Communications in Science and Technology

The effect of synthesis temperature on structural, morphological, and band gap energy of plate-like Bi4Ti2.95V0.05O12 prepared by molten NaCl/KCl salt method

Kanty Maryani — 2024-07-12

Vanadium (V)-doped Bi4Ti3O12 compound is reported to have good photocatalyst properties; however, efforts still need to improve the ability of the photocatalyst through various strategies, such as controlling the morphology and particle size. The molten salt method is one of the simple synthesis methods reported successful in synthesizing Bi4Ti3O12 compounds with plate-like/sheet morphology and reported having good photocatalyst activity. One of factor influenced to particle compound obtained by molten salt method is synthesis temperature. Therefore, in this work, V-doped Bi4Ti3O12 (Bi4Ti2.95V0.05O12) was prepared through the molten salt NaCl/KCl method at various synthesis temperatures: 700, 750, and 800?C and the effect of temperature synthesized on (a) structural (b) morphological, and (c) band gap energy were studied. These studies used X-ray diffraction data (diffractogram), scanning electron microscope (SEM) and diffuse reflectance ultraviolet-visible spectroscopy. The diffractograms showed that the target compound was successfully obtained at all temperature synthesis. The crystallographic data indicated that temperature synthesis determined the lattice parameter values. However, there are no clear trend changes that is possibly due to changes in the valence of the V atom. The synthesis temperature also causes increasing the crystallite size but does not affect the crystallinity samples. SEM images showed that all samples had plate-like/sheets morphology and the particle size became larger at higher temperature. It indicated that the particle growth rate was faster than nucleation rate. Meanwhile, the result of Kubelka-Munk calculation showed that all samples had relatively same band gap energy value (Eg(1) was ~ 2.90, and Eg(2) was ~1.85 eV.

Ultrafiltration membranes for dye wastewater treatment: Utilizing cellulose acetate and microcrystalline cellulose fillers from Ceiba Pentandra

Romario Abdullah — 2024-07-12

Dye hurts the threat of human health problems and environmental pollution. Microcrystalline cellulose (MCC) based membrane is a good material to be used as an dye separation membrane for having the high hydrophilicity of the membrane. It has been successfully isolated from kapok (ceiba pentandra) with characteristic X-ray diffraction patterns and FTIR absorption peaks, which corresponded to the typical peaks of cellulose. The ultrafiltration membrane was made up of a cellulose acetate matrix created using the phase inversion method. Characterization results indicated that the inclusion of MCC derived from kapok led to a reduction in the contact angle from 65 to 52^o, and an increase in membrane porosity from 82 to 85%. In the separation of dye, the composite membrane incorporating MCC filler demonstrated superior performance compared to the membrane lacking MCC, manifesting in an elevated water flux from 43 to 84 L/m².h and methylene blue (MB) rejection from 64 to 99%. The use of MCC as a filler in cellulose acetate membranes can enhance the characteristics and performance of the membrane in MB separation.

Synthesis and characterization of hydroxyapatite/SiO2/gelatin composites as bone scaffold candidates

Indah Wahda — 2024-07-12

This study aims to determine the characteristics of hydroxyapatite/SiO₂/gelatin composites to fulfil the bone scaffold standards. XRF analysis showed that limestone has a high CaO content of 92.89%, allowing it be used for hydroxyapatite synthesis. The wet precipitation method was used to synthesize hydroxyapatite; meanwhile, the freeze-drying method was used to synthesize the hydroxyapatite/SiO₂/gelatin scaffold. FTIR analysis confirmed the characteristic peaks, which indicated the presence of compounds of hydroxyapatite (OH^- and PO₄^3-), SiO₂ (Si-OH and Si-O-Si), and gelatin (N-H, C-H, and C=O). XRD analysis showed 98.1% hydroxyapatite phase and 1.9% SiO₂ phase and SEM analysis showed a scaffold pore size of 155-218?m, optimal for cell attachment. Furthermore, mechanical testing resulted in a compressive strength of 1.71 MPa and porosity testing resulted in a porosity of 75%. This characterization showed the potential use of hydroxyapatite/SiO₂/gelatin composites as bone scaffolds. This research can enable further development of scaffold materials in the field of tissue engineering.

