Jurnal Akademika Kimia
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Analysis of Student’s Creative Thinking Ability on Colloid Material
Get PDFThis study aimed to describe students' creative thinking skills in Colloid material in class XI SMA Negeri 7 Palu. The type of this research was descriptive quantitative. The research sample consisted of 30 students. The data collected were in the form of test results for the ability to think creatively, which were obtained through giving essay questions as many as five items that expert validators had validated. The results of every item were on average 74.4% of fluency, while flexibility, elaboration, and originality, respectively, were 75.83%, 53.76%, 61.66%, and 47.5%. Based on the analysis of the four indicators above, it can be found that the students' creative thinking ability on colloid material in class XI SMA Negeri 7 Palu was in the medium category. Students need to be accustomed to working on questions that can require them to think creatively during learning to develop their ability in creative thinking and connect theory with everyday life
Development of Hollow Fiber Liquid Phase Microextraction Method for Determination of Diazinon Residues in Vegetable Samples
Get PDFAn extraction method based on a combination of hollow fiber liquid-phase microextraction with high-performance liquid chromatography diode array detector (HF-LPME HPLC-DAD) has been developed and demonstrated to analyze pesticide residues in vegetables. This study aims to determine the optimum extraction conditions and validation performance of this method. Diazinon pesticide was selected as the target model analyte. HF-LPME is performed by stacking microliter organic solvent droplets through an HPLC syringe coated with polypropylene hollow fiber by directly dipping it into the sample solution and stirring it during the extraction process. Finally, the organic solvent was put into an HPLC syringe at the end of the extraction. Then, it was injected into the HPLC-DAD at the wavelength of 247 nm. Several important extraction parameters have been optimized. The optimization results showed the type of organic solvent of n-hexane, the length of the hollow fiber of 1.5 cm, the volume of the sample solution of 20 mL, and the stirring speed of 600 rpm. The validation performance obtained a limit of detection (LoD) of 0.10 mgL-1, limit of quantification (LoQ) of 0.33 mgL-1, percent recoveries of 99.88%, a coefficient of variation of 3% (n=15), and the enrichment factor of 19,982 times. Under optimal conditions, the developed method was applied to extract diazinon in vegetable matrix samples using the spiking method. Mustard green was selected as a model matrix sample. From the research, the percentage recoveries of diazinon obtained in the mustard green matrix sample are 98.80% - 100.41%
Adsorption of Fe(III) Ion in Tablets Fe Supplement by Black Tea Dregs and its Application in Inorganic Chemistry Learning
Get PDFThe study of the adsorption of Fe(III) ion in Fe supplement by black tea dregs has been done. This study aims to investigate: (a) the Adsorption ability of Fe(III) ion in Fe supplement by black tea dregs (b) the Analysis result of Fe(III) amounts in a sample of Fe supplement when using black tea dregs. Several parameters were analyzed, such as; water and ash contents of the adsorbent, the optimum time, and the concentration of ion Fe(III) with tea dregs in a buffer medium (pH 4,8). The analysis of sample solution concentration of Fe(III) in this study using Genesys spectrophotometry at 590 nm. The result showed that the water and ash contents were 3.03 % and 0.9 %, respectively. Small percentages indicate that the adsorbent has met the standard (SNI) 06–3730-1995. The time and concentration optimum adsorption of Fe(III)-tea dregs were 60 minutes and 100 mg/L, respectively. The result of the adsorption ability of Fe(III) ion in Fe supplement by tea dregs was 70.4% with the adsorption concentration of ion Fe(III) were 7.07 mg/L. The research results obtained can be used as teaching materials for inorganic chemistry learning, and as a reference for new materials in the field of coordination chemistry and materials
Development of Mouthwash Formulations based on Natural Ingredients with Antimicrobial Activity
Get PDFDental and oral health problems are one of the problems that need attention. The oral cavity is colonized by various microflora and some bacteria, so it is necessary to develop additional oral cleaning methods besides brushing teeth. Mouthwash with natural ingredients, such as a combination of chitosan and Eucalyptus grandis, is the right choice. Chitosan is a type of water-soluble chitosan characterized using FT-IR. Meanwhile, Eucalyptus grandis was isolated using the Stahl method to obtain its essential oil. Mouthwash was evaluated through organoleptic testing, pH, viscosity, and antimicrobial testing. The most optimal formula is formula III, with an inhibition zone diameter of 11.9 ± 1.5 mm for Streptococcus mutans bacteria, 12.8 ± 0.9 mm for Staphylococcus aureus, and 12.2 ± 0.15 mm for Candida albicans
The Effect of Surfactants on Separation of Light Rare Earth Metals using Emulsion Liquid Membrane Method: Review
Get PDFRare earth metals (REM) are scarce elements and are only found in the form of complex compounds of phosphate and carbonate. REM consists of 17 elements classified into light REM, medium REM, and heavy REM. This article is focused on lightweight REM, which is widely applied in various industrial fields. Many REM applications are increasing the demand for high-purity and bulk REMs. However, REM has almost the same physical and chemical properties, making it difficult to separate. Therefore, the separation of REM is interesting to study with various methods, one of which is Emulsion Liquid Membrane (ELM). ELM is developing a solvent extraction method involving three phases: the external phase, the internal phase, and the membrane phase. The key to the success of ELM lies in the stability of the emulsion, which is very dependent on the type and concentration of surfactants, so in the ELM process, it is necessary to choose the right concentration and type of surfactant. Therefore, this article was made to know the effect of surfactants such as span-80, span-85, and T154 in separating light REM using the ELM method
Antioxidant Activity Test of Ethanol Extract of Ripe and Young Cocoa Pods (Theobroma Cacao L.)
