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Kinetic Studies on MB Adsorption by Graphene like Material from Coconut Shell Charcoal

Coconut shell (CS) activated carbon is widely used for water purification, but its adsorption capacity is inferior compare to graphene oxide (GO). GO has oxygen functional groups so it can effectively bind pollutants like methylene blue (MB). In this study we synthesized graphene-like material from CS charcoal using the modified Hummers method by varying its oxidation times. The XRD decomposition results for H-CS3.2 show a structural composition similar to GO material. The diffraction peak at 10.7° (3.04%) falls within GO's characteristic range of 8°-11°, supported by a Raman ID/IG ratio of 0.95. In contrast, H-CS3.1 material does not exhibit GO's structural composition, with a diffraction peak at 13.9° (1.09%). An increasing of oxidation time, enhanced adsorption capacity in the equilibrium state of H-CS3.2 (22.368 mg/g) surpassing H-CS3.1 (17.079 mg/g). The heightened adsorption was linked to an increased O/C ratio or higher % of atomic oxygen (0.04 for H-CS3.1 and 0.17 for H-CS3.2). The pseudo second-order Ho (PSO) adsorption kinetic model demonstrated the adsorption mechanism, with active sites (oxygen functional groups) such as carbonyl (C = O) and epoxy (C – O) at basal plane carbon. Steric hindrance caused by hydroxyl functional groups (C – OH) led to a reduction in π-π interactions and decreased adsorption ability of the H-CS3.1 material. Desorption of H-CS3.1 material was influenced by MB detachment through interface diffusion.

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The Effectiveness of Concentration of Chitosan Extracted from Tiger Shrimp Shells as a Natural Preservative of Kenyar Fish

A study to find the effectiveness of chitosan concentration as a natural preservative on Kenyan fish (Sarda orientalis) has been conducted. The chitosan powder used is extracted from tiger prawn (Penaeus monodon) shells, and it is used in the form of a solution with a concentration of 1%, 1.5%, 2%, and 2.5%. Fresh kenyar fish of 500 g were soaked in those chitosan solutions and named A1, A2, A3, and A4, respectively. Two sample groups were prepared as a comparison; they weren’t treated with any chitosan solution; they were A02, 500 g of kenyar fish soaked in 2% acetic acid, and A01, 500 g of kenyar fish without any treatment. The soaking times were varied as 20, 40, and 60 minutes. Storage is carried out at room temperature. The activity of chitosan as a fish preservative was analyzed using various methods, including pH, organoleptic, and antimicrobial tests. The measurements of pH and organoleptic test were made at 0, 24, 48, and 72 hours. The antimicrobial tests were carried out after 24 hours of storage. The study concluded that the effective concentration of chitosan as a preservative agent of fresh kenyar fish is 2.5% (A4) with 40 minutes of soaking time, with the quality parameters are pH 5, an organoleptic score of 9, and the total number of microbes is 1.2 x 105 CFU/g.

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Antifeedant Nanosuspension Formula of <i>Tithonia diversifolia</i> Leaf Extract by Emulsion Inverse Method to Control <i>Crocidolomia pavonana</i> Cabbage Pest Insect

The leaf extract from Tithonia diversifolia is recognized for its ability to deter feeding in various Lepidoptera insect pests, including the larvae of Crocidolomia pavonana. Presently, transformation efforts from conventional formulations into nano-based formulations for biopesticides exhibit enhanced effectiveness and efficiency. Utilizing a low-energy process, an inversion emulsion facilitates the dispersion of the extract suspension in an organic solvent into a water-immiscible solvent using a suitable surfactant. The forming nano-size droplets in water (t1, t2, t3, t4) are influenced by the ratio of surfactant and organic suspension (Water: Tween 80: Organic suspension). The emulsification method successfully formulated T. diversifolia leaf extract, into dispersed nano-size and submicron suspensions in water. The t3 formula exhibits the smallest nano-size dispersed in water (D=23.6 ± 39.6 nm; polydispersity index IP=0.702) and enhanced wettability, evident in the lower contact angle of the droplet on the cabbage leaf surface (49.4°) compare with the control group. The Phytochemicals confirmed by IR-spectra analysis identified the phenols, alkaloids, and steroids constituents of leaf extract, which are known to have antifeedant properties. The enhanced antifeedant properties of T. diversifolia nanosuspension against C. pavonana third-instar larvae demonstrated by the antifeedant test results showing that t3 is the most successful deterrent larvae feeding activity compared to the control (P<0.05), due to the highest total antifeedant coefficient (74.27%) in a category medium antifeedant activity, while the non-emulsification displayed the lowest antifeedant coefficient (25.36%) in a category as low antifeedant activity. T. diversifolia leaf extract with a nano-based formula succeeded resulting in dispersed nano-size and submicron suspension in aqueous media, thereby reducing surface tension and enhancing wettability on the leaf surface during application. The improved dispersion of antifeedant nanosuspension on the leaf surface results in more effective delivery to target insects.

