In this study, cellulose nanocrystals (CNC) were produced using acid hydrolysis method. Kenaf core was pretreated with 4
wt. % sodium hydroxide (NaOH), followed by bleaching using 1.7 wt. % sodium chlorite (NaClO2
) in acetate buffer. The
bleached fiber was acid hydrolyzed for 45 and 55 min using 64 wt. % sulfuric acid (H2
SO4
). The size distribution of the
CNC segregated via differential centrifugation with different speed was also investigated. The CNC suspension obtained
was centrifuged at 3000, 6000, 9000 and 12000 rpm. The resultant CNC suspension collected was characterized using
Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD) and transmission electron microscopy (TEM). FTIR
results showed the progressive removal of non-cellulosic constituents for each subsequent treatment. It also showed that
the CNC produced after hydrolysing for 55 min has the highest degree of crystallinity (81.15%). CNC produced from acid
hydrolysis process of 45 min have lengths between 50 and 270 nm while CNC produced from acid hydrolysis process of
55 min have length around 40 to 370 nm.
Hydroxyapatite (HAP) is a significant bone mineral that establishes bone strength. HAP composites in combination with biodegradable and bioactive polymer poly xylitol sebacic adipate (PXSA) would result in a constant release at target sites. Numerous studies have shown that vitamin K (VK) might possess a vital function in bone metabolism. The purpose of the present study was to inspect the synthesized composite HAP/PXSA/VK in developing polymeric biomaterials composite for the application of bone tissue regeneration. FTIR, X-ray diffraction, SEM and TEM techniques were applied to characterize the prepared composites. The release of VK from the HAP/PXSA/VK composite was evidenced through UV-Vis spectroscopy. In vitro studies proved that the HAP/PXSA/VK composite is appropriate for mesenchymal stem cell culture. Compared to pure HAP prepared following the same method, HAP/PXSA/VK composite provided favourable microstructures and good biodegradation distinctiveness for the application of tissue engineering, as well as tissue in-growth characteristics and improved scaffold cell penetration. This work reveals that the HAP/PXSA/VK composites have the potential for applications in bone tissue engineering.
Two inorganic pigments (TiO2 and SiO2) were used to prepare composites with polyaniline (PANI) by situ polymerization method. PANI and PANI composites with SiO2 and TiO2 were characterized using Fourier transform infrared spectroscopy and X-ray diffraction. The morphology of the synthesized pigments (PANI , PANI-SiO2 and PANI-TiO2) was examined using scanning electron microscopy. Samples were then used as pigments through blending them with acrylic paint and applied on the surface of carbon steel panels. Corrosion was evaluated for coating of carbon steel panels through full immersion test up to standard ASTMG 31. Mass loss was calculated after they have been exposed in acidic media. A digital camera was also used for monitoring corrosion visually on the surface of carbon steel specimens. The results revealed that acrylic paint pigmented by PANI-SiO2 composite was more efficient in corrosion protection for carbon steel compared with the other synthesized pigments.
The present study reports on the fabrication of porous zinc oxide by wet chemical etching. ZnO thin films were deposited via radio-frequency magnetron sputtering on p-type silicon with (111) preferred orientation. The etchants used in the present work were 0.1% and 1.0% nitric acid (HNO3) solutions. ZnO were etched at various times and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy to allow the examination of their structural and optical properties. The XRD results revealed that the intensity of ZnO(002) decreased when the thin films were etched in varying HNO3 concentrations over different periods of time. The above observation is attributed to the dissolution of the ZnO(002). The SEM images showed that the thickness of the ZnO layers decreased over the etching time, which resulted from the isotropic etching by the HNO3 solution. The PL emission intensity initially increased with increasing etching time. However, with further etching of the samples, the PL spectra showed a decreasing trend in intensity as a result of the decrease in the surface-to-volume ratio. All results lead to the conclusion that 1.0% HNO3 has the capability to change the ZnO surface significantly.
Cellulose nanocrystals (CNC) from mengkuang leaves (Pandanus tectorius) were investigated as potential reinforcement
in poly(vinyl chloride) (PVC) matrix. The surface of CNC was modified with silane coupling agent to improve fillermatrix
adhesion. Solution casting method was used to prepare PVC nanocomposites with various amounts of modified
(SCNC) and unmodified (CNC) nanocrystals. Both SCNC and CNC were examined by Fourier transform infrared (FTIR)
spectroscopy and X-ray diffraction (XRD) which showed that surface chemical modification has occurred. An increase
in tensile strength was observed with the addition of SCNC compared to the CNC. However, the elongation at break of the
nanocomposites was found to decrease with the increase of both fillers loading. An increasing trend was observed in the
tensile modulus with the addition of CNC to the PVC matrix, but decreasing with the addition of SCNC. The morphology
of a fractured surface of nanocomposites showed silane modification reduced the number of voids in the structure of
PVC. The observation indicated the adhesion between the fiber and the matrix had improved upon surface modification
of the nanocrystals with silane.