Characterization and electrochemical properties analysis of reduced graphene oxide from corncob carbon as an electrode candidate: Synthesized using modified Hummers method

Eka Anggriani Odja — 2024-07-12

This research aims to synthesize and characterize reduced graphene oxide (RGO), as well as analyse its electrochemical properties. The synthesis of RGO material from corn cobs went through several stage: carbonization, oxidation and reduction. The synthesis of RGO used a modified Hummer method, and was reduced using the reducing agent ascorbic acid. The synthesized RGO was then characterized using Fourier Transform Independent Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). Electrochemical analysis using the cyclic voltammetry method, the specific capacitance value obtained showed that RGO had a higher capacitance value than GO. The research results showed that carbon from corn cobs, which has not been utilized optimally, can be synthesized as a basic material for making RGO as a quite promising material.

Study in the impact of quaternized graphene oxide (QGO) composition as modifier on the chemical, physical, mechanical, and performance properties of polyvinylidene fluoride (PVDF)-based nanocomposite membrane

Ashabul Kahfi — 2024-07-12

Polyvinylidene Fluoride (PVDF) membranes were modified with quaternized graphene oxide (QGO) synthesized from graphene oxide and quaternized ammonium groups. PVDF/QGO membranes were created by blending PVDF and 0.01-0.05 g QGO via phase inversion. FTIR confirmed the successful QGO incorporation. PVDF/QGO membranes exhibited increased mechanical stiffness. Meanwhile, SEM revealed asymmetric morphology with surface and internal pores. AFM showed the membrane with 0.05 g and QGO had the highest surface roughness of 101.2 nm, which increased filtration area and flux. QGO improved hydrophilicity through hydroxyl and quaternary ammonium groups, enhancing water flux up to 1208 Lm^?2h^?1 for 0.05 g QGO. Cu²⁺ rejection increased to 75% for 0.05 g QGO membrane due to chelation and adsorption effects. PVDF/QGO membranes displayed bacterial growth inhibition, unlike pristine PVDF. The inhibition zone diameter increased with more QGO, indicating improved antibacterial activity. Overall, this study demonstrated that QGO improved PVDF membranes' hydrophilicity, antibacterial properties, and mechanical strength.

On the characterization of EM emission of electronic products: Case study for different program modes

Tito Yuwono — 2024-07-12

The characterization of the EM emissions for electronic products is crucial to ensure that the emissions have met the requirements of the EMC standards. For this, a more comprehensive testing is required to get more meaningful results. While, the emergence of non-stationary emissions is a challenge to obtain valid analysis results. So far, non-stationary EM emissions is not considered and treated properly in the emission analysis. This paper presents a new method for the analysis of EM emissions from electronic devices as a case study by testing three different program modes (scenarios) of Intel Galileo board. These program modes were designed to vary processing intensity in its memory and processor. A comparison was also made between the actual situation (the presence of non-stationary signals) and the hypothetical situation with the assumption that all emissions were stationary. As a result, a significant difference was observed when the analysis considered the real scenario of a non-stationary emission. The ratio between the average autocorrelation using the proposed algorithm and the average correlation by ignoring the non-stationarity of the emission signal was 113.6 times. The study concludes that different program modes produce the different characteristics of EM emissions, making some of them non-stationary. Hence, we strongly suggest the consideration of the non-stationarity of the EM emissions in characterizing complex electronic devices.

