Percentage Of Absorption Research Articles

Characterization of Heavy Metal Ions Removal from Water by Improved Cuttlebone Powder with Magnetic Fe3O4 Nanoparticle as a Bioadsorbent

AbstractScientists are constantly striving to develop improved methods for reducing or eliminating the discharge of harmful heavy metals into drinking water sources and the environment. In light of this, this study investigates the potential of utilizing a naturally available and sustainable bio‐waste material, Sepia pharaonis cuttlebone Powder (SCP), as an exceptionally effective adsorbent for the adsorption of Ni (II), Pb (II), Cu (II), and Fe (II) ions. SCP is also characterized by Fourier‐transform infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Xray diffraction (XRD), and Energy dispersive Xray (EDX) analysis. The results reveal that the highest absorption values for Ni (II), Cu (II), and Fe (II) ions are observed at pH 8, while Pb (II) ions exhibit the highest absorption at pH 4. The absorption percentage of the ions displays an increasing trend with the amount of SCP used, as well as with contact time and magnetizing SCP duration. Additionally, the addition of Fe3O4 to SCP significantly improves the absorption rate of the samples. Both Langmuir and Freundlich adsorption models are found to fit the experimental data well. Overall, SCP, with or without Fe3O4 nanoparticles, shows great promise for water remediation processes by effectively removing heavy metals.

Enhancing pashmina fabric aesthetics: Assessing the dyeing efficacy of indigenous wild underutilised plants

AbstractThis study explores the use of dyes extracted from Berberis aristata and Bistorta amplexicaulis for dyeing pashmina fabric. The effectiveness of these plant‐derived dyes was evaluated based on colour strength, absorption efficiency and fastness properties including washing, light and rubbing. Results indicate that both Berberis aristata and Bistorta amplexicaulis dyes significantly enhance the colour quality of pashmina fabric, with simultaneous mordanting yielding the highest colour strength and fastness properties, followed by premordanting. Berberis aristata exhibited poor light fastness (1), but showed excellent rubbing and washing fastness (5), while Bistorta amplexicaulis demonstrated good light fastness (4) and (4/5), as well as excellent performance in rubbing and washing fastness (5). Dye concentrations positively impacted colour strength, with higher concentrations resulting in deeper shades. The percentage absorption of the dye into the fabric was notably high, reflecting effective dye uptake. Mordant enhanced the colour quality of the fabric because of the increased efficiency in absorption, colour strength, colour coordinates and fastness grades in terms of washing, light and rubbing, respectively. These findings suggest that dyes from Berberis aristata and Bistorta amplexicaulis are promising for textile applications, offering vibrant, durable colours and adaptable dyeing methods.

Production of mortar with calcined alum sludge as partial cement replacement

Alum sludge is a largely generated and disposed waste from water treatment plants. This study aimed to produce mortar using alum sludge calcined at different temperatures (600 – 900 ºC). After the optimal calcination temperature was selected, the calcined alum sludge was used to replace 5, 10, and 15 % of cement by mass in mortar. The performance of the mortars was evaluated based on the workability, compressive strength, flexural strength, porosity, and percentage of water absorption. Mortars with alum sludge calcined at 800 ºC had the highest strength as compared to the other temperatures. The mechanical strength of mortars reduced while the porosity and percentage of water absorbed increased with increasing calcined alum sludge content. Although replacing 5 % of cement with calcined alum sludge would reduce the mechanical strengths by 13 – 15 %, it was still acceptable as it had negligible influence on the porosity and water absorption value of the mortar. In short, the partial substitution of cement with calcined alum sludge should be limited within 5 % to maintain the performance of the mortar.

Analisis Penyerapan Anggaran Serta Implikasinya Terhadap Kinerja Manajerial

This study examines budget absorption and its implications for managerial performance, focusing on the case of the Tea and Cinchona Research Center (PPTK) Gambung, Bandung Regency, West Java. The research was motivated by the issue of low budget absorption at PPTK, which has impacted operational efficiency and managerial performance outcomes. The independent variables analyzed include sales volume, labor, and raw material costs. Budget absorption is an intervening variable, while managerial performance is the dependent variable. The study employed a quantitative method with descriptive and verificative approaches. Primary data were collected through questionnaires distributed to PPTK managers, and secondary data were obtained from financial and budget reports from 2018 to 2022. Statistical analysis was applied to assess the relationships among the variables. The findings reveal that sales volume, labor, and raw material costs significantly influence budget absorption. Additionally, effective budget absorption positively affects managerial performance. However, challenges such as declining budget absorption percentages and sales volumes in the last two years were identified, indicating room for improvement in budget management. This research recommends adopting more realistic and efficient budget planning, optimizing production processes, and enhancing monitoring mechanisms to improve budget utilization. These measures are expected to strengthen managerial performance and support the organization’s sustainability.

