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INDONESIA
KOVALEN: Jurnal Riset Kimia
Published by Universitas Tadulako
ISSN : -     EISSN : 24775398     DOI : https://doi.org/10.22487/kovalen
Core Subject : Science, Engineering,
Chemical Engineering, Chemistry & Bioengineering Chemistry
KOVALEN: Jurnal Riset Kimia is a peer-reviewed journal of chemistry published by the Tadulako University, Indonesia. This journal concern with publishing the original research articles, review articles, and the current issues related to chemistry. Publishing frequency 3 issues per year, in April, August, and December.
Arjuna Subject : Kimia(semua kategori) - Kimia (Lain-Lain)
Articles 325 Documents
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Optimization and Kinetic Study of Ende-Natural Zeolite as Candidates of Ammonia Adsorbent on Broiler Chicken Litter Abner Tonu Lema; Cytske Sabuna; Yehezkial Wila Balu
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15914

Abstract

Zeolite Natural Ende (ZNE) is a local material from Ende, East Nusa Tenggara which can be used as an adsorbent candidate to reduce environmental pollution due to poultry farm wastes. The purpose of this study is to obtain optimal conditions and adsorption kinetics of ZNE as an adsorbent in terms of absorbing NH3, water content, and neutralizing pH on broiler litter. This study consisted of 3 stages such as sample preparation, optimization of acid concentration, particle size, contact time, adsorbate concentration, as well as determination of ZNE-methylene blue adsorption kinetics. The results of the analysis revealed that the best conditions are using 1 M H2SO4, particle size 80 mesh, contact time for 30 minutes with an adsorption capacity of 1.999 mg/g, and methylene blue 80 ppm as an optimal condition. Furthermore, ZNE-methylene blue adsorption kinetics model is the second order type 1 kinetics by R2 = 1, and also adsorption rate constant is 0.0019 g.mg-1.min
Pengaruh Konsentrasi Inhibitor dari Eceng Gondok dalam Air Hujan dan Air Kran terhadap Laju Korosi: Effect of Water Hyacinth Inhibitor Concentration in Rain Water and Tap Water Media on Corrosion Rate Emma Hermawati; Yunus Tonapa Sarungu; Bambang Soeswanto; Rispiandi; Alfiana Adhitasari; Sudrajat Harris Abdulloh; Rony Pasonang Sihombing; Retno Indarti
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15931

Abstract

Organic inhibitors in the corrosion process could be obtained from water hyacinth plant. This plant contained antioxidants such as saponins, which could bind to protective metals from corrosion. The objective of this study was to observe the corrosion rate degradation in rainwater and tap water with saponin content of water hyacinth extract with novelty of using methanol in the maceration process. The sample: methanol ratio used in the maceration process was 1 : 9 (w/v). Steel testing was carried out for 5 days in rainwater and tap water. Based on the test results, the saponin content in the water hyacinth extract could be proven by the stability of the foam produced. The experimental results showed a corrosion rate escalation in tap water samples from 47.7% to 94.5% and samples in rainwater from 11.3% to 52.9% at 75 ppm inhibitor concentration. Based on the research, water hyacinth extract using methanol solvent could be used as a corrosion inhibitor.
Pengaruh Penyimpanan dan Lama Pemanasan Terhadap Kadar Asam Galat pada Kacang Tanah (Arachis hypogaea L.): Effect of Storage and Heating Time on Gallic Acid Levels in Peanuts (Arachis hypogaea L.) Devyana Dyah Wulandari; Ersalina Nidianti; Ary Andini; Rahmawati Fitri Awalia; Halimah Prisilia
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15947