Simultaneous tartrazine-tetracycline removal and hydrogen production in the hybrid electrocoagulation-photocatalytic process using g-C3N4/TiNTAs

Saddam Husein — 2024-07-12

This study aimed to investigate the removal of tartrazine dye & tetracycline antibiotic and hydrogen (H₂) production simultaneously through the hybrid electrocoagulation-photocatalytic process using g-C₃N₄/TiO₂nanotube arrays (TiNTAs) nanocomposite. The g-C₃N₄/TiNTAs was used as the photocatalyst. The melamine as the precursor of g-C₃N₄ was varied to obtain the optimal loading on the removal of tartrazine dye & tetracycline antibiotic and hydrogen (H₂) production simultaneously. The integrated acrylic photoreactor was equipped with two 250-W mercury lamps. The nanotubular morphology of TiNTAs and nanostructure features of g-C₃N₄/TiNTAs were examined using FESEM/EDX and HR-TEM/SAED. The XRD patterns indicated the composition of TiNTAs, confirming the presence of anatase and rutile crystalline phases. UV-Vis DRS also showed a redshift in the composite absorbance and a reduced bandgap with g-C₃N₄introduction. The results showed that when tartrazine and tetracycline were treated simultaneously, tartrazine was more dominantly degraded compared to tetracycline. In mixed pollutant system condition, the H₂ production increased by 17.0% and 41.1% compared to single pollutant system of tartrazine and tetracycline, respectively. The photocatalyst used in the hybrid process was the g-C₃N₄/TiNTAs (3 g) which provide the optimum H₂ production.

Block-based optimization for enhancing reversible watermarking using reduce difference expansion

Aulia Arham — 2024-07-12

In recent years, reversible watermarking has emerged as a promising technique that safely embeds data in digital images without compromising their originality. This method is particularly useful for sensitive images such as military, art, and medical images, where each pixel contains important information requiring authentication. Researchers have been attempting to develop this method further to increase payload capacity while maintaining visual quality and low computational complexity. In this study, we developed a reversible watermarking with block-based optimization based on Reduced Difference Expansion (RDE) applied to 3×3 pixel blocks, allowing for the embedding of 8?bit data. Based on experimental results from tests conducted on 2 common images and 3 medical images, our method could consistently achieve a payload capacity of up to 0.8924 bpp with a PSNR of 41.077 dB while maintaining good visual quality across various image categories, outperforming previous approaches.

The renewable energy research contribution of Tanzania: A review

Buruhan Haji Shame — 2024-07-15

The central objectives of this study are to locate existing research on renewable energy, examine the energy policy of Tanzania, assess bibliometric factors, determine the direction of the current research, and comprehend unexplored research topics. This exploration focuses on a bibliometric-based study using computer-assisted software tools known as VOS viewer and RStudio in analyzing the Scopus data retrieved package for the key phrase of "Renewable energy" in the article titles published from 2002 to 2022. A total of 661 publications (which is only 0.45% and 6.3% of the global and continental publications from Africa respectively) were analysed after refining using different bibliometric criteria like study site, type of document, publication stage, language used in the document, and publication time interval. The results shows that Energy fuels, engineering, technology, environmental sciences, ecology, and business economics are the most frequently studied fields. Also, from a total of 661 publications, only 32 documents were published from Tanzania for 20 years from 2022 which is less than 2 publication/year. This study concludes that there is a notable lack of research output from Tanzania in this critical field. This gap underscores the need for greater investment in renewable energy research and development within the country, as well as targeted efforts to build research capacity and foster collaboration among academia, government, and industry stakeholders.

Preparation, synthesis and characterizations of La0.7Sr0.3Mn(1-y)Ni(y)O3 alloy

Jan Setiawan — 2024-07-15

Nickel (Ni) doped in the perovskite manganite could result in superior properties. The effect of the Ni on the morphology, crystallographic orientation, and magnetic properties of La_0.7Sr_0.3Mn_(1-y)Ni_(y)O₃ alloy (y = 0.1, 0.3, 0.5, and 0.7), therefore, was undertaken. La_0.7Sr_0.3Mn_(1-y)Ni_(y)O₃ alloy was firstly processed using a ball milling process, and again processed through heat treatment and crushing at the end of the synthesis process. Powder alloy was then investigated using a scanning electron microscope equipped with scanning electron microscope and energy dispersive spectroscopy (SEM-EDS), x-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The particle size became smaller and agglomerated as the amount of Ni doping increased. The polycrystal structure phase formed would become more complex when the Ni doping was 0.5 and 0.7, where the dominant phase formed was La₂NiO₄ even though the La_0.7Sr_0.3Mn_(1-y)Ni_(y)O₃ phase was still formed. The magnetic characteristics showed that the Ni doping of 0.1 had a higher magnetization value around 4.2 emu/g at room temperature.

