Md. Abdul Gafur’s research while affiliated with Bangladesh Council of Scientific and Industrial Research and other places

Microhardness testing is a quick and efficient way to assess some distinct mechanical properties of polymer composites that are difficult to measure experimentally. This study examined the Vicker’s microhardness of microfibrillated cellulose (MFC)-reinforced poly(L-lactic acid) (PLA) composites with different weight fractions 0.00 wt% to 0.05 wt%. The composites of PLA and MFC were prepared using the solvent casting method. The hardness of samples was measured with indentation loads of 0.098, 0.2452, 0.4903, 0.9807 and 1.971 N. The effects of XMFC in the composites were further assessed by tensile strength test, thermogravimetry test and SEM analyses. The load-oriented indentation size effect behaviour of the composites was studied with well-established theoretical models, namely, Meyer’s Law, Hays – Kendall, elastic/plastic deformation, proportional sample resistance, and modified proportional sample resistance models. The composites exhibited a plastic deformation tendency under indentation loads that closely fit the Hays – Kendall model. The calculated true hardness data were used to determine several distinct mechanical properties, viz. yield strength (Y), elastic modulus (E), brittleness index (B), and fracture toughness (K). The values of Y, E, B, and K changed successively with increasing MFC fraction. In conclusion, Vicker’s microhardness analyses will provide valuable information for selecting the filler‒matrix ratio of cellulose/PLA composites.

Talipot palm tree (Coryphe umbraculifera) is a plant species of eastern–southern countries. Like other palm species, talipot palm fiber exhibits potential as a reinforcement in polyester composites. Due to the unevenness present in the fiber body, natural fibers show different values for the same mechanical property across their length. Due to these scattered data, the calculation of the tensile properties of natural fiber using traditional methods is not adequate. This research aims to statistically estimate the ultimate tensile strength of talipot palm fiber, both untreated and treated with chemicals. The data have been fitted using a two-parameter Weibull distribution model. Kolmogorov–Smirnov test and Anderson–Darling test are used to check the goodness of fit of the empirical distribution. Alkalization, acetylation, and benzylation treatments were carried out for three different chemical concentrations (5, 10, and 15 wt%). X-ray diffraction (XRD) analysis and FTIR spectroscopy were done to ensure the effect of chemical treatments. The tensile strength of raw talipot palm fiber has been assessed at five distinct lengths (10, 15, 20, 25, and 30 mm). 10 mm raw palm fiber exhibited the highest tensile strength of 321.13 MPa, while 30 mm raw palm fiber showed the lowest tensile strength of 237.35 MPa. The 10% NaOH-treated talipot palm fiber had the highest tensile strength of 462.47 MPa, whereas the 5% benzylated talipot palm fiber displayed the lowest tensile strength of the treated fibers.

All-solid-state lithium-ion batteries (ASSLBs) are the next advancement in battery technology which is expected to power the next generation of electronics, particularly electric vehicles due to their high energy density and superior safety. ASSLBs require solid electrolytes with high ionic conductivity to serve as a Li-ion battery, driving extensive research efforts to enhance the ionic conductivity of the existing solid electrolytes. Keeping this in view, the B-site of Li0.33La0.56TiO3 (LLTO) solid electrolyte has been partially substituted with Ga and novel Ga-doped LLTO (Li0.33+xLa0.56Ti1−xGaxO3) solid-electrolytes are fabricated using the solid-state reaction method, followed by sintering at 1100 °C for 2 h. The effects of Ga substitution on the structural changes, chemical states, ionic conductivity, and electrochemical stability of LLTO are systematically analyzed. The XRD analysis of the LLTO samples confirms the formation of a tetragonal perovskite structure and increasing bottleneck size up to 3% Ga-doped samples. XPS results have further confirmed the successful substitution of Ti⁴⁺ by Ga³⁺. The Ga³⁺ substitution has successfully enhanced the conductivity of LLTO solid electrolytes and the highest conductivity of 4.15 × 10⁻³ S cm⁻¹ is found in Li0.36La0.56Ti0.97Ga0.03O3 (x = 0.03), which is an order of magnitude higher than that of pristine LLTO. This increase in ionic conductivity is a synergistic effect of B–O bond stretching resulting from the size difference between Ga³⁺ and Ti⁴⁺ and the increase in grain size. Moreover, the synthesized solid electrolytes are stable within the range of 2.28 to 3.78 V against Li/Li⁺, making them potential candidates for all-solid-state lithium-ion batteries.