Abstract

One of the most prevalent phenolic acids to be found in foods such as fruits, vegetables, and herbal remedies is gallic acid, also known as 3,4,5-trihydroxybenzoic acid. The free acids, esters, catechin derivatives, and hydrolyzed tannins are the different ways that these substances are obtained. The specialty of this compound is due to its pharmacological activity as a radical scavenger. The total phenolic content in peanuts varies from 132.5 to 248.8 mg GAE/100 g. The purpose of this study was to determine the effect of storage time and heating time of peanuts (Arachis hypogaea L.) on gallic acid levels. Determination of gallic acid using the High Performance Liquid Chromatography (HPLC) method with the column used is an ODS (Octadesil Silica) C18 column and the mobile phase is a mixture of acetonitrile and aquadest (1:3). Peanuts were stored for 1 week, 2 weeks, and 3 weeks at 25°C and fried at 160°C for 2 minutes, 4 minutes, and 6 minutes. The results of this study on the length of storage obtained a P value of 0.000 where the results are smaller than 0.05. This indicates that storage time has a significant effect on gallic acid levels in peanut samples. Gallic acid levels appear to increase from the first week to the fourth week. Based on the results of the research at the time of heating obtained a P value of 0.189 where the results are higher than 0.05. This shows that the length of heating time does not affect on the gallic acid content in the peanut samples. From these results, it was concluded that gallic acid content was affected by storage time, but not by heating time.
Pengaruh Penambahan Minyak Zaitun Terhadap Karakteristik dan Reologi Edible Film Berbahan Dasar Gluten: The Effect of Addition of Olive Oil on The Properties and Rheology of Gluten-Based Edible Films Nancy Siti Djenar; Joko Suryadi; Nisa Siti Nursaadah; Erina Putri
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15948

Abstract

Gluten vegetable protein can be used as an alternative source of biopolymer as the basic material for edible film other than polysaccharides. Gluten-based edible films have a poor water vapor barrier and high cohesive and viscoelastic properties, therefore the addition of lipids and plasticizers is required. In this study, olive oil was added to reduce its permeability to water vapor, while glycerin was added to produce a more flexible edible film. The results showed that the addition of 1% olive oil could reduce the lowest water vapor transmission rate of 9.14 g/m2/24 hours with a thickness of 0.248 mm, tensile strength of 16.64 mPa, and elongation of 419.5%. The four characteristics are in accordance with the Japanese Industrial Standard. The antimicrobial testing on edible films showed that the addition of 0-2% olive oil could inhibit the growth of E. coli, while A. niger and R. oryzae 0-2% olive oil could not inhibit the growth of the two fungi. The measurement of optical properties showed that the transparency of the edible film was highest at the addition of 0% olive oil at 55%. The highest opacity value was with the addition of 1% olive oil, which is 2.96. The Fourier Transform Infrared (FTIR) identification showed that the edible film added with 1% olive oil had three characteristic absorption bands from gluten, olive oil, and an absorption band from glycerin. These bands indicate that olive oil, glycerin, and gluten do not react but only physically interact. The measurement using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) showed that the microstructure of gluten-based edible film produces a varied structure where the gluten structure network can be clearly observed and contains elements of C, O, N where the intensity of C and O elements of 160-400 cps and 30-100 cps, respectively.
Antioxidant Potential of Ethanol Extract from Mango Parasite (Dendrophthoe petandra) to Maintain Crude Palm Oil (CPO) Quality Ninik Triayu Susparini; Rohmatulloh; Boima Situmeang; Isna Lailatusholihah; Siti Rohmiyati
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15954

Abstract

The present study aimed to determine the effectiveness of adding natural antioxidants from ethanolic extract of mango parasite (Dendrophthoe petandra) to oxidation stability of crude palm oil (CPO) during storage. The parameters tested were levels of free fatty acid (FFA), acid values, and deterioration of bleachability index (DOBI). The antioxidant activity of D. petandra extract obtained was IC50 of 6.369 ppm. Concentrations of D. petandra extract range from 200 to 1000 ppm. Based on the results, the ethanolic extract of D. petandra was able to reduce the FFA and acid value and increase the DOBI compared to the negative control. The lowest FFA levels and acid numbers were obtained from samples with addition of 1000 ppm natural antioxidants with FFA of 4.2% and acid value of 7.4 mg KOH/g, while the DOBI value increased to 1.300.
Validation of Boron Analytical Methods on Standard Reference Material Tomato Leaves from NIST No. 1573a with Isothermal Distillation by UV-Vis Spectrophotometry Isna Lailatusholihah; Roto; Agus Kuncaka; Ninik Triayu Susparini
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15955

