Indo. J. Chem. Res.
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Antioxidant and Anti-inflammatory Activity of Ethanol Extracts from Sambal Orange Peel (Citrus microcarpa Bunge) on Erythrocyte Membrane Stabilization
Full text linkInflammation is the body's defense response to various stimuli. Sambal orange (Citrus microcarpa Bunge) belongs to the Rutaceae family and is widely cultivated in West Kalimantan. This study uses the erythrocyte membrane stabilization method to test the secondary metabolite content, antioxidant activity, and anti-inflammatory activity of ethanol extracts of sambal orange peel. Antioxidant activity was assessed using the DPPH method, while anti-inflammatory activity was evaluated through erythrocyte membrane stabilization. The results showed that the extract had an antioxidant IC50 value of 17.90 ppm, which is very strong. Membrane stability at concentrations of 50, 100, 150, 200, and 250 ppm showed increases of 32.20%, 38.39%, 47.37%, 55.18%, and 65.52%, respectively. The % stability values of sodium diclofenac at the same concentrations were 50.10%, 58.40%, 66.69%, 78.59%, and 87.70%, respectively. The one-way ANOVA test showed a significance value of 0.000 (p < 0.05), indicating a significant difference between treatments. The Tukey post-hoc test showed no significant difference between the 250 ppm extract concentration and the 150 ppm sodium diclofenac concentration. The IC50 value for the extract's anti-inflammatory activity was 163.55 ppm (moderate activity), while sodium diclofenac exhibited stronger activity with an IC50 value of 54.09 ppm
Physicochemical Characterization and Recyclability of CaO/SiO₂ Catalysts Derived from Eggshell and Rice Husk for Biodiesel Application
Full text linkThis study aims to evaluate the physicochemical characteristics and reusability of CaO/SiO₂ heterogeneous catalysts synthesized from eggshell and rice husk waste for biodiesel production. The catalyst, prepared with a 2:1 CaO to SiO₂ ratio, was applied in three transesterification cycles using waste cooking oil. Between cycles, the used catalyst was washed with n-hexane and dried at 80 °C for 12 hours. Catalyst characterization was performed using SEM-EDX, FTIR, and N2 adsorption-desorption analysis. The biodiesel yield decreased from 65 ± 4.95% (first cycle) to 54 ± 1.41% and 46 ± 2.12% in subsequent cycles, indicating reduced catalytic activity. SEM-EDX revealed particle agglomeration, calcium content declined (from 24.78% to 19.22%), and increased silicon exposure (from 4.66% to 21.86%). FTIR analysis detected organic residue accumulation, while N2 adsorption-desorption results showed a decrease in surface area (20.79 to 11.67 m²/g) and pore volume (0.03 to 0.02 cc/g), with increased pore size. The biodiesel showed a density of 1112–1119 ± 1.41 kg/m³ and a kinematic viscosity of 2.03–2.07 cSt, indicating it still requires purification to meet SNI 7182:2015 standards. These findings highlight the catalyst's promising initial performance and underscore the need for regeneration strategies to maintain catalytic efficiency over multiple uses
The Analysis of the Ability NaOH Activated Rice Husk Ash Silica to Reduce Cl Ion Levels
Full text linkResearch has been carried out to analyze the ability of NaOH-activated rice husk Ash Silica to reduce Cl Ion Levels. This study aimed to determine the optimum mass, optimum pH, optimum contact time and apply NaOH-activated rice husk ash silica to reduce Cl ion levels in seawater. The method used in this study was an experimental method with the parameters studied, namely optimum mass, optimum pH, optimum contact time, and the ability of NaOH-activated rice husk ash silica to reduce Cl ion levels in seawater. The results showed that the optimum adsorbed percentage of Cl ions occurred at an optimum mass of 0.025 gram, optimum pH of 7, and optimum contact time of 30 minutes with an adsorbed percentage of 45.7% and an adsorption capacity of 9.14 mg/g. The Cl ion content of seawater samples that can be reduced using NaOH-activated rice husk ash silica is 16.925 ppm with an adsorbed percentage of 33.85%, so it can be concluded that NaOH-activated rice husk ash silica can be used to reduce Cl ion levels
Influence Of Silica Content into Nickel/Silica Electrodeposited Composite Coating for Mechanical and Corrosion Resistant Properties Enhancement: A Review