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Exploring the Potential of Pangasius Catfish Oil as a Base Oil for Nanoemulsion Products: Optimization and Characterization

Pangasius catfish, also known as striped catfish, is a high-fat fish compared to other freshwater fish like snakehead fish and carp. The oil extracted from this fish contains unsaturated and polyunsaturated fatty acids that are beneficial for health. The quality of the oil is affected by the extraction method, especially the preliminary heating temperature for the extraction. Pangasius catfish oil contains omega-3 fatty acids (EPA and DHA) that have the potential to inhibit inflammation, hyperpigmentation, accelerate skin healing for topical applications, and act as a skin permeation enhancer and oil base for nanoemulsion due to its high oleic acid content. In this research, an experimental design was conducted on pangasius catfish oil extraction using the pressing method to optimize predetermined parameters using Response Surface Methodology (RSM). The factors considered for optimization included the quantity of water and extraction temperatures, with water content ranging from 50% to 150% (w/v) and extraction temperatures ranging from 25°C to 55°C. These ranges were intended to yield results and characterization values of oxidation parameters are tested according to the International Fish Oil Standard (IFOS) through tests including Acid Value (AV), Peroxide Value (PV), Anisidine Value (p-AnV), and Total Oxidation (TOTOX). Subsequently, the optimal conditions were confirmed to obtain the best fish oil results, which were achieved at 1.5 times the amount of pre-treatment water and a pre-treatment temperature of 55°C. The pangasius catfish oil obtained from the confirmation of optimal conditions is used as a raw material for producing nanoemulsions. The D-Optimal Mixture Design of Design Expert approach is utilized to formulate the nanoemulsion. The nanoemulsion formula containing 0.5% pangasius catfish oil was determined as the optimal formula according to the range of physical characteristics of the referenced nanoemulsion preparations with a desirability value of 0.974. This study has demonstrated the potential utility of pangasius catfish oil as a prominent base oil in nanoemulsion products.

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Ultraviolet Light Resistance on the Properties of Polyurethane Coating with the Addition of Chlorinated Rubber

Resistance to ultraviolet light is an essential factor that coating materials must possess, especially for outdoor applications. In this study, the effect of ultraviolet light exposure on the properties of polyurethane coating with the addition of chlorinated rubber was systematically examined. The ultraviolet light exposure was performed using an ultraviolet weathering tester for 500 hours. The samples were investigated through mechanical testing, complemented by scanning electron microscope and Fourier transform infrared spectroscopy. The increase in the tensile strength and elongation at break of the polyurethane coating with the addition of chlorinated rubber was observed and compared to the pristine sample. In the beginning of the ultraviolet exposure, the tensile strength increased 486% and 114% for pristine polyurethane and polyurethane/chlorinated rubber until of 80 hours ultraviolet exposure, indicating repolymerization during the ultraviolet exposure. It was confirmed by the Fourier transform infrared spectra which showed an increase in peak intensity at wave number of 1712 cm־ˡ which indicated C=O bond in the polyurethane. The surface morphology showed micro-cracking caused by ultraviolet exposure. Finally, it was concluded that the addition of chlorinated rubber improved the resistance to ultraviolet light.

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