Jurnal Kimia Sains dan Aplikasi
ISSN / EISSN : 1410-8917 / 2597-9914
Current Publisher: Institute of Research and Community Services Diponegoro University (LPPM UNDIP) (10.14710)
Total articles ≅ 248
Latest articles in this journal
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 409-413; doi:10.14710/jksa.23.11.409-413
Curcuma xanthorrhiza Roxb (temulawak) is a native Indonesian plant; ethnobotanically, it can facilitate breast milk, body fresheners, stomach lozenges, and seizure medications. Temulawak contains essential oils, curcuminoids, and xanthorrhizol. Curcuminoids and xanthorrhizol have potential as antioxidants. Antioxidants in the body are useful for preventing oxidation reactions caused by free radicals, both from body metabolism and external factors. Curcuminoids are difficult to dissolve in water and have a very low bioavailability. Combining curcuminoids with oil can increase the absorption of curcuminoids into the systemic system. The low solubility and bioavailability can be overcome by combining temulawak rhizome extract and red fruit oil. Pandanus conoideus Lamk (red fruit), ethnobotanically, effectively prevents blindness, intestinal worms, skin diseases, and increasing stamina. Red fruit contains vitamin C, vitamin E, flavonoids, and β-carotene, potentially as antioxidants. Each sample of Curcuma and red fruit, as well as a mixture of Curcuma and red fruit samples, were tested for their antioxidant activity using the DPPH method (1,1-diphenyl-2-picrylhydrazyl). The ethanol extract of temulawak rhizome has intense antioxidant activity because it has an IC50 of 55.21 ppm. Red fruit oil has feeble antioxidant activity because it has an IC50 of 2604.77 ppm. The 1: 1 ratio between red fruit oil and the ethanol extract of temulawak rhizome has weak antioxidant activity because it has an IC50 of only 1568.24 ppm. Meanwhile, the 1:10 ratio of red fruit oil and ethanol extract of temulawak rhizome has robust antioxidant activity because it has an IC50 of 19.85 ppm. It is concluded that the addition of oil to the ethanol extract of Curcuma can increase antioxidant activity.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 403-408; doi:10.14710/jksa.23.11.403-408
This study aimed to obtain the most efficient Dye-Sensitized Solar Cell (DSSC) using yellow sweet potato extract (Ipomoea Batatas L.) as a dye sensitizer, with acetic acid, polyethyleneglycol (PEG), and polyvinylalcohol (PVA) as TiO2 binding solution. This research includes the preparation of TiO2 paste with variations: 4 g TiO2 plus 2 M acetic acid (Paste-1), 3.5 g TiO2 plus 15 mL PEG-400 (Paste-2), and 0.5 g TiO2 plus 0.75 mL. PVA (Paste-3). Anthocyanin dye from yellow sweet potato was prepared and used to soak the TiO2 photoelectrode for 24 hours. UV-vis and FTIR spectra of dye solution from yellow sweet potato extract showed anthocyanin content at a maximum wavelength of 283 nm and were strengthened by the appearance of hydroxyl groups in the infrared spectra. The highest DSSC efficiency of 0.302% was obtained from PVA as a TiO2 binder, with an electric current of 0.0204 mA and an electric voltage of 338 mv.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 383-389; doi:10.14710/jksa.23.11.383-389
The effective isolation of intracellular enzymes from thermophilic bacteria is challenging because of their sturdy membrane. On the other hand, the low-cost and nontoxic method is essential for industrial food enzymes. The freeze-thaw cycles using acetone-dry ice as a frozen system was studied for efficient isolation of thermostable b-galactosidase from Geobacillus sp. dYTae-14. This enzyme has been known for application in the dairy industry to reduce the lactose content. In this study, the freeze-thaw method was performed with cycle variations 3, 5, and 7 cycles. Acetone-dry ice (-78°C) is used as a frozen system and boiling water for thawing. The b-galactosidase activity was assayed using ortho-Nitrophenyl-β-galactoside (ONPG) as substrate and protein content determined with the Lowry method. The results show that the most effective freeze-thaw is five cycles. The enzyme’s highest specific activity is 3610.13 units/mg proteins at 40-60 % ammonium sulfate saturation, with a purity value of 2.52.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 390-395; doi:10.14710/jksa.23.11.390-395
