cover
Article Per Year (5 Year)
All
Home Page
OAI Link
Editorial Team
Contact
Reviewer
Google Scholar
Contact Name
Jaya Hardi
Contact Email
jr.hardi0803@gmail.com
Phone
+6281341314717
Journal Mail Official
kovalen.journal@gmail.com
Editorial Address
Program Studi Kimia Fakultas MIPA, Uniiversitas Tadulako Jl. Soekarno-Hatta Km. 9, Tondo Palu, 94117
Location
Kota palu,
Sulawesi tengah
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 11 Documents
 1   2 
Search results for , issue "Vol. 9 No. 3 (2023): December Edition" : 11 Documents clear
Validasi Metode Analisis Iodin Secara Spektrofotometri UV-Vis pada Dua Variasi Pelarut: Validation of The Method of Iodin Analysis by Uv-Vis Spectrofotometry with Two Variations of Solution Abdilah, Fauzi; Karina Aulia Rahmawati; Widya Tresna Dewi; Keryanti; Hulupi, Mentik
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16448

Abstract

In this study, the method of analysis of iodine by UV-Vis spectrophotometry was validated. Two other solvents, ethanol, and cyclohexane were used to validate this approach. The UV-Vis Spectrophotometer method's linearity, detection, and quantization limitations, precision, and accuracy were investigated as variables. The results of the linearity tests indicated that the method was proportionally verified because the r values for the two iodine solutions in ethanol and cyclohexane varied between 0.990 and 0.999, respectively. This suggests that the values were higher than 0.99. The LOD values for the ethanol solvent were 4.441 mg/kg and the LOQ was 14.802 mg/kg, whereas the cyclohexane solvent had an LOD value of 2.660 mg/kg and the LOQ was 8.866 mg/kg. According to the required precision acceptance, the %RSD value of 2%, precision values for both standard iodine solutions with two modifications of solvents demonstrated good results. Recovery percentages of ethanol solvents are 96% and cyclohexane solvents are 86%, respectively, according to accuracy measurements. The combined uncertainty value for this test is 0.109 for the ethanol solvent and 0.019 for the cyclohexane solvent, respectively. This research provides a comprehensive understanding of the validity of the iodine analysis method, establishing a robust foundation for the sustainability and reliability of using UV-Vis spectrophotometer in the analysis
Comparison of Total Flavonoid, Phenolic Levels, and Antioxidant Activity between Robusta and Arabica Coffee Ngibad, Khoirul; Yusmiati, Siti Nur Husnul; Merlina, Diana Mey; Rini, Yenny Puspa; Valenata, Valenata; Jannah, Elok Faiqotul
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16506

Abstract

Coffee contains a lot of phenolic compounds, especially chlorogenic acid, therefore many studies have examined the potential of coffee as an antioxidant. Antioxidants can inactivate oxidation reactions and prevent the formation of free radicals. This research aimed to determine the total phenolic and flavonoid content of the ethanol extract of robusta coffee (Coffea canephora) and the ethanol extract of arabica coffee (Coffea arabica), as well as determine the % inhibition value of Arabica coffee ethanol extract and Robusta coffee ethanol extract and their combination as antioxidants in vitro. Robusta and Arabica coffee powders were soaked in ethanol solvent, respectively, and the filtrate was concentrated using a rotary evaporator. The extract’s flavonoid and total phenolic content were measured by UV-Vis spectrophotometry. An antioxidant activity test was carried out using the DPPH method. The phenolic content of the ethanol extract of robusta coffee powder and the ethanol extract of arabica coffee powder were 7.98 and 9.16 mg QE/g, respectively. The total flavonoid content of the ethanol extract of robusta coffee powder and the ethanol extract of arabica coffee powder were 11.5 and 14.2 mg GAE/g, respectively. The highest % inhibition values of the ethanol extract of arabica coffee powder and the ethanol extract of robusta coffee and their combination as antioxidants in vitro were 71.1, 85.1, and 86.4%.
Pembuatan dan Karakterisasi Kertas Kemasan Berbasis Ampas Kunyit dan Jahe Merah dengan Variasi Konsentrasi Natrium Hidroksida: Preparation and Characterization of Packaging Paper Based on Turmeric and Red Ginger Pulp with Varying Concentrations of Sodium Hydroxide Jannah, Devia Fataya Miftahul; Febryanti, Chyntia Wahyuni; Alfiah, Diana; Huwaida, Melina Rahma; Marhani, Della Agustia; Riniati, Riniati
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16537

