Jurnal Pendidikan Kimia
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Effect of Glycerol Modification on Mn-Doped ZnO–Chitosan Membranes for Tartrazine Photodegradation
Get PDFThis study evaluates the photocatalytic performance and charge transfer behavior of Mn-doped ZnO chitosan membranes, both with and without glycerol, for the degradation of tartrazine under visible light. The membranes were prepared by homogeneous mixing using chitosan as the polymer matrix, ZnO as the photocatalyst, Mn2+ as the dopant, and glycerol as a plasticizer. Membrane morphology and elemental distribution were examined using SEM and EDX, and supported by physical tests. Glycerol increased membrane flexibility and mechanical strength, but reduced porosity and surface hydrophilicity, indicating a denser polymer network and water accessibility. Photocatalytic activity was quantified from UV Vis monitoring of tartrazine and fitted to pseudo-first-order kinetics. The glycerol-containing membrane showed a higher rate constant (k = 0.4398 h−1) than the membrane without glycerol (k = 0.0893 h−1). The performance improvement is attributed to better catalyst retention and dispersion in the matrix, which supports photon utilization and charge separation. Mechanistic interpretation suggests that Mn2+ acts as an electron trap, thereby suppressing electron-hole recombination and promoting the formation of reactive species. At the same time, glycerol can suppress the generation of hydroxyl and superoxide radicals by limiting contact among tartrazine, water, and photocatalytically active sites. Overall, the results reveal a trade-off between transport properties and catalytic efficiency, identifying glycerol content as a key parameter for optimizing Mn-doped ZnO chitosan membranes for dye wastewater treatment
Synthesis and Characterization of Sucrose-Modified CaO Catalyst Derived from Dolomite for Transesterification of Reutealis trisperma Oil
Get PDFThis study presents a novel method for synthesizing solid base catalysts by modifying calcium oxide (CaO) from dolomite via a sucrose-mediated hydrothermal process. In this approach, sucrose acts as a complexing agent to remove magnesium ions (Mg²⁺), a structure-directing agent, and a carbon-based template. After Mg²⁺ removal, calcium species were recovered through coprecipitation using sodium carbonate. The synthesized catalysts were characterized to evaluate their structure using X-ray diffraction (XRD), identify functional groups via Fourier-transform infrared spectroscopy (FTIR), observe morphology and elemental composition through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), measure particle size distribution by particle size analysis (PSA), and determine surface area through Brunauer-Emmett-Teller (BET) analysis. The catalysts exhibited a surface area of 27.411 m²/g and reduced crystallite size, both contributing to enhanced catalytic activity. In the transesterification of Reutealis trisperma oil under optimal conditions (65 °C, 3 hours, methanol-to-oil ratio 9:1), the catalyst achieved 99.40% oil conversion and 88.82% biodiesel yield. A catalyst dosage of 7.5 wt% was optimal, while higher amounts caused emulsion and soap formation due to viscosity-related mass transfer limitations. This environmentally friendly synthesis route offers a reusable catalyst system for sustainable biodiesel production from non-edible feedstocks
Safer and Sustainable Co-precipitation Synthesis of NCA (LiNi0.80Co0.15Al0.05O2) Cathodes: Eliminating Ammonia in Favor of NaOH for pH Control
Get PDFDeveloping safer and more sustainable synthesis routes for lithium ion battery cathodes is important for both environmental practice and laboratory education. This study reports an ammonia free oxalate coprecipitation route to synthesize LiNi0.80Co0.15Al0.05O2 (NCA), in which ammonia as the usual pH controller was fully replaced by sodium hydroxide (NaOH). NaOH dosage was varied at 20 g, 40 g, 60 g, and 80 g to control precipitation, precursor quality, and the properties of the final cathode after calcination and sintering. X ray diffraction confirmed formation of a layered α NaFeO2 type structure with R3m symmetry for all samples without detectable secondary phases. The 40 g NaOH condition showed the best structural ordering, reflected by a relatively high I(003)/I(104) intensity ratio associated with reduced cation mixing. Fourier transform infrared spectra verified oxalate ligand decomposition during thermal treatment and the appearance of metal oxygen lattice vibrations consistent with NCA formation. Scanning electron microscopy revealed that the 40 g NaOH sample produced more uniform particles with a narrower size distribution than other variants. Based on these results, the 40 g NaOH sample was selected for electrochemical evaluation and delivered an initial discharge capacity of about 110 mAh g−1 at 0.1 C in a full cell configuration. Overall, NaOH is demonstrated as an effective and safer substitute for ammonia in oxalate coprecipitation, enabling greener NCA synthesis protocols for research and teaching
Analysis of the Effect of Fixators and pH Conditions on the Color Absorption of Cotton with Natural Teak Leaf Dyes (Tectona grandis Linn. f.)