Multiwalled carbon nanotubes filled pineapple/kenaf hybrid laminated composites structures for electromagnetic interface shielding applications

AbstractThe main objective of the present research is to investigate the mechanical and electrical properties of multiwalled carbon nanotube (MWCNTs) filled pineapple and kenaf fiber‐based hybrid laminated composite structures using the hand layup technique. 0, 0.1, 0.2, 0.3, 0.4, and 0.5 wt%. of MWCNTs are incorporated into the proposed composite structures. The incorporation of MWCNTs into the hybrid composite structure increases flexural, tensile and impact strength by 173%, 53%, and 29% respectively. The morphological studies are presented to understand fiber pull‐out, matrix breakage, delamination and debonding phenomena. Further, the addition of MWCNTs into the laminated composites decreased the water absorption properties from 8.3% to 4.3%; however, the density of the composites increased slightly due to a more compact structure. The incorporation of MWCNTs into the laminated composite structure enhances the electrical properties such as dielectric constant and AC conductivity by forming a conductive network. The and of developed composites increased by 3.0 and 6.8 times due to the interfacial polarization. The results from the study demonstrate that incorporating MWCNTS into pineapple and kenaf fiber‐based hybrid laminated composite structures helped to enhance both the mechanical and electrical properties, making it a primary choice for electromagnetic interface shielding applications.Highlights Laminated composites are fabricated using the hand layup technique. , and of the composites are increased by 173%, 56%, and 29%. The water absorption percentage decreased from 8.3% to 4.3%. and of composites increased by 3.04 and 6.8 times.

Mechanical properties and microstructural analysis of laterite stone masonry from India for sustainable construction

Laterite is a naturally occurring rock formation that is used worldwide as a building material in tropical regions. Its unique features have enabled some of the most astounding architectural feats, which irrevocably altered the cultural and historical contexts of their surroundings. This study examines the laterite stone masonry performance, with a specific focus considering its mechanical properties, mineral composition, and microstructure. However, mineralogical composition and microstructural features vary, affecting mechanical qualities and endurance. The study also extensively examines four varieties of laterite samples used for construction in the Udupi region. Experiments were performed to determine the percentage of water absorption and its impact on the compressive strength of Laterite stone. L1 Laterite stone showed better performance due to its exceptional strength. It surpasses the other samples and is well-suited for the construction of load-bearing structures as it aligns with the IS 3620 standards. Stack bond masonry prism samples were built using four varieties of laterite stones with 1:6 cement mortar for the joints. These prism specimens were subsequently tested under compression, tension, and shear loading to determine the variation in their behaviour. The series of tests performed revealed that the prisms failed due to splitting and crushing under compression loads. In shear and tensile bond tests, all laterite masonry prism samples failed due to rupture of the joint. Microstructure study confirmed that the increased strength of lateritic samples L1 and L2 is due to less prominent clay particles coupled with a higher percentage of ferrous content.

Experimental Characterization of Banana-Palm Fiber Reinforced Hybrid Polymer Composite

Composite materials are synthesized by using natural cellulose fibers with matrix, due to their improved properties. In this work, banana and palm fibers are treated with 2% and 8% NaoH, respectively, for the removal of lignin and hemicelluloses. The hybrid composite was fabricated by using epoxy resin as the matrix and both the fibers as reinforcement through the hand lay-up method. By varying the banana and palm fibers in the range of 5-15% wt. and 7.5-22.5% wt. in the composite of 20% wt. and 30% wt. reinforcement, respectively, The composite consists of 5/15% wt. treated fibers, having more influence on compressive strength of 222.46 MPa and flexural strength of 535 MPa. However, 7.5/22.5% wt. treated composite has a higher impact resistance of 14.6 J and 10/10% treated composite gained a higher water absorption percentage weight of 1.16% at 216 hours. From the experiment, the composite with 5/15% wt. fibers of 20% wt. reinforcement and 80% wt. epoxy is suitable for making kitchen slabs.

Water Absorption of Underwater Products by Additive Manufacturing.