Utilizing Pometia Pinnata leaf extract in microwave synthesis of ZnO nanoparticles: Investigation into photocatalytic properties

Ari Sulistyo Rini — 2024-07-15

In this work, ZnO photocatalyst has been synthesized using matoa (Pometia pinnata) leaf extract under various microwave irradiation powers at 360, 540, and 720 Watts for 3 minutes on each. The UV-Vis absorption spectra of ZnO exhibited a peak in the ultraviolet region 300-360 nm. UV-Vis absorption analysis revealed a decrease in the band gap energy from 3.15 eV to 3.10 eV as the irradiation power increased. Field emission scanning electron microscopy (FESEM) images displayed spherical and nanoplatelet morphology with a decrease in particle size observed from 773 to 709 nm with increasing irradiation power. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite structure of ZnO with crystallite sizes in the range of ~18-20 nm. The synthesized ZnO nanoparticles was successfully employed as a photocatalyst in 4-nitrophenol degradation, achieving the highest degradation percentage of 82.7% at 540 Watts with a corresponding reaction rate constant of 0.0126/min. In conclusion, the microwave-assisted synthesis of ZnO using on matoa leaf extract demonstrated significant potential for the degradation of organic pollutants, thereby contributing to water purification efforts.

Physico-chemical characteristics of Ca/P ratio on the composition and structure of oxygenated apatite

S. Jerdioui — 2024-07-15

Phosphocalcic apatites have osteoconductive and bioactive properties that make them suitable for bone reconstruction. But, they are inactive against pathogenic microorganisms that can infect bone tissue. To overcome this limitation, we synthesized oxygen-doped phosphocalcic apatites that can release molecular oxygen as a bioactive molecule. We investigated how the calcium-to-phosphorus ratio (Ca/P) gave impacts on the chemical and structural composition of the oxygen-doped phosphocalcic apatites. We here used the double decomposition method, which involved mixing calcium nitrate and diammonium phosphate solutions in an ammonia buffer. We then characterized the products using several analysis, including infrared absorption spectroscopy, X-ray diffraction, thermal analysis, nitrogen adsorption-desorption, and elemental chemical analysis. It was found that the oxygen-doped phosphocalcic apatites were calcium-deficient and had a well-defined crystallinity at room temperature. After calcination at 900°C, the crystallinity improved further. The thermal analysis showed two mass losses: one at 50°C due to water adsorption and another at 450°C due to CO₂ release. The specific surface area was about 100 ± 2 m²/g without any change with the Ca/P ratio. The quantity of molecular oxygen increased with the Ca/P ratio and reached an optimal value of the order of 3.6 ×10^-4 mol for Ca/P=1/65 with the chemical formula of Ca_9.9(PO₄)₆(OH)_1.25(O₂)_0.74(CO₃)_0.01. It is important to make further analysis to know more about the properties of oxygenated apatite, and to combine this apatite with polymers purposely to have biomedical composites. It then can be concluded that the oxygen-doped phosphocalcic apatites could be a promising biomaterial for bone infection prevention and treatment. This research highlights an oxygenation treatment of phosphocalcic apatite and brings new ideas and possibilities for future research and development to get better understanding of the behavior of these biomaterials to be more effective, especially in the biological field. As a perspective, improving the biological properties in these biomaterials needs to be further explored, including experimental parameters for the obtainment of more conclusive results.