Full text linkThe ratio cost/efficiency of electrodeposited composite coating has boosted the development of this method in the last decades. Thus, electrodeposited nickel with silica particles as reinforcement was successfully designed and the conditions to increase particles in the composite are better understood. Those composites' morphological, mechanical, and corrosion properties as a function of the embedded silica particles were also investigated. In this review, the last findings about nickel/silica preparations and their properties are specifically summarized. Data collected here indicate that silica particles entrapment depends on current density, particle load in the bath, particle surface modification, and hydrodynamics. The presence of silica particles in the composite led to the refinement of the nickel grain and consequently enhanced the mechanical and corrosion properties
Kinetic of Hexavalent Chromium (Cr(VI)) Removal by Corn Cob-Based Activated Carbon Modified with Nitric Acid
Full text linkThe presence of heavy metal Cr(VI) in water indicates environmental pollution. Heavy metal Cr(VI) that exceeds the standard can be harmful to health because it is toxic and carcinogenic. Activated carbon can be used as a heavy metal adsorbent. Modification of activated carbon using nitric acid can increase metal adsorption capacity. Therefore, this study aims to determine the kinetic of hexavalent chromium (Cr(VI)) removal by corn cob-based activated carbon modified with nitric acid. The modified activated carbon was characterized by Boehm titration and FTIR spectrophotometer. The adsorption capacity was identified in various parameters, involving the initial concentration of Cr(VI), pH value, contact time, and concentration of the adsorbent to obtain the optimal Cr(VI) removal efficiency value. The most optimal Cr(VI) adsorption was obtained at an activated carbon dosage of 3 g/L, pH value of 1, contact time of 140 minutes, and 100 mg/l Cr(VI) concentration. Based on adsorption kinetics data, the pseudo-second-order equation was obtained (R2 =0.994). The adsorption phenomenon followed the Langmuir isotherm model (R2 = 0.998) with an optimum adsorption capacity of 28.32 mg/g. Corn cob-activated carbon modified with nitric acid has many acidic groups that act as effective active sites for reducing Cr(VI) from water
Enhanced Recovery of Bioactive Compound from Pineapple Peel Using Ultrasonic-Assisted Extraction with Enzyme Treatment at Varying Extraction Time
Full text linkPineapple peel is considered waste, but it has numerous beneficial uses due to its rich content of nutrients and bioactive compounds. The selection of extraction methods is essential to produce optimal bioactive compound extracts. Ultrasonic-assisted extraction (UAE) is a modern extraction technique that uses ultrasonic waves to improve the extraction by enhancing the release of compounds into the solvent. The UAE method was performed by varying extraction times at 30, 60, 90, and 120 min. The addition of cellulase enzyme was also applied as an optimization method for the extraction results. The addition of Cellulase elevated the yield, phenolic, and flavonoid content. The highest yield was obtained at an extraction time after 90 min. The highest total flavonoid content was 497.8±4.5 µgQE/mL, while the highest total phenolic value was 1007.6±7.6 µgGAE/mL at extraction of 60 min. However, the extracted samples without enzymes performed the highest results at an extraction of 90 min. The effect of the enzyme resulted in the most potent antioxidant activity (<10 ppm) in all-time extraction. To conclude, the addition of enzymes in the extraction process successfully optimized the extraction of phytochemical compounds from pineapple peel, as evidenced by testing phenolic and flavonoid content and antioxidant activity
Optimizing Photovoltaic Performance in p-Cu2O/n-TiO2 Heterojunction Solar Cells: The Impact of Annealing Temperature, Layer Thickness, and Carbon Doping
Full text linkThis study analyzes the photoresponse behavior and optimizing the efficiency of p-Cu₂O/n-TiO₂ heterojunction solar cells. The impact of annealing temperature, layered thickness, and carbon doping on the optical and electrical characteristics of the solar cells was investigated. The findings reveal that the annealing temperature continuously affects the optical absorption and energy gap of Cu2O, with the best performance at 250°C. Increasing the layer thickness of Cu2O resulted in further improvement in absorption and efficiency. It was also found that doping carbon into TiO2 lowered the energy gap, increasing efficiency. The maximum efficiency of 0.003593% was obtained with carbon-doped TiO2. This work guides optimizing the design of heterojunction solar cells for better photovoltaic performance