Get PDFGrowing concern about the environmental impacts of synthetic dyes has renewed interest in plant-based colorants for sustainable textile dyeing. Teak leaves (Tectona grandis Linn. f.) are rich in polyphenolic compounds with strong chromophoric properties, but the influence of fixation conditions and dye-bath pH on fabric performance requires further clarification. This study evaluated the effects of mordant type and dye-bath pH on color intensity and washing fastness of cotton fabrics dyed with teak leaf extract. Cotton samples were dyed at pH 4, 6, 8, 10, and 12, then post-mordanted using alum, ferrous sulfate, or tamarind extract. Color characteristics were quantified using the CIE Lab* system, and washing fastness was assessed following SNI ISO 105-C06:2010. Ferrous sulfate consistently produced the darkest shades and the highest washing fastness ratings (TLW 3–4 to 4), likely due to stable metal ligand complex formation among Fe2+ ions, dye molecules, and cellulose fibers. Mildly alkaline dye baths (pH 8–10) enhanced color depth, whereas extreme alkalinity (pH 12) decreased dye uptake, presumably because stronger electrostatic repulsion limited adsorption. Overall, teak leaf extract shows strong potential as an eco-friendly natural dye, and the results emphasize that careful mordant selection and pH optimization are essential to achieve durable coloration for sustainable textile processing
GC-MS and ADMET Profiling of Bruguiera gymnorrhiza Mangrove Leaf Extract Origin Sulawesi with Antioxidant Properties
Get PDFMangrove plants, particularly Bruguiera gymnorrhiza, are recognized as sources of bioactive compounds. This study analyzed the chemical profiles, safety, and antioxidant activity of B. gymnorrhiza leaf extract origin Sulawesi, a biodiversity-rich Wallacean region. Research on B. gymnorrhiza leaves from Sulawesi remains scarce. GC-MS analysis identified inositol, fatty acid, ester, and terpenoid derivatives as major chemical profiles related to stress tolerance and remedial properties. ADMET predictions showed good intestinal absorption but suggested potential hepatotoxicity at high doses. Brine shrimp lethality tests revealed low acute toxicity with an LD₅₀ of 873.381 µg/mL, supporting in silico findings. The extract exhibited strong antioxidant activity (IC₅₀ 49.78 µg/mL), comparable to Vitamin E, and higher than reports from other regions. These results indicate that Sulawesi mangroves store valuable chemical compounds and serve as environmental health indicators. Combining chemical profiling, computational prediction, and experimental validation highlights their pharmaceutical potential while emphasizing the need for careful dose optimization and ecological monitoring. This study reinforces the importance of conserving Wallacean biodiversity and offers a foundation for safe, natural antioxidant commercialization. Future work should assess in vivo effectiveness, long-term toxicity, and the ecological impacts of pollutant immobilization in mangrove ecosystems
Profiling Multicomponent Chemical Reasoning: A Learning Analytics Approach to Applied and Socio-Chemical Dimensions
Get PDFScientific reasoning in chemistry involves the ability to apply conceptual knowledge in problem-solving, as well as to evaluate issues within broader social, ethical, and environmental contexts. However, conventional assessments often fail to capture this multidimensionality by reducing performance to a single final score. This study uses an integrated learning analytics approach to analyze students’ reasoning performance across two core domains of chemistry learning—applied reasoning and socio-chemical reasoning. A quantitative descriptive design was employed, involving 56 pre-service chemistry teachers who completed four open-ended essay questions, two in each reasoning domain. Student responses were scored using an