Enhancing bioelectricity generation through co-cultivation of bacteria consortium and microalgae in photosynthetic microbial fuel cell

Pimprapa Chaijak — 2024-07-16

This study investigates the effect of microbial configuration on the electrochemical performance of photosynthetic microbial fuel cells (PMFCs). The PMFC configuration incorporating both bacteria and microalgae exhibited the highest open-circuit voltage (OCV) of 397.95 ± 31.53 mV, significantly higher than that of the OCVs obtained in the sterile control (C1) and the microalgae-only configuration (C2), which were 32.47 ± 22.43 mV and 284.59 ± 12.63 mV, respectively. Furthermore, the PMFC containing only microalgae achieved a current density (CD) of 20.96 ± 0.18 mA/m³ and a power density (PD) of 0.40 ± 0.01 mW/m³ under room temperature conditions. Notably, the combined bacteria and microalgae configuration demonstrated a substantial performance improvement, yielding a significantly higher CD of 49.33 ± 0.36 mA/m³ and PD of 0.78 ± 0.01 mW/m³ at room temperature. This configuration also achieved a maximum decolorization of 93.57 ± 0.10% with a corresponding algal biomass recovery of 134.90 ± 2.69 mg/L. These findings highlighted the critical role of microbial composition in PMFC performance. The combination of bacteria and microalgae yielded superior results compared to other configurations under the investigated conditions.

The impact of bacillus sp. NTLG2-20 and reduced nitrogen fertilization on soil properties and peanut yield

Nguyen Van Chuong — 2024-07-16

The excessive use of nitrogen (N) fertilizers has led to farmland degradation and reduced crop yields. To address this drawback, reducing the amount of nitrogen fertilizer and Bacillus sp. NTLG2-20 inoculant are the optimal cultivation method. The impact of different N rates (0, 20, and 40 kg ha-1) combined with the Bacillus sp. NTLG2-20 inoculant on soil chemical properties, growth, development, and peanut yield was designed in the field in Phuoc Hung commune, An Phu district from May to August 2023. The field experiment was designed with 6 treatments and 4 replications. The research results showed that different N rates adequately augmented soil chemical traits such as pH, cation exchange capacity (CEC), soil organic matter (SOM), total N, available phosphorous (AP), and exchangeable potassium (EK). Furthermore, different N fertilizers rates combined with Bacillus sp. NTLG2-20 inoculant adequately augmented plant height, number of leaves, total chlorophyll, nodulous number and weight per groundnut plant. Reducing N fertilizer application by 50% (20 kg N ha-1) was the optimal N reduction rate when combined with the Bacillus sp. NTLG2-20, which resulted in 17.6% higher peanut yield compared to no N application and no difference compared to 100% of recommended N application (P<0.01)). Bacillus sp. NTLG2-20 inoculant increased peanut yield by 19.6% when compared to no Bacillus sp. NTLG2-20 inoculant (P<0.01). Nitrogen – fixing ability of Bacillus sp. NTLG2-20 promoted peanut yield and reduced fifty percentage of the N fertilizer application. Bacillus sp. NTLG2-20 is the promising species for the production of biological fertilizer in the future.

Improving the activity of CO2 capturing from flue gas by membrane gas – solvent absorption process

Maysoon Anwar Abdulla — 2024-07-16

This work is focused on increasing the capturing efficiency of carbon dioxide (CO₂) through flue gas purification systems. To maximize the CO₂ capture process, many process variables such as temperature, flow rates, absorbent concentrations, and nanoparticles were investigated. This study describes the use of a polypropylene hollow fiber membrane contactor to separate CO₂ from nitrogen using different solvents, including Potassium carbonate (K₂CO₃), N-methyl diethanolamine (MDEA), and monoethanolamine (MEA). Also, the presence of silica nanoparticles and piperazine (PZ) enhances the process performance. On the other hand, the amine and mixed amino absorbents MDEA-PZ and MDEA-MEA were prepared and compared based on the absorption capacity. The optimal order of amine absorbent performance when applied to CO₂ membrane absorption is MDEA-MEA followed by MDEA-PZ. At a solute concentration of 9%, MDEA-MEA exhibits the highest CO₂ removal efficiency, which is 74.12%. However, at a concentration of 11%, MEA, MDEA-PZ, and MDEA have the highest CO₂ removal efficiencies of 80.15%, 75.13%, and 63.12%, respectively.