Abstract

The production of herbal beverages such as ginger, turmeric, and other spices generates waste that is commonly discarded. The cellulose content in red ginger is about 60-80%, and in turmeric, it is 50%. The high cellulose content makes red ginger and turmeric waste suitable for use as raw materials for paper production. The objective of this research is to determine the optimum conditions for making paper based on red ginger and turmeric waste. The pulp formation process was carried out using the Semi-Mechanical Method, which involves the addition of chemical solutions and grinding, on a mixture of turmeric and red ginger waste (60:40) with variations of NaOH concentration at 8%, 10%, and 13% (w/v). The papermaking process began with refining and drying the waste, cooking the pulp, adding water and kaolin filler, and then printing. Characterization included antibacterial testing, tensile strength, and grammage. Based on the pulp characterization results at the optimum NaOH concentration of 8%, the moisture content was 8.89%, cellulose content was 49.28%, and lignin content was 9.28%. These parameters comply with the national standard (SNI) for packaging paper. The paper characterization results showed a tensile index of 2.12 Nm/gram, an antibacterial inhibition zone of 5 mm, and a grammage of 13 g/m2. This research indicates that the NaOH concentration influences the moisture, cellulose, and lignin content. Furthermore, based on the characterization results, paper made from turmeric and ginger waste has the potential to be used as antimicrobial packaging paper.
Karakterisasi Pelet Pupuk Organik Berbahan Eco Enzyme: Characterization Of Organic Fertilizer Pellets Eco enzyme Winaningsih, Ima; Suramta, Suramta; Mala, Yanti
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16541

Abstract

Eco enzyme has nutrients for liquid organic fertilizer. However, the eco enzyme's N, P, K elements are still below the quality standard. Liquid organic fertilizer is disadvantaged in handling, packaging, use, and transportation compared to pellet form. Nutrient levels can be increased through fish bones and rice bran addition. This research aims to determine the characteristics of the best pellets based on Ministry of Agriculture quality standards No. 261/2019, such as length, diameter, density, water content and N, P, K levels. The eco enzyme, water, fish bones, and rice bran’s formula were: C1 (1: 0: 1: 1), C2 ( ¾: ¼: 1: 1 ), and C3 ( ½: ½: 1: 1). Pellets were made by mixing the ingredients with 5% tapioca solution. The tools used to measure pellet length, diameter, and pH were caliper and pH meter. The water content using the gravimetric method. The N, P, and K levels were tested at BALISTA Lembang, Bandung. All formulations’ pellet length and diameter averaged ±12 mm and 4 mm. Water content of C1, C2, and C3 pellets were 8.63%, 8.97%, and 9.18%, respectively. pH of C1, C2, and C3 pellets were 5.7, 5.8, and 5.9, respectively. Particle density for C1, C2, and C3 were 1.37 g/cm3, 1.44 g/cm3, and 1.46 g/cm3, respectively, while the bulk densities were 0.58 g/cm3, 0.63 g/cm3, and 0.64 g/cm3, respectively. The N, P, K levels in C1, C2, and C3 were 5.2%, 4.79% and 4.3%, respectively. C3 is the best formulation. All pellets meet quality standards.
Studi Awal Sintesis ZnO/SiO2 dengan Silika dari Limbah Padat Geothermal dan Uji Performansinya dalam Penghilangan Metilen Biru : Preliminary Study of ZnO/SiO2 Synthesis with Silica from Geothermal Solid Waste and Its Performance Test in Methylene Blue Removal Paramitha, Tifa; Joko Suryadi; Rahma Ardelia Raissa; Teguh Aditya Nugraha; Nirmala Utami
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16557

Abstract

Industrial development impacts environmental problems, such as the emergence of wastewater containing methylene blue. In this research, SiO2 was composited with ZnO to remove methylene blue. The steps of this study include SiO2 extraction from geothermal solid waste, ZnO/SiO2 synthesis, and methylene blue removal test. The process of extracting SiO2 from geothermal solid waste used the sol-gel method. The FTIR analysis showed that SiO2 contains siloxane group (Si-OH) and silanol group (Si-O-Si). ZnO/SiO2 synthesis was done by making SiO2 suspension and continued with adding the addition of several Zn(NO3)2.6H2O. The FTIR analysis of ZnO/SiO2 showed no absorption at the wavenumber 960 cm-1 and there is a shoulder around the number 950 cm-1 which indicates the vibration of Si-O-Zn. Meanwhile, methylene blue removal tests were carried out on artificial wastewater. Based on the research results, the highest percent removal (99%) was obtained under operating conditions, including a dose of 500 mg/L, pH 10, and contact time of 30 minutes. Based on box-benkhen analysis, it is known that dose and pH singularly affect the percent removal, while contact time does not affect the percent removal. The optimization results obtained optimum conditions for methylene blue removal at a dose of 581.952 mg/L, pH of 10, and contact time of 30 minutes. Percent removal in conditions without irradiation and with irradiation of UV light were 98.758% and 99.178%. It shows that the adsorption process is the main process in removing methylene blue, while the photocatalytic process has little effect because it is possible that only a small amount of ZnO can attach to the surface of SiO2.
The Effect of Solvent-to-Coffee Ratio on Caffeine Content in Ethyl Acetate Extracts of Arabica Gayo Coffee Beans Soeswanto, Bambang; Sihombing, Rony Pasonang; Suryadi, Joko; Hariyadi, Tri; Paramitha, Tifa; Yusuf, Yusmardhany; -, Alfiana Adhitasari
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16573