Rapid prototyping techniques offer significant advantages in terms of fabrication speed, accessibility, and low cost. This study explores the use of low-cost stereolithographic resins to produce prototypes intended for underwater conditions. The objective is to evaluate the feasibility of different low-cost resin brands by identifying their water absorption percentage and their response in terms of appearance and deformation after prolonged exposure to an underwater environment. Through three different tests, the suitability of the resins and possible coatings is evaluated, allowing for obtaining data not disclosed by commercial manufacturers and indicating that there are low-cost brands that offer water absorption levels suitable for underwater use. The coefficients for water absorption at saturation begin at 3.3% in saltwater and increase for chlorinated water. Additionally, significant insights are gained regarding the use of coatings. It is found that coatings commonly applied to filament-printed prototypes are generally less suitable for parts produced through stereolithography intended for underwater applications. The most effective strategy is to avoid using coatings altogether.

Analysis of Limestone Characteristics on the South Coast of Gorontalo Based on Specific Gravity and Water Absorption Tests

The southern coast of Gorontalo has complex geological conditions. This is indicated by the strong tectonic influence with the uplift of the Quaternary limestone at high elevations. The distribution of this limestone is very unique because it is located between the dominance of volcanic and plutonic rocks that form the northern arm of Sulawesi. The purpose of this study was to focus on the characteristics of limestone on the south coast of Gorontalo based on specific gravity and water absorption tests. The research methods used to achieve these objectives consist of field geological surveys and laboratory analysis of the specific gravity and water absorption tests of coarse aggregate. The field geological survey consisted of taking limestone samples for laboratory analysis and petrological analysis. The results showed that the limestone on the southern coast of Gorontalo is dominated by the coralline floatstone facies. Characteristics of the coralline floatstone facies based on laboratory analysis showed an average specific gravity of 1.74 and an apparent specific gravity of 2.04. While the average percentage of limestone water absorption is 8.41%.

Evaluating the moisture absorption percentage in the adhesive layers of carbon fiber reinforced plastic joints via electromagnetic induction testing and diffusion analysis

In this study, we propose a method that combines moisture absorption analysis and electromagnetic induction testing (EIT) to detect weak bonds formed in the adhesive layers of carbon fiber reinforced plastic (CFRP) joints due to moisture absorption. Although EIT is effective for assessing CFRP joint adhesive moisture absorption, early-stage detection of weak bonds is challenging. Our method addresses this by combining calculations of moisture absorption percentage via the diffusion equation and EIT-based measurements. First, we conducted diffusion analysis using the finite difference method (FDM). The moisture absorption percentage calculated via the FDM was validated by comparing it with the results of the moisture absorption tests of the CFRP adhesive joints, and good agreement was observed. Second, EIT was applied to the CFRP adhesive joints, and the experimental results indicated that the moisture absorption percentage of the CFRP joint can be qualitatively evaluated using EIT. Finally, the moisture absorption of the CFRP joint adhesive layer was quantitatively evaluated by combining the results of EIT on the CFRP joints with those of the numerical analysis. Therefore, the proposed method enables the previously difficult quantitative evaluation of the early-stage moisture absorption percentage of CFRP joint adhesive layers and is effective for the detection of weak bonds created by moisture absorption in CFRP joints.

Evaluation of Admixture Silane Added into Cementitious Pastes.

This manuscript evaluated the performance of silanes in cementitious matrices in the partial replacement of superplasticizers by silanes. For this, pastes with a water/cement ratio of 0.186 were produced and the superplasticizer admixture based on polycarboxylate esters was partially substituted by three types of silanes-vinyltriethoxysilane silanes (VTES), n-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), and methacryloxypropyltrimethox-ysilane (MCPTMS)-in two substitutions levels (20% and 40%), and then tested in Portland cement pastes. Specific gravity, trapped air, mini-slump, and hydration kinetics (evaluated by isothermal calorimetry up to 48 h) of the pastes were determined in the fresh state. Thus, in the hardened state, the compressive and flexural strength tests (7 and 28 days), specific gravity, and absorption by immersion of the pastes were carried out. The results showed that the substitution of 20% and 40% of VTES and AEAPTMS considerably reduced the workability and increased the air content of the pastes in comparison to the reference sample. In contrast, the incorporation of 20% and 40% of MCPTMS did not significantly affect these properties. The presence of silane, for all analyzed samples, had a delaying effect on the hydration process: the maximum delay verified had a hydration peak in approximately 36 h for the 40% MCPTMS sample and the minimum delay verified had a hydration peak in approximately 11 h for the 20% VTES sample. The replacement of 20% and 40% by any of the silanes progressively reduced the flexural strength at both 7 and 28 days. In the compressive strength, as well as in the tensile strength in flexion, there was a decrease in the results when compared to the reference, except for the MCPTMS, at 7 and 28 days. In immersion absorption, all samples showed high percentages of absorption and void index when compared to the reference.