Effect of layered double hydroxide-graphene oxide modifier composition on characteristics of polyvinylidene fluoride based nanocomposite membranes in the separation of Cu2+

Nita Kusumawati — 2024-07-16

This research explored the modified polyvinylidene fluoride (PVDF) nanofiber membranes with a composite of layered double hydroxide (LDH) and graphene oxide (GO) to enhance biofouling resistance. The PVDF/LDH-GO nanocomposite membranes were synthesized via vacuum filtration. FTIR analysis confirmed nanocomposite formation with new peaks indicating the presence of GO and LDH. Variations in the LDH:GO ratio affected the physical, mechanical, and performance properties of the membranes. Based on SEM imaging, the 1:1 LDH: GO ratio exhibited the highest Young's modulus and smallest pore sizes. LDH-GO incorporation increased the mechanical strength, porosity, roughness, hydrophilicity, and pure water permeability of the PVDF membranes. The combination of these factors led to balanced permeability and selectivity values towards Cu²⁺ solution feeds. LDH-GO was proven effective in modifying the PVDF membrane surface for water treatment and inhibiting biofouling up to 64% against E. coli.

Stabilizing fine-grained soil by electrically injecting Ca2+, CO32-, and HPO42- ions

R M Rustamaji — 2024-07-16

This paper presents a new technique that can electrically inject stabilizing ions, which can be used to stabilize soil. Other processes also occur simultaneously during treatment such as electrolysis, dissociation, sorption, and exchange mechanisms, etc. The aim of the research is to evaluate the effectiveness of the injection of stabilizing ions (Ca²⁺, CO₃^2-, and HPO₄^2-) in enhancing the shear strength of fine-grained soils. The shear strength of the soil increased up to 127% after treatment when measured near the anode and up to 495% when measured near the cathode. The results show that the proposed method can significantly increase soil strength; hence, it overcomes bearing capacity problems in soft fine-grained soils with low hydraulic conductivity.

Evaluating 3-D positioning infrastructure quality and utilization: The potential improvement with multi-GNSS methods

Dedi Atunggal — 2024-07-16

This article evaluates the quality of the national 3-D positioning infrastructure using multi-criteria decision making (MCDM) to simulate the potential application of multi-GNSS method. The MCDM evaluation used coverage and availability of Indonesia Continuous Operating Reference System (INACORS) services, distribution of survey pillars, and accuracy of height determination using the Indonesian Geoid Model (INAGEOID). The term multi-GNSS method refers to the utilization of PPP method as a complement to the conventional differential GNSS method for the production of mapping control points. The results of this evaluation were complemented by a questionnaire analysis on the utilization of positioning infrastructure by respondents from various professional backgrounds. The MCDM evaluation results showed that Java had nearly 100% good or excellent 3-D positioning infrastructure quality. Other regions in Indonesia still had significant areas of average, fair, or even poor quality. The questionnaire results showed that many users have faced some problems in areas with fair or poor infrastructure quality. The application of multi-GNSS method can contribute to reduce up to half of the area with fair and poor positioning infrastructure quality.

QS-Trust: An IoT ecosystem security model incorporating quality of service and social factors for trust assessment

Warsun Najib — 2024-07-16

In the rapidly growing and increasingly complex Internet of Things (IoT) ecosystem, securing communication and data exchanges between devices is a major concern. To address this, we proposed QS-Trust, a trust-based security model considering both Quality of Service (QoS) and social parameters. QS-Trust uses a trust value to determine the trust level between devices and employs a QoS-aware trust-based algorithm to improve the security of data transmissions. Additionally, the model incorporates intelligence parameters such as computing power, memory capacity, device behavior and context information to enhance the accuracy of trust evaluation. Our simulation results demonstrated that QS-Trust effectively improved the security of the IoT ecosystem while maintaining the high level of QoS. The execution time of QS-Trust was in the range of 21 to 128 milliseconds, which is efficient for real-time IoT applications. QS-Trust offers a promising solution for securing the IoT ecosystem. The QS-Trust model effectively addresses the challenges of maintaining accurate and up-to-date trust levels in dynamic IoT environments through its decentralized approach, multi-factor evaluations, and adaptive algorithms. By continuously monitoring device performance and interactions and dynamically adjusting trust scores, QS-Trust ensures that the IoT network remains secure and reliable.