A thin layer preparation of CuO from Cu2O powder using Fehling's solution for photoelectrochemical applications has been performed. The research was focused on studying the effect of annealing temperature and the number of drops on the performance of CuO thin layer semiconductors from Cu2O powder prepared by spin coating with a rotation rate of 500 rpm for 15 seconds. The thin layers were treated with annealing with temperature variations of 300°C, 400°C, and 500°C for 1 hour and variations in the number of drops of 10, 20, and 50 drops. The CuO thin layer was tested in a photoelectrochemical process as a photocathode to split water with a simulated light of 1.5 AM (100 mW/cm2). The process of splitting water as a method of producing hydrogen energy by photoelectrochemistry is assisted by semiconductors, such as CuO, in an electrolyte solution to capture photons and drive the water-splitting reactions. Copper (II) Oxide (CuO) is a p-type semiconductor with a band gap of 1.2-2.5 eV, which can be used as a photocathode. The optimum photoelectrochemical measurement results were obtained at an annealing temperature of 400°C and 50 drops with a current density of 0.584 mA/cm2 at a potential of 0.2 V versus the Reversible Hydrogen Electrode (RHE). The results of the Scanning Electron Microscopy (SEM) analysis show that the morphology of the oxide is spherical. Energy dispersive X-ray (EDX) analysis displays that the sample contained 51.46% and 48.54% of Cu and O, respectively. The X-ray diffraction pattern (XRD) analysis shows that the oxide grain size is 44.137 nm.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 396-402; doi:10.14710/jksa.23.11.396-402
The adsorption efficiency and selectivity of activated carbon as an adsorbent for ions can be improved. One way is to convert activated carbon into surfactant modified activated carbon (SMAC). The surfactants used in this study were the anionic surfactant Sodium Lauryl Sulfate (SLS) and the cationic surfactant hexadecyltrimethylammonium bromide (HDTMA-Br). This research aims to synthesize SMAC to obtain a material with a surface charge and absorb ions better than activated carbon. This research consisted of four stages. The first step was the carbonization of rice husks using a pyrolysis reactor at 400°C for 1 hour. The second stage was carbon activation using 30% ZnCl2 and microwave radiation for 5 minutes and 400 W. The third stage was the modification of activated carbon and characterization by FTIR, SEM, SAA. The fourth stage was the adsorption of Pb cations and nitrate anions by carbon, activated carbon, and SMAC. Several variables were applied, such as the type of surfactant, time, and method of modification. There are three ways of modification: (1) method A, in which activated carbon is brought into contact with SLS then HDTMA-Br. (2) Method B in which activated carbon was contacted with HDTMA-Br then SLS. (3) Method C in which activated carbon was brought into contact with SLS together with HDTMA-Br. All variables were investigated. The results showed that the optimum time for making SMAC for both surfactants was 4 hours, the optimum concentrations of SLS and HDTMA-Br were 60 and 300 ppm, respectively. SMAC made by the C method was the most effective at adsorbing Pb2+ and NO3- with adsorption capacities of 1.376 and 0.896 mg/g, respectively. The success of SMAC synthesis was evidenced by the S=O and (CH3)3N+ groups in the FTIR spectra. The SMAC surface area is smaller than activated carbon, 14.472 m2/g, but the surface morphology is smoother and more homogeneous.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 377-382; doi:10.14710/jksa.23.11.377-382
