Jurnal Akademika Kimia

Degradation of Natural Rubber as Asphalt Mixes Modifier using UV-Ozone Light

2023-04-04T04:42:17+00:00

The 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.

Potential Antioxidant Activity in Octyl p - Methoxycinnamate (OPMC) Compound Synthesized by Sonochemical Method

2022-12-18T23:55:26+00:00

Octyl 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)

2024-07-30T06:53:35+00:00

This 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 %).

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

2024-07-30T05:42:56+00:00

The 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 rGO_PS- 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 rGO_PS- 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 rGO_PS- ZnO electrode and obtained 2.97897 mg/LO2 close to the theoretical value.

Morphological Effect on Swelling Behaviour of Carboxymethyl Cellulose–Maleic Acid Hydrogel Modified with Kombucha Bacterial Cellulose

2023-05-02T02:14:10+00:00

The 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.

Effect of Avocado Leaves Extract on Creatinin and Urea Levels in Rats Induced NaCl and Prednison

2023-04-11T02:41:35+00:00

Creatinine and urea are metabolic waste substances excreted by the kidneys. Kidneys excrete metabolic waste substances. Renal dysfunction is associated with the increased level of creatinine and urea in the blood. The ethanolic extract of avocado leaves (Persea americana Mill.) contains flavonoid compounds, alkaloids, tannins, saponins, and steroids which act as antioxidants and antihypertensive. It is known to reduce creatinine and urea levels in the blood. The animal model was divided into five groups: normal control, negative control (CMC - Na 0.5 %), and avocado leaves ethanolic extract group with doses of 75, 150, and 250 mg/kg BW rats. All groups except the normal control group were induced by oral administration of NaCl solution 2 % and prednisone suspension 1.5 mg/kg BW rats for 21 days and following treatment by oral administration for 7 days based on its group. Flavonoid compounds of avocado leave ethanolic extract identified as 5,7-di-OH-dihydroflavonol. Results show Kruskal - Wallis test between groups (p < 0.05) is significantly different. Concluded that administration of avocado leaves ethanol extract at doses of 75, 150, and 250 mg/kg BW rats might reduce creatinine levels, while avocado leaves ethanol extract at a dose of 250 mg/kg BW rats could reduce urea levels.

Synthesis of Fluorescent Carbon Dots from Soybean Residuals Using Hydrothermal Method

2023-03-20T05:03:40+00:00

Soybean residuals are biowaste composed of carbon chains and amine groups bounded in peptide linkages. The component was identified through FTIR analysis which showed the vibration of the diamide bond (N=C=N) at wave number 2132cm^-1. Owing to the existence of these components, soybean has the potential to be used as a precursor to synthesize carbon nano-material, such as Carbon Dots (C - Dots). In this study, the synthesis of C - Dots material from soybean residuals was carried out using the facile hydrothermal method at a temperature of 200 ^oC for 6 hours. Afterward, the as-synthesized C - Dots were analyzed for their optical property, structure, and morphology. Based on the analysis of the UV - Vis and photoluminescent spectra, C - Dots exhibited absorbance peaks of 292 nm and 301 nm in the UV light region, and fluorescence emission peaks of 468 nm, with blue luminescence characteristics. The observation was supported by the morphological analysis using the HR - TEM, C - Dots exist in a spherical shape with an average particle size of 3.467 nm and a lattice distance of 0.363 nm. Besides, the C - Dots exhibited a good quantum yield of 28.15 %. From the results of the analysis, it is known that the synthesis of C - Dots material has been successfully carried out with particle size < 10 nm.

Synthesis of Silver Nanoparticles using Gandaria Seeds Bioreductor

2024-07-30T06:36:32+00:00

The silver nanoparticles (NPP) are synthesized with the chemical reduction method by using a water extract bioreductor of gandaria seed (Bouea macrophylla G.) which acts as a reducing precursor, in this case, AgNO₃ Ag⁺ is reduced to AgO. The concentration of AgNO₃is made between 0.5 mm and 1 mm. The characteristic of NPP is unstable, so a modification is needed with and without the addition of PVA 1 %. The process of NPP shaping is monitored by observing the uptaken of UV - Vis when the color changes occur. The high NPP concentration of AgNO₃ has higher absorbance and is wider if compared to the lower AgNO₃ concentration. The result of this research based on the absorbance value and the wavelength showed the NPP synthesized without the addition of PVA 1 % (b/v) is wider. The addition of PVA 1 % (b/v) provides better stability and maintains the absorbance of spectrum changes from day to day. The maximum uptaken of UV-Vis from NPP AgNO₃ 0.5 mm by using green synthesis and 1 mm without adding PVA are 0.946 and 0.980, respectively. However, NPP with the addition of PVA has 0.968 and 0.978 absorbance. The best concentration of NPP produced was 1 mm AgNO₃.

Antioxidant Activity Test of Ethanolic Extract of Tempuyung Leaves (Sonchus Arvensis L.) Based on Linoleic - Thiocyanic Method

2023-05-08T04:40:53+00:00

Free radicals chemically have free electrons, free radicals tend to take electrons from other molecules, which then give rise to abnormal compounds. Antioxidants are substances that can delay or prevent free radical oxidation reactions in lipid oxidation. Tempuyung leaves contain flavonoids which can act as antioxidants. This research aims to determine the antioxidant activity of the ethanol extract of tempuyung leaves using the linoleic-thiocyanate method and to determine the total phenolic and total flavonoid content using the Folin-Chiocalteu reagent method. The results showed that the ethanol extract of tempuyung leaf extract had antioxidant activity. Percentage of antioxidant activity of 10 % extract = 82.91 %, 5 % extract = 70.07 %, 1 % extract = 57.70 %, Vitamin E 1 % = 70.2 1%. Total phenolic content of 10% extract = 0.48 %, 5 % extract = 0.25 % and 1 % extract = 0.04 %. The total flavonoid content of the extract is 10 % = 0.14 %, 5 % extract = 0.07 %, and 1 % extract = 0.02 %. Pearson correlation test showed that phenolic and flavonoid compounds greatly influenced the antioxidant activity of the ethanol extract of tempuyung leaves.

Analysis of Water-Soluble Vitamin Change in Tomato (S.lycopersicum) Due to Ozonolysis of Imidacloprid Degradation Treatment by Using Spectrometry and HPLC Method

2023-04-14T02:34:10+00:00

In this study, the effect of imidacloprid degradation on the reduction of water-soluble vitamins in tomatoes was observed, such as ascorbic acid, pyridoxine, niacin, and thiamine. Analysis was carried out using a spectrophotometer and high-performance liquid chromatography. The degradation method with ozone water for 15 minutes showed a better result than the ozonolysis method because the decrease in levels of water-soluble vitamins is smaller. The percentage decrease of each water-soluble vitamin in the ozone water method is ascorbic acid by 17.103 %, pyridoxine by 6.723 %, niacin by 2.781 %, and thiamine by 0.333 %. Ozone water methods also produce a high percentage of degradation which is 90.56 %.