Jurnal Riset Kimia
ISSN / EISSN: 1978628X / 24768960
Published by: Universitas Andalas
Total articles ≅ 259
Latest articles in this journal
Jurnal Riset Kimia, Volume 13, pp 226-235; https://doi.org/10.25077/jrk.v13i2.555
Silver nanoparticles (AgNPs) are silver metal particles with nanoscale size. In the scale, they generate different properties compared to the original particle or material. AgNPs can be synthesized in several ways, one of which is through chemical reduction. This method is accelerated by heating, usually using conventional heating. However, the heating takes time, so it is less effective for application. In this study, AgNPs were synthesized by chemical reduction with sodium citrate as a reducing agent accompanied by microwave irradiation to speed up the synthesis process. The resulting AgNPs were then applied to cotton fabric as an antibacterial agent. The reaction lasted for 6 minutes, much faster than using conventional heating. The synthesized particles have an average size of 56.2 nm and are stable for up to 41 days of storage. The AgNPs then can be applied to cotton fabric and inhibit the growth of S. aureus and P. aeruginosa bacteria with a Minimum Inhibitory Concentration of 70%.
Jurnal Riset Kimia, Volume 13, pp 163-177; https://doi.org/10.25077/jrk.v13i2.501
The synthetic chemicals is a common substance used to extend the shelf life of postharvest fruit. But it can have health impact. The use of edible coatings from natural ingredients has begun to be developed. Modification of aloe vera gel by guava leaf extract as the edible coating to increase guava fruit shelf life has not been reported yet. Guava fruit coated by several compositions of aloe vera gel and guava leaf extract have been carried out. Observations on physichochemical in fruit on the days 0, 3, 6, 9, 12 and 15 were evaluated. The best quality found on guava fruit treated with the compotition of aloe vera gel:ethanol guava leaf extract: CMC:glycerol (90: 5:0.25: 0.5) on the day 15. It had a weight loss of 9.88%, a spoilage of 3.33%, the decrease of water content 11.61%, titratable acidity 0.5%, total antioxidant 1.08 mg AA/g FW, total phenolic 0.51 mg GAE/g FW, and increase of total dissolved solids 3.01 oBrix. This result was significantly better than the uncoated fruit. It can be concluded that guava leaf extract can be used to maintain the physicochemical properties during storage.
Jurnal Riset Kimia, Volume 13, pp 130-137; https://doi.org/10.25077/jrk.v13i2.485
A study on the effect of S doping and K+ adsorption to the electronic properties of graphene has been conducted by DFTB (Density Functional Tight Binding) calculation. The supercell of 40 x 40 x 1 configured from the 4x4x1 unit cell of graphene was optimized. The calculation shows that the Fermi level of graphene shifted from -4.67 eV into -3.57 eV after S doping. In addition, the S presence caused the formation of gap within the Dirac K of valence band and conduction band. Meanwhile, K+ charge distribution was dominantly occurred within the S-graphene than the graphene.
Jurnal Riset Kimia, Volume 13, pp 216-225; https://doi.org/10.25077/jrk.v13i2.503
Obesity is a major public health problem in developing countries and is a significant risk factor for metabolic disorders. Microalgae Scenedesmus dimorphus (S. dimorphus) contains bioactive compounds such as pigment function as antioxidants, and omega-3 and omega-6 PUFAs have potential as nutraceuticals. The study aimed to evaluate the lipid profile and liver function after the administration of S. dimorphus in obese mice. The research design uses mice which are divided into 6 groups; Group 1 (G1) normal control, G2 control Obesity, G3 treatment with Orlistat, G4 treatment S. dimorphus (0.25mg/g BW), G5 treatment S. dimorphus (0.5 mg/g BW) and G6 treatment S. dimorphus (0.75 mg/g BW) each group consisted of 5 mice and 21 days of observation time. The parameters observed were lipid profile and liver function of mice. Based on the results of the study, the effective dose for treating obesity is a dose of S. dimorphus 0.75 mg/g (BW) can reduce cholesterol, triglycerides, and LDL levels, respectively 67.7 mg/dl, 49.2 mg/dl, 10 , 2 mg/dl, and increased HDL, 68.32 mg/dl compared to control of obesity (G2), respectively 108.7 mg/dl, 139.1 mg/dl, 20.6 mg/dl and HDL 60, 28 mg/dl, this dose is also effective for improving the function of blood pressure by reducing AST and ALT 15.6 U/L and 18.8 U/L, respectively, compared to the obesity group (G2), which is 26.6 U/L, and 29,7 U/L. Based on the results of the study it can be concluded that S. dimorphus is useful for anti-obesity for mice (Mus musculus).
