Crystalline Size Research Articles

CuSbS2 thin films and solar cells produced from Cu/Sb/Cu stacks via sulfurization

Phase-pure crystalline chalcostibite (CuSbS2) thin films were prepared by depositing Cu/Sb/Cu metal stacks using a thermal evaporation method, followed by sulfurization at 400oC and 430oC for different durations. The investigation revealed the formation of a dominant orthorhombic CuSbS2 phase accompanied by a minor Sb2S3 phase in the film stacks sulfurized at 400oC for 10–60 min. Extending the reaction time to 90 min triggered a decrease in the Sb2S3 phase and the emergence of an additional famatinite (Cu3SbS4) phase alongside the dominant CuSbS2 phase. Sulfurization of the film stack at 430oC for 10 min similarly produced a Cu3SbS4 secondary phase. When sulfurization was maintained beyond 30 min at 430oC, it resulted in phase-pure CuSbS2 films, characterized by a crystalline grain size of 25.9 nm, direct bandgap of 1.41 eV, and hole mobility ranging from 0.6–1.0 cm2V−1s−1. Thin film solar cells fabricated using the CuSbS2 absorbers grown at 430oC for 30–90 min displayed exceptional device efficiency due to the formation of phase-pure and highly crystalline films. Specifically, solar cells fabricated using the CuSbS2 absorber sulfurized for 60 min demonstrated a peak device efficiency of 2.2%, featuring an open-circuit voltage of 546.6 mV, short-circuit current density of 12.8 mA/cm2, and a fill factor of 31.3%. This study provides a reference for preparing highly crystalline CuSbS2 thin films for efficient solar cells.

Communication—Texture and Bandgap Tuning of Phase Pure Cu2O Thin Films Grown by a Simple Potentiostatic Electrodeposition Technique

Highly textured phase pure Cu2O thin films have been grown by a simple electrodeposition technique with varying deposition voltages (−0.3 to −1.0 V). The surface morphology characterized by Scanning Electron Microscopy (SEM) revealed that the deposited thin films coherently carpet the underlying substrate and are composed of sharp faceted well-defined grains of 0.5–1.0 μm sizes. XRD analyses showed that all films are composed of polycrystalline cubic Cu2O phase only and have average crystalline domain size in the range of 30–73 nm. The preferred crystalline orientation of phase pure Cu2O films was found to be changing from (200) to (111) with increasing cathodic voltages and showed the highest (111) and (200) crystalline texture coefficient while growing at −1.0 and −0.8 V respectively. The optical bandgap of the as-grown samples was calculated in the range of 1.95–2.20 eV using UV–vis Transmission data. The performance of Cu2O/FTO photocathodes was tested by estimating LED “ON/OFF” modulated surface photovoltage into a photoelectrochemical cell at a zero bias.

Preparation of fluorinated zirconia doped with tin oxide nanocomposites for photocatalytic degradation of organic dyes in contaminated water bodies

Abstract In this study, a novel SnO2–Zr–F nanostructured composite was successfully synthesized through a mild chemical reaction. The crystalline nature of the composite was characterized using XRD, revealing an average crystalline size of 28.31 nm. FE-SEM images illustrated an agglomerated spherical morphology with appropriate elemental ratios. The optical properties of the nanocomposite are identified by UV–vis spectroscopy with Tauc plot, and the calculated bandgap is 2 eV. Photocatalytic activity was assessed against cationic (Rhodamine B) and anionic (Eosin yellow) dyes under sunlight for 150 min, resulting in a maximum degradation efficiency of 92 % and 98 %, respectively. Furthermore, the antibacterial performance of the composite was evaluated against S. aureus and E. coli bacteria. The findings suggest that the prepared nanocomposite exhibits promising potential for environmental applications, showcasing its efficacy in both photocatalytic and antibacterial domains.

