Nurul Ismillayli
Department of Chemistry, Faculty of Mathematics and Fundamental Sciences, University of Mataram, Jalan Majapahit No.62, Mataram 83125, Nusa Tenggara Barat

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PENERAPAN FREUNDLICH MODEL PADA ADSORPSI-REDUKTIF ISOTHERM AUCL4¯ DENGAN ASAM HUMAT Ismillayli, Nurul; Santosa, Sri Juari; Siswanta, Dwi
Jurnal PIJAR Vol 10, No 2 (2015)
Publisher : Jurnal PIJAR

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Abstract

Abstrak: Telah dilakukan adsorpsi reduktif isotherm AuCl4¯ dengan menggunakan asam humat hasil isolasi tanah gambut Rawa Pening, Ambarawa. Isolasi dilakukan melalui perendaman alam 0,1 M NaOH dan dilanjutkan dengan pemurnian menggunakan 0,1 M HCl/0,3 M HF. Asam humat hasil isolasi dikarakterisasi menggunakan spektroskopi inframerah, ditentukan kadar abunya dan diaplikasikan untuk adsorpsi reduksi isotherm larutan AuCl4¯. Hasil karakterisasi menunjukkan bahwa asam humat hasil isolasi memiliki gugus –COOH, -OH fenolik, hidrokarbon alifatik dan aromatis dengan kadar abu sebesar 1,13%. Data adsorpsi AuCl4¯  dengan menggunakan asam humat lebih menunjukkan kecocokan dengan persamaan Freundlich di banding Langmuir, dengan harga R=0,92, n=1,7184 dan log KF= 4,1707. Reduksi Au(III) menjadi Au(0) oleh asam humat dikonfirmasi dengan munculnya puncak tajam baru dengan nilai 2θ =38, 44, 64 dan 77° yang merupakan puncak karakteristik dari partikel emas. Kata kunci: adsorpsi reduktif isotherm, AuCl4¯, asam humat, Freundlich.                                                                                   Abstract: Isotherm adsorption reductive of AuCl4¯ by using isolated humic acid of Rawa Pening peat soil, Ambarawa had been conducted. Isolation was done by soaking peat soil in 0.1 M NaOH and following by purification in 0.1M HCl/0.3 HF. The isolated humic acid was characterized using infrared spectroscopy, determined its ash contain and aplicated for isotherm adsorption reductive of AuCl4¯. FTIR spectra indicated that isolated humic acid consist of COOH group, phenolic –OH, aliphatic hydrocarbon and aromatic ring, its ash content was 1.13%. Asorption data of AuCl4¯  showed more suitable for Freundlich model than Langmuir model, with R=0,92, n=1,7184 and log KF= 4,1707. Reduction of Au(III) to Au(0) was confirmed by appearance of sharp peak at 2θ = 38, 44, 64 dan 77° as characteristic peak of gold particles.Keywords: Isotherm adsorption reductive, AuCl4¯ , humic acid, Freundlich.
CHEMICAL DEGRADATION OF NAFION MEMBRANES UNDER PEMFC AS INVESTIGATED BY DFT METHOD Sanjaya, Rochmad K; Juliandri, Juliandri; Rahayu, Iman; Ismillayli, Nurul; hermanto, dhony
Jurnal Sains Materi Indonesia Vol 21, No 2: JANUARY 2020
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (916.989 KB) | DOI: 10.17146/jsmi.2020.21.2.5582

Abstract

CHEMICAL DEGRADATION OF NAFION MEMBRANES UNDER PEMFC AS INVESTIGATED BY DFT METHOD. An exsitu method has been developed to performance of Nafion's membrane in PEMFC (Proton Electrolyt Membrane Fuel Cells), caused by the chemical degradation of ·OH and ∙H radicals. The change of the chemical structure occurring during the degradation were primarily calculated of the relative energy of reactions by DFT (Density Functional Theory) method approach in the Gaussian software. This study aims to determine whether DFT method with functional B3LYP, PBEPBE, and B3PW91 and base sets 6-311++G can be used in determining the relative energy of a reaction and knowing the difference in role between ·OH and ∙H in the degradation process of the main chain Nafion with the final group are -CF2H, -CF=CF2 and -COOH. The three functionalities applied showed that the ·OH radical has more role than the ∙H radical in the degradation process of the Nafion main chain. In the -CF2H group was shown the relative energy value of reaction 2 is lower than reaction 5, in the -CF=CF2 group was shown the relative energy value of reaction 8* is lower than reaction 11 and in the -COOH group the relative energ value of reaction 14 is lower than reaction 16. By knowing the relative energy of the Nafion main chain degradation reaction with a certain final group and the role of certain radical compounds in the degradation process, the DFT method with functional B3LYP, PBEPBE and B3PW91 and base sets 6-311++G can recommend various modifications of the Nafion as a fuel cell membrane, particularly in increasing of membrane performance.
Polyelectrolyte Complex (PEC) of the Alginate-Chitosan Membrane for Immobilizing Urease Dhony Hermanto; Mudasir Mudasir; Dwi Siswanta; Bambang Kuswandi; Nurul Ismillayli
Journal of Mathematical and Fundamental Sciences Vol. 51 No. 3 (2019)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2019.51.3.8

Abstract

PEC of the alginate-chitosan membrane as supporting material for immobilizing urease was produced. This study aimed to develop a supporting material for enzyme immobilization that has high stability, a fast response time and an easy and relatively inexpensive preparation procedure. An alginate-chitosan PEC membrane was produced by reacting alginate hydrosol and chitosan (1:1 in mass) at pH 5.28, followed by mixing and drying at room temperature. The FTIR spectra, XRD patterns and SEM assay confirmed that alginate-chitosan PEC was obtained. The color change of the BTB indicator proved that urease was trapped in the cavities of the alginate-chitosan PEC membrane while the immobilized urease still showed catalytic activity. Thus, the membrane of alginate-chitosan PEC has good characteristics as a matrix for urease immobilization.