Fabrication and Physio-chemical characterization of Biocompatible and Antibacterial Vitis Vinifera(grapes) loaded PVA Nanomembranes for Dermal Applications

Nano-dermal patches are more effective than traditional ones due to higher surface energy, deeper penetration, and more entrapment sites. We developed a novel and dry nanomembrane that incorporates Vitis Vinifera (V.v) extract and polyvinyl alcohol (PVA) through the electrospinning method. Physiochemical characterization of nanomembranes under different concentrations of PVA and V.v was accomplished by employing scanning electron microscopy (SEM), ultraviolet spectroscopy (UV-Vis), drug release, water absorption percentage, radical scavenging activity, biocompatibility, and antibacterial activity (qualitative and quantitative). Optimized nanofibers with a 446 ± 102nm diameter were produced using 8% wt./wt. PVA and 100% V.v concentration. Water contact angle (WCA) of less than 50° and water absorption exceeding 660 percent demonstrated the hydrophilicity of V.v/PVA nanomembranes. DSC analysis showed that the developed PVA nanofibrous membranes are thermally stable, with new interactions supporting this increased stability. Released V.v particles from the nanomembrane ranged in size from 40 to 250nm, as detected by the Zeta sizer. The nanomembrane had 92% cell viability, excellent biocompatibility, and 75% bursting release in 5minutes. The nanomembranes have up to 79% antioxidative abilities and 99.8% antibacterial efficiency against Staphylococcus aureus (S. aureus). Lastly, the nanomembrane's tensile strength (51N, elongation 1.62%) and breathability (16.04mm/sec) further support its potential use as a multipurpose dermal skin patch.

Optimization of Starch-Based Bioplastic from Sweet Potato using Box-Behnken Design with Plasticizer and Filler for Reduced Water Absorption

Plastic is a ubiquitous material used in a wide range of applications, but its disposal has become a significant environmental concern. Bioplastics, which offer several advantages over conventional plastics, including a smaller carbon footprint, greater biodegradability, and adaptability, are being explored as a potential alternative. Among the bioplastics, starch-based polymers have gained significant attention due to their natural abundance, biocompatibility, low cost, and renewability. In this study, a starch-based bioplastic was developed using glycerol and sorbitol as plasticizers and wood dust as a filler through the casting method. Starch was extracted from sweet potato (Ipomoea batatas). The optimal conditions for preparing the bioplastic with minimum water adsorption were determined using a three-level Box-Behnken design. The amount of starch, plasticizer, and filler were the key parameters for this study. The percentage of water absorption was determined by immersing the prepared bioplastic in distilled water for 24 hours and weighing it. The result of the Fourier Transform Infrared (FTIR) spectroscopy of extracted starch showed a similar observation peak pattern when compared to the FTIR spectrum of commercial starch. The linear response model produced a good coefficient of determination (R2 = 0.8237), indicating that the chosen parameters implicitly affect the percentage of water absorption. The prediction percentage of water absorption after optimization is 20.069 with a desirability value of 0.806. This study shows that the response surface approach helps in determining the optimum conditions for the minimum percentage of water adsorption from starch-based bioplastic.

Pemanfaatan Limbah Hidrogel Popok Bayi Sebagai Bahan Campuran Pembuatan Bata Ringan

Baby diapers are made of plastic and a mixture of chemicals, a solution to use diaper waste by utilizing hydrogel and plastic contained in diapers. The plastic contained in diapers can be utilized as a lightweight construction material in the form of lightweight bricks to increase compressive strength. This study aims to determine the effect of a mixture of baby diaper waste on water absorption and compressive strength in making lightweight bricks. This research method is experimental, which is carried out at the Structure and Materials Laboratory of the Muhammadiyah University of Parepare. The results showed that each variation with dimensions of 5cm x 5cm with a curing age of 28 days, a variation of 0% with an average compressive strength of 4,000 MPa, a variation of 7% with an average compressive strength of 5,333 MPa, a variation of 12% with an average compressive strength of 9,333 MPa and a variation of 17% with an average compressive strength of 13,333 MPa. Meanwhile, the percentage of water absorption of lightweight bricks with a variation of 0% was 21.2%, a variation of 7% was 23.6%, a variation of 12% was 27.4% and a variation of 17% was 30.1%