Abstract

This paper studies the optimal ratio that gives the highest caffeine amount and improves the efficiency and quality of extraction from Arabica Gayo coffee beans. No previous studies have explored the best ratio of Gayo Arabica coffee beans to ethyl acetate solvent for extracting caffeine. The paper explains the method used, which has four main steps: preparing materials, extracting and measuring caffeine, and analyzing the results. The paper presents the experimental findings and discusses how different ratios affect caffeine content in Arabica Gayo coffee beans. It uses statistics to show significant differences between the ratios and compares them using Tukey tests. The paper concludes that the best solvent-to-coffee ratio for maximizing caffeine in ethyl acetate extracts is 1:5, resulting in a concentration of 1411.1 ppm. This ratio gives the best balance between caffeine yield and solvent usage.
Penurunan Logam Fe dan Co Pada Kerang Hijau (Perna viridis) dengan Metode Perendaman Larutan Belimbing Wuluh: Reduction Fe and Co Metals in Green Mussels (Perna viridis) by Soaking in Starfruit Solution Widiyanto, Holisha; Asad, Hafidz Al; Sriwijayanti; Susvira, Dian; Situmeang, Boima
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16586

Abstract

Green mussels with the Latin name Perna viridis are an animal that lives in the ocean and is a type of shellfish that is widely consumed by the public. Along with time, the emergence of factories that can pollute the oceans can cause contamination of marine life in it, one of the pollutants is the heavy metals of Fe and Co. The accumulation of heavy metals Fe and Co in green mussels can be toxic to people who consume them. This study aims to determine the concentration of heavy metals Fe and Co in green mussels before and after immersion in starfruit solution. Tests for immersion of the starfruit solution were carried out at 15, 30, and 45 minutes, then the destruction results were analyzed using inductively coupled plasma (ICP) with the calibration curve method. The Fe content in the green mussel sample before treatment was 2.946 mg/kg and the Co content in the green mussel sample before treatment was 2.6081 mg/kg. After soaking in starfruit solution for 15, 30, and 45 minutes, the Fe metal was 1.572 mg/kg, 1.275 mg/kg, and 1.035 mg/kg and the Co metal was 1.572 mg/kg, 1.275 mg/kg, and 0.683mg/kg. Research of immersing starfruit solution with soaking for 15, 30, and 45 minutes is effective in reducing levels of heavy metals Fe and Co in green mussels. The highest reduction was observed during a 45-minute immersion, with a decrease of 64.87% for Fe and 73.81% for Co, respectively.
Ekstraksi Komponen Lipid dari Mikroalga Nannochloropsis oculata dan Nitzschia sp. dengan Metode Sokletasi dan Bligh Dyer: Extraction of Lipid Components from Nannochloropsis oculata and Nitzschia sp. Microalgae with Soxhletation and Bligh Dyer Methods Stepanus, Jamius Bin
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16596

Abstract

Dependence on fossil energy sources as non-renewable energy will trigger the threat of an energy crisis in Indonesia in the future. The solution to this issue is through the development of renewable energy and one of them is through the exploration and utilization of biomass such as microalgae. Microalgae have a high lipid content (4-77%) and have potential as raw materials for producing biofuel (biodiesel, bioethanol, and biogas). Lipids can be converted into biodiesel through acid or base-catalyzed esterification and transesterification reactions. The aim of this research was to determine the percentage of lipid components, namely free fatty acids (FFA), monoglycerides (MAG), diglycerides (DAG), and triglycerides (TAG) from microalgae extracts of Nannochloropsis oculata and Nitzschia sp. using Soxhletation and Bligh Dyer extraction methods. This research also aims to determine the comparison of lipid yields from the two extraction methods. Lipid yield percentage was determined through gas chromatography analysis. The research results showed that the percentages of FFA, MAG, DAG, and TAG for N. oculata ranged from 3.34 - 33.79% (soxhletation) and 0 - 17.54% (bligh dyer). Meanwhile, for Nitzschia sp., the percentage ranged from 7.16 - 26.28% (soxhletation) and 0.45 - 13.73% (bligh dyer). Lipid yield for N. oculata was 1.81% (soxhletation) and 2.21% (bligh dyer), while for Nitzschia sp., 0.96% (soxhletation) and 2.10% (bligh dyer). Based on the results of both extraction methods, it was found that the total lipid percentage of the microalgae N. oculata was higher than Nitzschia sp.
Total Metabolit Sekunder dan Uji Aktivitas Antioksidan Daun Juwet (Syzygium cumini L.) dengan Spektrofotometer Uv-Vis: Total Secondary Metabolites and Test of Antioxidant Activity of Juwet Leaves (Syzygium cumini L.) with Uv-Vis Spectrophotometer Tien, Tien Wahyu Handayani; Rasmiyanti, Ni Kadek Evy; Tandi, Joni; Magfirah
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16672

