Jurnal Pendidikan Kimia
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Preparation and Characterization of White Mineral Trioxide Aggregate (WMTA) using Silica from Rice Husk Ash
Get PDFThe preparation of white mineral trioxide aggregate (WMTA) was carried out using a solid technique using silica (SiO2) from rice husk ash (RHA). The process included extraction of SiO2 from RHA, the effect of SiO2 composition on material characterization and material compressive strength. Silica was extracted from RHA using NaOH and washed with distilled water until it was sodium-free. WMTA was prepared by mixing extracted SiO2, Bi2O3 commercial (18.0%), CaO commercial and Al2O3 commercial (2.0%), and the mixture was heated at various temperatures (900, 1000, 1100 oC). MTA was made from two variation silica sources: RHA and extracted silica, and each source varied at 15, 20, and 25% by weight, while the CaO content was adjusted. Characterization was carried out by FT-IR spectrophotometry, XRD and UTM for compressive strength measurement conducted after cementation for a day. The RHA extraction results were obtained from sodium-free SiO2. The peak showed the success of WMTA preparation at wave number 910 cm-1 in FTIR spectra, indicating the presence of C-S-H and C3S, C2S, and C3A bonds both before and after thermal treatment in XRD data. The highest compressive strength test after cementation for one day (3.21±0.13MPa) was given by WMTA using RHA, heating at 900 oC, and the percentage of CaO and SiO2 were 60% and 20%, respectively
Measurement of Ambient Ozone Concentration using Passive Sampler
Get PDFMeasurement of ozone concentration in ambient air was carried out using the passive sampling method in Cipedes, Bandung, from 2012 – 2020. Sample analysis was done using ICS 1500 Dionex ion chromatography. The results showed a fluctuating concentration from 2012 -2020 with the highest average value in 2015 of 29.94 g/m³. The monthly pattern shows the highest ozone concentration in September and the lowest in December; this condition was related to the intensity of rainfall that can clean ozone in the atmosphere. The seasonal pattern showed in the dry season ozone concentration is relatively higher than in the rainy season. A comparison of passive and continuous sampling was made to see the performance of the passive sampler showing a similar pattern with a correlation coefficient of r = 0.48. This difference in value was related to the absorption of ozone gas in the passive sampler absorbing filter and the meteorological factors
The Effect of Integrated Instagram and Tiktok Learning Media With PBL Learning Model on Increasing Student Learning Outcomes on The Topic of Qualitative Analysis of Cation
Get PDFInformation and communication technology development demands a transformation of education, especially in fulfilling innovation in learning media. Learning media is an urgent means of teaching and learning chemistry. Students' skills can be developed by increasing motivation and collaboration through digital technology. This research aims to determine the effect of the integrated Instagram (IG) and TikTok with the PBL learning model on student learning outcomes in qualitative analysis courses. The research method used was a quasi-experimental research design with a Pretest-Posttest Control Group design. The sample used came from a 2nd-year undergraduate student, Department of Chemistry, the State University of Malang, which consisted of 4 classes, two control classes with 44 students and two experimental classes with 50 students. Data analysis used preliminary tests and hypothesis testing. The preliminary test of the research data showed that the data were not normally distributed, so the hypothesis test used the Mann-Whitney test. The results of the hypothesis test show the Asymp value. Sig. (2-tailed) of 0.021 (0.021<0.05), it can be concluded that the use of integrated IG and TikTok learning media with the PBL learning model can increase student learning outcomes of 2nd-year undergraduate students on qualitative analysis of catio
Highly Selective and Sensitive Determination of Hg(II) Ions Using Ion Selective Electrodes (ISE) Coated with the BEC4ND1 Ionophore as Membranes
Get PDFThe research on the highly selective and sensitive determination of Hg(II) ions using ion-selective electrodes (ISE) coated with the BEC4ND1 ionophore as a membrane has been successfully carried out. ISE was designed using the membrane composition of the [(BEC4ND1 ionophore : PTCPB : DOS : PVC) (3 : 2 : 60 : 35 % w/w)]. The ESI-BEC4ND1 ionophore has good characteristics where it shows a sensitivity value of 29.933 mV/decade in the Hg(II) ion concentration range of 10-9 - 10-1 M with a limit of detection (LoD) of 10-7 M. The response time obtained is in the range of 4 - 8 minutes with a relative standard deviation (RSD) of 0.548. The ESI-BEC4ND1 ionophore also shows the average value of selectivity coefficient (Kij) < 1. These results indicate that the presence of Zn(II), Cd(II), and Pb(II) ions as interfering ions in the analyte solution does not affect the performance of the ESI-BEC4ND1 ionophore in detecting Hg(II) ions. The ESI-BEC4ND1 ionophore that has been developed shows good selectivity, sensitivity, stability, and reproducibility, so the ESI-BEC4ND1 ionophore is promising to be used as a Hg(II) ion detector in the environment