Temperature-dependent heterojunction ternary nanocomposite: Assessing photocatalytic and antibacterial applications

Heterojunction nanocomposites (ZnO:NiO:CuO) were synthesized via a hydrothermal method and annealed at three different temperatures (400 °C, 600 °C, and 800 °C). The structural, optical, and electrical properties were examined by employing XRD, SEM, UV–Vis, FTIR, and LCR meter techniques to investigate the effects of annealing. Increasing the annealing temperature resulted in the nanocomposites (NCPs) exhibiting enhanced crystallinity, purity, optical properties, and improved electrical and dielectric behavior. The calculated crystalline sizes (Debye-Scherrer method) of the NCPs were determined to be 21, 26 and 34 nm for annealing temperature 400 °C, 600 °C, and 800 °C, respectively. The calculated bandgaps of synthesized samples were found in the range of 2.92-2.55 eV. This temperature-dependent annealing process notably influenced particle size, morphology, band-gap characteristics, and photocatalytic efficiency. EDX analysis affirmed the sample purity, with elemental peaks of Zn, Cu, Ni, and O. These NCPs demonstrated exceptional photocatalytic activity against various dyes solutions (Methyl orange (MO), Methylene Blue (MB), and mixed solution of dyes) under sunlight and also showed good antibacterial properties assessed by the disc diffusion method. Notably, the nanocomposite annealed at 400 °C exhibited a particularly high degradation efficiency by degrading 96% MB and 91% MO in just 90 min under sunlight.

Electrical properties of PVC:BN nanocomposite as interfacial layer in metal-semiconductor structure

In this study, a comprehensive examination is assumed to investigate the influence of interfacial layers composed of polyvinyl chloride (PVC) and polyvinyl chloride-boron nitride (PVC: BN) on the electrical characteristics of the Au/n-Si structure. Two distinct structures, namely Au/PVC/n-Si (MPS1) and Au/PVC: BN/n-Si (MPS2), are fabricated for this purpose. The provided boron nitride (BN) nanostructures are analyzed using X-ray diffraction (XRD) patterns to determine their average crystalline size and surface morphology. Following the structural analysis, current-voltage (I–V) measurements are conducted over an extensive voltage range (± 3 V). Subsequently, the fundamental electrical properties of the developed Schottky structures are determined using various methods and compared. Experimental results indicate that the PVC: BN nanocomposite leads to an increase in the potential barrier height (BH), shunt resistance (Rsh), and rectifying rate (RR = IF/IR), while simultaneously decreasing the ideality factor (n), series resistance (Rs), and surface states density (Nss). It was discovered that the MS structure’s RR was 7 times lower than that of the MPS2 structure. Moreover, the energy-dependent Nss density is also derived using n(V) and ΦB0(V) functions. Based on the ln(IR)−VR0.5 profile at the reverse bias region, the Schottky-emission (SE) type conduction mechanism is effective for MS structures, whereas Poole-Frenkel-emission (PFE) is effective for MPS structures.

Magnetic Fe3O4 /Al2O3 /MnO2 ternary nanocomposite: Synthesis and characterization for phosphorus desorption from acidic soils using dialysis membrane tube

Monitoring phosphorus fertilization is crucial for controlling the concentration of biologically available soil P. Over the years, several methodologies have been used, including successive cropping in a greenhouse or field, as well as extractions employing P sink procedures. The latter procedures are ideal laboratory experiments to show the soil's ability to supply P and to explore the P-residual release kinetics. Following these methodologies, long-term P desorption studies have been developed using dialysis membrane tubes filled with nanomaterial solutions. In this study, a magnetic nanocomposite (Fe3O4/Al2O3/MnO2) was synthesized and characterized utilizing cutting-edge instruments such as XRD, FTIR, FAAS, BET, SEM, and EDX. The resulting material had a crystalline size and surface area of 22.75 nm and 203.69 m2/g, respectively, and was employed for long-term P-desorption and kinetics experiments while filled in dialysis membrane tubes. The P-desorption experiment was conducted on four separate acidic soil samples that were cultured for 122 days with four different P concentrations. The findings demonstrated a direct relationship between P-desorbed and P-treatment, as well as with desorption time. The minimum desorption was obtained from the control of Boji Dirmaji soil P0 (1.16–9.36) and the highest desorption from Nedjo soil with P3 (5.23–30.35 mg/kg) treatment over 1–28 days. The rate of P release from soil to solution or diffusion through the membrane was determined by pseudo-first-order kinetics with a rate constant (0.021–0.028 hr−1). This method has the potential to measure fixed-P availability by mimicking it as a plant would, with high P-desorption efficiency and quick P-release capacity.

