Environmental and Materials
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Preparation of boron-doped diamond microelectrodes to determine the distribution size of platinum nanoparticles using current transient method
Get PDFBoron-doped diamond (BDD) microelectrodes were prepared to investigate the correlation of hydrazine oxidation current responses with Pt nanoparticle (Pt NP) size distribution. The BDD film was grown on the surface of a tungsten needle with a diameter of 25 µm. An average particle size of around 5 µm BDD crystalline was successfully synthesized using a microwave plasma-assisted chemical vapor deposition technique. The Raman spectrum confirmed the presence of diamond formation as indicated by peaks corresponding to C-C sp3 bonds, while X-ray photoelectron spectroscopy spectrum showed the presence of C-H and C-OH bonds on the surface of the BDD microelectrode. Meanwhile the Pt nanoparticles was synthesized through reduction reaction of PtCl62- solution using NaBH4 with citric acid as the capping agent. Particles size between 4.46 to 4.78 nm were observed by using TEM measurements. The BDD microelectrodes were utilized to investigate the relationship between Pt nanoparticle size distribution and the current generated from the oxidation reaction of 15 mM hydrazine in a 50 mM phosphate buffer solution pH 7.4 in the presence of 1.0 mL nanoparticle solutions. A current range of 5 and 6 nA with a noise level of 0.15 nA was observed showing a good correlation with the particle sizes of Pt NPs. Comparison was also performed with the measurements using Au microelectrodes, indicated that the prepared BDD microelectrodes is promising for the measurements of nanoparticle sizes distribution, especially Pt NPs
Synthesis and characterization silica-MB@GO-NH2 particle as fluorescence-based chlorine sensor
Get PDFIn this research, we developed a fluorescence-based sensor to determine the sodium hypochlorite concentration (NaOCl) in tap water and swimming pool water samples. The detection of NaOCl was conducted by measuring the luminescence response of analyte in the paper-based sensor modified Silica-MB@GO-NH2 material were synthesized using Hummer's and Stober's methods under UV Light irradiation. Additionally, the prepared material exposed a couple peak 2D and 2G at 2938 cm-1 and 3286 cm-1 with ID/IG ratio 0.98 using Raman characterization which appropriate with the presence of GO structure in the mixture. This result was validated by the appearance of several functional groups like Si-O-Si, NH, OH, and C-C at 1079, 1391, 1611, and 3457 cm-1, respectively. Moreover, the existence of Si-O-Si bond indicates that the silica-MB interaction was perfectly formed, which plays the main role to absorb ultraviolet light that is used as sensor probe. The morphology of particles depicted an aggregated formation of spherical structure with 288 nm particle size, indicating the existence of silica-coated methylene blue. In this work, the paper-based sensor modified Silica-MB@GO-NH2 can detect the NaOCl species with concentration range 10-150 µM (R2 = 0.9757), a detection limit at 2.60 µM and quantification limit at 7.88 µM. Furthermore, this developed sensor has stable measurement with recovery performance 3.65%-6.67% for tap water and 0.05%–0.14% for swimming pool water. This result indicates that the prepared sensor can be potentially applied to calculate the hypochlorite species in the aquatic environment
Study of levofloxacin electrochemical sensors on screen-printed carbon electrodes
Get PDFLevofloxacin (LEV) is a type of fluoroquinolone antibiotic that usually used for treating the bacterial infection. The released of LEV in environment may impact a significant risk to the ecosystems. Thus, a fast and sensitive sensor device is required. In this work, the detection of LEV is carried out using a screen-printed carbon electrode (SPE). The measurement methods used were square wave voltammetry and cyclic voltammetry. The limit of detection and limit quantitation were 4.34 µM, 14.4 µM, respectively. The relative standard deviation was obtained at 5.4%. The %recovery results obtained using screen printed electrode in drug, milk, and wastewater were in the range of 95-110%. The validated method was successfully applied to detect the levofloxacin and resulted in a sensitive and efficient measurement
Synthesis of gold nanoparticles with allicin to modify boron-doped diamond surface for oxygen sensor applications
