Jurnal Akademika Kimia
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Analysis of Learning Difficulties of Students Class XI in Chemistry Subjects
Get PDFThis study aimed to determine (1) the internal factors that cause learning difficulties in chemistry subjects for students of class XI MIA SMA Negeri 1 Tinombo Selatan, including attitudes towards learning, motivation, interest, and health; (2) the external factors that cause learning difficulties for class XI students of SMA Negeri 1 Tinombo Selatan include family, school, and community environment. This research was descriptive. The research subjects were 92 students. The collection technique used a questionnaire on the factors of learning difficulties. The data analysis technique used was descriptive with a percentage. The results showed that (1) the internal factors that caused learning difficulties were as follows: the attitude indicator towards learning was 16.44 %, the motivation indicator was 13.45 %, the interest indicator was 18.26 %, and the health indicator was 18.88 %. (2) External factors that cause learning difficulties are the family indicator was 23.23 %, the school indicator was 87.77 %, while the community indicator was 25.16 %
Application of Think-Pair-Share (TPS) Cooperative Learning Model to Student Learning Outcomes in Hydrocarbon Material in Senior High School
Get PDFThis study aims to describe the improvement of student learning outcomes by applying the Think-Pair-Share (TPS) cooperative learning model on hydrocarbon material in class XI SMA Negeri 2 Sigi. This study's research type is pre-experimental with a one-group pretest posttest design. This study utilized purposive sampling. The sample consisted of two classes: class XI IPA 3 as the experimental class 1 (n = 22) and class XI IPA 4 as the experimental class 2 (n = 24). Student learning outcomes data are processed using the learning improvement test (N-gain). The application of the Think Pair Share (TPS) cooperative learning model to improve student learning outcomes on Hydrocarbons can be seen from the average N-gain value in the two experimental classes, including in the high category, namely 0.77 and 0.78. Therefore, applying the Think Pair Share (TPS) cooperative learning model can improve student learning outcomes on average greater than 75 (KKM) of SMA Negeri 2 Sigi students in Class XI on hydrocarbon material
Biofoam from The Waste of Durian Seeds and Corn Cobs
Get PDFBiofoam is a styrofoam substitute packaging made with starch and fiber as the basic ingredients. This study aims to determine the characteristics (biodegradation test, pressure strength and water absorption) of biofoam produced from durian seed waste and corn cobs. The best treatment in this study was biofoam made using a mixture of durian seeds starch and corn cobs fiber made with 5 % NaOH concentration, where the results obtained were the water absorption test values with 1 minute, 2 minutes, and 3 minutes, namely 11.20 %, 14.22 % and 16.81 %. While the compressive strength test value obtained is 16.85 10-5 Pa, and the results of the biodegradation test are obtained at 35.42 % within 14 days of burial in the soil. The FTIR test results showed that the biofoam groups produced from a mixture of corn cob fibers with different concentrations of NaOH still showed similarities in their functional groups, where none gave rise to new peaks. The functional group content of the resulting biofoam includes the CH group (alkane) and the C. C Group (alkyne) C=C group (aromatic ring and OH group
Potential Antioxidant Activity in Octyl p - Methoxycinnamate (OPMC) Compound Synthesized by Sonochemical Method
No full textOctyl p - methoxycinnamate (OPMC) is a cinnamic acid derivative compound synthesized from p-methoxy cinnamic acid (PMCA) which is reacted with octanol in an acidic condition. OPMC has a substituted benzene group at the para position and conjugated at the carbonyl group. The method used to synthesize OPMC compounds is an esterification reaction with the help of ultrasonic waves at a sonication temperature of 60 0C for 4 hours. The synthesized compounds were then subjected to organoleptic tests, thin layer chromatography tests, solubility tests, melting point tests, FTIR - ATR, and GC - MS. The results showed that the OPMC results were in the form of fine white crystals. The qualitative test was carried out using thin-layer chromatography (TLC) showing an Rf value of 0.65 using n-hexane: ethyl acetate (4:1) eluent. OPMC synthesized is soluble in ethanol, methanol, chloroform, and