ZnO nanowires have been synthesized using a catalyst-free carbothermal reduction approach on SiO2-coated Si substrates in a flowing nitrogen atmosphere with a mixture of ZnO and graphite as reactants. The collected ZnO nanowires have been characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and photoluminescence spectroscopy. Controlled growth of the ZnO nanowires was achieved by manipulating the reactants heating temperature from 700 to 1000 oC. It was found that the optimum temperature to synthesize high density and long ZnO nanowires was about 800 0C. The possible growth mechanism of ZnO nanowires is also proposed.
The chemical reactions of dry-disposed ash dump, ingressed oxygen, carbon dioxide, and infiltrating rainwater affect mineralogical transformation, redistribution, and migration of chemical species. Composite samples of weathered coal fly ash taken at various depths and fresh coal fly ash were examined using organic petrographic, X-ray diffraction, X-ray fluorescence techniques, and successive extraction procedures. Results obtained show relative enrichment of glass, Al-Fe-oxides, calcite, and tridymite in the weathered CFA, but the fresh CFA is enriched in mullite, inertinite, maghemite, and ettringite. The enrichment of the weathered CFA in amorphous glass suggests higher reactivity when compared to fresh CFA. The evident depletion of soluble oxides in the weathered CFA is attributed to flushing of the soluble salts by percolating rainwater. Comparative enrichment of examined elements in water-soluble, exchangeable, reducible, and residual fractions of the weathered CFA is partly due to the slow release of adsorbed chemical species from the alumina-silicate matrix and diffusion from the deeper sections of the particles of coal fly ash. Sodium and potassium show enrichment in the oxidisable fraction of fresh CFA. The estimated mobility factor indicates mobility for Ca, Mg, Na, Se, Mo, and Sb and K, Sr, V, Cu, Cr, Se, and B in fresh and weathered CFAs, respectively.
A series of polystyrene nanoparticles (PS-1, PS-2, PS-3, and PS-4) in aqueous solutions were investigated in terms of morphological structure, size, and size distribution. Synchrotron small-angle X-ray scattering analysis (SAXS) was carried out, providing morphology details, size and size distribution on the particles. PS-1, PS-2, and PS-3 were confirmed to behave two-phase (core and shell) spherical shapes, whereas PS-4 exhibited a single-phase spherical shape. They all revealed very narrow unimodal size distributions. The structural parameter details including radial density profile were determined. In addition, the presence of surfactant molecules and their assemblies were detected for all particle solutions, which could originate from their surfactant-assisted emulsion polymerizations. In addition, dynamic light scattering (DLS) analysis was performed, finding only meaningful hydrodynamic size and intensity-weighted mean size information on the individual PS solutions because of the particles' spherical nature. In contrast, the size distributions were extracted unrealistically too broad, and the volume- and number-weighted mean sizes were too small, therefore inappropriate to describe the particle systems. Furthermore, the DLS analysis could not detect completely the surfactant and their assemblies present in the particle solutions. Overall, the quantitative SAXS analysis confirmed that the individual PS particle systems were successfully prepared with spherical shape in a very narrow unimodal size distribution.
Highly ordered vertically grown zinc oxide nanorods (ZnO NRs) were synthesized on ZnO-coated SiO2/Si substrate using zinc acetylacetonate hydrate as a precursor via a simple hydrothermal method at 85 °C. We used 0.05 M of ZnO solution to facilitate the growth of ZnO NRs and the immersion time was varied from 0.5 to 4 h. The atomic force microscopy revealed the surface roughness of ZnO seed layer used to grow the ZnO NRs. The morphology of vertically grown ZnO NRs was observed by field emission scanning electron microscopy. X-ray diffraction examination and transmission electron microscopy confirmed that the structure of highly ordered ZnO NRs was crystalline with a strong (002) peak corresponded to ZnO hexagonal wurtzite structure. The growth of highly ordered ZnO NRs was favorable due to the continuous supply of Zn2+ ions and chelating agents properties obtained from the acetylacetonate-derived precursor during the synthesis. Two-point probe current-voltage measurement and UV-vis spectroscopy of the ZnO NRs indicated a resistivity and optical bandgap value of 0.44 Ω.cm and 3.35 eV, respectively. The photoluminescence spectrum showed a broad peak centered at 623 nm in the visible region corresponded to the oxygen vacancies from the ZnO NRs. This study demonstrates that acetylacetonate-derived precursors can be used for the production of ZnO NRs-based devices with a potential application in biosensors.