The Adsorption Performance and Characterization of Activated Charcoal of Bone Char Against Acid Orange 7
Get PDFThe use of Acid Orange 7, a synthetic dye, in the textile industry harms the environment because it is carcinogenic. This research aims to remove the Acid Orange 7 dye dissolved in the water. This study used cow bone charcoal as an alternative adsorbent made by the carbonization method. In addition, the batch adsorption method was applied in the bleaching process of the synthetic dye waste, Acid Orange 7. Several tests, such as SEM, EDX, BET, XRD, and FTIR, were carried out to determine the characteristics and ability of activated charcoal from cow bones as an adsorbent for acid Orange 7 dye waste. Other organic adsorbents, such as graphene oxide and activated carbon, were used to compare the results. Bone char adsorption Acid Orange 7 62.2% efficiently. The adsorption efficiency of activated carbon is 79.8%, while graphene oxide has an adsorption rate of 89.4%. The findings revealed that bone char could be used to cure synthetic dye waste, Acid Orange 7, as an alternative. Additional treatment
Analysis of The Nature of Science in Chemistry Textbooks on The Topic Acid-Base Equilibrium: a Content Analysis
Get PDFThis study was conducted to describe aspects of the Nature of Science (NoS), its presentation, and its scores from chemistry textbooks used in Surakarta on acid-base equilibrium topics. This research was qualitative research with a content analysis method. Three high school chemistry textbooks for class XI from different publishers were analyzed by two raters based on ten aspects of the NoS. Interrater reliability was calculated using the cohen Kappa. The results showed that a scientific law is the only aspect that is not included in the three textbooks A, B, and C. Other aspects of NoS contained in textbooks A and B are slightly different from textbook C. Textbooks A and B contain the same aspects: empirical, inferential, creative, theory-driven, tentative, scientific methods, scientific theories, social science, and the application of science in socio-cultural, while textbook C does not contain tentative and theory-driven aspects. The implicit-correct category dominates the presentation of the NoS aspects in the textbooks. Presentations with implicit-incorrect and explicit-incorrect categories were not found in this study. The scores obtained by textbooks A, B, and C based on the presentation of aspects of NoS are 9, 11, and 8, respectively, of the maximum total score that can be obtained of 30. It did not show the presence of the NoS aspects explicitly, correctly, consistently, and completely, so textbooks containing NoS explicitly are required. Teachers also need to guide students in interpreting NoS in learning.
Combination of Corn Waste and Egg Shell as Zn Metal Adsorbent with Batch System
Get PDFThis study aims to determine: the ability of corn cobs and eggshells as Zn metal adsorbents, functional groups of corn cobs and eggshells adsorbent, what isotherm patterns occur in the adsorbent corn cobs and eggshells in adsorbing Zn metal, the optimum ratio and optimum mass of the adsorbent composition of corn cobs and eggshells in Zn metal adsorption, the optimum contact time for adsorbent corn cobs and eggshell in adsorbing Zn metal, the optimum concentration of adsorbate to be adsorbed by corn cobs and eggshell adsorbents. This study used an experimental method in the laboratory. characterization includes functional groups using FTIR, and test the effectiveness of adsorbents using the AAS instrument. Kinetic analysis of adsorbent by adsorption isotherm with Langmuir isotherm, Freundlich isotherm, Temkin isotherm, and dubinin-radushkevivh isotherm. The results showed that: Corn cobs and eggshells can be used as zinc metal adsorbents; in the corn cobs adsorbent, there is a functional group -OH at wave number 3415,15 cm-1 and in the eggshell, there is a bent vibration of calcium carbonate at wave number 3400,65 cm-1, the adsorption process of Zn metal by adsorbent corn cobs and egg shells follows the Langmuir isotherm pattern (chemical adsorption), the comparison of the optimum composition and mass of the adsorbent corn cobs and eggshells in Zn metal adsorption are 1:2 and 0,15 grams with Zn metal adsorbed by 80,4571%, the optimum contact time for the adsorbent corn cobs and eggshells in adsorbing Zn metal is 90 minutes with the percentage of absorbed Zn metal concentration is 75,5957%, and the optimum concentration of adsorbate for adsorbed by corn cob and eggshell adsorbents is 1 mg/L with adsorbed Zn percentage of 82,8377%