Biogenic ZnO Nanoparticles Derived from Garcinia gummi-gutta Leaves: Synthesis, Characterization and its Multifaceted Applications

The current study focused on the bioreduction synthesis of ZnO nanoparticles using Garcinia gummi-gutta leaf extracts. The UV-vis analysis of the nanoparticles has reported the formation of an SPR peak at 379 nm. The functional groups taking part in the reduction reaction were analyzed using the FTIR technique and the average crystalline size of ZnO nanoparticles were found to be 22.27 nm from XRD measurements. The SEM and TEM images revealed the hexagonal shape of the nanoparticles with an average size 72.78 nm and 71.91 nm, respectively. Further, the synthesized nanoparticles were reported to be efficient degradation reactive textile dyes. The photodegradation results reported 92-100% degradation of the reactive dyes within 80-320 min. The antibacterial efficacy of the nanoparticles was investigated and the MIC of the nanoparticles was found to be 100 µg/mL. The synthesized ZnO nanoparticles have exhibited significant cytotoxic effects on the MCF and HEP-G2 cell lines.

Enhancing grain growth of caesium-formamidinium-based lead halide perovskite thin films through PbI2 precursor engineering in vapor-solid reaction

Vapor-solid reaction methods are highly regarded as potential solutions for large-scale production of perovskite thin films due to their scalability, compatibility with silicon tandem technology, and lack of solvents. However, the limited penetration of organic vapor through the solid inorganic film results in a slow growth rate of perovskite, leading to poor crystallinity and small grain size. This high defect density in the grain boundaries hinders the enhancement of device performance. In this study, we used 1,3-diaminoguanidine monohydrochloride as an additive in the PbI2 precursor films, which effectively improved perovskite grain growth in the vapor-solid reaction process. After optimization, we achieved high-quality perovskite thin films with a large grain size exceeding 5 μm. Notably, solar devices based on these large-grain perovskite thin films achieved a high power conversion efficiency up to 21.13%.

Testing and characterization of high-temperature degradation performance of para-aramid fibres

Para-aramid fibres possess excellent properties, including high modulus, high strength, and high-temperature resistance, making them highly practical and cost-effective reinforcement materials. To further analyse the usage performance of para-aramid fibres under extreme conditions and explore their degradation behaviour and mechanisms at high temperatures, this paper investigates para-aramid fibres through high-temperature annealing. Various tests, including thermogravimetric analysis, infrared spectroscopy, X-ray diffraction, Ubbelohde viscometry, and universal material testing, were employed to analyse changes in the thermal degradation temperature, molecular structure, and mechanical properties of para-aramid fibres. Tests have shown that after high-temperature treatment of para-aramid fibres, different protruding particles and pits appear on the surface of the fibres, and the molecular structure gradually undergoes cleavage and cross-linking. This results in varying degrees of increase in the crystallinity, intrinsic viscosity, and apparent grain size of crystal planes in different directions of the para-aramid fibres with rising temperatures. On the other hand, the degree of orientation, the rate of the second type of lattice distortion, thermal performance, and mechanical properties show a declining trend. The thermal degradation conforms to the kinetics of a second-order reaction.

Role of substrate temperature on the performance of BaTiO3/Si photodetector prepared by pulsed laser deposition

