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Jaya Hardi
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Program Studi Kimia Fakultas MIPA, Uniiversitas Tadulako Jl. Soekarno-Hatta Km. 9, Tondo Palu, 94117
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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 14 Documents
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Search results for , issue "Vol. 8 No. 3 (2022): December Edition" : 14 Documents clear
Adsorpsi Ion Pb(II) Menggunakan Silika Berbasis Pasir Alam Takari-NTT : Ion Pb(II) Adsorption Using Silica from Natural Sand of Takari-NTT Johnson N. Naat
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.i3.16143

Abstract

This article reported the adsorption of Pb(II) ions using silica extracted from the natural sand of Takari, Timor island, Nusa Tenggara Timur province. The silica was extracted using hydrothermal and coprecipitation methods. The extracted silica was then used for Pb(II) adsorption under several optimization conditions: pH, contact time, concentration, kinetic model, and adsorption isotherm. The determination of Pb(II) concentration used dithizone reagent, forming complexes, and then measured using Uv-Vis. The pH, contact time, and optimum concentration results were 7, 60 minutes, and 80 mg/L, respectively, with an adsorption capacity (qe) of 0.679 mg/g, 0.745 mg/g, and 18.096 mg/g. The kinetic model followed a pseudo-order-2 with R2 = 0.93, and the adsorption isotherm of Pb(II) metal ions followed the Temkin isotherm model. The results showed that the silica extracted from the natural sand of Takari of Timor island-Nusa Tenggara Timur could adsorb Pb(II) metal ions
Efektivitas Fotodegradasi Lignin dari Limbah Ampas Sagu (Metroxylon sagu Rottb.) Menggunakan Katalis TiO₂: The Effectiveness of the Photodegradation of Lignin from Sago (Metroxylon sagu Rottb.) Waste Using TiO₂ Catalyst Muh. Natsir; Aden Mula Pratiwi; Thamrin Azis; Nohong; Imran; Wa Ode Harlis; Alimin; La Ode Kadidae; Ruslan; C Bijang; La Ode Abd Kadir; Laily Nurliana
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.i3.16149

Abstract

Lignin degradation from sago (Metroxylon sagu Rottb.) waste has been carried out using a TiO2 catalyst. This research aims to determine the effectiveness of lignin degradation from sago waste using a TiO2 catalyst. Lignin from sago pulp was isolated using 10% NaOH and characterized using Fourier Transform Infra Red (FTIR) spectroscopy. The results of the characterization using FTIR show that the absorption at wave number 2937.59 cm-1 is the -C-H stretching vibration of the alkane functional groups, the absorption at wave number 2360.87 cm-1 is the vibration of the C≡C triple bond, the wave numbers 1795.73 cm-1 and 1637.56 cm-1 are associated with the stretching of the carbonyl group. The absorption at wave number 1427.32 cm-1 is a C-H vibration connected to an unsaturated bond in an aromatic ring. Absorptions at wave number 1105.21 cm-1, 1128.36 cm-1, 1153.43 cm-1 were the stretching vibration of -C-H on the guaiasil ring, and the absorption at wave number 1022.27 cm-1 was the stretching vibration of C-O-C ether. From this spectrum, it can be seen that lignin is not completely pure because it is probably still mixed with cellulose. The results of the effectiveness test of lignin degradation using a TiO2 catalyst with the help of UV light were able to degrade the lignin isolated by 31.43%, for 3 hours at a lignin concentration of 40 ppm.
Ekstraksi Teh Hijau dan Aplikasinya sebagai Pengendali Korosi Pada Pompa di Lingkungan Garam NaCl 3,56%: Green Tea Extraction and Its Application as Corrosion Controller in 3.56% NaCl Retno Indarti
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.i3.16160

Abstract

Green tea leaves contain antioxidant compounds that can be used as organic inhibitors in a corrosion process. Tea leaves were extracted by maceration method using 70% ethanol solution with a solid:solvent ratio of 1:8 (w/v) for 1 x 24 hours in an atmospheric room. The extract was then concentrated with a rotary evaporator and separated with solvent under vacuum conditions at 852 mbar, temperature of 70oC and rotation of 80 rpm. The results of the qualitative test of extra tea leaves using 10% NaOH and 1% FeCl3 changed the color to brownish orange and blue-black. This indicates the content of flavonoids and tannins. Green tea leaf extract is also applied to control the corrosion rate of brass metal. Variations in the concentration of tea leaves were 200, 400, 600 ppm in 3.56% NaCl solution. The pump circulation is carried out for 40 hours, the weight loss method is carried out every 8 hours. The average corrosion rate without inhibitor is 3.95 mmpy, the corrosion rate with 200 ppm inhibitor is 1.24 mmpy, the corrosion rate with 400 ppm inhibitor is 0.46 mmpy, the corrosion rate with 600 ppm inhibitor is 0.23 mmpy. A significant decrease in the corrosion rate occurred at a concentration of 600 ppm with an efficiency of 92.32%.
Evaluasi Kadar Senyawa Fenolat, Flavonoid Total, serta Aktivitas Antioksidan Secara in vitro dalam Ekstrak Metanol Bawang Dayak (Eleutherine palmifolia (L.) Merr : Evaluation of Phenolic Compounds, Total Flavonoid Content and in vitro Antioxidant Activity of Methanol Extract of Dayak Onion Bulbs (Eleutherine palmifolia (L.) Merr Farida Laila; Ika Resmeliana; Wina Yulianti; Atep Dian Supardan
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.i3.16175

Abstract

Dayak onion bulbs are a plant originating from Kalimantan which has been used for generations to treat various diseases. This plant is quite easy to grow and develop in many places in Indonesia. The aims of the present study were to evaluate the antioxidant potential of the methanol extract of Dayak onion bulbs based on the total of the phenolic and flavonoids contents and also the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging ability, ferric reducing power and total antioxidant capacity. The results showed the total phenolic and flavonoid methanol extract of Dayak onion bulbs were 14.49 ± 1.42 mg GAE/g dry weight and 5.41 ± 1.01 mg QE/g dry weight, respectively. Antioxidant activity as measured by the DPPH, total antioxidant capacity, and ferric reduction assay with IC50 values of 16.95 ± 1.58 μg/mL, 24.22 ± 2.51 µg/mL, and 85.40 ± 16.88 µg/mL, respectively. These results suggest that the methanol extract of Dayak onion bulbs has potential bioactive compounds with good antioxidant activity and can be developed as an effective and safe source of natural compounds for functional food or herbal medicine.

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