Carbonation for the curing of cement-based materials has been gaining increased attention in recent years, especially in light of emerging initiatives to reduce carbon dioxide (CO2) emissions. Carbonation method or CO2 curing is founded on the basis of the reaction between CO2 and cement products to form thermally stable and denser carbonate, which not only improves the physical and mechanical properties of cement-based materials, but also has the ability to utilize and store CO2 safely and permanently. This study aims to assess the effect of CO2 curing technology on the high-temperatures performance of cement blocks. Upon molding, dry-mix cement blocks were cured under statically accelerated carbonation condition (20% CO2 concentration with 70% relative humidity) for 28 days, followed by exposure to elevated temperatures of 300 °C to 800 °C in order to comprehensively study the principal phase changes and decompositions of cement hydrates. The results indicated that CO2 curing improved the performance of cement blocks, such as enhancement in the residual compressive strength and reducing the sorptivity. At 600 °C, the scanning electron microscopy (SEM) revealed a denser microstructure while thermal analisis and X-ray diffraction (XRD) analysis also clearly demonstrated that higher amounts of calcium carbonate were present in the cement blocks after CO2 curing, suggesting better high-temperature performance compared to natural cured cement blocks. In general, an improved high-temperature performance, specifically at 600 °C of the dry-mixed cement blocks was demonstrated by adopting the CO2 curing technology. This confirms the potential of utilizing CO2 curing technology in not only improving quality of cement blocks, new avenue for storing of CO2 in construction material can be realized at the same time.
A novel layer-by-layer (LBL) based electrode material for supercapacitor consists of polypyrrole/graphene oxide and polypyrrole/manganese oxide (PPy/GO|PPy/MnO2) has prepared by electrochemical deposition. The formation of LBL assembled nanocomposite is confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The field emission scanning electron microscopy images clearly showed that PPy/MnO2 was uniformly coated on PPy/GO. The PPy/GO|PPy/MnO2 symmetrical supercapacitor has revealed outstanding supercapacitive performance with a high specific capacitance of 786.6 F/g, an exceptionally high specific energy of 52.3 Wh/kg at a specific power of 1392.9 W/kg and preserve a good cycling stability over 1000 cycles. It is certain that PPy/GO|PPy/MnO2 has an extraordinary perspective as an electrode for future supercapacitor developments. This finding contributes to a significant impact on the evolution of electrochemical supercapacitor.
In this study, the adsorption efficiency of methyl violet (MV) dye onto Ce0.3Al0.7 and Ce0.3Al0.7Agx (x = 0.1, 0.3 & 0.5) mixed oxides was investigated. The properties of mixed oxide were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), N2 adsorption-desorption isotherm, diffuse reflectance UV-vis spectroscopy (UV-vis DRS) and X-ray absorption near edge structure (XANES). Characterization showed that synthesized mixed oxide with fluorite has a pure cubic structure of a mesoporous nature and a small grain size with rough surface. Batch adsorption experiments were used to study parameters including contact time and initial dye concentration. The results showed that these parameters affected the degree of MV dye adsorption. The dye adsorption of mixed oxides attained equilibrium at 120 min. The equilibrium adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherms. The adsorption behavior of MV dye onto Ce0.3Al0.7 was found to follow the Langmuir isotherm (R2 = 0.9951), providing a maximum monolayer adsorptive capacity of 2.35 mg/g. Alternatively, the adsorption of MV dye onto Ce0.3Al0.7Ag0.1 (R2 = 0.7839), Ce0.3Al0.7Ag0.3 (R2 = 0.9301) and Ce0.3Al0.7Ag0.5 (R2 = 0.9396) followed the Freundlich isotherm. The possible adsorption mechanisms of MV dyes onto the Ce0.3Al0.7 and Ce0.3Al0.7Agx were also discussed.