Surface Treatment of Oak Wood with Silica Dioxide Nanoparticles and Paraloid B72

Wood is a valuable material with incomparable advantages, though it is susceptible to biotic and abiotic factors action that affect it adversely and shorten its service life. In the current study, the surface modification of oak wood is carried out through brief immersion in a solution of acrylic polymer Paraloid B72, in which silica dioxide nanoparticles in the form of nanopowder were dissolved at different contents (1, 2, 3, and 4% w/v of the solution) aiming at the elimination of wood material hygroscopicity, and the protection and improvement of other properties. Specifically, the modified and unmodified wood specimens were characterized in terms of physical characteristics (density, equilibrium moisture content, colour, and surface roughness), hygroscopic properties (swelling and absorption percentage) and accelerated weathering performance using xenon light and cycles of moisturizing and drying. The results revealed the dimensional stability of the samples and a significant increase in the hydrophobicity of the modified wood, as well as a significant increase in the resistance to the ageing/weathering factors of oak wood, which was proportional to the increase in the presence of nanoparticles in the Paraloid B72 solution. The colour of the treated samples slightly changed towards darker shades, more reddish and yellowish (with L* to decrease, while a* and b* to slightly increase), though the treated wood revealed higher colour stability. The surface roughness parameters (Ra, Rq, and Rz) increased significantly, restricting the wide application of the treated wood in indoor or outdoor applications where surface roughness constitutes a critical factor. The findings of the current work contribute not only to the production of longer-lasting wood and timber structures, but also to the conservation of the existing weathered heritage timber structures.

Agro‐waste areca nut husk and bagasse fiber reinforced epoxy‐based hybrid composite for thermal insulated false ceiling application

AbstractIn recent years, there has been a significant push toward using environment‐friendly composite materials derived from renewable resources. Areca nut husk and bagasse fibers are excellent examples of agricultural by‐products that possess valuable properties for various applications. In this work, three samples containing 23.06%, 28.54%, and 33.33% of areca nut husk and bagasse fibers‐reinforced epoxy matrix (ABFR) hybrid composites were prepared to assess their suitability for use as thermally insulated false ceilings in affordable housing, civil structures, and the automotive industry. The novel hybrid composites were characterized by tensile strength, flexural strength, morphology, thermal conductivity, thermogravimetric analysis (TGA), and percentage of water absorption. The composite containing 23.06% fiber exhibited the lowest thermal conductivity at 0.1631 W/m K and demonstrated excellent thermal insulating properties at 0.03629%. It achieved a maximum tensile strength of 30.05 MPa and a flexural strength of 19.72 MPa. The thermogravimetric analysis indicated that the composites undergo multiple degradation steps; however, they remain stable within the temperature range of 280–328°C. The scanning electron microscope (SEM) observations revealed effective interfacial bonding between the fibers and the epoxy matrix. These characteristics suggest that this hybrid composite could be a suitable option for thermally insulated false ceilings when compared to existing synthetic fiber alternatives.Highlights The study aims to create eco‐friendly composites from areca nut husk and bagasse fiber. The hybrid composite containing 23.06% fiber showed the lowest thermal conductivity and best insulation, ideal for ceilings. More fiber in composites increased water absorption, balancing insulation with resistance. SEM micrographs clarify the proper bonding between resin and reinforcing material. Mechanical tests demonstrate superior strength and durability.

Utilizing Ceramic Factory Waste to Produce Low-Cost Refractory Ceramics

The use of solid waste such as ceramic sludge, ceramic rollers, and magnesite was studied to obtain cheap refractory ceramics at temperatures of 1300 °C based on XRF, XRD SEM, EDX, bending strength, and dielectric properties. The prepared samples were examined. The results showed that the significant crystalline phases formed were mullite, spinel, and corundum. They also showed that mullite hindered the formation of cordierite and enhanced spinel formation. With increased cordierite content, the microstructure varied from fine grained to coarse grained. Bending strength increased with increasing mullite content and bulk density, ranging from 10.80 to 13.50 MPa. Bulk density increased with the increase in mullite content and sintering temperature and ranged from 1.99 to 1.94 g/cm3, while the percentage of porosity and water absorption decreased and ranged from 29.40 to 38.83, respectively. To examine the effect of the produced phases on the dielectric characteristics, the permittivity (ε′), dielectric loss (ε″), and AC conductivity (σac) were measured in the frequency range of 10−1 Hz to 106 Hz. As the concentration of cordierite increased, there was a noticeable drop in ε′ from 35.6 to 8.2 and σac from 10−8 s/cm to around 10−11 s/cm and high values of resistivity from 108 cm/s to about 1010 cm/s, suggesting that this material might be an excellent insulator.