First, due to the brittle nature of the PLLA‐fiber (poly(L‐lactic acid)‐fiber) composite and then the poorer physical properties of the PVA‐fiber (Poly(vinyl alcohol)‐fiber) composite, composites with balanced properties were prepared using PVA, PLLA, and cotton or bleached jute. Here PVA and PLLA will serve as matrices while composites of PVA/PLLA/Cotton or bleached jute were prepared with different compositions (85/10/5), (70/20/10) and (55/30/15). The composites' physical, mechanical, thermal, and morphological properties were analyzed. Composites with larger amounts of PVA have higher water absorption capacities while composites with higher amounts of PLLA exhibit greater bulk densities. Tensile strength and elongation of PVA/PLLA/Cotton composites decrease with an increase in fiber loading, whereas that of PVA/PLLA/Bleached jute composite increases with fiber loading up to 10%, followed by a decrease. Young's modulus diminishes when the percentage of fiber in the composites increases. The peak temperature related to the second step of decomposition for the neat matrix was highest for the composite containing 10% of cotton and lowest for the 15% jute. Thermal expansion coefficient decreases with increasing fiber percentages. SEM images show that interfacial adhesion between PVA/PLLA blends with bleached jute is stronger than that of cotton fiber; cotton fiber reinforced composites reveal fiber slips during failure.

In this current study, a new class of multifunctional biobased ecofriendly nanosorbents namely crystalline nanocellulose-activated char (CNC-AC) nanosorbents were fabricated by employing a much more innovative and beneficial solvent evaporation induced phase separation (EIPS) technique. While the crystalline nanocellulose (CNC) were extracted from a very much new, innovative, and beneficial agrowaste source namely banana tree (M. oranta) rachis fibers by conducting a series of chemical treatments like scouring, alkali treatment, bleaching, and acid hydrolysis reactions. Additionally, the biochar were synthesized from the residual mass of Magnolia champaca L. barks after methanol extraction and functionalized by 30 % H3PO4 to improve their overall properties. Besides these the fixed-bed continuous column adsorption study were carried out by optimizing the various influential factors such as preliminary concentration and flow rates of the inlet wastewater solution, along with the nanosorbent bed heights into the applied column. For better understanding the overall physicochemical, thermomechanical, and morphostructural behavior of the newly fabricated polyfunctional CNC-AC bionanosorbents the samples were characterized by conducting FTIR-ATR, FESEM, BET, XRD, TGA analysis. Meanwhile the treated and nontreated water specimens were examined by conducting AAS and UV–vis-NIR techniques. The obtained results recommended that the newly produced CNC-AC nanosorbents have contained a quite number of active edges/binding sites along with substantial sp. surface area (around 316.95 m2/g). Additionally, they possessed a crystallinity index about 59.98 ± 0.027 %, greater thermal steadiness up to 600 °C, and outstanding 2D honeycomb-like mesoporous peripheral surface microstructure with a promising spherical shapes and smaller size nearly 5–10 nm. The highest removal capacity were found at 538.91 mg/g and 455.70 mg/g for Pb2+ and CR respectively. Additionally, for better understanding the experimental breakthrough curves (BTC) were evaluated by several well established column models while the maximum R2 value was found around 0.999 for the Thomas model and reduced chi squire (χ2) value was around 0.0001.

Currently, CNC is attractive to the researchers to fabricate multifunctional bionanocomposite because of their outstanding physicochemical, thermomechanical, morphological properties, and eco-friendly nature. Whereas in most cases CNC is extracted from the bast/bark of primary plants, which have other beneficial applications in several sectors. Hence, it is crucial to find out alternative sources of CNCs to diminish the extra pressure on the primary plants. While the useless agrowaste biomass of okra stalks would be a new and beneficial alternative to produce CNCs as a reinforcement. Here, a series of chemical reactions were directed to produce CNCs. The samples were characterized by FTIR-ATR,TGA/DTA,FESEM,EDX,XRD,UV-vis-NIR, and DLS analysis. The obtained results suggested that the newly produced CNCs possessed substantial active functional groups(–OH,C-O-C,–NH), high thermal stability, greater crystallinity(86.09±0.001%), and notable microstructure indicating a well-organized porous surface with encouraging spherical shapes. The CNCs are free from impurities and coloring materials; additionally, they exhibit a highly negative surface charge and smaller particle sizes. It can be stated that the produced CNCs should have a good agreement with the sustainable environment and be beneficially applied as a reinforcing agent to fabricate bionanocomposites. Also acts as a sustainable alternative to the fossil-based hazardous ones for various uses.

