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INDONESIA
Indonesian Chimica Letters
Published by Universitas Jember
ISSN : -     EISSN : 29646782     DOI : https://doi.org/10.19184/icl
Core Subject : Science,
Chemistry
ICL is an international peer-reviewed and open access journal that publishes scientific articles covering all branches of chemistry: organic chemistry, physical chemistry, inorganic chemistry, analytical chemistry, biochemistry, chemometry, and applied chemistry
Arjuna Subject : Kimia(semua kategori) - Kimia (Lain-Lain)
Articles 45 Documents
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Potential of Tannin Extract From Coffee Grounds as an Exfoliant in Ultrasonic-Assisted Graphene Synthesis and Optimized Response Surface Methodology Bagaskara, Eldo Delta; Nela Mafazah; Muhammad Reza; Sudirman; Fry Voni Steky; Veinardi Suendo
Indonesian Chimica Letters Vol. 5 No. 1 (2026)
Publisher : Department of Chemistry, FMIPA, UNEJ

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/icl.v5i1.60005

Abstract

Graphene is a carbon-based nanomaterial with excellent electrical, thermal, and mechanical properties, making it very promising for various advanced applications. However, conventional graphene synthesis methods generally involve hazardous chemicals and environmentally unfriendly processes. This study investigated the use of tannin extract derived from coffee grounds as a green exfoliating agent for sustainable graphene synthesis via liquid-phase exfoliation. The effects of graphite:tannin ratio, ultrasonication time, and ultrasonication temperature on graphene formation were evaluated using the Response Surface Method (RSM) with Box–Behnken Design. The synthesized graphene was characterized using UV-Vis spectrophotometry and Raman spectroscopy. The UV-Vis response was represented by Absorption Peak Area (APA), while the quality of the graphene layer was evaluated using the Raman I2D/IG ratio. The results showed that lower graphite:tannin ratios generally resulted in better APA and I2D/IG responses, indicating the important role of tannin in exfoliation and dispersion stabilization through π–π stacking interactions. Longer ultrasonication time improved the exfoliation efficiency by maximizing the cavitation intensity. Qualitative observations after 5 days of storage showed that the dispersion with higher tannin concentration exhibited slower sedimentation and reduced re-stacking tendency. RSM optimization showed optimal parameters at a graphite:tannin ratio of 2 mg/mL, an ultrasonication time of 60 min, and an ultrasonication temperature of 54 °C, resulting in a predicted response of 0.009 for APA and 0.548 for I2D/IG
Optimization of Cyanidation Parameters in the Merrill-Crowe Method for Copper Recovery from Electroplating Wastewater Afrianti, Lia; Haryati, Tanti; Mintadi, Mukh; Asnawati, Asnawati; Oktavianawati, Ika; Andarini, Novita; Sulistiyo, Yudi Aris; Suwardiyanto, Suwardiyanto
Indonesian Chimica Letters Vol. 5 No. 1 (2026)
Publisher : Department of Chemistry, FMIPA, UNEJ

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/icl.v5i1.60006

Abstract

Electroplating wastewater contains heavy metals (copper, chromium, zinc, and nickel) at concentrations that frequently exceed safe discharge limits, posing serious risks to aquatic ecosystems. This study examines whether the Merrill–Crowe process, conventionally used for gold and silver recovery, can be adapted to recover copper from industrial electroplating effluent. The wastewater tested carried an initial copper concentration of 235.7 ppm. Cyanidation conditions were optimized by varying pH (7-11) and contact time (5-25 hours) to generate copper–cyanide complexes, which were subsequently precipitated with zinc powder. Complex formation was monitored by UV-Vis spectrophotometry; copper concentrations were quantified by atomic absorption spectrophotometry. Optimal conditions were pH 8 and 20 hours of contact time. Under these parameters, copper recovery reached 58.5% from electroplating wastewater and 43.5% from a standard reference solution. The higher efficiency in the wastewater sample reflects the presence of pre-formed copper–cyanide complexes, which accelerated both cyanidation and cementation. These results suggest the Merrill–Crowe process is a viable, low-complexity recovery strategy, one that not only reduces copper discharge but returns it in elemental form with potential economic value.
UV-Visible Spectrophotometric Quantification of Diazinon Residues in Brassica juncea L.: Method Development and Validation Analisa, Mulia Dila; Yeni Maulidah Muflihaha; Indarti, Dwi; AbuBakar, Noor hidayat
Indonesian Chimica Letters Vol. 5 No. 1 (2026)
Publisher : Department of Chemistry, FMIPA, UNEJ

