Jurnal Pendidikan Kimia
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Optimization of Nitration of 3-Hydroxypyrazine-2-Carboxamide to 3-Hydroxy-6-Nitropyrazine-2-Carboxamide
Get PDFThis study focuses on optimizing the synthesis of 3-hydroxy-6-nitropyrazine-2-carboxamide, a critical intermediate in producing various pyrazine-based pharmaceuticals. The compound is synthesized through the nitration of 3-hydroxypyrazine-2-carboxamide, employing sulfuric acid (H2SO4) and potassium nitrate (KNO3) as reagents. The research aimed to refine the synthesis process to enhance yield purity for pharmaceutical applications. The optimization entailed adjusting the reagents' composition and solvents, specifically the ratio of substrate to KNO3, the volume of H2SO4 used per gram of substrate, and the temperatures for both the reaction and product precipitation. Optimal results were observed at a substrate-to-KNO3 ratio of 1:2, with 12 mL of H2SO4 per gram of substrate. The reaction temperature was set at 50°, and precipitation occurred effectively at 0°C. This optimized method significantly improved the yield and purity of the compound. The process demonstrated excellent repeatability, with yields ranging from 77% to 80%, a considerable increase from the 48% yield reported in previous studies. The molecular structure of the synthesized compound was confirmed through comprehensive spectroscopic analyses, including 1H NMR, 13C NMR, and High-Resolution Electrospray Ionization Time-of-Flight Mass Spectrometry (HRESI-TOF-MS). This research represents a significant advancement in synthesizing 3-hydroxy-6-nitropyrazine-2-carboxamide, offering a more efficient and reliable method for producing this key pharmaceutical intermediate. The improved synthesis process ensures higher yields and maintains the purity required for pharmaceutical applications, thereby contributing to the efficient development of pyrazine-based drug compounds
Ability Test of C-4-Methoxyphenyl-Calix[4]resorcinarene as An Inhibitor of Calcium Carbonate (CaCO3) Crust Growth at Various Concentration
Get PDFThe primary objective of this study was to evaluate the capacity of C-4-methoxyphenyl-calix[4]resorcinarene in impeding the development of CaCO3 crust at varying concentrations of the inhibitor and different durations of contact. The research employed a seeded experimental approach using a 0.1 M CaCO3 growth solution maintained at 80 °C. The concentrations of C-4-methoxyphenyl-calix[4]resorcinarene introduced into the CaCO3 growth solution were 0, 5, 10, 20, and 40 ppm. The experimental procedure commenced with preparing crystal seeds, which is pivotal for gauging crystal growth rates. Results obtained from crystal weighing and morphological analysis through Scanning Electron Microscopy (SEM) indicated that C-4-methoxyphenyl-calix[4]resorcinarene effectively impeded the pace of CaCO3 scaling. The inhibitory efficacy of C-4-methoxyphenyl-calix[4]resorcinarene as a CaCO3 scaling inhibitor was contingent on well-regulated temperature during the heating phase. The inhibition effectiveness was positively correlated with the inhibitor's concentration; higher concentrations yielded superior suppression of CaCO3 scaling. Optimal scale reduction was observed at an inhibitor concentration of 10 ppm during a 20-minute contact period. These findings underscore the promising potential of C-4-methoxyphenyl-calix[4]resorcinarene as a viable inhibitor for mitigating scaling growth rates in various industrial fluid systems and related contexts
Analysis Thin Film Polymer Composite of Polymethyl Metacrylate-Reactive Mesogen Diacrylate and its Conductivity Properties
Get PDFThis study aimed to investigate the impact of temperature during the UV curing process on the formation of a thin film polymer composite composed of polymethyl methacrylate-reactive mesogen diacrylate. The thin film polymer composite was successfully synthesized using the UV curing method, and the reactive mesogen diacrylate employed in this study was RM 82. Methyl methacrylate and RM 82 were polymerized through UV curing with photopolymerization additions using Benzoyl Peroxide as the initiator. The photopolymerization process was performed at various temperatures of 125℃, 150℃, and 200℃ for 5 minutes. The thin film photopolymerized at 125℃ and 150℃ exhibited greater