In this study, the pulsed laser deposition (PLD) method was employed to fabricate nanostructured BaTiO3 films on glass and silicon substrates at varying temperatures. The structural analysis confirmed the formation of crystalline nanostructured BaTiO3 with mixed tetragonal and hexagonal phases, and the film deposited at 150 °C has the best crystallinity and largest particle size. The optical energy gap of the BaTiO3 nanostructure decreases from 3.94 to 3.84 eV, with increasing substrate temperature from 60 to 150 °C. Photoluminescence spectra of BaTiO3 films deposited at 25, 60, 100, and 150 °C exhibit emission peaks centered at 450, 512, 474, and 531 nm, respectively. Raman spectra of BaTiO3 films show E (LO), A (TO), E (LO) + TO, and B1 vibration modes. Hall measurements reveal that the mobility of the BaTiO3 film increases with temperature up to 100 °C and then decreases at 150 °C. The current–voltage characteristics of the BaTiO3/p-Si heterojunction, deposited over a temperature range of 25 to 150 °C, were investigated in the dark and under illumination. The heterojunctions exhibit rectifying properties, with the best rectification factor observed for the heterojunction prepared at 100 °C. The values of the ideality factor for the heterojunctions fabricated at 25, 60, 100, and 150 °C were 4.3, 3.8, 2.8, and 5, respectively. The study reveals an improvement in both the figures of merit and the photodetector performance with increased substrate temperature. The responsivity increases from 2.2 to 9.25 A/W as the deposition temperature rises from 25 to 100 °C. The detectivity (D*) and external quantum efficiency (EQE) of the photodetector prepared at the optimum substrate temperature of 100 °C, were found to be 4.62 × 1012 Jones and 114%, respectively, at 500 nm.

Antimicrobial activity of probiotic bacteria-mediated cadmium oxide nanoparticles against fish pathogens

The current research was designed to investigate the antibacterial activity of probiotic bacteria mediated cadmium oxide nanoparticles (CdO NPs) on common fish pathogenic bacteria like Serratia marcescens, Aeromonas hydrophila, Vibrio harveyi, and V. parahaemolyticus. CdO NPs were synthesized using probiotic bacteria as follows: Lactobacillus species with different precursor of cadmium sulfate concentrations (5, 10, and 20 mM). The average crystalline sizes of the CdO NPs were determined based on the XRD patterns using the Debye-Scherrer equation for different precursor concentrations. Specifically, sizes of 40, 48, and 67 nm were found at concentrations of 5, 10, and 20 mM, respectively. The antibacterial efficacy of CdO NPs was estimated using a well diffusion assay, which demonstrated the best efficacy of 20 mM CdO NPs against all pathogens. AFM analysis of nanoparticle-treated and untreated biofilms was performed to further validate the antibacterial effect. Antibacterial activity of CdO nanoparticles synthesized at varying concentrations (5, 10, and 20 mM) against fish pathogens (S. marcescens, A. hydrophila, V. harveyi, and V. parahaemolyticus). The results indicated the highest inhibitory effect of 20 mM CdO NPs across all concentrations (30, 60, and 90 μg/mL), demonstrating significant inhibition against S. marcescens. These findings will contribute to the development of novel strategies for combating aquatic diseases and advancing aquaculture health management practices.

Deep separation of arsenic and alkali from alkaline arsenic containing solution using hydrothermal lime precipitation method

A new strategy of lime precipitation of arsenic (As) under hydrothermal conditions was proposed for the treatment of alkaline arsenic-containing wastewater (AAW). On the basis of theoretical analysis, a study was conducted on the reaction law and mechanism of lime precipitation of arsenic in hydrothermal systems, as well as the environmental stability of precipitation products. Results of theoretical calculations showed that increasing the reaction temperature was beneficial the formation of insoluble Ca5(AsO4)3OH, which promoted the removal of arsenic. It is shown that the arsenic concentration could be reduced from 35.38 mg/L to 9.16 mg/L with increasing the reaction temperature from 90 °C to 210 °C. The experimental results further confirmed the above conclusion. When the reaction temperature was increased from 90 °C to 210 °C, the arsenic concentration in the final liquid decreased from 706.21 mg/L to 15.21 mg/L. The leaching toxicity evaluation results of the products showed that the stability of the arsenic precipitates was improved significantly with the hydrothermal conditions. The arsenic leaching concentration for the products obtained at 170 °C was only 2.1 mg/L, which was lower than the U.S. Environmental Protection Agency (USEPA) limit of 5 mg/L for solid waste containing hazardous arsenic. It is found that the improved stability of the arsenic precipitates could be attributed to the increased crystallinity and crystal size of the product obtained under hydrothermal conditions.