The anthropogenic activity and hasty fluctuating technologies have been responsible for the generation of massive effluent which is so hazardous due to the loading of several toxicants. While most industries usually discharge it directly into the environment resulting in harsh damage to the ecology/public security. Therefore, it is critical to treat with a sustainable/cost-effective technique. Here, a new route of fabrication of chitosan-coated activated natural bentonite clay (CCANBC) bionanocomposites/ bionanosorbents from waste biomass has been developed. Their potential application for the simultaneous removal of Ni2+ and Eosin Y from wastewater were investigated. The effective parameters like concentration (10–30 ppm), flow rate (2–4 mL/min), and bed height (0.5–1.5 cm) were inspected. The bionanosorbents were characterized by FTIR-ATR, XRD, FESEM, TGA, and BET analysis. Additionally, the effluents were explored by AAS and UV–vis-NIR spectroscopy. According to the findings it has been stated that the CCANBC bionanosorbents possessed significant dynamic edges, greater crystallinity (94.27 %), and higher thermal stability. They have exhibited a remarkable 2D honeycomb-like mesoporous microstructure with substantial specific surface area (19.29 m2/g). These outstanding features could be responsible for the dramatic adsorption enactment around 186.42 and 238.37 mg/g for Ni2+ and Eosin Y. The obtained data were evaluated by several mathematical models for better understanding the experimental BTC curve, reaction mechanism, and adsorption isotherm.

Heat management in industries and other areas is a major issue currently worldwide. Conventional heat transfer fluids like water and ethylene glycol are not very effective. Nanofluids (NFs), composed of nanoparticles (NPs) dispersed throughout a base fluid (BF), have recently been identified as promising heat management agents for various industrial and other applications. Heat transmission is one of the many uses for AgNPs–water NFs (silver NPs (AgNPs) dispersed in water). The goal of this work was to determine the AgNPs–water NFs' forced convective heat transfer coefficient (HTC) in laminar flow. Due to this, we present the results of the HTC study of AgNPs–water NFs in laminar flow in this paper. First, using AgNO3 as a precursor, a chemical reduction approach was used for facile synthesis of AgNPs in one pot at ambient temperature. Synthesized NPs were examined using ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), and transform electron microscopy (TEM) techniques. The average particle size obtained from TEM is 25 nm. The required quantity of AgNPs was added to the water to produce 0.5 and 1.0 vol% of AgNPs–water NFs. Next, zeta potential and dynamic light scattering (DLS), in addition to time-lapse observation and captured picture comparison, were used to assess the stability of the formulated NFs. To calculate the forced convective HTC of prepared NFs in laminar flow, a vertical shell and tube heat transfer apparatus and computer-based data recorder were used. According to the results, in comparison to BF, the HTC of 0.5 and 1.0 vol% NFs was 3.3 and 5 times greater, respectively which encourages the use of AgNPs–water NFs in industry and other heat management. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 13−22

Fiber extracted from two species of jute, Corchorus olitorius (tossa) and Corchorus capsularis (white), is chemically treated with different concentrations (1–6 wt%) of NaOH. Chemical composition, crystallinity, fineness, whiteness, surface morphology, mechanical strength, and thermal stability of both untreated and treated fibers from both jute species are studied. The effects of alkali treatments on the two jute species are characterized using chemical composition analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), digital fiber fineness tester, photovoltmeter, universal testing machine (UTM), and thermogravimetric analyzer (TGA). Based on the comprehensive findings, the optimal NaOH treatment concentration was determined to be 5%. The 5% NaOH treatment on both species showed improvements in cellulose content (tossa 13.08%, white 12.88%), crystallinity (tossa 7.81%, white 8.09%), and single fiber strength (tossa 58.61%, white 72.22%). The higher mechanical strength of tossa fiber compared to white jute fiber indicates its potential for composite preparation. On the other hand, the comparatively thinner white jute fiber, when compared to tossa jute fiber, is suitable for blending with cotton or man-made fibers.