Variation in Thickness of Embryo Covering Structures and Their Role in the Regulation of Seed Physiological Dormancy of Chenopodium hircinum (Amaranthaceae)

Chenopodium hircinum, the putative wild ancestor of quinoa, is a source of traits that could improve the tolerance of crop quinoa to high temperatures. However, seeds of C. hircinum have physiological dormancy (PD), which is an obstacle for plant propagation and use in breeding programs. We studied the intraspecific variability in morpho-anatomical traits of embryo covering structures and their association with PD. We also evaluated the effects of different dormancy-breaking treatments on PD alleviation and germination. Seeds were dispersed with a remnant perianth and a persistent pericarp that could be removed by scraping. The seed coat was formed by palisade cells impregnated with tannins, and the seed contained a thin layer of peripheral endosperm surrounding the embryo. In our investigation, the thickness of the pericarp (P) and/or seed coat (SC) varied among populations. Populations with higher P and/or SC thickness showed lower percentages of germination and water absorption. The combined dormancy-breaking treatment (bleach + perforated coverings + gibberellic acid) promoted dormancy release and increased germination. C. hircinum seeds showed non-deep physiological dormancy. Based on previous knowledge about quinoa, and our results, we conclude that embryo coverings, especially the seed coat, have an important role in dormancy control, imposing a mechanical restraint on radicle emergence.

Developing some models to predict the uniaxial compressive strength of various sedimentary rocks (Case studies: Large dam site and mine in Southeast China)

Direct determination of uniaxial compressive strength (UCS) is time-consuming, expensive, and challenging. Therefore, this study aims to indirectly predict UCS using statistical and machine learning methods. First, laboratory measurements were conducted to determine carbonate percentage, water absorption percentage, moisture content, porosity percentage, P-wave velocity, and UCS of sandstone, dolomite, dolomitic limestone, marl limestone, and limestone samples. Subsequently, various models were established to predict UCS using multivariate linear regression (MVLR), random forest regression (RFR), Gaussian process regression (GPR) based on squared exponential kernel function, and adaptive neuro-fuzzy inference system (ANFIS). The influence of Jurassic limestone texture on physical and mechanical properties in stable and unstable slopes in the Three Gorges Dam site and reservoir (TGDSR) showed that the percentage of mudstone texture in unstable slopes is higher than in stable slopes. The UCS, density, compressional wave velocity, and percentage of carbonate in unstable slopes is less than stable slopes. The results indicated that the average measured UCS is 60.60 MPa. Moreover, the average predicted UCS based on the three intelligent methods was 60.55 MPa. The percentage difference between the measured and predicted UCS was −0.09 %, demonstrating that the average error of the three employed methods is less than one percent, highlighting the high accuracy of these methods in estimating rock UCS. Notably, based on error level, Taylor diagram, Wilmot agreement index (WAI), A10 and A20 indices, Nash-Sutcliffe efficiency (NSE), and PM (performance metric) criteria the RFR exhibited superior precision (R2=99 %, and RMSE= 0.06 MPa) compared to the other used methods. The Kruskal-Wallis test (KWT) results showed that there is no significant difference between the measured and predicted values.

Design of Biomaterial Absorber using coconut shell charcoal for 38 GHz frequency

Abstract Activated carbon derived from coconut shells has gained significant attention as an effective and sustainable absorber material. The process involves carbonizing coconut shells to create a carbon-rich base, followed by activation through heat and steam, leading to a porous structure with a vast surface area. In this research, coconut shell charcoal is used to make an absorber for microwave application. We used relative permittivity (ε) 3.178, relative permeability, (µ) 1.215 and dielectric loss tangent (σ) 0.0719 to simulate the material based of coconut shell charcoal. We investigate the absorption in terms of design and the size of the proposed absorber in the frequency region of 26.5 GHz to 40 GHz (Ka band). The optimal absorption was achieved with a transmission factor of -29.22 dB and -52.94 dB in both simulation and measurement. The absorption percentage > 99 % for the flat design of the coconut shell charcoal design with the thickness of 16.9 mm.