A carbon-promoted galvanic replacement method to synthesize efficient PdNi nanoalloy catalyst

PdNi nanoalloy catalysts were prepared by a carbon-promoted galvanic replacement method. Characterizations and control experiments show the increased replacement rate of metal Ni with Pd2+ ion can be attributed to the higher electrode potential and smaller crystalline sizes caused by carbon doping. Introduction of carbon (C) into Ni particles not only accelerates the formation process of PdNi nanoalloys, but also enables C atoms to successfully enter the lattice interstices of PdNi nanoalloys. C regulates the surface electronic properties of PdNi nanoalloys by the electron transfer between different elements and improves their activity. The PdNi@C-650 exhibits extraordinary activity and long-term stability for hydrogenation reduction of hexavalent chromium (Cr (VI)) and hydrodechlorination of chlorophenols in comparison with PdNi/CNTs (carbon nanotubes) and commercial Pd/C. Density functional theory calculations together with investigations of mechanism reveal that the high electron-deficient PdNi nanoalloys from the redistribution of electron between Ni, Pd and C of the PdNi@C-650 promote the surface adsorption of substrate molecules and H2, which accordingly enhances the hydrogenation activity. This study brings a new method for the design and preparation of high active noble metal nanoalloy.

Rare earth elements and radioactive elements in black sands from the Konkan and Malabar coasts of India

ABSTRACT The objective of the present work is to demonstrate the ability of the laser-induced breakdown spectroscopy (LIBS) technique for quick detection and quantification of rare earth elements (REEs) and radioactive elements in the black sands at selected locations of the Konkan coast (Goa) and Malabar coast (Kerala) in India. Several REEs such as Ce, Nd, Sm, Dy, Ho, Tm, Gd, and Th have been detected in the LIBS spectra. Calibration-free LIBS method has been used to calculate the concentration of REEs and radioactive elements. The experimental result shows that the concentration of REEs such as Sm, Dy, Ho, and radioactive element Th is maximum in the sands collected from Thiruvananthapuram (Kerala) beach and minimum in the Baga (Goa) beach. The reliability of the results (qualitative and quantitative) obtained by the LIBS method has been examined by other spectroscopic techniques like XRF and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and found to be in close agreement. The multivariate approach (principal component analysis) has been applied to discern the samples based on their spectral data. Photoacoustic spectroscopy and XRD technique are used to detect compounds/minerals of REEs. The relative hardness, degree of crystallinity (DOC), and crystallite size have been calculated.

In-vitro bactericidal and anti-oxidant efficacy of biosynthesized CuO/Cu2O-NiO nanocomposites against the pathogenic bacteria and DPPH free radical

The biosynthesis of CuO/Cu2O-NiO nanocomposites with ratios of 90:10, 80:20, and 70:30 was conducted using Ipomoea carnea leaf extract. This study investigates, for the first time, the antioxidant and antibacterial activities of these nanocomposites against 1,1-diphenyl-2-picryl hydroxyl, Bacillus subtilis, Escherichia coli, and Staphylococcus aureus pathogens. The antibacterial effect of 90:10 nanocomposites (NCs A1) was found to be enhanced compared to 80:20 (NCs B1) and 70:30 (NCs C1) due to particle aggregation, significant reactive oxygen species production, uniform quantum size, and ideal crystalline size. However, 70:30 nanocomposites (NCs C1) exhibited high radical scavenging activity (96.40%), surpassing ascorbic acid (98.63%). The current study revealed that Ipomoea carnea plant extract-based 90:10, 80:20, and 70:30 CuO/Cu2O-NiO NCs work as a new substitute for the currently utilized antibacterial agents, which are answerable for the multi-drug resistance in common bacteria for living beings and also used for biological importance as antibacterial agents in food packaging industries.

Influence of iron substitution on the microstructure and properties of ettringite in calcium sulfoaluminate cement: A comprehensive study on the Al/(Fe+Al) ratios