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/icl.v5i1.60007

Abstract

Diazinon, an organophosphate pesticide used in agriculture, may leave harmful residues on vegetables. This study determined diazinon residues in green mustard (Brassica juncea L.), optimized extraction solvents, and evaluated spraying intervals before harvest using UV–Visible spectrophotometry as a simple and low-cost method. The novelty lies in developing a validated spectrophotometric approach combined with optimized hexane:acetone extraction (9:1), offering a practical alternative to chromatographic techniques. The method showed excellent linearity (r = 0.999), LOD of 0.018 ppm, LOQ of 0.060 ppm, recovery of 87–108%, and precision with 1.87% RSD. Results indicated that longer spraying intervals reduced residue levels, highlighting the method’s reliability and the importance of proper spraying management.
Strategic Optimization of Fractionation and Dialysis Buffer pH to Enhance Goat Liver-Uricase Activity Zain, Romzi Al Amiri; Handayani, Wuryanti; Sjaifullah, Achmad; Pertiwi, Andriana Kusuma; Ratnadewi, Anak Agung Istri; Sudarko, Sudarko
Indonesian Chimica Letters Vol. 5 No. 1 (2026)
Publisher : Department of Chemistry, FMIPA, UNEJ

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/icl.v5i1.60008

Abstract

Uricase is an important enzyme that catalyzes the oxidation of uric acid to allantoin and has potential applications in clinical diagnostics and biotechnology. However, its activity and stability are greatly influenced by purification conditions. This study aimed to optimize ammonium sulfate fractionation and the pH of the dialysis solution to enhance the activity of uricase isolated from goat liver. The enzyme was extracted and subjected to stepwise ammonium sulfate precipitation at different saturation levels, followed by dialysis using buffers with varying pH values. Enzyme activity and protein concentration were determined to calculate specific activity, and SDS–PAGE analysis was performed to evaluate the purification profile. The results showed that the optimal ammonium sulfate fraction for uricase precipitation was 0–20% saturation, yielding the highest specific activity of 0.0034 ± 0.001 U/mg. Further dialysis optimization indicated that a pH of 8.5 was the most favorable condition, yielding the highest enzyme activity of 0.0038 ± 0.001 U/mg. SDS–PAGE analysis showed reduced contaminant protein bands after purification, indicating improved enzyme purity. These findings suggest that precise control of salt concentration and buffer pH is crucial for maintaining uricase stability and enhancing its catalytic performance. Overall, the combination of optimized ammonium sulfate fractionation and dialysis conditions effectively improved the purity and activity of uricase, providing a useful basis for further development and application of this enzyme in biochemical and industrial processes.
Preparation of Cellulose Acetate Membranes via Phase Inversion for Osmometric Molecular Weight Determination of Macromolecules Syarifatul Lailah; Indarti, Dwi; Piluharto, Bambang; Mulyono, Tri; dwi ananda, Tinok
Indonesian Chimica Letters Vol. 5 No. 1 (2026)
Publisher : Department of Chemistry, FMIPA, UNEJ

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/icl.v5i1.60009

Abstract

Membrane osmometry is a crucial analytical technique for determining the molecular weight of macromolecules, demanding highly selective semi-permeable membranes to prevent solute leakage. This study investigates the effect of solvent evaporation time (1 to 5 minutes) during the phase inversion fabrication of cellulose acetate (CA) membranes on their physicochemical properties and semi-permeability. The synthesized membranes were evaluated for macroscopic appearance, density, swelling degree, and semi-permeability performance using dextran (100-200 kDa) as a model macromolecule. The results demonstrated that while the macroscopic structures remained uniform, prolonging the evaporation time significantly altered the microscopic morphology. Increasing the evaporation time to 5 minutes maximized the localized polymer concentration, resulting in the highest membrane density (1.55 g/mL) and the lowest swelling degree (17.62%). This highly compact structure provided a superior physical barrier, yielding the most optimal semi-permeability with minimal solute leakage. Furthermore, the application of this 5-minute optimized membrane in a membrane osmometer successfully determined the average molecular weight of dextran to be 122.45 kDa, which perfectly aligns with the theoretical range. The analytical measurement exhibited excellent reproducibility with a coefficient of variation (CV) of 1.8% and an accuracy of approximately 80%. These findings conclusively establish that controlling the evaporation time is a highly effective approach to tailoring the strict selectivity of CA membranes for precise osmometric applications.

Page 5 of 5 | Total Record : 45

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