Preparation of Ni/ZSM-5 and Mo/ZSM-5 catalysts for hydrotreating palm oil into biojet fuel

Wega Trisunaryanti — 2024-07-16

With the increasing demand for fuel for global usage and CO₂ emissions, greener alternatives are needed, especially in biojet fuel production. Catalyst preparation involves the impregnation of Ni and Mo metals into H-ZSM-5 using a dry impregnation method with spray deposition, resulting in Ni/ZSM-5 and Mo/ZSM-5 catalysts. Catalyst characterization utilizes FT-IR, XRD, SAA, SEM-EDX, XRF, and NH₃-TPD instruments. The activity and selectivity tests of the catalysts were conducted in the hydrotreating of palm oil using Ni/ZSM-5 monolayer, Ni/ZSM-5 bilayer, Mo/ZSM-5 monolayer, Mo/ZSM-5 bilayer, as well as Ni/ZSM-5 bottom-layer and Mo/ZSM-5 top-layer arrangements. The result showed double-layer Ni/ZSM-5 as the best catalyst in activity and selectivity in producing biojet fuel fractions with consecutive conversion, selectivity, and yield of 29.71%, 84.76%, and 24.34%, respectively. The layers of catalyst affected the catalytic activity and selectivity, resulting in a higher yield.

Efficient removal of amoxicillin, ciprofloxacin, and tetracycline from aqueous solution by Cu-Bi2O3 synthesized using precipitation-assisted-microwave

Fatkhiyatus Sa'adah — 2024-07-16

This study investigates the synthesis and characterization of Cu-Bi₂O₃for degradation of antibiotics AMX, CIP, and TC using precipitation-assisted-microwave method at varying concentrations of Cu at 0%, 2%, 4%, 6%, and 8%. The effect of Cu concentration on the structural, morphological, and optical properties were studied by XRD, UV-Vis, and SEM-EDX. The optimal results were obtained by adding 4% Cu to the Bi₂O₃ matrix. With an energy band gap of 2.32 eV, a crystal size of 37.04 nm, and ?-Bi₂O₃ and CuBi₂O₄phases. The removal efficiency of each antibiotic using the photocatalytic method varies, with AMX at 52.06%, CIP at 61.72%, and TC at 69.44%. Cu-Bi₂O₃ degraded TC-type antibiotics more rapidly. The high removal efficiency and rapid reaction rate indicate that Cu-Bi₂O₃ is an effective antibiotic removal agent. This further confirms the fact that the addition of Cu to Bi₂O₃material can increase its ability to degrade antibiotics more effective.

Predictive mapping of surface roughness in turning of hardened AISI 4340 using carbide tools

Armansyah Ginting — 2024-07-16

This study presents a novel approach to predict surface roughness in the hard turning of AISI 4340 steel using carbide tools, aimed to develop a comprehensive predictive map. The hypothesis that surface roughness can be accurately predicted using a linear regression model was tested and confirmed. Experimental results showed surface roughness in the range of 1.946 to 5.636 microns. Statistical analysis revealed a normal distribution of surface roughness data with linear regression as the best-fit model, significantly determined by feed rate and explaining 98.41% of the variance. Machine learning validated this model, achieving high prediction accuracy (R² = 96.91%, MSE = 0.058, RMSE = 0.242). The innovative predictive map, created using a full factorial design, demonstrated a strong agreement between predicted and validated values. This work highlights the potential of integrating statistical and machine learning techniques for precise surface roughness prediction, recommending industrial validation to enhance machining productivity.