Abstract

Boron analysis by UV-Vis spectrophotometry has been developed through distilling triethoxy borane into the curcumin solution. In the distillation of ester borane, an esterification reaction occurs between borate and ethanol. Validation of isothermal distillation methods by UV-Vis spectrometry needs to be done to obtain specific, accurate, and reproducible results. The distillation for 24 hours at 25°C gave the optimum result. UV-Vis spectrophotometry wavelength was 535 nm. The standard curve was linear in the concentration range of 1-5 ppm (R2 = 0.9995) with a sensitivity of 0.0902 ppm-1, a limit of detection of 0.002±0.001 ppm, the limit of quantification of 0.006±0.001 ppm, and percent recovery of 88%.
Potensi Ekstrak Batang Kayu Gempol (Nauclea orientalis L.) dalam Menghambat Pertumbuhan Bakteri: Potency of Gempol (Nauclea orientalis L.) Stem Extracts to Inhibiting Bacterial Growth Ni Kadek Atmiyanti; Pasjan Satrimafitrah; Abd. Rahman Razak; Nov Irmawati Inda; Indriani; Dwi Juli Puspitasari
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15962

Abstract

The study of the potential of Gempol wood stem extract (Nauclea orientalis L.) with three solvent polarities has been exercised to determine the extract with a certain polarity and the smallest concentration that can inhibit the growth of bacteria Staphylococcus aureus and Escherichia coil. Extraction is performed using the maceration method with n-hexane, ethyl acetate, and ethanol as solvents. Furthermore, the potency in inhibiting the growth of bacteria was observed by the diffusion method with a range of extract concentrations from the largest to the smallest. The extract's ability to inhibit bacterial growth in the time range of up to 24 hours was measured using the turbidimetric method. The results showed that ethyl acetate and ethanol extracts were able to inhibit the growth of both bacteria in a wide concentration range (100 %– 5%), although n-hexane extracts showed the highest percentage in inhibiting both bacteria (15.27 mm and 16.89 mm, respectively). Turbidimetric assays showed the extract was stronger in inhibiting S. aureus compared to E. coli in the logarithmic phase range of 12 hours. This study showed that semipolar and polar extracts can inhibit the growth of bacteria with a wider concentration range compared to non-polar extracts despite having a higher inhibition capability.
Penurunan Kadar Chemical Oxygen Demand (COD) pada Limbah Cair Industri Tahu Menggunakan Arang Aktif dari Pelepah Kelapa Sawit (Elaeis guenensis Jacq.) : Reducing Chemical Oxygen Demand (COD) Levels in Tofu Industrial Liquid Waste Using Activated Charcoal from Palm Oil (Elaeis guenensis Jacq.) Mid-ribs Khairuddin; Ruslan Ruslan; Muh.Ricky Arisandi M. Tahili; Dwi Juli Puspitasari; Indriani; Husain Sosidi; Prismawiryanti; Moh. Mirzan
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15966