Ettringite, as the dominant hydration product of calcium sulfoaluminate cement, significantly contributes to cement strength. Its formation is closely related to the Fe and Al ratio in raw materials. During cement hydration, Fe present in ferrite can replace some of the Al in ettringite, which notably affects the microstructure and properties of the latter. To understand the relationship between the Al/(Fe + Al) ratios and the ettringite phase, we synthesized ettringite with varying Al/(Fe + Al) ratios using a chemical synthesis method. The microstructure was then characterized to determine the formation process of this phase. Various analysis methods, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscope (TEM), and N2 adsorption-Brunauer Emmett Teller (BET), were used to study the solid phases. For aqueous solutions, inductively coupled plasma emission spectroscopy (ICP-OES) was employed. Our results reveal that Fe replacing Al leads to regular changes in the ettringite crystal's microstructure. As the Al/(Fe + Al) ratio decreases, there is a reduction in the ettringite unit cell parameter a, an increase in c, and an enlargement of the unit cell volume. Concurrently, Fe substitution shrinks the crystallinity and grain size of ettringite crystals. SEM-TEM and BET demonstrate that Fe substitution boosts ettringite's particle size and aspect ratio, while the specific surface area contracts with a decreasing Al/(Fe + Al) ratio. Moreover, Fe substitution tends to lower ettringite's thermal stability and OH group binding ability. When the Al/(Fe + Al) ratio reached 80%, the ettringite crystal exhibited optimal thermal stability.

Impact of hydrothermal and solvent-thermal synthesis on the electrochemical performance of V2O5

This research focuses on synthesizing vanadium oxide through hydrothermal and solvent-thermal methods, to explore their potential application in supercapacitors. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) are used to determine the crystalline size and functional group, while scanning electron microscopy (SEM) is used to investigate their morphologies. The electrochemical performance was evaluated through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The results demonstrated that the V2O5 synthesized by the hydrothermal method exhibited two-fold increases in specific capacitance compared to those produced by the solvent-thermal method. Experimental results also indicate that nanoparticles V2O5 by hydrothermal can deliver a capacitance of 121 Fg−1 and solvent-thermal deliver a capacitance of 72 Fg−1 at the current density of 1 Ag−1 in the potential range from 0 to 0.45 V in a 3 M KOH aqueous electrolyte.

Photocatalytic degradation of naphthol blue black dye using undoped and Al-doped cobalt ferrite nanoparticles

The current study aims to evaluate the effectiveness of undoped (CoFe2O4) and aluminium-doped cobalt spinel ferrite (CoFe1.1Al0.9O4) nanoparticles as photocatalysts in the process of photocatalytic degradation of organic naphthol blue black (NBB) dye. In the sol-gel auto combustion method, a combination of metal nitrates, citric acid, sodium hydroxide, and liquid ammonia was utilized as the raw chemical ingredients for synthesizing nanoparticles of CoFe2-xAlxO4 (x = 0.0, 0.3, 0.6, 0.9, 1.2, 1.5) spinel ferrites. The nanoparticles were subjected to various characterization techniques including thermal analysis (TGA/DTA), X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and UV–visible spectroscopy for comprehensive analysis. The XRD analysis confirmed the presence of a spinel cubic structure in the synthesized spinel ferrite nanoparticles. The interplanar distance (d) and crystalline size (D) were determined using Bragg's equation and Scherrer's relationship, respectively. The morphological characteristics and elemental composition of the spinel ferrites were confirmed through FE-SEM and EDS. Furthermore, the UV spectrum of the synthesized photocatalyst was investigated to compare the energy band gap between undoped and Al-doped cobalt spinel ferrites. The analysis of photoluminescence (PL) spectra was conducted to investigate the dynamics of charge carriers, focusing on their transfer, relocation, and recombination processes. The surface area of the synthesized photocatalyst ranged from 3.525 to 16.113 m2/g. Photocatalytic degradation of naphthol blue black (NBB) dye was carried out under visible light exposure utilizing both cobalt spinel ferrite nanoparticles without doping and those doped with aluminium. Several factors, including pH level, H2O2 concentration, amount of photocatalyst (spinel ferrite) and initial dye concentration, were considered through the photocatalytic degradation of NBB dye. The highest percentage degradation (%) of NBB dye was determined at pH 11. For NBB dye with an initial concentration of 20 ppm, the maximum degradation was achieved using 200 mg of spinel ferrite nanoparticles per 100 mL dye solution under visible light irradiation for 40 min.