Jurnal Riset Kimia, Volume 13, pp 138-151; https://doi.org/10.25077/jrk.v13i2.506
This study aimed to investigate the effects of storage time and dilution of black liquor (BL) from Acacia mangium kraft pulping on the characteristics of isolated Lignin. Lignin isolation was carried out by 1 and 2 steps of isolation using HCL 1M to precipitate Lignin, diluted before isolation. Isolated Lignin was analyzed for its acid-soluble Lignin (ASL), insoluble acid lignin (AIL), functional groups by FTIR, solubility in dioxane and NaOH and thermal properties. The effect of BL storage time was also evaluated on the characteristics of the Lignin produced. The results suggest that the longer BL is stored, the higher the lignin yield. When compared to the isolation approach without dilution, the dilution process produced a higher yield and ash content up to 84% and 21%, respectively. Without dilution, the AIL isolated was lower than the dilution during BL storage. The longer the storage duration, the higher the lignin purity. Compared to two-step lignin isolation, dilution treatment in single-step isolation improves yield and purity. The thermal stability of lignin isolation without dilution (184 ⁰C and 167 ⁰C for 1 and 2 steps, respectively) was higher than that of isolated Lignin with dilution (154.8 ⁰C and 160.9 ⁰C for 1 and 2 steps, respectively), according to thermal study. Both lignin isolates with and without dilution have comparable functional groups, as shown by FTIR spectra. Due to the high yield and purity of isolated Lignin, BL dilution could be a viable alternative in lignin isolation from BL. Moreover, the properties of isolated Lignin are also influenced by BL storage.
Jurnal Riset Kimia, Volume 13, pp 208-215; https://doi.org/10.25077/jrk.v13i2.557
The thermal properties of the double perovskite SmBa0.5Sr0.5Co2O5+δ (70%) + SDC (30%) have been investigated as potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFC). This study also includes the oxygen content and electrochemical performance of long-term tests carried out to evaluate the electrochemical stability. Cathode powder is fabricated by a simple and relatively inexpensive solid-state reaction. Oxygen content decreased gradually from room temperature to 800oC by 18.3%. Doping 30% SDC into SBSC oxide can reduce the thermal expansion coefficients (TEC) value from 19.80 x 10-6 (K-1) to 18.17 x 10-6 (K-1) or a decrease of 8.23%. The activation energy (Ea) identified by the electrochemical impedance spectroscopy (EIS), low field (LF), and high field (HF) techniques were 125.3 kJ mol-1, 60.6 kJ mol-1, and 62.5 kJ mol-1, respectively. The SBSC73|SDC|SBSC73 symmetric cell test for 96 hours at 600oC showed an increase in the average polarization resistance value of 0.30% h-1. The cathode grains are evenly distributed with a size of 2-3 µm and tend to be porous. These results exhibit that SmBa0.5Sr0.5Co2O5+δ (70%) + SDC (30%) is a promising cathode material for IT-SOFCs.
Jurnal Riset Kimia, Volume 13, pp 198-207; https://doi.org/10.25077/jrk.v13i2.551
Caraway (Carum carvi L.) is one of the oldest medicinal plants found in various countries such as West Asia, North Africa, Pakistan, India, North America, Northern Europe, Iran, Russia, and Indonesia. This plant has been use for traditional medicines to treat digestive disorders, flatulence, colic in infants, headaches, coughs, hypertension, eczema, pneumonia, diabetes, scabies, mouthwash and as an antiseptic. This plant is reported to contain around 1-9% essential oil in the seeds with various components and potential as bioactive compounds. In this study, essential oils were isolated from caraway seeds and determined their chemical content as well as their antimicrobial and toxicity. Isolation of essential oils was carried out by hydrodistillation and analysis of the chemical components of the isolated essential oils was carried out using the Gas Chromatography-Mass Spectrometry (GC-MS) method. The results of the GC-MS analysis showed the presence of 35 compounds with four main compounds, namely carvone (62.54%), limonene (23.39%), and trans-dihydrocarvone (8.20%). The antimicrobial activity test was carried out using the disc diffusion method, which showed strong activity against Staphylococcus aureus at a concentration of ≥75%, and against the fungus Candida albicans. The results of the toxicity test using the Brine Shrimp Lethality Test (BSLT) method showed that caraway seed essential oil was low toxic against Artemia salina Leach shrimp larvae with an LC50 value 568.3292 mg/L.