Get PDFAntioxidant activity test of Ethanol Extract of Ripe and Young Cocoa Pod Skin (Theobroma Cacao L.) with DPPH (1,1-diphenyl-2-picrylhydrazyl) using UV-Vis spectrophotometer has been carried out. This study aimed to determine the IC50 value of the ethanol extract of ripe cocoa pods and young cocoa pods (Theobroma Cacao L.). The mature and young cocoa pods were extracted using absolute ethanol solvent and tested for their antioxidant activity using DPPH (1,1-diphenyl-2-picrylhydrazyl). The concentration variations used in the ethanol extract of ripe cocoa pods and young cocoa (Theobroma Cacao L.) were 20 ppm, 40 ppm, 60 ppm, and 80 ppm. The results showed that the IC50 values of the ethanol extract of ripe and young cocoa pods were 76.094 ppm and 91.884 ppm, respectively. Meanwhile, the IC50 value of vitamin C compared was 63.519 ppm. Based on the IC50 value data above, it can be seen that the antioxidant activity of the ethanol extract of young cocoa pods and ripe cocoa pods are potent antioxidants
Ethanol Extract Antioxidant Activity Test of Tembelekan (Lantana camara L.) using 1,1-diphenyl-2-picrylhydrazyl (DPPH) Reagent
No full textThe plant prickly lantana (Lantana Camara L.) contains alkaloids, flavonoids, saponins, tannins, and triterpenoids and has the potential to be used as a natural antioxidant source. The research objective is to determine the IC50 value for the antioxidant activity of prickly lantana leaf extract. Prickly lantana leaves were macerated in a 96% ethanol solvent for 3x24 hours. Phytochemical analysis of prickly lantana leaves revealed that the leaves contained alkaloids, flavonoids, saponins, and tannins. This antioxidant activity test was performed using the reagent 1,1-diphenyl-2-picrylhydrazyl (DPPH), whose absorption at 517 nm was measured using a UV-Vis spectrophotometer, and by varying the sample concentration after the addition of prickly lantana leaf extract. The concentrations of prickly lantana leaf extract used varied from 20 ppm to 40 ppm, 60 ppm, and 80 ppm. The positive control was vitamin C at the same concentration variation, and the negative control was DPPH solution dissolved in 96% ethanol. The results showed that the IC50 of prickly lantana leaf extract was 164.639 ppm, while vitamin C had an IC50 of 18.754 ppm
Analysis of Students' Learning Difficulties in Physical Chemistry: Perspective on Various Sub-Variable
Get PDFThis study aims to identify student learning difficulties in physical chemistry lectures. The subjects are 61 students in the chemistry education study program from two different classes. The research method used is mixed. Data were obtained by using instruments in the form of structured and unstructured questionnaires. Based on the results of the data analysis, several student learning difficulties were identified. Based on unstructured questionnaires, students' learning difficulties in physical chemistry material based on internal factors are caused because students find it difficult to do calculation problems, formulate derivation, and use many formulas. Based on external factors, namely the learning method used. Students prefer learning that is carried out face-to-face in a class by doing a lot of practice questions connected with applying formulas to questions and in everyday life. 55.7% of students in the medium category in learning disorder, 72% of students in the high category in learning disability, 65.5% of students in the medium category in learning dysfunction, 57% of students in the medium category in slowly learner, and 54% of students in the medium category in lower achiever. According to many students, physical chemistry is difficult. In addition, some of the causes of physical chemistry being considered difficult are confusion in analyzing questions, and learning conducted online during the Covid-19 pandemic is considered less effective. Students expect the learning method used to provide many examples and practice questions
Equilibrium and Adsorption Kinetic Study of Metal Ni(II) using Persimmon Tannin Gel
Get PDFHeavy metal concentration exceeding the threshold amount is hazardous to the environment, so it needs some treatment. The study aimed to know the capacity and kinetics of adsorption. This study used the adsorption method to remove the heavy metal ion Ni(II) using persimmon tannin gel. Influences of time contact, pH, and ion concentration in the adsorption process were also investigated. Results showed optimum adsorption at 60 minutes of time contact and pH 5. Variation of concentration made the adsorption decrease as metal ion Ni(II) concentration increased. The maximum adsorption capacity was 23.14 mg/g by using pseudo-second-order adsorption kinetic model
The Use of Augmented Reality Based-Learning Media to Reduce Students' Misconceptions
Get PDFThe research objective is to determine whether using AR molecules as a learning medium can assist students in reducing their misconceptions about molecular materials. It was pre-experimental research with a one-group pre-test-post-test design. The average level of validity of the learning media used, according to the findings, is 70.3% ("valid" classification). The average reduction of misconceptions (MC) among students using learning media for the entire concept is 12.8 %, 9.2 % for students who do not understand the concept (DUC), and 22.0 % for students who understand the concept (UC). Based on these findings, it is possible to conclude that AR molecule-based learning media can be used to reduce students' misconceptions about molecular materials