Titanium dioxide (TiO2
) nanoparticles thin film has been successfully synthesized by a spray pyrolysis deposition method
by using an air compressor on a fluorine-doped tin oxide (FTO) substrate and was annealed at different temperature. TiO2
is the most common oxide as an electrode in dye sensitized solar cell (DSSC) which still has chances of improvements to
increase its efficiency as an electrode. The efficiency of a DSSC was relatively low but modifications on every part of a
DSSC were currently in research progress and an increase in adsorbed dye molecules was considered a potential. Thus,
the influences of annealing temperature on structural and morphological properties of TiO2
have been studied using
X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively, while the efficiency of
the films in a solar cell was studied by a solar simulator. The FESEM result showed several degrees of porosity obtained
by varying the annealing temperature. The crystallinity of TiO2 investigated by XRD showed that the crystallinity of the
TiO2
thin films was generally unaffected by the annealing temperature. The relationship between the properties and the
efficiency of the films as an electrode was also studied
Sn-Ag based solder alloy seems to be a promising lead-free solder for the application on electronic assembly. The corrosion behavior of different lead free solder alloys such as Sn-3.0Ag, Sn-1.0Ag-0.5Cu and Sn-3.0Ag-0.5Cu was investigated in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to characterize the samples after the tests. The results showed that the addition of 0.5 wt. % copper with Sn-3.0 Ag solder alloy led to a better corrosion resistance while lowering of Ag content from 3.0 to 1.0 wt. % decreased the resistance. Sn-3.0Ag-0.5Cu exhibits a better corrosion resistance in terms of increased charge transfer resistance and impedance values as well as the lowest capacitance. These characteristics signify its suitability for the application in electronic packaging.
Environmental concerns have significantly influenced the construction industry regarding the identification and use of environmentally sustainable construction materials. In this context, enzymes (organic materials) have been introduced recently for ground improvement projects such as pavements and embankments. The present experimental study was carried out in order to evaluate the compressive strength of a sedimentary residual soil treated with three different types of enzymes, as assessed through a California bearing ratio (CBR) test. Controlled untreated and treated soil samples containing four dosages (the recommended dose and two, five and 10 times the recommended dose) were prepared, sealed and cured for four months. Following the curing period, samples were soaked in water for four days before the CBR tests were administered. These tests showed no improvement in the soil is compressive strength; in other words, samples prepared even at higher dosages did not exhibit any improvement. Nuclear magnetic resonance (NMR) spectroscopy tests were carried out on three enzymes in order to study the functional groups present in them. Furthermore, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) tests were executed for untreated and treated soil samples to determine if any chemical reaction took place between the soil and the enzymes. Neither of the tests (XRD nor FESEM) revealed any change. In fact, the XRD patterns and FESEM images for untreated and treated soil samples were indistinguishable.
The magnetic adsorbents i.e. oil palm frond-magnetic particles (OPF-MP) and oil palm frond activated carbon-magnetic particles (OPFAC-MP) have been prepared by impregnation of iron oxide via co-precipitation method. The magnetic adsorbents and their parent materials were characterized using Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), Brunauer Emmett Teller (BET), Barrett, Joyner & Halenda (BJH) and t-plot method, x-ray diffraction (XRD) and also using vibrating sample magnetometry (VSM) to study their properties and surface chemistry. The activated carbon magnetic adsorbent confers high surface area of 700 m2/g with amorphous structure and magnetic properties of 2.76 emu/g. The OPF-MP and OPFAC-MP were then applied in adsorption study for ions removal of Pb(II), Zn(II) and Cu(II). OPFAC-MP has shown high removal efficiency of 100 % with adsorption capacity up to 15 mg/g of Pb(II), Zn(II) and Cu(II) ions compared to OPF-MP. In addition, the magnetic adsorbents were also compared with their parent materials to observe the effect of magnetic particles. Accordingly, the impregnation of magnetic particles enhances the metal ions adsorption comparing to their parent materials.
Zinc oxide (ZnO) utilization in advanced oxidation process (AOP) via solar-photocatalytic process was a promising method for alternative treating wastewater containing phenol. The ZnO photocatalyst semiconductor was synthesized by sol-gel method. The morphology of the ZnO nanostructures was observed by using scanning electron microscope (SEM) and the crystallite phase of the ZnO was confirmed by x-ray diffraction (XRD). The objective of this study was to synthesis ZnO nanoparticles through a sol-gel method for application as a photocatalyst in the photodegradation of phenol under solar light irradiation. The photodegradation rate of phenol increased with the increasing of ZnO loading from 0.2 until 1.0 g. Only 2 h were required for synthesized ZnO to fully degrade the phenol. The synthesized ZnO are capable to totally degrade high initial concentration up until 45 mg L-1 within 6 h of reaction time. The photodegradation of phenol by ZnO are most favoured under the acidic condition (pH3) where the 100% removal achieved after 2 h of reaction. The mineralization of phenol was monitored through chemical oxygen demand (COD) reduction and 92.6% or removal was achieved. This study distinctly utilized natural sunlight as the sole sources of irradiation which safe, inexpensive; to initiate the photocatalyst for degradation of phenol.