Comparison Study of Ionic Gelation and SNEDDs Method in the Preparation of Cocoa Peel Extract Nanoparticles as Antibacterial Against Klebsiella pneumonia
Get PDFCocoa peel is the primary waste from chocolate production. It contains flavonoids that can inhibit the growth of Klebsiella pneumonia which causes chronic bronchitis. This study aims to obtain cocoa peel extract nanoparticles for antibacterial caused by K. pneumonia. The isolation of flavonoids was done using the maceration method in 96% ethanol. Phytochemical and Thin Layer Chromatography (TLC) analyses have been used to identify the active compounds contained in the extract. Flavonoid levels have been investigated using UV-Visible spectrophotometry. The preparation of nanoparticles from cocoa peel used ionic gelation and Self-Nano Emulsifying Drug Delivery System (SNEDDS). The nanoparticle obtained has been analyzed for particle size and polydisperse index. In vitro test was carried out to determine the antibacterial activity of K. pneumonia. Identification of active compounds using a UV-Visible spectrophotometer showed that cocoa peel extract contained flavonoids of 6.33%. Nanoparticle preparations using the SNEDDS method were more optimal than the ionic gelation method, with particle sizes 135.2 nm (4%), 156.1 nm (12%), and 235.3 (20%). Based on the in vitro test, nanoparticles from cocoa peel extract were able to inhibit the growth of K. pneumonia
Revealing Chemical Misconceptions Through The Microteaching Process in The Era of The Covid-19 Pandemic
Get PDFUnlimited access to information during the Covid-19 pandemic allows students with limited basic knowledge to experience misconceptions. Misconception happens because there are no adequate filters for many students, and there is no guarantee of content validity by information providers. This research aim is to show the misconceptions experienced by pre-service chemistry teachers. This research is a qualitative design with the case study method. This research used a naturalistic paradigm framework. The study was conducted for one semester of the 2020/2021 academic year for 16 meeting courses. The research participants consisted of pre-service chemistry teachers who were taking microteaching courses. Researchers are the main instrument. Data were collected through observation, focus group discussions (FGD), and document media analysis. The results showed six chemical misconceptions. Five misconceptions are non-proposition statements, and one is a chemical representation. Two of the six misconceptions found are resistant. Misconceptions that originate from written media and structured writing are difficult to overcome. Based on the study results, misconceptions about prerequisite concepts need to be eliminated before learning a new concept. Pre-service chemistry teachers need to use learning resources from the author's work according to their field of expertise. They have gone through the review and validation stages to avoid misconceptions
A Green Synthesis of Acetyl Eugenol by Sonochemical Method and Potential as Anti-Inflammatory In-Vitro
Get PDFClove oil is an essential oil from the clove plant (Syzygium aromaticum) containing eugenol compounds. One of the properties of eugenol is as an anti-inflammatory with a mechanism of inhibition of prostaglandin synthesis and neutrophil chemotaxis. Several derivatives of eugenol have active compounds that have been developed into new drug compounds as anti-inflammatory such as acetyl eugenol (4-allyl-2-methoxyphenyl acetate). This study aims to determine the % yield of acetyl eugenol produced from synthesis using ultrasonic 0.0323 mol of eugenol added to Erlenmeyer, and 0.25 mol of 10% sodium hydroxide was added. The mixture was put in a sonicator for 15 minutes and heated at 600C. Then, 0.0974 mol acetic anhydride was reacted with DCC, added to the mix and sonicated with time variations (60, 80, and 100 minutes). The chemical structure was elucidated using FTIR, ATR, and GC-MS. The synthesized % yield is 32.75%. Based on the interpretation data from FTIR, 3405 cm-1 is an O-H group (free phenol), 1405 cm-1 is an alkene group (C=C) aliphatic, and 1560 cm-1 is an aromatic compound with the presence of a C=C aromatic bond. The presence of the (C-O) ether group is indicated in the wave number at 1301 cm-1. The C=O ester bond in the ester group is shown at 1700 cm-1. GC-MS shows that the synthesized compound has a molecular ion with m/z = 206. According to the molecular weight of acetyl eugenol of 206 g/mol, it can be concluded that acetyl eugenol was successfully synthesized. The most stable ionic fragment, 37, has a molecular weight of m/z = 164. The activities of anti-inflammatory, acetyl eugenol compounds at 400 concentration ppm get % inhibition of 32.20%.