transparency than the thin film photopolymerized at 200℃. The FTIR results indicated the breakdown of the vinyl group and the triple bond. The FTIR spectrum displayed successful polymerization, with peak wave numbers of 1147 cm-1 and 1221 cm-1 for PMMA in the presence of C-O-C in the ester and a peak at 1465 cm-1. The SEM results demonstrated that the thin film photopolymerized at 200℃ had become distorted. The XRD results revealed that the thin films of all variations were semi-crystalline. Meanwhile, the conductivity test revealed that the thin film photopolymerized at 125℃ had a conductivity value of 2.095 x 10-12 S, while the photopolymerized thin film at 150℃ had a conductivity of 2.14 x 10-12 S. Hence, the addition of reactive mesogen RM82 by 50% may increase the conductivity value of the thin film, making it a potential material for applications as a thin film polymer composite of PMMA-RM 82
The Impact of Online Learning in Chemistry on Student Interest, Motivation and Learning Outcomes
Get PDFUnstable network connections, including chemistry learning, often hamper the implementation of online learning during a pandemic. The study aims to investigate the effects of online learning on chemistry students' interest, motivation, learning outcomes, and the challenges faced during the implementation. The method used is a quantitative method with descriptive research. Using the proportional stratified random technique, this study determined 72 high school students (33 boys and 39 girls). In online learning, data is collected using student and teacher response questionnaires. In addition, student reactions to teacher efforts in online learning. Then, interviews with teachers and students were conducted. Questionnaires and interview guidelines were used as research instruments. Data analysis techniques were used to determine respondents' level of achievement using the percentage formula (TCR). The study's findings revealed that the average response value for learning interest was 76%, motivation was 79%, and learning outcomes were 75%. Students achieve a minimum completeness criterion score of 81% for eleventh-grade students in the science program and 89% based on the results of the chemistry test scores in online learning. The study concludes that while online learning positively impacts students' interest, motivation, and learning outcomes, there are significant barriers identified by respondents, such as a less stable internet network, for further research is expected to be able to update the data taken by researchers
A Bibliometric Analysis of Publications on Systems Thinking in Chemistry Education using Vosviewer,
Get PDFThis study utilizes a bibliometric approach along with computational mapping analysis. This study employs a bibliometric approach, complemented by computational mapping using VOSviewer, to explore systems thinking research in chemistry education. The primary goal is to identify key research themes and trends in this field. The initial step involved searching for articles with keywords like "systems thinking" and "chemistry education" using the Publish or Perish software and Google Scholar database. This yielded 922 articles, which were carefully selected based on specific criteria. The comprehensive analysis included co-authorship, co-citation, co-occurrence, cluster, and content analysis using VOSviewer. The quantitative analysis highlights the significance of publications related to systems thinking in chemistry education and broader educational contexts. Over the past decade, prominent themes emerged, including sustainability education, design thinking, outcomes assessment, critical systems, climate change, and more. Qualitative insights further emphasize the relevance of understanding systems thinking in chemistry education, influencing pedagogical approaches and research initiatives. This research aims to provide valuable insights for researchers, educators, and practitioners in the chemistry education field. This study offers a roadmap for future developments by delineating prevalent themes and trends. Understanding the challenges and opportunities in systems thinking research within chemistry education can contribute to enhancing teaching methods and shaping research agendas. This analysis provides a comprehensive overview of the evolving landscape of systems thinking in chemistry educatio