Antibacterial Activity Test of Silver Nanoparticle Composites With Gandaria Seed (Bouea macrophylla G.) Bioreductor and Ouw Natural Clay Matrix (ONC)
Full text linkAn antibacterial activity test of silver nanoparticle composite with bioreductor of gandaria seeds (Bouea macrophylla G.) and Ouw natural clay (ONC) matrix was conducted. Silver nanoparticles (AgNPs) were synthesized by forming the colloidal silver solution by chemical reduction method using gandaria seed bioreductor. The formation of AgNPs can be known through UV-Vis absorption when there is a color change. Based on the results, the maximum wavelength of colloidal NPP is 435-444 nm. Silver nanoparticles synthesized through the preparation process were tested to determine their effectiveness as antibacterial agents against Escherichia coli and Staphylococcus aureus. The test results showed that the NPP formulation, containing an aqueous extract of gandaria seeds with the addition of polyvinyl alcohol (PVA), produced an inhibition zone of 10.6 mm against E. coli, indicating strong antibacterial activity. In contrast, the activity against S. aureus was classified as moderate, with an inhibition zone measuring 6.8 mm. For the antibacterial activity test with Ag/ONC nanocomposite samples on both test bacteria, there was no inhibition zone or antibacterial activity
Characterization of Lapindo Mud-Based Nanocatalyst and Quality Testing of Biodiesel from Used Cooking Oil via Transesterification Reaction
Full text linkThis study explores the transesterification of used cooking oil using a Lapindo mud-based nanocatalyst and evaluates the resulting biodiesel quality. The reaction was carried out via the reflux method for 2 hours at 65°C, with a methanol-to-oil molar ratio of 9:1 and a catalyst-to-oil weight ratio of 3:100. The high SiO₂ metal oxide content in Lapindo mud functions as a heterogeneous catalyst. Nanocatalyst synthesis involved calcination followed by ball milling. Characterization confirmed the presence of SiO₂: FTIR analysis identified Si-O-Si functional groups at 1168 cm⁻¹, XRD revealed SiO₂ crystals at 2θ values of 20.18°, 26.68°, 42.40°, and others, while XRF showed 47.0% SiO₂ content. PSA results indicated a particle size distribution of 514.3 ± 361.8 nm. Biodiesel analysis using GC-MS showed a methyl ester content of 99.26%. Other quality parameters included density (929.4 kg/m³), viscosity (4.52 mm²/s), water content (0.097%), and acid number (0.50 mg-KOH/g). These findings suggest that the Lapindo mud-based nanocatalyst is highly effective in promoting transesterification and presents a promising, eco-friendly alternative for biodiesel production from used cooking oil
Adsorption of Methylene Blue Using Composite Fe3O4-Ihau Fruit Peel Powder (Dimocarpus longan var. malesianus Leenh.)
Full text linkA study has been conducted on the adsorption of methylene blue dye using Fe3O4-ihau fruit peel powder composite as the adsorbent. The Fe3O4-ihau fruit peel powder composite adsorbent was synthesized using the co-precipitation method from FeSO4.7H2O and FeCl3.6H2O in a 3:2 ratio, then composited with ihau fruit peel powder. The resulting Fe3O4-ihau fruit peel powder composite was characterized using Fourier Transform Infra-Red (FTIR), Scanning Electron Microscopy (SEM), and X-Ray Diffractometer (XRD). FTIR characterization results of the Fe3O4-ihau fruit peel powder composite showed an absorption peak at a wave number of 586.36 cm-1, corresponding to the Fe-O group. SEM revealed that the Fe3O4-ihau fruit peel powder composite has an uneven surface and smaller pores compared to the ihau fruit peel powder, and XRD showed a diffractogram of the Fe3O4-ihau fruit peel powder composite that closely resembled that of Fe3O4. Methylene blue adsorption by the Fe3O4-ihau fruit peel powder composite adsorbent was optimal at pH 4 with an optimum contact time of 75 minutes, and it had a maximum adsorption capacity of 43.7267 mg/g. The adsorption isotherm followed the Langmuir isotherm, and the adsorption of methylene blue dye using Fe3O4-ihau fruit peel powder composite adsorbent occurs spontaneously, endothermically, and by physisorption