Get PDFModification of surface of boron-doped diamond (BDD) film with gold nanoparticles (AuNPs) was carried out to increase its catalytic activity for an application as an oxygen sensor. Allicin was isolated from garlic by salting out extraction technique, and then used as the capping agent to synthesize AuNPs as it has a double bond structure that could be reacted to attach the BDD surface under UV light radiation. An average size of AuNPs at around 46,00 ± 9,06 nm was obtained, while the modification of the BDD surface by the synthesized AuNPs indicated that the surface of BDD could be covered by gold at around 0.6 % (w/w). Investigation of the AuNPs-modified BDD as a working electrode for the oxygen reduction by using cyclic voltammograms in 0.1 M phosphate buffer solution pH 7 observed a current peak at around -0.45 V (vs. Ag/AgCl). The current of this peak linearly increased proportionally to the dissolved oxygen concentrations (R2=0.9986). Moreover, a limit of detection of the dissolved oxygen of 0.12 ppm and limit of quantity 0.41 ppm could be achieved with excellent stability at 6.86% RSD with 6 repetitions and sensitivity at 19.086 μA/ppm indicated that the modified BDD is promising for applications as an oxygen sensor
The effect of lime leaf extract (Citrus aurantifolia) through drinking water on the chemical and physical quality of broiler meat
Get PDFThis study aims to investigate the impact of supplementing lime leaf extract (EDJ) in broiler chickens' drinking water on both the chemical and physical qualities of their meat. A total of 128 New Lohmann MB 202 strain broiler roosters were subjected to the same basal feed regimen but received distinct drinking water treatments over a 35-day rearing period. The drinking water treatments included plain water without additives (negative control; T0), water supplemented with 50 ppm Tetracycline antibiotics (positive control; T1), water enriched with 15 ml/liter EDJ (T2), and water infused with 30 ml/liter EDJ (T3). The basal diet consisted of corn and soybean flour, with a crude protein content of 22.01% and a metabolic energy level of 3113.12 kcal/kg. Feed and drinking water are provided ad libitum during the rearing period. The parameters observed in this study were the chemical and physical quality of the meat, which included variables: moisture content, ash content, protein content, fat content, pH value, water holding capacity, cooking loss, and tenderness. The data obtained were then analyzed for variance (ANOVA) using a one-way Complete Randomized Design based on a P value of less than 5%. The findings of the study indicated that the supplementation of EDJ through drinking water did not produce significant alterations in water content, protein content, fat content, cooking loss, or tenderness of the broiler meat. However, a notable outcome was observed: the addition of 30 ml/liter of EDJ to the drinking water led to a substantial increase in water holding capacity (P<0.05) while simultaneously reducing the meat's pH value (P<0.05). These results suggest that EDJ supplementation has the potential to enhance the physical quality of broiler meat, primarily by increasing water retention and decreasing pH values, which can contribute to improve meat texture and juiciness
Diversity analysis of moray eel (muraenidae) on artificial reef structure in mengiat beach, Nusa Dua, Bali
Get PDFoai:ojs2.journal-iasssf.com:article/62Optimal coral growth has a positive impact on increasing biodiversity. This can be observed through the increase in the number of marine species as the transplanted coral reefs age. One natural indicator in coastal ecosystems is the presence of moray eels. Within the coral reef ecosystem, the diversity of moray eels as natural predators belonging to the category of reef fish can serve as an indication of a healthy and balanced ecosystem. The method used in this research is visual counting or visual observation of several species of marine eels on three different major installed reef star media, as part of coral reef restoration efforts. The data collection locations include three points of reef star media installation: BTN, Coral Garden, and Cluster 5. The water conditions in these locations, such as salinity, temperature, pH, and conductivity, indicate the adequate quality to support coral reef restoration efforts. In this study, five species of marine eels frequently encountered in the three data collection locations identified as: Echidna nebulosa, Gymnothorax thyrsoideus, Gymnothorax fimbriatus, Gymnothorax pictus, and Gymnothorax richardsonii. The highest abundance and diversity were found in Coral Garden, followed by Cluster 5, with BTN being the lowest
Electroreduction of carbon dioxide (CO2) with flow cell system using tin-modified copper foam electrode