Abstract

The aim of this research is to determine the total amount of secondary metabolites (alkaloids, flavonoids, saponins and tannins) contained in the ethanol juice of juwet leaves (Syzygium cumini L.) using the UV-Vis spectrophotometry method and to determine the antioxidant activity of the ethanol juice of juwet leaves based on IC50 value. Determination of total levels of secondary metabolites using UV-Vis spectrophotometry and antioxidant testing using the DPPH method. The results of qualitative analysis of the ethanol juice of juwet leaves contained secondary metabolite compounds, namely flavonoids, saponins, tannins and alkaloids. The average value obtained for the level of total secondary metabolites for flavonoid compounds was 0.417% w/w., saponins 0.766 w/w., tannins 0.282 w/w and alkaloids 0.384% w/w. The results of testing the antioxidant activity of juwet leaf ethanol extract and quercetin as a comparison had antioxidant activity, the average IC50 results were 14.289 ± 0.255 ppm and 102.45 ppm, therefore they were classified as moderate antioxidants.
Determination of Boron Concentration at Sausage Samples with Distillation of Ester Borane Method using Fluorescence Spectrophotometry Lailatusholihah, Isna; Aisyiah Restutiningsih Putri Utami; Micha Mahardika
KOVALEN: Jurnal Riset Kimia Vol. 9 No. 3 (2023): 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.2023.v9.i3.16673

Abstract

The study of borax contamination in food samples was successfully analyzed. This study used sausage samples using the Fluorescence Spectrophotometry method. Sausage samples were from Daerah Istimewa Yogyakarta (DIY). This study used 4 sausage samples. The samples were given labels A, B, C, and D. The steps of the research were optimation of distillation time, optimation of catalyst, optimation of solvent, and then followed by analyzing the borax concentration on sausage samples. Based on this study, the optimum distillation time was 24 hours. On the other hand, the best catalysts and solvents were sulphuric acid and ethanol. The A and B samples contained borax contamination and the concentration was under 5 ppm. The C and D samples contained borax contamination and the concentration was above 5 ppm. The conclusions were that A and B samples were not given borax addition and C and D samples were given borax addition.

Page 1 of 2 | Total Record : 11

 1   2 

Filter by Year

2023 2023


Reset
Filter By Issues
All Issue Vol. 11 No. 1 (2025): August Edition Vol. 10 No. 3 (2024): December Edition Vol. 10 No. 2 (2024): August Edition Vol. 10 No. 1 (2024): April Edition Vol. 9 No. 3 (2023): December Edition Vol. 9 No. 2 (2023): August Edition Vol. 9 No. 1 (2023): April Edition Vol. 8 No. 3 (2022): December Edition Vol. 8 No. 2 (2022): August Edition Vol. 8 No. 1 (2022): April Edition Vol. 7 No. 3 (2021): Edisi Desember Vol. 7 No. 2 (2021): Edisi Agustus Vol. 7 No. 1 (2021): Edisi April Vol. 6 No. 3 (2020): Edisi Desember Vol. 6 No. 2 (2020): Edisi Agustus Vol. 6 No. 1 (2020): Edisi April Vol. 5 No. 3 (2019): Edisi Desember Vol. 5 No. 2 (2019): Edisi Agustus Vol. 5 No. 1 (2019): Edisi April Vol. 4 No. 3 (2018): Edisi Desember Vol. 4 No. 2 (2018): Edisi Agustus Vol. 4 No. 1 (2018): Edisi April Vol. 3 No. 3 (2017): Edisi Desember Vol. 3 No. 2 (2017): Edisi Agustus Vol. 3 No. 1 (2017): Edisi April Vol. 2 No. 3 (2016) Vol. 2 No. 2 (2016) Vol. 2 No. 1 (2016) Vol. 1 No. 1 (2015) More Issue