analytical rubric assessing conceptual accuracy, logical coherence, and justification relevance. Data were analyzed using single-domain and multicomponent strategies, including quadrant profiling, trajectory mapping, clustering, and distribution analysis. Visual tools such as radar charts, spaghetti plots, contour density plots, and alluvial diagrams were used to depict students’ reasoning profiles. Results revealed that most students demonstrated moderate reasoning abilities, although notable inconsistencies were observed between the domains. Individual trajectories exhibited non-linear variations, highlighting diverse cognitive patterns. Clustering and heatmaps indicated distinct learner segments, while alluvial diagrams illustrated transitions between reasoning levels across domains. These findings suggest that students’ reasoning abilities are varied and dynamic. It is concluded that chemistry reasoning is multidimensional and should be assessed through integrated, data-driven methods. The study recommends the adoption of formative, analytics-supported assessments to inform differentiated instruction and promote deeper conceptual and ethical engagement in chemistry education
The Utilization of Zn-C Battery Waste and Duck Eggshells in the Synthesis of ZnO/HAp Composite as a Photocatalyst for Methylene Blue Waste Treatment
Get PDFSynthetic dyes such as methylene blue pose a significant pollution threat due to their chemical stability, resistance to biodegradation, and adverse ecological impacts. Photocatalytic treatment with ZnO is promising; however, particle agglomeration commonly diminishes efficiency. To mitigate this limitation, a ZnO/hydroxyapatite (ZnO/HAp) composite was synthesized from Zn–C battery waste and duck eggshells via a solid-state dispersion method using ZnO: HAp molar ratios of 1:1, 1:3, and 3:1. The materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Photocatalytic activity was assessed by degrading 10 mL of 10 ppm methylene blue with 90 mg of photocatalyst under visible-light irradiation for 180 min. XRD confirmed the successful formation of ZnO, HAp, and ZnO/HAp composites with single-phase zincite and hydroxyapatite structures, crystallite sizes of 14.66–25.09 nm, and crystallinity values of 62.66–86.60%. SEM revealed irregular particle morphologies. All composites were photocatalytically active, achieving methylene-blue decolorization of 96.63%, 91.45%, and 81.07%, with the 1:1 composite exhibiting the highest performance. These results indicate that waste-derived ZnO/HAp composites are promising, low-cost photocatalysts for treating organic dye pollutants
Removal of Cu(II) and Pb(II) Ions from Wastewater Solutions Using Black Soldier Fly (Hermetia illucens) Pupal Shell: Adsorption and Characterization
Get PDFIndustrial wastewater often contains heavy metals such as Pb(II) and Cu(II) that pose significant environmental and health risks. This study investigates the utilization of Black Soldier Fly (BSF) (Hermetia illucens) pupal shells as an adsorbent material for the removal of Pb(II) and Cu(II) ions from aqueous solutions. BSF pupal shells were chosen due to their high availability, rapid life cycle, and chitin-rich composition, making them suitable for heavy metal adsorption. The preparation process included washing, drying, grinding, and activation with 1 M NaOH solution. Characterization of the adsorbent was performed before and after adsorption using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDX). Adsorption experiments were conducted to examine the effects of pH, contact time, and initial ion concentration. The optimum pH for adsorption was found to be 5.5, achieving removal efficiencies of 95.5% for Pb(II) and 71.81% for Cu(II). The optimum contact times were 180 minutes for Pb(II) and 240 minutes for Cu(II). Kinetic analysis demonstrated that the adsorption process followed a pseudo-second-order model. Adsorption isotherm studies indicated that the Langmuir model provided a better fit (R² = 0.99 for Pb(II) and 0.98 for Cu(II)) compared to the Freundlich model (R² = 0.90 for Pb(II) and 0.77 for Cu(II)). These results demonstrate that BSF pupal shells are a promising, cost-effective, and environmentally friendly material for industrial wastewater treatment application