Get PDFIn this study, modification of the copper foam (Cuf) electrode with tin (Sn) was carried out with the electrodeposition method for application in CO2 electroreduction. Characterization using SEM EDX, FTIR, and XRD confirmed the presence of Cu2O, CuO, and SnO2 thin layer mixture on the Cuf/Sn electrode. The electrochemical characteristics of the electrode were examined by using the cyclic voltammetry (CV) technique. Under optimized conditions, electrochemical reduction of CO2 in a flow cell system. At the optimum condition of CO2 reduction in a flow cell system (flow rate of 75 mL/min and –0.6 V vs Ag/AgCl applied potential), the Cuf/Sn electrode exhibited a remarkable 75.79% with an 8.84 µmol/h formic acid production rate. In a comparable experiment, the Cuf/Sn flow system revealed a twofold improvement in the faradaic efficiency compared to the batch system and a threefold increase compared to the unmodified Cuf electrode in the flow system. Stability tests demonstrated consistent performance up to the 4th cycle, followed by a decline in the 5th cycle, potentially indicative of surface deterioration. The elevated performance is attributed to the synergistic effect of the Cu-Sn oxide layer, reinforcing the catalyst’s potential for efficient electrochemical CO2 reduction to formic acid
Study of the sea urchins (echinoidea) influence on the coral reef communities in the Nusa Dua Bali conservation area
Get PDFCoral reef ecosystems are crucial for marine ecosystems as they support various other marine organisms. Sea urchins, such as Diadema setosum and Echinometra mathaei influence the coral reef communities by consuming algae that disrupt coral growth. This study aims to determine reef star coral media quantity, identify the dominant coral species at three points (BTN, Coral Garden, and Cluster 5) in Nusa Dua Beach, and assess the influence of sea urchins on coral reefs. The sampling method used was Purposive sampling, and visual observations which were conducted from June 27 to June 30, 2022. Results showed the varying sea urchin populations, with Acropora sp. and Pocillopora sp. dominating at BTN, Acropora sp. and Pectinia sp. at Coral Garden, and Acropora sp. at Cluster 5. The findings suggest that sea urchins play a key role in maintaining coral reefs by consuming macroalgae and supporting coral survival
Carbon-coated nickel foam for hypochlorous acid sensor
Get PDFThe electrochemical detection method of hypochlorous acid (HOCl) using carbon foam electrodes have been successfully developed. The carbon foam was prepared from carbon-coated nickel foam which is synthesized using a hydrothermal-carbonization method. SEM characterization indicated that the optimum synthesis of carbon-coated nickel foam has been achieved on the 4th layer coating process with an expected spherical structure, while characterization using FTIR and Raman spectroscopy confirmed the formation of graphitic material with D band and G band characteristics. An electroactive surface area of 0.0236 cm2 was achieved. Cyclic voltammetry of HOCl in 0.1 M phosphate buffer solution pH 6.0 showed the best current response for HOCl reduction occurs at a potential of -0.3 V (vs. Ag/AgCl). Further detection of HOCl using amperometry technique in the concentration range of 2-200 μg/mL showed good linearity with sensitivity of 9.112 mA/µg/L and an estimated detection limit of 1.96 µg/mL. Good repetition is indicated by the RSD value of 2.499 % (n=5). This developed sensor also showed good selectivity in the presence of interference compounds, such as FeCl2 and CuSO4. Besides, the determination of HOCl in tap water has been successfully conducted and generated a comparable result with the UV-VIS method (3.30 µg/mL hypochlorite). The results indicated that the developed sensor is promising for the detection of HOCl in environmental applications
Spatial and temporal study of estimating carbon stocks distribution of mangrove forest in coastal area of Teluknaga, Tangerang
Get PDFCoastal mangrove forests play a crucial role in balancing carbon emissions in the atmosphere as they are a significant carbon store. Previous studies have shown that mangroves can absorb carbon four times more efficiently than terrestrial tropical forests. Unfortunately, the massive development and land use changes in Teluknaga District's coastal areas threaten these ecosystems' existence. To address this concern, efforts are being made to increase conservation, including estimating carbon stock. The aim of this study is to analyze the spatial distribution of biomass and carbon stock of mangrove forests in Teluknaga between 2016-2022 based on vegetation indices such as ARVI, EVI, and SAVI. Sentinel-2 was calculated into ARVI, EVI, and SAVI vegetation indices to model biomass. Statistical correlation analysis was also used to determine the best vegetation index to model biomass in the coastal area of Teluknaga District. This study found that the ARVI vegetation index had the best correlation (R = 0.60) for modeling biomass, with an RMSE value of 36.67 kg/pixel. Most mangrove forests in the coastal area of Teluknaga District showed an increase in biomass and carbon stock between 2016-2022, with significant growth in Muara and Lemo villages' mangrove forests, which is in line with an increase in the area and density of mangrove forests