It is believed of great interest to incorporate silver nanoparticles (Ag-NPs) into stable supported materials using biological methods to control the adverse properties of nanoscale particles. In this study, in-situ biofabrication of Ag-NPs using Entada spiralis (E. spiralis) aqueous extract in Ceiba pentandra (C. pentandra) fiber as supporting material was used in which, the E. spiralis extract acted as both reducing and stabilizing agents to incorporate Ag-NPs in the C. pentandra fiber. The properties of Ag-NPs incorporated in the C. pentandra fiber (C. pentandra/Ag-NPs) were characterized using UV-visible spectroscopy (UV-vis), X-ray Diffraction (XRD), Field Emission Transmission Electron Microscope (FETEM), Scanning Electron Microscope (Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET), Thermogravimetric (TGA) and Fourier Transform Infrared (FTIR) analyses. The average size of Ag-NPs measured using FETEM image was 4.74 nm spherical in shape. The C. pentandra/Ag-NPs was easily separated after application, and could control the release of Ag-NPs to the environment due to its strong attachment in C. pentandra fiber. The C. pentandra/Ag-NPs exposed good qualitative and quantitative antibacterial activities against Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922) and Proteus vulgaris (ATCC 33420). The dye catalytic properties of C. pentandra/Ag-NPs revealed the dye reduction time in which it was completed within 4 min for 20 mg/L rhodamine B and 20 min for 20 mg/L methylene blue dye, respectively. Based on the results, it is evident that C. pentandra/Ag-NPs are potentially promising to be applied in wound healing, textile, wastewater treatment, food packaging, labeling and biomedical fields.
Solvothermal synthesis is the most preferable preparation technique of metal-organic frameworks (MOFs) that consists of reactants mixing, ultrasonication, solvothermal reaction, product washing, and solvent evacuation. Owing to fast reaction kinetics in solvothermal reaction, this technique allows for production of uniform MOF particles with high crystallinity, high phase purity, and small particle sizes. However, it exhibits some difficulties of washing processes that may involve the blockage of pores due to incomplete removal of reactive medium from MOF products. The present study proposes an improvement of washing processes by introducing centrifugal separations with optimized parameters at two different stages: after reaction and after product washing. Nickel‑based MOF‑74 was synthesized as the experimental material for this purpose. The quality of the produced sample was evaluated by gas adsorption performance using CO2 at 1 bar and 25 °C. The final sample of the optimized synthesis routes was able to adsorb 5.80 mmol/g of CO2 uptake, which was competitive with literature data and significantly higher than the sample of the basic synthesis. Fourier‑transform infrared spectroscopy (FTIR) and powder X‑ray diffraction (PXRD) analysis revealed that the sample displayed much higher crystallinity structure and was clean from impurities after centrifugations. The outcome indicated the success of separation between MOF products and reactive medium during washing processes, leading to the effective pore activation of MOFs.
Bamboo fibers are utilized for the production of various structures, building materials, etc. and is of great significance all over the world especially in southeast Asia. In this study, the extraction of microcrystalline cellulose (MCC) was performed using bamboo fibers through acid hydrolysis and subsequently different characterizations were carried out using various advanced techniques. Fourier transform infrared (FTIR) spectroscopy analysis has indicated the removal of lignin from MCC extracted from bamboo pulp. Scanning Electron Microscopy (SEM) revealed rough surface and minor agglomeration of the MCC. Pure MCC, albeit with small quantities of impurities and residues, was obtained, as revealed by Energy Dispersive X-ray (EDX) analysis. X-ray diffraction (XRD) indicates the increase in crystallinity from 62.5% to 82.6%. Furthermore, the isolated MCC has slightly higher crystallinity compared to commercial available MCC (74%). The results of thermal gravimetric analysis (TGA) demonstrate better thermal stability of isolated MCC compared to its starting material (Bamboo fibers). Thus, the isolated MCC might be used as a reinforcing element for the production of green composites and it can also be utilized as a starting material for the production of crystalline nanocellulose in future.