ether and insoluble in water. The percentage yield of OPMC synthesized 55.72 % Melting point test with melting point apparatus showed that octyl p - methoxycinnamate started to melt at 50 0C. Analysis using FTIR - ATR showed 2919 and 2851 cm-1 (C - H alkyl) The absorption of the extended C=O ester group was at 1692 cm-1 close to the C=O ester (1712 cm-1). C=C group of alkenes and aromatics (1636, 1603, 1573, and 1510 cm-1). The stretching of the C-O ester group at wave number 1252 cm-1, Absorption for the stretching of the C-O ether group at wave number 1170 and 1167 cm-1. The wave number of 820 cm-1 indicates the presence of an aromatic group substituted at the para position. Tests with GC - MS found an abundance of compounds with 97.52 % base peak 290 m/z. Synthesized OPMC compounds have activity as a strong antioxidant with an IC50 value of 96.092 ppm
SPF Activity Sunscreen Spray Gel Ethanol Extract of Cinnamon Bark (Cinnamomum burmanii Ness. BI, Syn)
No full textThis cinnamon bark contains cinnamaldehyde, which is a secondary metabolite compound derived from aldehydes, including the polyphenolic group, which activity as a sunscreen and antioxidant by absorbing UV rays, so it can protect the skin from direct sun exposure (sunscreen). The study aimed to determine whether there was an effect of the concentration of the ethanol extract of cinnamon bark (Cinnamomum burmanii Ness. BI, Syn) on the physical characteristics and SPF value of spray gel preparations and to determine the concentration of the ethanol extract of cinnamon bark that produced spray gel with physical characteristics and SPF value. best. The study was conducted by extracting cinnamon bark by the maceration method using 96 % ethanol for 3 days. The extract obtained was then subjected to phytochemical screening TLC and then applied to a spray gel preparation with concentrations of FI (10 %), FII (15 %), and FIII (20 %), followed by testing the activity of sunscreen using the UV-Vis spectrophotometry method. The results of phytochemical screening and TLC on the ethanol extract of cinnamon bark showed positive results for containing flavonoids, alkaloids, tannins, steroids, and antioxidants. The statistical test results showed that there was a difference with a sig value of 0.05. It was concluded that the ethanol extract of cinnamon bark affected pH, viscosity, spreadability, stickiness, drying time, and SPF value. The formula that gave the best physical characteristics and SPF value was found in the concentration of sunscreen spray gel: the ethanol extract of cinnamon bark with a concentration of FIII (20 %)
Analysis Of Flavonoid Levels on Skin Langsat Fruit (Lansium Domesticum) Using Uv-Vis Spectrophotometer
Get PDFLangsat fruit (lansium domesticum) is a plant included in the family meliaceace. Several compounds were reported to have been isolated from multiple constituents in langsat plants that contain lansic acid, triterpene amino sugar glycoside, and dukunolides A- C, tetranortripenoid was dukunolides D- F. With the development of sciense a lot of research on ingredients and benefits langsat fruit both the pulp of the fruit and the skin. Empirically, the skin of the langsat fruit has been used as an anti-oxidant and anti-cancer treatment. Langsat fruit skin is an essential source of bioactive components such as phenols, flavonoids, tannins, saponins, triterpenoids, and alkaloids. This study used a UV-Vis spectrophotometer to determine the levels of flavonoids in the ethanol extract of langsat fruit peel (Lansium domesticum). This study aims to determine the levels of flavonoids in the skin of langsat fruit (lancium domesticum) by comparing the wet and dry fruit skin. Extraction of the chemical content of langsat fruit skin (Lansium domesticum) was carried out by the meseration method using ethanol 70.0/0. The determination of flavonoid levels in langsat fruit peel extract was measured at 520 nm and 700 nm from the result of the study. The total flavonoid levels of each sample were 2.856 mg /100 grams of alkaline fruit skin and 4.209mg /100 grams of dried langsat fruit peel. This shows that dried langsat fruit peel samples have high anti-oxidant power and alkaline fruit peel extracts
Performance of The Composite Electrode of Reduced Graphene Oxide Palm Oil Shell - Zinc Oxide (rGOCKS - ZnO) as a Chemical Oxygen Demand (COD) Sensor by Photoelectrocatalysis
