Gunawan Gunawan
Chemistry Department, Faculty Of Sciences And Mathematics, Diponegoro University Jl. Prof. Soedarto, SH., Tembalang, Semarang

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Journal : Indonesian Journal of Chemistry

Degradation of Methylene Blue Using Cadmium Sulfide Photoanode in Photofuel Cell System with Variation of Electrolytes Gunawan Gunawan; Abdul Haris; Didik Setiyo Widodo; Linda Suyati; Wilman Septina
Indonesian Journal of Chemistry Vol 21, No 1 (2021)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.53131

Abstract

Methylene blue degradation carried out using cadmium sulfide (CdS) photoanode in photofuel cell (PFC) had been done. CdS synthesized by chemical bath deposition (CBD) on the FTO substrate was used as anode and platinum as a cathode in photoelectrochemical studies. Characterization of CdS thin film was done using EDX, XRD, SEM, Raman, UV-Vis absorption spectrophotometer as well as photocurrent test of the CdS thin film under illumination using potentiostat with the three-electrode system. The EDX result indicated the presence of CdS with an elemental composition of Cd rich. XRD showed the appearance of CdS crystals in cubic and hexagonal formations. SEM image of CdS gave results in the form of crystals of less than 1 mm. Raman spectrum showed the appearance of CdS peaks. The bandgap of CdS was estimated to be 2.38 eV, and the photocurrent test confirmed that the film had a property of n-type semiconductor. Application of CdS thin film as a photoanode in the PFC system using 100 mg/L methylene blue solution showed degradation up to 48% for 2.5 h using a 4 cm2 photoanode, and the maximum potential of 0.8 V was obtained with a photoanode area of 1 cm2. 
Synthesis, Characterization, and Study of Proton Exchange Polymer Membrane Properties of Sulfonated Copolymer Eugenol-diallyl Phthalate Ngadiwiyana Ngadiwiyana; Nor Basid Adiwibawa Prasetya; Gunawan Gunawan; Tutuk Djoko Kusworo; Heru Susanto
Indonesian Journal of Chemistry Vol 21, No 1 (2021)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.55353

Abstract

Synthesis biopolymer of sulfonated copolymer eugenol-diallyl phthalate (PEGDAF), its characterization, and study of proton exchange polymer membrane properties had been done. This synthesis was conducted by eugenol and diallyl phthalate reaction to form PEGDAF, which is sulfonated using sulfuric acid. In addition, the functional groups of the PEGDAF and its sulfonated form were analyzed using FT-IR. Furthermore, the polymer properties were determined by measuring values of sulfonation degree, cation exchange capacity, proton conductivity, and water uptake. FT-IR spectra showed that the vinyl group had been added to the process of PEGDAF formation, while spectra deconvolution was used to confirm the occurrence of sulfonation reaction. The sulfonation of PEGDAF in 2 h optimum reaction time produces a black solid with a melting point of 133 °C in 16.55% yield. The highest proton conductivity, cation exchange capacity (CEC), and water uptake were 8.334 × 10–6 S cm–1, 0.44 meq/g, and 73.0%, respectively.
Synthesis of Graphite Paste/Molecularly Imprinted Polymer (MIP) Electrodes Based on Polyeugenol as a Glucose Sensor with Potentiometric Method Muhammad Cholid Djunaidi; Mei Dian Risda Afriani; Gunawan Gunawan; Miratul Khasanah
Indonesian Journal of Chemistry Vol 21, No 4 (2021)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.58964

Abstract

Diabetes mellitus is a chronic disease in which the body is unable to metabolize carbohydrates, fats, and proteins. In this study, eugenol was polymerized and then contacted with glucose and crosslinked using polyethylene glycol diglycidyl ether (PEGDE). The resulted PE-Glucose-PEGDE was eluted using ethanol to form MIP-Glucose. It was then characterized by FTIR, SEM, electrodes using the Eutech 510 potentiostat and UV-Vis spectrophotometer. The result of polyeugenol synthesis is a reddish-brown powder with a yield of 99.90% and a molecular weight of 6318.033 g/mol. UV-Vis spectrophotometer analysis showed that the contacted glucose was 2152.505 ppm. SEM results showed differences in the surface morphology of the material, indicating the formation of cavities in MIP and ESM, while no cavities are found in NIP and ESN. The electrode optimization resulted in the best composition ratio of MIP 1 mol: paraffin: graphite, respectively of 20:35:45. The resulting electrode has a Nernst factor of 20.24 mV/decade with a measurement range of 10–5–10–1 M, a limit of detection value of 8.363 × 10–5 M, and the value of the selectivity coefficient (Kij) of the electrodes in a (10–5–10–1) M fructose solution was 0.3733; 0.23048; 0.17864; 0.12359; 0.1073.
Ferrate(VI) Synthesis Using Fe(OH)3 from Waste Iron Electrolysis and Its Application for the Removal of Metal Ions and Anions in Water Gunawan Gunawan; Abdul Haris; Nor Basid Adiwibawa Prasetya; Eka Pratista; Azis Amrullah
Indonesian Journal of Chemistry Vol 21, No 6 (2021)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.64824

Abstract

Ferrate(VI) salt is an effective oxidant and coagulant for water treatment and removal of metal ions. This study demonstrates a new approach to processing metal ions and anions in water by Fe(VI) through Fe(III) obtained from the electrolysis of waste iron transformer. The electrolysis was successfully carried out in the Na2SO4 electrolyte using waste iron and zinc plates as anode and cathode, respectively. Fe(III) electrolysis results through the characterization of FTIR and XRD indicate compliance with Fe(OH)3 standards. Synthesis of ferrate was carried out by adding Fe(III) from electrolysis with NaOCl in alkaline conditions. The formed ferrate solution shows a purple color with a typical maximum wavelength of 505 nm. Furthermore, the ferrate obtained is used to remove metal ions (Fe(III), Cu(II), Zn(II), Mg(II), Pb(II)) and anions (sulfate, nitrate, and carbonate) in water with pH variations. Ferrate treatment filtrate was analyzed using AAS for metal ions, while sulfate, nitrate, and carbonate anions used UV-Vis spectrophotometry, turbidimetry, and titration methods. The results showed that ferrate effectively eliminates metal ions and anions in water with optimum pH 6. The mechanism of heavy metal removal by ferrate(VI) can be explained by ionic bonding and adsorption.
Improving the Electrical Conductivity of the Composite Comprising Bismuth Oxide, Activated Carbon, and Graphite for Use as a Battery Anode Yayuk Astuti; Faradina Azahra Zaqia; Aulia Zahra Ekaningsih; Gunawan Gunawan; Adi Darmawan
Indonesian Journal of Chemistry Vol 23, No 6 (2023)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.74155

Abstract

This research is concerned with the synthesis and characterization of a composite material that may be used as a battery electrode. Bismuth oxide (Bi2O3) was synthesized from Bi(NO3)3·5H2O, Na2SO4, and NaOH mixed with commercial activated carbon and graphite. The composite formation process was carried out using the hydrothermal method at 110 °C for 5 h. The characterization data indicated the composites produced contained Bi2O3 with a monoclinic crystal system, and Bi2O3 particles were evenly distributed in the composite. The composites were characterized to be mesoporous, with the electrical conductivity reaching 10−1 S m−1. The development of this composite material has potential applications in the field of energy storage, particularly in the development of battery anode.