pH-Sensitive Strips Based on Cellulose and Anthocyanins from Dried Java Plum Fruits (Syzygium cumini)
Get PDFThis study aimed to develop pH-sensitive strips made of cellulose incorporated with anthocyanins extracted from dried Java plum fruits (Syzygium cumini) which potentially can be used to monitor food freshness. The spoilage of animal protein typically produces total volatile basic nitrogen (TVB-N), which can be easily detected using pH-sensitive indicators. pH-sensitive indicators can be developed by combining biopolymers and anthocyanins. Biopolymers were cellulose from Whatman filter paper. While anthocyanins in this study were extracted from dried Java plum fruits (Syzygium cumini) with acidified water (0.01% v/v HCl) followed by SPE. Anthocyanins were incorporated into Whatman filter paper and dried at 70 °C for 10 min. Cellulose incorporated with anthocyanins was analysed using FT-IR and tested for pH 7-10. LC-MS spectra showed cyanidin-3-O-glucoside (m/z 449.3), delphinidin-3-O-glucoside (m/z 465.3), and petunidin-3-O-glucoside (m/z 479.3). These anthocyanins were the products of the deglycosylation of anthocyanin diglycosides. The deglycosylation of anthocyanins takes place through two different routes in either hemiketal or quinonoid forms. Those proposed two pathways are through protonation on an oxygen atom connecting an aglycone and a sugar moiety or through protonation on an oxygen atom within a sugar ring moiety. UV-Vis studies showed the colour profiles of anthocyanins in buffer solutions pH 1-12. The λvis-max of flavylium at pH < 3 ranged from 515-524 nm. At pH 4 to 6, colourless hemiketal was observed. The λvis-max of the quinonoid base was 575 nm at pH 7 and 590-599 nm for quinonoid anion at pH > 8. In alkaline pH, chalcone was observed
Anti-Dandruff Shampoo Formulation from Rambutan Leaf Extract (Nephelium lappaceum L.) as Antifungal Malassezia furfur
Get PDFA shampoo is a product that is used to maintain hair. The most common hair problem is dandruff. A microorganism that causes dandruff is Malassezia furfur. Malassezia furfur is the causative microorganism that infects the skin and scalp into dandruff. This fungus can grow quickly if the head has excess oil glands. Rambutan leaf extract contains secondary metabolites that can inhibit fungal growth. Alkaloids can inhibit the growth of fungi because fungi can grow well at a pH of 3,8 – 5,6. Flavonoids and tannins can cause damage to cell membrane proteins, causing changes in membrane permeability and fungal cell membrane lysis. Saponins can break down fungal cells. A shampoo formulation from Rambutan leaf extract sets it apart from other anti-dandruff shampoos because its herbal composition is safe and increases bioavailability benefits. The method used is laboratory experimental. This research procedure is making rambutan leaf extract using a rotary evaporator, making shampoo by compounding the formulation components, growing test mushrooms on PDA media, making test mushroom suspensions, and conducting the research and data collection. The result showed that shampoo from rambutan leaf extract has an inhibition zone diameter of 0.3 cm to 0.6 cm had a moderate growth inhibition response. The results of the antifungal activity test showed that the rambutan leaf extract shampoo concentration of 10%, 15% and 30% can inhibit the growth of fungi with the best inhibitory concentration at 30% in a strong category
Biosynthesis of Methyl Esters from Used Cooking Oil (UCO) using Lipase Enzyme from Aspergillus oryzae on Moldy Copra
Get PDFThe successful production of methyl esters from used cooking oil (UCO) using lipase enzymes from Aspergillus oryzae on moldy copra has been achieved. This method offers an eco-friendly substitute for crude palm oil (CPO) in generating methyl esters or biodiesel, contributing to waste reduction, economic benefits, and lowered greenhouse gas emissions for sustainable development. This study aimed to synthesize methyl esters from UCO using the Aspergillus oryzae lipase enzyme sourced from moldy copra. The enzyme was purified through ammonium sulfate fractionation and gel filtration column chromatography. Electrophoresis validated its purity, and activity was assessed through the Erdmann and Lowry method. Methyl ester synthesis involved transesterification with a UCO (1 mol): methanol (9 mol): lipase enzyme (15% v/v) ratio. The enzyme displayed notable characteristics, including 43.76 units/mg protein activity, a 41.7 kDa molecular weight, optimum pH of 8.2, temperature preference of 35°C, Km of 0.046, and a 1.926 µmol/minute Vmax. This enzyme efficiently catalyzed UCO (triolein) into methyl ester (methyl oleate), yielding 75.65%. Characterization using Fourier Transform Infrared (FTIR) revealed specific functional groups like –OH carboxylic acid, C=C alkenes, C=O esters, methyl (CH3-), and methylene (-CH2-). Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified prominent compounds: methyl palmitate (12.53%), methyl vacsenate (16.44%), and, notably, methyl oleate (41.08%). This underscores the potential of Aspergillus oryzae lipase as an effective biocatalyst for UCO transesterification, yielding valuable methyl esters or biodiesel
Laminarin crude extract characterization of Sargassum sp. originated from Jepara-Indonesia with Laminarin Acid Extraction method using acetic acid solvent
Get PDFLaminarin is a bioactive compound found in Sargassum sp. whose existence is widespread in Indonesia, including in Jepara, Central Java, Indonesia. Laminarin can be used in food, pharmaceutical, cosmetic, and feed industries as it is beneficial as an anti-inflammatory, antioxidant and regulates gut microbiota. This study aimed to extract laminarin from Sargassum sp. that originated from Jepara-Indonesia by laminarin acid extraction procedure with an acetic acid solvent (CH3COOH) which was safer, cheaper and easy to obtain. Characterization of laminarin crude extract use Fourier Transform Infrared (FT-IR); meanwhile, nutrition tested are moisture, ash, crude protein and crude fiber content. The results showed that laminarin extraction of Sargassum sp. from Jepara using acetic acid solvent (L-ACT) obtained the highest yield of 15.5% with a solvent ratio of 1:5 (w/v) but still lower than the yield extraction using hydrochloric acid (L-HCl) with a solvent ratio of 1:10 (w/v) that was 24.17%. FT-IR absorption band at 2359.96 cm-1 (-OH bending; transmission angle peak), 1538.54 cm-1 (C-C aromatic; carboxyl groups), 1409.35 cm-1 (C-H bending; carboxyl groups), 1230.89 cm-1 (C-O-C stretching; sugar region), 1022.58 cm-1 (R-O-R (acetal)), and at 944.94 cm-1 (O-R cyclic) of the L-ACT samples were similar to those of the L-HCl and standard laminarin references in other studies that used as a positive control, confirming the presence of laminarin. The L-ACT extract had lower ash, crude protein content and higher water content compared to L-HCl crude extract. Meanwhile, the crude fiber content in both L-ACT and L-HCL was not identified. The results showed that Sargassum sp. from Jepara was the potential source of laminarin for many industries (pharmacy, cosmetic, food), and acetic acid could be used as a suitable solvent to extract laminarin in the LAE method.
How to Improve Students' Environmental Literacy on Plastic Waste Issues: Problem-Based Flipped Classroom
Get PDFThe research aimed to enhance students' comprehension of plastic waste concerns by implementing problem-based flipped classrooms, focusing on environmental literacy. Carried out on a cohort of 32 students using a one-group pre–test–post–test design, the study employed various data collection methods, including observation sheets, performance assessment rubrics, and environmental literacy assessment tools. The findings unveiled a commendable overall student engagement level, with a 95% activity rate, signifying a highly positive interpretation. Notably, students' environmental literacy exhibited advancements across knowledge, cognitive skills, and actionable behaviors. The calculated N-Gain value of 0.64 reflected substantial growth, falling within the medium interpretation range. Concerning the attitude facet, students garnered an average score of 80, with 79% expressing alignment with the prescribed attitudes, positioning them within the fairly good category. This underscores the students' positive stance toward environmental concerns. Significantly, implementing the problem-based flipped classroom model targeting plastic waste topics effectively enhanced students' environmental literacy, fostering a more comprehensive understanding of these critical issues