Abaca Fiber as a Potential Reinforcer for Acoustic Absorption Material at Middle-High Frequencies

Recently,abacafibers have become the focus of specialized research due to their intriguing characteristics,with their outstanding mechanical properties being a particularly notable.In the conducted study,the abacafibers underwent a preliminary treatment process involving an alkaline solution,which was composed of 0.5%sodium hydroxide(NaOH)and 50%acetic acid(CH3COOH).This process entailed immersing eachfiber in the solution for a period of one hour.This treatment led to a 52.36%reduction in lignin content compared to the levels before treatment,resulting in a dramatic decrease in the full width at half maximum(FWHM)in the XRD spectra from 1.13 to 0.13.This change indicates that thefibers became more crystalline following the treatment.The abacafibers were also characterized using BET(Brunauer Emmett Teller)measurements,which revealed that the aver-age pore length ranged from 33–49 nm and the surface area was between 13–28 m^(2)·g^(-1).The morphology of the abacafiber after alkali an hydrolisis treatment(AFAH)appeared rougher and more uniform.DMA measurements revealed a significant rise in the storage modulus of the singlefiber post-treatment,with dependencies on both frequency and temperature.AFAH exhibited an optimal absorption coefficient ofα=0.9 for frequencies above 2500 Hz.The combined effect of alkalization and hydrolyzation treatments,while resulting in an enhancement in the mechanical properties of thefibers,also reduced high-intensity noise produced by sources such as machin-ery,aircraft takeoffs and landings,etc.,across a broader working frequency range.

Activated Carbon from Nipa Palm Fronds(Nypa fruticans)with H_(3)PO_(4) and KOH Activators as Fe Adsorbers

Nipa palm is one of the non-wood plants rich in lignocellulosic content.In this study,palm fronds were converted into activated carbon,and their physical,chemical,and morphological properties were characterized.The resulting activated carbon was then applied as an adsorbent of Fe metal in peat water.The carbonization process was carried out for 60 min,followed by sintering at 400℃ for 5 h with a particle size of 200 mesh.KOH and H_(3)PO_(4) were used in the chemical activation process for 24 h.KOH-activated carbon contained 6.13%of moisture,4.55%of ash,17.02%of volatile matter,and 78.84%of fixed carbon,while its Fe reduction efficiency was 28.09%.The H_(3)PO_(4)-activated carbon contained 4.67%of moisture,2.84%of ash,16.41%of volatile matter,and 80.57%of bonded carbon,and the Fe reduction efficiency was 52.25%.KOH-activated carbon and H_(3)PO_(4)-activated carbon contained fixed carbon of 78.84%and 80.57%,respectively,while their average rates of efficiency of Fe reduction were 22.82%and 39.23%,respectively.Overall,the characteristics of activated nipa carbon met the Indonesian standards(SNI No.06-3730-1995).However,H_(3)PO_(4)-activated carbon was found to be better at adsorbing Fe metal from peat water.

Simple and High-Yield Synthesis of a Thinner Layer of Graphenic Carbon from Coconut Shells

Biomass has become of recent interest as a raw material for‘green’graphenic carbon(GC)since it promotes an environmentally friendly approach.Here,we investigate a single pyrolysis route to synthesize GC from coconut shells which provides a simple method and can produce a high yield,thus being convenient for large-scale pro-duction.The pyrolysis involves a stepped holding process at 350℃ for 1 h and at 650℃ or 900℃ for 3 h.The GC sample resulted at the 900℃ pyrolysis has a thinner sheet,a less porous structure,a higher C/O ratio,and an enhanced electrical conductivity than those pyrolyzed at 650℃.The addition of Na3PO4 catalyst has no signifi-cant effects on the GC structures obtained by this route.The single pyrolysis route generates thinner GC sheets compared to the two-step heat treatment followed by the liquid phase exfoliation(LPE)procedure.Nevertheless,the latter method offers a formation of clean samples with a porous or holey feature which has potential for advanced energy-storage applications.

Nitrogen-Doped Amorphous Carbon Homojunction from Palmyra Sugar as a Renewable Solar Cell

An a-C/a-C:N junction,which used palmyra sugar as the carbon source and ammonium hydroxide(NH4OH)as the dopant source,was successfully deposited on the ITO glass substrate using the nano-spraying method.The current-voltage relationship of the junction was found to be a Schottky-like contact,and therefore the junction shows the characteristic rectifiers.This means the a-C and a-C:N are semiconductors with different types of conduction.Moreover,the samples showed an increase in current and voltage value when exposed to visible light(bright state)compared to the dark condition,thereby,indicating the creation of electron-hole pairs during the exposure.It was also discovered that the relationship between current and voltage for the a-C/a-C:N junction sample formed a curve that satisfies the rule of the photovoltaic effect when exposed to visible light from a light bulb.The exposure of this sample to direct sunlight at AM 1.5 conditions produced a curve that meets the rules for the emergence of the photovoltaic effect with higher characteristics for the current-voltage relationship.Thus,the a-C/a-C:N junction sample is a solar cell successfully fabricated using a sample method and has a maximum efficiency of 0.0013%.