No full textThe preparation of reduced graphene oxide composite electrodes from palm shells (rGOCKS-ZnO) as a chemical oxygen demand (COD) sensor by photoelectrocatalysis has been successfully carried out. The preparation of rGOPS - ZnO electrodes by thermal reduction method and modified Hummer. The XRD results showed several peaks of rGOCKS - ZnO namely 23.287 º, 26.781 °, 29.889 °, 32.468 °, 35.109 °, 37.14 °, 39.822 °, 43.559 °, 47.927 °, and 48.537 °. SEM-EDX analysis reveals the surface of graphene sheets containing aggregates in the shape of small particles attached to graphene sheets. The results of the EDX analysis consisted of C 67.82 %, O. 19.2 %, Zn. 7.85 % and 5.13 % impurity. The CV and LSV tests showed that the rGOAK - ZnO electrode with a variation of 1 gram: 0.3 gram had a good response to the oxidation process under visible light. The profile tests of these organic dyes (methylene blue) in concentrations of 0.5 ppm, 1.0 ppm, 2.0 ppm, and 3.0 ppm were applied by Multi Pulse Amperometry (MPA). The performance of the rGOPS - ZnO electrode has been in determining the value of COD by photo electrocatalytic good sensitivity, linearity, limit of detection, repeatability, and service life. The COD value was determined using the rGOPS - ZnO electrode and obtained 2.97897 mg/LO2 close to the theoretical value
Coagulant Capacity of Moringa (Moringa Oleifera) Seed on NaCl Solution
Get PDFMoringa seeds are one of the natural coagulant ingredients that contain protein and carbohydrates that can be used in water purification, especially in reducing turbidity. This study aims to determine the level of NaCl coagulated by Moringa seed powder. The capacity or coagulation ability of Moringa seed powder is measured by the percentage of NaCl in the solution coagulated by Moringa seed powder. To achieve this purpose, several experiments have been used, namely variations in the concentration of NaCl as samples including; 0.5 %, 1 %, 3%, and 5% with treatment using Moringa seed powder as much as 1 g, 3 g and 5 g—determination of NaCl content using Flame Photometers BWB Technologies. The results of this study indicate that the optimum level of NaCl coagulated by Moringa seed powder is 3 %. The concentration can increase the effectiveness of reducing NaCl levels by obtaining a coagulated percentage value of 95.30 %
Degradation of Natural Rubber as Asphalt Mixes Modifier using UV-Ozone Light
No full textThe elastic properties of natural rubber are indispensable in improving the physical properties of asphalt mixtures. However, the long natural rubber molecule chains make it difficult to modify with other polymeric materials, so it needs to be degraded. In this study, the authors succeeded in degrading natural rubber using a combination of UV light and ozone with the addition of an H2O2 initiator; from the FTIR data, it appears that there are peaks indicating vibrations of the C=O and –OH groups indicating that natural rubber chain termination has occurred. The addition of natural rubber to asphalt was carried out with several variations, namely 8; 10; 12; 14; 16 % (to asphalt content), from the results of the softening point and ductility test of the asphalt mixture explained that the addition of 12 % natural rubber was the most optimum mixture. This result explains that efforts to degrade natural rubber using the UV - ozone combination method can increase the optimum insertion of natural rubber into asphalt mixtures by up to 100 % from previous studies
Morphological Effect on Swelling Behaviour of Carboxymethyl Cellulose–Maleic Acid Hydrogel Modified with Kombucha Bacterial Cellulose
No full textThe incorporation of bacterial cellulose from kombucha tea in carboxymethyl cellulose / maleic acid (CMC / MA) hydrogels has been successfully conducted. This study aims to analyze the relationship between the pores on the surface of the hydrogel with their water-absorbing ability. Bacterial cellulose from kombucha (KBC) was confirmed by the spectrum of OH, C-O-C, and C-OH functional groups with FT - IR analysis. Filler KBC was added to CMC / MA hydrogel with variations in the concentration of 2, 4, 6, and 8 % wt. The CMC / MA / KBC hydrogels were characterized by swelling test, degree of crosslinking, FTIR, and SEM. The swelling results showed that hydrogels with 2 % KBC produced the best water absorbing ability up to 172 %, water absorption decreased with the increase of KBC concentrations. Furthermore, SEM image results showed that the addition of KBC affects the morphological shape and pore size of the hydrogel. Meanwhile, FTIR analysis showed that there were no major changes in the functional groups of hydrogels