Abstract

Oil palm midribs (Elaeis guenensis Jacq.) are one of the wastes from oil palm plantations. The high carbon element composition in the palm midribs has the potential to be used as charcoal or activated carbon. Activated carbon can reduce COD levels in tofu industrial wastewater. This study aims to determine the effect of activated carbon mass and contact time on decreasing COD levels in tofu industrial wastewater. Palm midrib charcoal was activated using HCl 1N with the independent variable of activated charcoal mass (1, 3, 5, 7, and 9 grams) and contact times (30, 60, 90, 120, and 150 minutes), while the dependent variable was the percentage decrease COD levels. Activated charcoal from the palm midribs was in accordance with SNI 06-3730-1995 concerning the Quality Standard of Activated Charcoal. The effect of the adsorbent mass showed that the mass increase in activated charcoal was directly proportional to the percentage decrease in COD levels in the tofu industrial wastewater, while the optimum contact time of activated charcoal was obtained at 60 minutes with a decrease in COD levels of 82.13%.
Aktivitas Antibakteri Ekstrak Kulit Batang Tumbuhan Johar (Senna siamea Lam) pada Berbagai Polaritas Pelarut : Antibacterial Activity of Johar (Senna siamea Lam) Stem Bark Extract on Various Solvent Polarities Djumidar; Abd. Rahman Razak; Ahmad Ridhay; Ni Ketut Sumarni; Syamsuddin; Jusman; Nurhaeni; Erwin Abdul Rahim
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 2 (2022): August Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i2.15970

Abstract

Johar plant is a type of plant from the Fabaceae family which is widely used in traditional medicine such as malaria, itching and diabetes medicine. This study aims to determine the antibacterial activity of Johar stem bark extract with different levels of solvent polarity on the growth of Staphylococcus aureus and Escherichia coli bacteria and to determine the active compound class by TLC-Bioautography. The extraction of active compounds used a multilevel maceration method starting with n-hexane (non polar), followed by ethyl acetate (semi-polar) and ethanol (polar) solvents. Antibacterial activity testing was carried out by diffusion well method with a concentration variant of 25% and 50%. The results showed that n-hexane, ethyl acetate, and ethanol extract had antibacterial activity against the two test bacteria. Ethyl acetate and ethanol extract from Johar stem bark at a concentration of 50% were classified as very strong antibacterials with inhibition zone diameters against S. aureus, which were 22.02±0.84 mm and 20.16±0.23 mm, respectively. The results of the TLC-Bioautography test showed that the three test extracts had strong antibacterial activity against S. aureus and E. coli. In the n-hexane extract with n-hexane: ethyl acetate (9:1) eluent using Lieberman-Burchard spray reagent, it was suspected that triterpenoid compounds were present. In ethyl acetate extract with n-hexane: ethyl acetate (6:4) eluent and ethanol extract with chloroform: methanol (8:2) eluent using FeCl3 1% spray reagent, it was suspected that the tannin compound was present in both extracts.
Sintesis dan Karakterisasi Fe₂TiO₅ dari Besi Oksida dan Titanium Dioksida dengan Metode Planetary Ball-Mill: Synthesis and Characterization of Fe₂TiO₅ from Iron Oxide and Titanium Dioxide Using the Planetary Ball-Mill Method Laode Kadir; M. H Azis; S. Musiam; V. A. Fabiani; Karnelasatri; D. Permana; T Azis; Syahrir
KOVALEN: Jurnal Riset Kimia Vol. 8 No. 3 (2022): December Edition
Publisher : Chemistry Department, Mathematics and Natural Science Faculty, Tadulako University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22487/kovalen.2022.v8.i3.15644

Abstract

The method of solid hydrogen storage through integration in metal hydride compounds is a new, promising method. This research has succeeded in synthesizing and characterizing the metal hydride alloy Fe-Ti system through a planetary ball-mill process. Based on the XRF analysis, it was found that the composition of Fe oxide content reached 56.22% while Ti oxide reached 43.78%. The FTIR study showed absorption at wavenumbers of 900 cm-1 and 500 cm-1. Both are typical absorptions for Ti-O and Fe-O groups, suggesting that the synthesized sample was successful. It can be seen from the XRD data that some of the diffractogram peaks of the resulting Fe-Ti compound match the peaks of the Fe2TiO5 and TiO2 compounds obtained from the Powder Diffraction File (PDF) database number 00-003-0374. After the refinement was performed, information was obtained that the synthesis of Fe-Ti alloy material using the planetary ball mill technique produced Fe2TiO5.

Page 24 of 33 | Total Record : 325

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