zirconia Nanopowder

Abstract: The modification of commercial zirconia nanopowder by sulfuric acid and heat treatment was conducted. The aim of this present research was to obtain a stable modified zirconia nanopowder chemically and thermally by studying the effect of sulfuric acid treatment and calcination temperature on commercial zirconia nanopowder. The material was prepared by dispersing the commercial zirconia nanopowder into 0.2, 0.5 and 0.8 M sulfuric acid solutions, followed by calcination at varied temperatures, i.e. 600, 700, 800 and 900 °C. The so called sulfated zirconias then were characterized their physicochemical properties using FT-IR, XRD and SEM-EDX analysis methods. The optimized condition for that modification was obtained by using sulfuric acid of 0.8 M and calcination temperature of 600 °C. The characterization results also revealed that using ammonia adsorption method, the acidity of the catalyst was found to be 1.06 mmol/g.

Investigation of the Structural and Dynamical Properties of Cu + in Liquid Ammonia: A Quantum Mechanical Charge Field (QMCF) Molecular Dynamics Study

Abstract: A quantum mechanical charge field (QMCF) molecular dynamics (MD) simulation has been carried out to describe the structural and dynamical properties of Cu + ion in liquid ammonia. The first and second shells were treated by ab initio quantum mechanics at the Hartree−Fock (HF) level with the DZP-Dunning basis set for ammonia and LANL2DZ ECP basis set for Cu. The system was equilibrated for 4 ps, then the trajectory data was collected every fifth step for 20 ps at 235.15 K. The structural analysis showed that in the first solvation shell, Cu + is solvated by 4 ammonia molecules forming a stable structure of tetrahedral with Cu-N bond length of 2.15 A, whereas in the second solvation shell there are 29 ammonia molecules that have an average distance of 4.79 A to Cu + ion. Mean residence time of 3.06 ps was observed for the ammonia ligand in the second solvation shell indicating for a highly unstable structure of the solvation shell. The obtained structure of the first solvation shell from this simulation is in excellent agreement with experimental data.

Determination of Effective Functional Monomer and Solvent for R(+)-Cathinone Imprinted Polymer Using Density Functional Theory and Molecular Dynamics Simulation Approaches

Abstract: Determination of effective functional monomer and solvent for R(+)-cathinone imprinted polymer through modeling has been done using density functional theory (DFT) and molecular dynamics (MD) simulation approaches. The selection criteria of the best monomer and solvent are based on the classical potential energy (ΔE MM ) from molecular dynamics simulation and confirmed further by quantum potential energy (ΔE DFT ) from DFT calculation. The DFT calculation was performed in B3LYP exchange-correlation functional within the 6-31G(d) basis set of function including Polarizable Continuum Model (PCM) solvation effect. From this research, it is obtained that N,N’-methylene bis acrylamide and chloroform are respectively the best candidates for effective functional monomer and solvent, for the synthesis of R(+)-cathinone imprinted polymer.

Penggunaan Metode Semiempirik AM1 Untuk Pemilihan Monomer Fungsional Efektif Pada Prasintesis Polimer Tercetak Diazinon

Abstract: Pemilihan monomer fungsional yang efektif untuk sintesis Molecular Imprinted Polymer (MIP)untuk diazinon dapat dilakukan dengan pendekatan kimia komputasi dengan menerapkan metode semiempirik AM1. Proses seleksi menggunakan parametermomen dipol, energi interaksi, dan ikatan hidrogen yang terbentuk. Energi interaksi yang optimum menunjukkan kompleks yang terbentuk stabildan mengindikasikan MIP akan dapat terbentuk baik.Semua perhitungan pada penelitian ini dilakukan dengan menggunakan software Hyperchem 7.5. Hasil penelitian menunjukkan monomer fungsional efektif untuk prasintesis polimer tercetak diazinon yaitu akrilamida, asam akrilat, asam metakrilat, hidroksi etil metakrilat, asam urokanat, asam itakonat, dan asam urokanat etil ester. Hasil ini secara teoritik dapat memberikan informasi mengenai monomer fungsional efektif yang dapat digunakan sebagai pertimbangan sintesis MIP untuk diazinon dengan selektivitas relatif baik.