Jurnal Riset Kimia, Volume 13, pp 152-162; https://doi.org/10.25077/jrk.v13i2.517
Consuming food containing high level of purin leads to increase uric acid in the blood which, in turn, cause hyperuricemia or high uric acid level. The use of improper allopurinol for hyperuricemia medication that doesn’t follow medical doctor’s prescription can give harmful side effect. It is therefore required to use an alternative safe medication. Uncaria cordata (Lour.) Merr.) is a plant often used for medication of high levels of blood uric acid by communities in Pasar Ngalam village, Bengkulu Province. This research aims to evaluate the potency of extracted compounds from Uncaria cordata (Lour.) Merr.) in reducing uric acid of Mus musculus suffering from hyperuricemia. This research is a laboratory experiment using completed random design. As many as 25 Mus musculus were divided into 5 groups of treatment: PN = normal treatment, PA = treated with allopurinol, P1 – P3 = treated with extracted compound of Uncaria cordata (Lour.) Merr.) with a dose of 5.3 mg/30gBW (P1); 10.6 mg/30gBW (P2); and 21.2 mg/30gBW (P3). In order for Mus musculus to suffer from high uric acid level, potassium oxonate-induced hyperuricemia was injected. The result showed that extracted compounds of Uncaria cordata (Lour.) Merr.) using ethanol exhibited antihyperuricemia proven by decline of uric acid level of Mus musculus from hyperuricemia on each given dose. Decreasing uric acid level for each given dose of ethanol extract (5.3 mg/30gBW, 10.6mg/30gBW and 21.2mg/30gBW) was not significant different (0.541; with a ³0.05).
Jurnal Riset Kimia, Volume 13, pp 178-187; https://doi.org/10.25077/jrk.v13i2.509
Tannins from tamarind seed husk were extracted and applied as a biomordant for natural dyeing process of Timor woven fabrics. Tannins were extracted using hot distilled water, qualitatively and quantitatively analyzed and applied as a color binder to the woven fabrics. The color characteristics of woven fabrics with tannins were compared to the woven fabrics that mordanted with Al2(SO4)3 and FeSO4 at the concentration of 15%. Tamarind seed husk tannins are in the form of a brownish red powder. Qualitative and quantitative tests showed that tamarind seed coat contained condensed tannins with a total concentration of 70.08 ± 0.14%. Tannins identification by FT-IR spectroscopy showed a strong band absorption at 3369 cm-1 for O-H group and a weak absorption at 1721 cm-1 due to the C=O stretch. A strong absorption at 1611-1608 cm-1 was observed for C=C group in the aromatic ring and was strengthened with a strong absorption at 1520 cm-1, C-O-C group which is specific for condensed tannins was observed at 1285 cm-1. Application of 15% tannin as a biomordant without natural dye on Timor woven fabric produced a brownish red color, while the use of 15% tannin and turmeric dye showed a brownish yellow color. Tannin exhibited a better color fastness than metalic mordants in natural dyeing of Timor woven fabrics.
Jurnal Riset Kimia, Volume 13, pp 188-197; https://doi.org/10.25077/jrk.v13i2.520
Feun Kase seed extract can be used as a corrosion inhibitor on zinc metal in HCl solution. This study aims to determine the secondary metabolites contained in Feun Kase seed extract, inhibition efficiency and corrosion rate, and surface morphology of zinc metal in the inhibition process using Feun Kase seed extract in HCl media. Feun Kase seed extract was obtained by maceration extraction using methanol. In the corrosion inhibition test, the concentration and temperature variations were carried out to determine the effect on the inhibition efficiency and the corrosion rate per year. The results showed that the methanol extract of Feun Kase seeds contained secondary metabolites of alkaloids, flavonoids and saponins. The optimum inhibition efficiency was obtained at an inhibitor concentration of 30 ppm of 82.70% with a corrosion rate of 5.80 mm/year and at a temperature of 35ºC of 75.84% with a corrosion rate of 7.28 mm/year in the test of increasing the temperature of the corrosion medium. The morphological analysis of the zinc plate using the SEM instrument showed that the zinc plate without surface treatment (not immersed in HCl media) was still smooth. This is indicated by the surface of the zinc plate which is still clearly visible because it has not been affected by the corrosion medium. The zinc plate when immersed in HCl media, is damaged which is indicated by the presence of pores or holes. Zinc plate when added with Feun Kase seed extract in HCl media, the zinc surface was damaged but the damage was not as prominent as in HCl media without using an inhibitor.