N-Doped rGO-Like Carbon Prepared from Coconut Shell:Structure and Specific Capacitance

An rGO−like carbon compound has been synthesized from biomass,i.e.,old coconut shell,by a carbonization process followed by heating at 400°C for 5 h.The nitrogen doping was achieved by adding the urea(CH4N2O)and stirring at 70°C for 14 h.The morphology and structure of the rGO-like carbon were investigated by electron microscopies and Raman spectroscopy.The presence of C-N functional groups was analyzed by Fourier transform infrared and synchrotron X-ray photoemission spectroscopy,while the particle and the specific capacitance were measured by particle sizer and cyclic voltammetry.The highest specific capacitance of 72.78 F/g is achieved by the sample with 20%urea,having the smallest particles size and the largest surface area.The corresponding sample has shown to be constituted by the appropriate amount of C–N pyrrolic and pyridinic defects.

Structure,Dynamic-Mechanical and Acoustic Properties of Oil Palm Trunk Modified by Melamine Formaldehyde

The performance of oil palm trunk wastes from Banjarbaru of South Kalimantan was improved with the help of chemical modification in a two-step treatment.The first was formalization with formaldehyde solution with varying pH,and the second was impregnation with melamine-formaldehyde resin under 5 bar pressure for an hour.In these processes,the samples were cured at 120℃ for 10 min and then dried in an oven at(103±2)℃ in order to attain a moisture content of less than 6%.These treatments improved the physical properties(density,moisture content,and volume swelling),mechanical resistance,dynamic-mechanical and acoustic performance of the woods.The combination of impregnation and formalization changed the structure and the morphology of the woods such that the surface became flatter and denser.This was confirmed by results from FTIR,SEM,and DMA.Samples with alkaline modification displayed the best results for dimensional stability,storage modulus,and damping factor in varied frequencies.The treatments in this study also heightened acoustic performances as evidenced by the resulting characteristics of sound absorption coefficient and acoustic impedance.

Hydrogenated Amorphous Carbon Films from Palmyra Sugar

A simple,highly reproducible,and environmentally friendly method is a considered approach in generating renewable energy materials.Here,hydrogenated amorphous carbon(a-C)films have been successfully prepared from palmyra liquid sugar,employing spin-coating and spraying methods.Compared with the former method,the latter shows a significance in producing a better homogeneity in particle size and film thickness.The obtained films have a thickness of approximately 1000 to 100 nm and contain an sp^(2) hexagonal structure(~70%)and sp^(3) tetrahedral configuration(~30%)of carbons.The introduction of boron(B)and nitrogen(N)as dopants has created the local structural modification of bonding,inducing a slight change of electrical conductivity,electronic energy bandgap,and optical transparency near-infrared region.The obtained α-C film features a“green”semiconducting material.

Enhanced production of hydrogen via catalytic methane decomposition on a Pt_(7)-Ni(110) substrate:a reactive molecular dynamics investigation

Numerous researchers in the energy field are engaged in a competitive race to advance hydrogen as a clean and environmentally friendly fuel.Studies have been conducted on the different aspects of hydrogen,including its production,storage,transportation and utilization.The catalytic methane decomposition technique for hydrogen production is an environmentally friendly process that avoids generating carbon dioxide gas,which contributes to the greenhouse effect.Catalysts play a crucial role in facilitating rapid,cost-effective and efficient production of hydrogen using this technique.In this study,reactive molecular dynamics simulations were employed to examine the impact of Pt_(7) cluster decoration on the surface of a Ni(110)catalyst,referred to as Pt_(7)-Ni(110),on the rates of methane dissociation and molecular hydrogen production.The reactive force field was employed to model the atomic interactions that enabled the formation and dissociation of chemical bonds.Our reactive molecular dynamics simulations using the Pt_(7)-Ni(110)catalyst revealed a notable decrease in the number of methane molecules,specifically~11.89 molecules per picosecond.The rate was approximately four times higher than that of the simulation system utilizing a Ni(110)catalyst and approximately six times higher than that of the pure methane,no-catalyst system.The number of hydrogen molecules generated during a simulation period of 150000 fs was greater on the Pt_(7)-Ni(110)surface than in both the Ni(110)and pure methane systems.This was due to the presence of numerous dissociated hydrogen atoms on the Pt_(7)-Ni(110)surface.