Eco-Friendly Revolution in Fingerprint Detection: Synthesis of Zno Nanoparticles Using Durian (Durio Zibethinus) Peel Extract Pakpak Bharat
Get PDFFingerprints are a reliable means of forensic identification because ridge patterns are unique and permanent. Conventional fingerprint powders, however, may contain hazardous ingredients that pose health and environmental risks. This study synthesized zinc oxide (ZnO) nanoparticles via a green route using durian peel (Durio zibethinus) extract and evaluated their potential as an eco-friendly latent fingerprint developer. ZnO nanoparticles were characterized by FTIR to identify functional groups, SEM to examine morphology and particle size, and EDX to verify elemental composition. The biosynthesized ZnO showed semi-spherical to granular particles with sizes of 40–90 nm and no severe agglomeration. FTIR indicated hydroxyl and carbonyl groups from durian peel biomolecules, suggesting their role as reducing and stabilizing agents. EDX confirmed dominant Zn (72.5%) and O (15.2%) signals, supporting high purity ZnO formation. Latent fingerprint development was tested using prints from 40 respondents on porous surfaces (black cardboard and oil paper) and nonporous surfaces (microscope slide, aluminum foil, and compact disc). The ZnO nanopowder produced clear ridge patterns and higher contrast on nonporous substrates, while conventional powders tended to leave residues and may require less safe reagents. These results indicate that durian peel derived ZnO nanoparticles are a promising, economical, and environmentally friendly alternative for latent fingerprint visualization and provide added value for agricultural waste utilization in forensic applications
Phytochemical Screening and Antibacterial Activity of Ethanolic Extracts from Delonix regia Against Laboratory Strains of Diarrheal Bacteria
Get PDFThe present study evaluates the antibacterial efficacy of ethanolic extracts from Delonix regia leaves against diarrhea-inducing bacteria Escherichia coli and Salmonella typhimurium. Preliminary phytochemical screening revealed that D. regia leaves comprise flavonoids, alkaloids, saponins, tannins, phenolics, and terpenoids. Fourier Transform Infrared Spectroscopy (FTIR) analysis identified various functional groups in the D. regia leaf extract, including O-H, C-H, C=O, C=C, C-C, C-O, and C-O-C. Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) analysis further confirmed the presence of 16 distinct compounds comprising amino acids, alkaloids, phenolics, flavonoids, terpenoids, anthraquinones, n-acyl pyrrolidines, and fatty acids. The disc diffusion method (Kirby-Bauer) was employed for the antibacterial tests. The extracts of D. regia leaves at concentrations of 25%, 50%, 75%, and 100% generated inhibition zones measuring 5.26 mm, 6.37 mm, 7.27 mm, and 10.18 mm against E. coli, and 5.05 mm, 7.01 mm, 8.77 mm, and 10.04 mm against S. typhimurium, respectively. The commercial antibiotic ciprofloxacin (a positive control) produced inhibition zones of 30.02 mm for E. coli and 28 mm for S. typhimurium. The negative control, consisting of 10% ethanol, showed no inhibitory effect on bacterial growth. These findings indicate that the ethanolic extract of D. regia leaves possesses antibacterial properties against E. coli and S. typhimurium. It is likely that secondary metabolite compounds, such as flavonoids and phenolics, contribute significantly to the observed antibacterial activit