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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 5 Documents
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Search results for , issue "Vol. 11 No. 1 (2025): August Edition" : 5 Documents clear
Engineering and Application of Fe-TiO2/MOR Zeolite Photocatalysts for the Photodegradation of Methylene Blue Dye Waste Sholikah, Liqanatul Putri; Sumari, Sumari; Permatasari, Suryani Indah
KOVALEN: Jurnal Riset Kimia Vol. 11 No. 1 (2025): 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.2025.v11.i1.17427

Abstract

The use of dyes such as methylene blue is widespread. However, if methylene blue is discharged without prior treatment, it can lead to pollution problems. In this study, the engineering of zeolites and the degradation mechanism of methylene blue using Fe-TiO2/MOR zeolite as a photocatalyst were investigated. XRD characterization results revealed that Fe-TiO2/MOR zeolite has a crystalline phase. Based on XRF characterization, the percentage of Fe and Ti significantly increased, indicating the successful immobilization of TiO2 and doping of Fe3+ into the zeolite structure to form a composite. The morphological analysis of the Fe-TiO2/MOR zeolite composite showed a rough surface, which could affect its surface area. The Fe-TiO2/MOR zeolite photocatalyst has a band gap of 3.08 eV, allowing it to absorb visible light more efficiently. The study on the application of methylene blue photodegradation using Fe-TiO2/MOR zeolite as a photocatalyst demonstrated higher degradation efficiency compared to using inactivated, non-immobilized, and undoped mordenite zeolite. With an optimal mass of 0.03 grams, a contact time of 90 minutes, and a pH of 10, the percentage of degraded methylene blue reached 98.91%. The Fe-TiO2/MOR zeolite composite has the potential to be used as a photocatalyst in methylene blue photodegradation reactions.
Speciation and Bioavailability of Heavy Metals Pb and Cd in Palu Bay Sediments after the Earthquake and Tsunami Sosidi, Husain; Khairuddin; Ruslan; Abustiana, Rahma Lolita; Ramli, Aksar; Rahim, Erwin Abdul
KOVALEN: Jurnal Riset Kimia Vol. 11 No. 1 (2025): 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.2025.v11.i1.17671

Abstract

Major disturbances to seafloor morphology and input of terrestrial material due to the earthquake- tsunami in Palu City in 2018 have the potential to alter the chemical form (speciation), bioavailability, and flux of lead (Pb) and cadmium (Cd) in Palu Bay sediments. This study was conducted to analyze the speciation of Cd2+ ions and Pb2+ ions and determine the concentration of elusion ions using Diffusive Gradient in Thin Film (DGT). In this study, two methods were carried out, namely the fractionation method and the DGT method. The results showed that the analysis of ion speciation at 3 locations using the fractionation method obtained the highest concentration of Cd2+ ions of 1.4492 mg/L at location 1 and the highest concentration of Pb2+ ions of 0.0200 mg/L at location 3. The results of ion analysis at 3 locations using the DGT method obtained the highest elution yield concentration of Cd2+ ions of 0.0225 mg/L at location 1 and the highest elution yield concentration of Pb2+ ions of 0.0155 mg/L at location 3. This study shows that the presence of heavy metals Pb and Cd in Palu Bay sediments after the earthquake-tsunami is still detected with varying concentrations between locations. The fractionation method is able to describe the distribution of metal speciation in sediments, while the DGT method provides information on labile fractions that are more relevant to bioavailability. The combination of these two methods is important for understanding the potential risk of heavy metals to Palu Bay aquatic ecosystems and can be used as a basis for post-disaster environmental monitoring and management efforts.
Purification of Crude Glycerol Using Regenerated Spent Bleaching Earth as Palm Oil Refinery Process Wahyuni, Sry; Rizka Fadhillah, Dinda
KOVALEN: Jurnal Riset Kimia Vol. 11 No. 1 (2025): 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.2025.v11.i1.17785

Abstract

Spent Bleaching Earth (SBE) is a type of solid waste generated during the palm oil refining process. Several studies have investigated the potential reuse of SBE as a valuable material, particularly as an adsorbent in glycerol purification. Crude glycerol, a by-product of biodiesel and oleochemical production from palm oil, is typically of low quality and contains numerous impurities, including free fatty acids (FFA) and pigmented compounds such as beta carotene and chlorophyll. In this study, SBE was regenerated using various solvents and subsequently calcined at 500 oC for 2 hours. Its surface was further modified with cetyltrimethylammonium bromide (CTAB) to enhance its adsorption capacity. The results showed that SBE regenerated with n-hexane and subjected to calcination exhibited the highest removal efficiency for beta carotene and chlorophyll. Further analysis of the physical and chemical properties of crude glycerol purified using uncalcined, calcined, and CTAB-modified SBE demonstrated that the modified SBE delivered the best adsorbent performance. The purified glycerol using modified SBE had the following characteristics: Moisture content (10.3%), Density (1.25 g/cm3), Free fatty acid (FFA) content (1.2%), Salt content (4.6%), beta-carotene content (0.843 ppm), Chlorophyll content (0.11 ppm) and pH approximately 6.
Comparative Estimation of Some Contaminates in Products of Drinking Water Companies and Government Stations in the City of Mosul Maseer Nejres, Aws
KOVALEN: Jurnal Riset Kimia Vol. 11 No. 1 (2025): 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.2025.v11.i1.17787

Abstract

Recently, the concentrations of heavy metals have increased in water sources, soil and air, and their symptoms have clearly appeared on living organisms and the serious effects they leave on humans, animals and even plants. has become necessary to periodically monitor these metals, including nickel (Ni), cadmium (Cd), lead (Pb)and cobalt (Co). However, the problem does not stop with heavy metals, as there are other parameters that are closely related in one way or another, such as hardness, pH, Total dissolved solids (TDS) and even conductivity (EC), All of these are present in the water under study, in addition to the Microbiological Assessment test to search for pathogens. The environment of Mosul city was chosen as a source for collecting samples from three categories: local water projects, reverse osmosis water sales systems, in addition to companies accredited for sterilizing, bottling and marketing water. These Metals and parameters were studied using an atomic absorption device, and the results were within the limits established in the regulations of international organizations and bodies.
Evaluation of Antioxidant Activity of Branch Extract from Pouteria campechiana (Sawo Walanda) Batari, Nirmala Puteri; Setyo Purnomo, Adi; Seviani, Winda
KOVALEN: Jurnal Riset Kimia Vol. 11 No. 1 (2025): 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.2025.v11.i1.17792

Abstract

The objective of this research was to assess the antioxidant activity of branch extract (Pouteria campechiana) through analysis of bioactive compound content and antioxidant activity. The sample was extracted through maceration, utilizing methanol as the solvent which produced a yield of 6.03 %. The quantity of phenolic constituents in the extract was determined using the Folin-Ciocalteu method, with gallic acid as the standard, yielding a result of 195.22 mg GAE/g extract. The quantity of flavonoid constituents was determined using gallic acid as a standard resulting in a value of 830.5 mg QE/g extract. Antioxidant activity was tested using two methods, namely DPPH and ABTS. The results of the DPPH test showed an inhibition percentage of 91% with an IC50 value of 3,322 ppm, while the ABTS test showed an inhibition of 99% with an IC50 of 2,206 ppm at a concentration of 10,000 ppm. Based on these results, the Pouteria campechiana branch extract has very weak antioxidant activity, suggests a limited potential as natural bioactive compound source.

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