Jurnal Akademika Kimia
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The Utilization of Acid as a Color Stabilizer in the Extraction of Anthocyanins from the Lakum (Cayratia trifolia L.) Peel
Get PDFAnthocyanins are a group of natural dyes (pigments) that give many colors to plants’ leaves, flowers, and fruits. Anthocyanins are generally acidic and more stable under acidic conditions. One of the plants that contain anthocyanin is the lakum (Cayratia trifolia L.) fruit ripe with a blackish-purple color. This study aimed to determine the best type of acid used to extract anthocyanins from the lakum fruit peel. The extraction process was carried out by maceration method using 96% ethanol solvent acidified with three types of acids, HCl 1%, citric acid 3%, and acetic acid 3%, with an average level of anthocyanin obtained of 283.88, 220.70, and 226.55 mg/L, respectively. This study indicated that the best acid used to extract anthocyanin from the lakum fruit peel with the highest total anthocyanin results was by adding HCl 1%
Development of Nanocomposite Films with Durian Peel Nanocrystalline Cellulose
Get PDFThis research aims to synthesize and characterize nanocomposite film with nanocrystalline cellulose (NCC) durian peel waste filler. Nanocomposite film was prepared by adding NCC with concentrations of 0%, 1%, 3%, 5%, and 7% to each mixture of chitosan and guar gum. Characterization of nanocomposite film includes tensile strength test, elongation test, water-resistance test, and biodegradability. Nanocomposite film with NCC 7% showed a tensile strength value of 21.988 MPa; elongation of 10.3%; and experienced degradability of 4.05 mg/day, besides the characterization of the equal distribution of NCC in the chitosan-guar gum matrix was proven from the SEM results
The Analysis of the Honesty and Responsibility Characters of Chemistry Education Study Program Students on Examinations
No full textHonesty and responsibility should be a principle held by students. But, there are still problems of dishonesty and irresponsibility of students during exams. This study aimed to analyze the honesty and responsibility character of chemistry students during exams. The research samples were 39 students. Data were collected by observation and interviews technique, by using observation and questionnaires sheets. Data were analyzed by using descriptive statistics. The results showed that the honesty and responsibility of chemistry students were in the sufficient category where the percentage of honesty and responsibility of students based on the observation sheets was 43.6% and 49%, respectively. While the questionnaire responsibility students were 46.2% and 43.6%, respectively
The Utilization of Aleorites Moluccana Active Charcoal as Absorbent of Lead Metal in Used Oil
No full textCandlenut (Aleurites moluccana) shell is a waste produced from the processing of the plants having a fairly hard texture. This study aimed to determine the optimum weight and contact time for the candlenut activated carbon which can absorb lead metal in used oil. Analysis of lead levels was carried out using atomic absorption spectropometry (AAS). Determination of the optimum weight and contact time of activated charcoal was carried out on various weight of 3 g, 6 g, and 9 g, as well as various times of 1, 2, and 3 hours, respectively. The results show that the optimum weight and contact time of activated charcoal are 9 g for 3 h with the percentage of lead concentration absorbed of 90.716%
Analysis of Lycopene Content and Antioxidant Activity Test of Katokkon Chili Extract (Capsicum chinense Jacq)
Get PDFThis study aimed to determine lycopene contents and the antioxidant activity of katokkon chili extract. The extraction process of katokkon chili used the maceration method with the mixture of n-hexane : acetone : ethanol (2:1:1). The concentrated extract of katokkon chili was obtained through the evaporator process at a temperature of 40 ˚C. The analysis process used a UV-Vis spectrophotometer in which the absorbance reading was at λ = 472 nm. The average content of lycopene in katokkon chili extract was 1.457 mg/100g. Testing the antioxidant activity of katokkon chili extract used the DPPH (2,2-diphenyl-1-picrylhydrazyl) method with positive control the vitamin C. The absorbance readings for the antioxidant activity test were at λ = 517 nm. The test results showed that the antioxidant power of katokkon and vitamin C extracts in reducing DPPH free radicals had a similar result which was equally strong. The IC50 value for chili katokkon extract was 13.84 mg/L, and the IC50 value for vitamin C was 5.78 mg/L, so it can be concluded that chili katokkon can be an alternative source of natural antioxidants to replace vitamin C
Conceptual Changes of Students in Thermodynamics in Physical Chemistry Course Through The Implementation of Blended Learning
Get PDFThis study aims to determine the conceptual changes of students after participating in learning with a blended learning approach on Thermodynamics material. This research is a type of pre-experimental (pre-experimental design) with a One Group Pretest-Postest Design. The blended learning approach is applied using the Problem Based Learning model. The research sample was Class C Odd Semester 2019/2020 students which consisted of 34 students who programmed Physical Chemistry courses. The instrument used is a two-tier multiple choice test which includes concepts in Thermodynamics material which is equipped with a valid CRI. The blended learning approach is one approach that can be used that facilitates student activities in utilizing ICT through the delivery of materials, discussion of task completion, and training in the search for teaching materials on Thermodynamics material. The results showed that misconceptions still occur in every concept of Thermodynamics. The average reduction of misconceptions (MC) is 11.2%, the increase in the number of students to knowing concept (KC) classically is 19.2%, and the decrease in the number of students unknowing concept (UKC) is classically 8.1%. Students' conceptual changes to the material of Thermodynamics are still low. Students are required to understand well the content of the material related to basic concepts, mathematical equations (formulas), and the applicative forms of concepts in everyday life in accordance with the characteristics of the thermodynamic material