Olax zeylanica Leaf Extract-assisted Eco-Benevolent Synthesis of Sulfur Nanoparticles and the Determination of their Insecticidal Potential against Sitophilus oryzae (L.) (Coleoptera: Curculionidae)


 
 
 Stored-product insects are serious pests of dried, stored, durable agricultural goods and value-added foods worldwide. In spite of the commonest way of controlling pestiferous insects associated with cereal grains and their milled products via conventional insecticides, their usage on stored grains are not recommended due to expensiveness, inefficacy due to insect resistance, and potential health hazards to humans. These deleterious consequences thus have been encouraging to merit investigation on the plant extract-assisted eco-benevolent synthesis of nanoparticles, owing to their sustainable, non-noxious, convenient, and environmental friendly nature. In view of this background, the present study was aimed at evaluating the insecticidal effectiveness of green synthesized sulfur nanoparticles (SNPs) against Sitophilus oryzae adults. SNPs have been successfully prepared from sodium thiosulfate (Na2S2O3.5H2O) in the presence of Olax zeylanica leaf extract at room temperature. The resulting SNPs were then characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The toxicity of Sitophilus oryzae was bio-assayed by exposing the test insects to SNPs-treated rice grains at six different dosages at 1.5, 1.0, 0.5, 0.25, 0.125 and 0.0625 g/kg, whereby mortality counts were taken after every 24 hours for seven days. The UV- Vis spectroscopy showed a peak in the range of 260-280 nm, which showed the successful formation of SNPs, while being in accordance with the previous studies reported in the literature. According to the Debye-Scherrer formula of XRD data, the average crystalline size of the SNPs counted to be 72.7 nm. The particle size of SNPs is also confirmed by SEM images. FTIR results showed peak positions corresponding to S8 with slight differences due to the presence of biomolecules from the O. zeylanica leaf extract being bound onto the surface of SNPs. Bioassay results show that the mortality of insects increased with the increase of dosage and exposure time period, reporting 100% S. oryzae mortalities at 1.5 and 1.0 g/kg dosages within 7 days. Accordingly, the results of the present study thus suggest that the bio-transformed sulfur nanoparticles could be utilized not only as biocontrol agents, but also as ecofriendly candidates for the sustained-protection storage grain ecosystems from insect pest infestations.
 Keywords: Green-synthesized Sulfur nanoparticles, Olax zeylanica, Insecticidal, Sitophilus oryzae
 
 

Feasibility study on thermo‐mechanical performance of 3D printed and annealed coir fiber powder/polylactic acid eco‐friendly biocomposites

AbstractThe enhancement of the mechanical and thermal characteristics of 3D printed polylactic acid (PLA) composites reinforced by coir fiber powder (CFP) has been investigated by varying the weight percentage (wt%) of the reinforcement and annealing process. CFP/PLA composite filaments with CFP compositions of 0.1, 0.3, and 0.5 wt% were fabricated. These filaments were used to print CFP/PLA test specimens. The specimens were annealed at 90°C for 120 min in a hot air oven followed by cooling at room temperature. Mechanical, morphological, crystalline, and thermal characterizations were conducted on these specimens. The tensile and flexural strength of neat PLA were observed as 49.7 and 82.4 MPa which decreased by 6.4% and 8.13% respectively for printed composite specimens with 0.5 wt% CFP as reinforcement material. On the other hand, the annealed CFP/PLA composite specimen, with 0.1 wt% CFP as a reinforcement material, demonstrated higher tensile and flexural strength. Specifically, it exhibited a maximum tensile strength of 56.4 MPa and a maximum flexural strength of 92.9 MPa, which are 13.5% and 12.7% higher, respectively, than neat PLA. These strengths are 15.5% and 16.7% higher, respectively, than those of the unannealed CFP/PLA composite specimen with the same wt% of CFP reinforcement. The annealing process increased the crystallinity of composites by enhancing the crystallinity index (63%) and crystalline size (6.7 nm). The high thermal stability of composites (with a glass transition temperature of 256°C) makes them suitable for applications in food and medical packaging.Highlights Enhancement of thermo‐mechanical characteristics of 3D printed bio‐composites. Annealing process improved mechanical features of 3D printed bio‐composites. Annealed composite with 0.1 wt% as reinforcement demonstrated better properties. SEM and XRD studies confirmed failure mechanisms and crystalline structure. Thermal and mechanical assets favor its utilization in food wrapping applications.