Simulation and optimization of fatty acid extraction parameters from Nannochloropsis sp. using supercritical carbon dioxide

Ivander Jonathan Kim — 2024-07-16

Microalgae, which are rich in fatty acids, have potential applications in various sectors such as bioenergy, health, food, and biomaterials. The Supercritical Fluid Extraction (SFE) method is commonly used to extract microalgae. This research estimated the process parameters of desorption rate constant (k_d) and binary diffusion coefficient (D_AB) for SFE fatty acid from Nannochloropsis sp. using a mathematical model called as hot sphere diffusion. Desorption models were used to model the release of fatty acids into the solvent (supercritical carbon dioxide). The parameter estimation process was conducted at temperatures of 313 and 333 K and pressures of 12.5, 20, and 30 MPa. The value of k_d increased with increasing pressure and temperature and D_AB values were obtained at varying pressures and temperatures.

Development of CaCO3 novel morphology through crystal lattice modification assisted by sulfate incorporation and vibration

Wiji Mangestiyono — 2024-07-16

CaCO₃ has long been used as a filler to increase many properties of the material. The filler commonly consists of inexpensive materials that replace some volume of the more expensive materials, which can reduce the cost of the final product. CaCO₃ morphology that can be used as filler depends on the filler's function, such as filler for paper, paint, rubber, or composite. A filler for composite materials is needed to increase interfacing interactions between the particulate fillers and the matrix. So, the particulate in a broader shape will be the best choice to function for such filler. In this research, in an attempt to increase the interfacing interaction, CaCO₃ morphology was modified in such a way through crystal lattice modification assisted by sulfate incorporation and vibration. SEM analysis was implemented, and showed that the research successfully produced novel morphology in branchy-like polymorphs. FTIR analysis also proved that the crystal lattice has been modified. The morphology in branchy-like polymorph is supposed to increase interfacing interaction between CaCO₃ as the filler and the matrix. The methods are also supposed to be implemented as the research is scaled up to commercial scale.

Synthesis of silver (Ag) nano/micro-particles via green process using Andrographis paniculata leaf extract as a bio-reducing agent

Achmad Chafidz — 2024-07-16

In this work silver nano/micro-particles have been synthesized using sambiloto (Andrographis paniculata) plant extract as a bio-reducing agent. The effects of different plant extract concentrations, AgNO₃ precursor concentrations, and reaction time on the synthesized silver nano/micro-particles were investigated. The silver nano/micro-particles samples were then analyzed using UV-Vis spectrophotometer (UV-Vis), X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM), Particle Size Analyzer (PSA), and Fourier Transform Infra-Red (FTIR) spectroscopy. The UV-Vis absorbance spectrum of the colloid silver nano/micro-particles exhibited that all samples had absorbance peaks at a wavelength around 450 nm, confirming the formation of silver nano/micro-particles. It was also found that the UV-Vis absorbance peak of the silver nano/micro-particles inversely increased with decreasing AgNO₃ solution concentration. Whereas, the higher the sambiloto extract concentration the higher the UV-Vis absorbance peaks. The UV-Vis absorbance peak increased with increasing synthesis time, suggesting that silver nano/micro-particles became more prominent. The UV-Vis absorbance peaks of the silver nano/micro-particles were about 0.0462, 0.0637, 0.0729, and 0.0936 at reaction time of 5, 10, 20, and 40 min, respectively. The XRD analysis result confirmed that the synthesized silver nano/micro-particles were in the form of nanocrystals with a face-centered cubic centered without any impurities. Additionally, the FESEM images showed that the silver nano/micro-particles had the primary particle size of 150-300 nm. There was the formation of some secondary particles with the size of about 0.7-1.5?m due to the agglomeration of primary particles. The particle size distribution analysis further confirmed the presence of primary and secondary particles. Meanwhile, the FTIR analysis confirmed the presence of four main peaks, linked to functional groups in the sambiloto extract and involved in the creation of silver nano/micro-particles.