Surfactant Modified Activated Carbon (SMAC) is a surfactant-modified activated carbon product. The surfactant used in this study was the cationic surfactant Hexadecyltrimethylammonium Bromide (HDTMA-Br). These surfactants can change the activated carbon's surface to be positively charged due to the presence of the surfactant hydrophilic groups. This SMAC is more selective in absorbing anions, which in this study is for the adsorption of nitrate anions. This research aims to prepare a new material that is superior to activated carbon in absorbing nitrate anions. This research was conducted in several stages. In the first stage, rice husk was carbonized through pyrolysis at 300°C for 10 minutes. In the second stage, carbon was activated using 30% ZnCl2 and microwaves for 5 minutes and 400 W. The third stage was modifying activated carbon by contacting or adsorbing HDTMA-Br on activated carbon. The concentration of HDTMA-Br varied at 200-400 ppm and the adsorption time was 3-7 hours. The success of the modification was measured by the efficiency of HDTMA-Br in modifying activated carbon. This is supported by the results of the characterization of FTIR, GSA, SEM, and thermodynamic parameters. The resulting SMAC was applied for the adsorption of nitrate anions, and the results were compared to carbon and activated carbon. The results indicate that the best SMAC is formed at an optimum concentration of 300 ppm, within 4 hours, with an adsorption efficiency of 97.345%. The characterization results also show that SMAC has been formed, as evidenced by the presence of a peak at a wavenumber of about 1500 cm-1, a C-N group derived from N(CH3)3 in the HDTMA-Br surfactant structure. The SMAC spectra also appeared weak peaks at the wave number 2918 cm-1, which indicated the CH2-R group stretching from the HDTMA-Br surfactant. SEM image shows that HDTMA-Br has covered the pores of activated carbon. Meanwhile, the SMAC surface area is lower than that of activated carbon. Thermodynamic parameters indicate that HDTMA-Br interacts physically with activated carbon. The adsorption capacity of nitrate anion by SMAC is 3,638 mg/g, higher than carbon and activated carbon.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 346-352; doi:10.14710/jksa.23.10.346-352
The compatibility between anode, electrolyte, and cathode in a solid fuel cell determines its performance. Research on the compatibility between fuel cell components is challenging, especially for SOFCs that operate at high temperatures. Therefore, efforts to reduce the operating temperature to become intermediate temperature SOFC (IT-SOFC) are essential to facilitate compatibility between its components. La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) has been recognized as one of the most promising cathode materials for (IT-SOFC) due to its high electronic conductivity and excellent electrical performance. While La0.8Sr0.2Ga0.8Mg0.2O3–δ (LSGM) has a high oxygen ion conductivity at low temperatures, its chemical stability is still not good. LSGM is known to have interface reactivity with other components such as NiO and LSCF in fuel cells. This study looked at the compatibility of NiO/LSGM/LSCF cells prepared by the solid chemical synthesis method. Compatibility evaluation is determined by the Thermal Expansion Coefficient (TEC) parameter using the dilatometric method, Area Specific Resistance (ASR), and TBF area morphology by Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS). While the conductivity of the cells is determined by Electrochemical Impedance Spectroscopy (EIS). NiO/LSGM/LSCF cells have good compatibility with a value of 78.05 kg-1.K.A.s3.µ2 at a temperature of 600°C. The ASR values of cells tend to decrease with increasing temperature and conductivity values at small TEC values. Based on these parameter values, delamination in NiO/LSGM/LSCF cells did not occur.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 365-369; doi:10.14710/jksa.23.10.365-369