Determination of Iron (Fe), Zinc (Zn) Levels and Organoleptic Tests in Coconut Pulp Flour
Get PDFCoconut pulp is a by-product of coconut milk which contains high protein and good nutrition. This study aimed to determine the iron (Fe) and zinc (Zn) levels in coconut pulp flour using atomic absorption spectrophotometry and determine the characteristics of coconut pulp flour using organoleptic tests. The results showed that iron (Fe) level was 44.075 mg/kg and zinc (Zn) was 24.2 mg /kg. The organoleptic characteristics of the pulp were white and brownish for the dry powder, coconut-scented, a powder-shaped texture, and normal taste. The highest percentage level of hedonic scale for each criterion was 64% preferred for color, 52% preferred for aroma, 48% preferred for texture, and 52% preferred for taste. Based on these results, coconut pulp can be an alternative local food to meet iron and zinc needs for humans. The processing of coconut pulp as food can be used as a substitute flour in making bread, cakes, cookies, and other food preparations
Misconceptions Reduction of Science High School Students on Buffer through Remedial Using Conceptual Change
No full textThis study aimed to analyze the results of the reduction of misconceptions among SMA Negeri 5 Palu students on the buffer material using the conceptual change learning strategy. This research is a type of pre-experimental research with a research design that is One group pretest-posttest design. This study contained one experimental group, namely students whose learning outcomes did not reach the minimum completeness criteria (MCC), then given a pre-test to determine the initial state of the experimental group, then given treatment, and given a post-test. Testing student misconceptions data using CRI. The results showed that the average percentage of students, who knew the concept (KC), did not know the concept (DKC), and misconceptions (MC) before the application of conceptual change learning strategies were 38.1%, 45.2%, and 16, respectively. 6% and the percentage of students knowing the concept (TC), not knowing the concept (NKC), and misconception (MC) after the application conceptual change learning strategies respectively 87.4%, 12.6%, and 0%. In conclusion, the average percentage reduction in misconceptions of grade XI IPA SMA Negeri 5 Palu on the buffer through remedial using the conceptual change learning strategy was 16.6
Adsorption Capacity of Activated Charcoal Made of Rice Husk on Cd(II) Metal Ions
Get PDFRice husk is one of the by-products of the rice milling process that can be used as activated charcoal to adsorb metal ions. This study aimed to determine the optimum pH and adsorption capacity of Cd(II) ions by activated charcoal made of rice husk using the Atomic Absorption Spectrophotometry (AAS) method. Determination of the optimum pH adsorption of activated charcoal was carried out by varying the pH of 2, 3, 4, 5, 6, 7, and 8. Based on the analysis results of the optimum pH for metal adsorption, pH 7 with percent absorbed metal 99.94%, while adsorption of Cd(II) ions using activated charcoal was carried out with several variations of concentration to study adsorption isotherm. The adsorption isotherm model of activated charcoal adsorption followed the Langmuir isotherm model. The results of this analysis obtained that the maximum adsorption capacity (qmax) of Cd(II) ions were 2.068 mg Cd/g
Application of Learning Models of Concept Attainment and Problem Based Learning Against High School Students' Creative Thinking Ability on Redox Material
Get PDFCreative thinking is thinking to determine the new relationships between things, such as finding new solutions to a problem, finding new systems, and finding new artistic forms. This study aimed to analyze students' creative thinking ability by applying concept attainment and problem-based learning models in the redox material of class X SMA Negeri 9 Palu. This type of research was pre-experimental with the static group pre-test post-test design. This study used 2 classes, namely class X MIA 1 as experimental class 1 (n = 22) and class X MIA 2 as experimental class 2 (n = 22). Data analysis of students’ creative thinking was performed using the test given after learning (post-test). The results of this study indicated that the percentage value of the average creative thinking of the experimental class 1 students was 74.5% with the high category and the achievement of aspects of creative thinking of students with the percentage from highest to lowest in the originality aspect were 76.7%, flexibility aspect was 74.1%, and the fluency aspect was 72.7%. While the average percentage of experimental class 2 was 76.6% with the high category and the achievement of aspects of creative thinking of students with the highest to lowest percentage of the fluency aspect was 84.5%, the originality aspect was 75.1%, and the flexibility aspect was 70.2%. The results of this study can be concluded that the application of the Concept Attainment and Problem Based Learning models were very good in creative thinking skills of students class in SMA Negeri 9 Palu on Redox material