Research on the synthesis and characterization of SiO2/ZnO nanocomposites from zinc waste and Mount Merapi volcanic ash has been carried out. The semiconductor used was ZnO using a SiO2 as the host material. The use of SiO2 was due to its high efficiency and abundant raw materials. This is because the eruption of Mount Merapi occurs regularly every four years. Apart from the abundant presence of SiO2, the source of ZnO from lathe workshop waste is also easy to obtain. The research aims to reduce the volume of zinc waste from the lathe and volcanic ash, which was not optimized. Zinc waste and volcanic ash were synthesized into nanocomposites. Then the obtained nanocomposites were characterized to determine their effectiveness in degrading various wastes. The synthesis of SiO2/ZnO nanocomposites was carried out using the sol-gel method as easy and highly effective. The method used is to transform zinc waste into Zn(OH)2. The volcanic ash was extracted with KOH to form potassium silicate (K2SiO3). Zn(OH)2, (K2SiO3) and HCl were reacted together when sonicated, then calcined at 550°C. The results showed that SiO2/ZnO nanocomposites made from volcanic ash and zinc waste produced composite sizes with a size range of 100-200 nm and a uniform circular shape. FTIR analysis results show that SiO has the peaks at wavenumbers of 993.34 and 1109.07 cm-1, while the ZnO peak is at wavenumbers of 443.63 cm-1. The XRD diffractogram of SiO2/ZnO nanocomposites shows peaks at 2θ of 30.42°, 31.56°, and 44.40°.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 338-345; doi:10.14710/jksa.23.10.338-345
Chromium (VI) in the form of chromate anions that have toxic properties needs to be overcome. This study aims to reinforce cationic sorbent quaternary amine-modified silica with magnetite (QAMS-Fe3O4) to adsorb chromate ions. QAMS prepared by reflux methylation ammine modified silica (AMS) obtained from destruction silicate from rice husk ash followed by the addition of 3-APTMS. Characterization QAMS-Fe3O4 by FT-IR showed successfully of methylation process indicated by disappearing absorbance at 1388 cm-1, and emerging absorbance at 2939 cm-1 in QAMS and QAMS-Fe3O4 indicated a transformation of N-H from -NH2 group to [-N+(CH3)3]. XRD analysis denotes 2θ = 30.15°, 35.53°, 43.12°, 57.22°, and 62.90° (JCPDS No. 00-033-0664) fathomed as a characteristic peak of magnetite. SEM-EDX reveals the homogenous topological spherical form with an average particle size 0.006 µm that is dominated by Si element (52.81%) with magnetic moment value = 34.1 emu/g. The stability test shows that this material stable in an acid condition. The adsorption of chromate ions was conducted by the SPA method. Optimal pH obtained by pH range 4-7 with more than 90% adsorbed chromate ions. Variation of increasing series flow rate from 0.05 to 1.5 mL min-1 resulted in decreased adsorbed chromate ions. The use of SPA methods offered simpler and easier handling than the batch method without overriding the adsorption process effectiveness.
Jurnal Kimia Sains dan Aplikasi, Volume 23, pp 353-359; doi:10.14710/jksa.23.10.353-359
The use of enzymes in the bio-deinking process of newspaper waste has promising potential. However, investigations on the concentration of enzyme combinations need to be carried out to obtain the optimum ratio of cellulase and laccase enzymes for the bio-deinking process of recycled newspapers. The mixture of the two enzymes at various ratios was used to remove the ink on paper pulp from used newspapers by mechanical disintegration method treatment and followed by the bio-deinking process in an incubator shaker. The characterization of functional groups, structures, and thermal properties of bio-deinked pulp paper was carried out by FTIR, XRD, DTG/TGA, and an analysis of the degree of brightness to the prepared paper. FTIR results confirmed three main components of papers, such as cellulose, hemicellulose, and lignin. The XRD results showed that the equal ratio of cellulase and laccase enzymes had an effect on a higher crystallinity index, which was 78.8% compared to those obtained from the conventional methods with a crystallinity index of 69.7%. Thermal analysis showed that the optimum combination of both enzymes contributed the most at the highest temperature where the rate of degradation decreased. Brightness analysis showed that bio-deinking had met the quality requirements for newsprint paper in SNI 7273:2008. Our findings show that the combination of cellulase and laccase enzymes at the same ratio can produce optimal bio-deinked pulp for paper fabrication with excellent characteristics in brightness, thermal, and physical properties.