Materials Science Forum Vol. 1112

Abstract: Cyclodextrin metal-organic frameworks (CD-MOFs) are synthesized from green precursors, making them an ideal material for green adsorbents. However, CD-MOFs are unstable in water, thus limiting their applications. Here, we report encapsulating CD-MOFs in polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP) polymeric support to produce PAN/PVP/CD-MOF composite beads. Batch adsorption studies showed that high dye adsorption capacities could be obtained at intermediate PVP, high PAN, and low CD-MOF loadings. Maximum MB and CR sorption capacities under optimum bead formulation: PAN = 6.96 wt.%, PVP = 2.20 wt.%, and CD-MOF = 2.88 wt.%. The optimized composite beads have a sorption capacity of 37.40 mg/g for MB and 18.42 mg/g for CR. We showed that PAN/PVP/CD-MOF composite beads could be an excellent adsorbent for textile dye removal in water.

Abstract: Metal-Organic Framework (MOF)-based composite beads consisting of MIL-101(Fe), Chitosan (CS), and Polyethyleneimine (PEI) crosslinked with glutaraldehyde (GLA) were synthesized. Response Surface Methodology was used to optimize the synthesis conditions of the beads to maximize Methyl Orange (MO) removal via batch adsorption experiments. Using an experimental design with three independent variables MIL-101(Fe) (500-1500 ppm), PEI (1-2%), GLA (0.5-2.5%), a second-order polynomial model was obtained to relate MO removal and these variables. A high R² (0.9944) and F-value (176.97) suggested good agreement between experimental data and the model. The optimum beads were found to consist of 500 ppm MIL-101 (Fe), 1.44% PEI, crosslinked in 2.11% GLA corresponding to a percent MO removal of 95.75%. Validation experiments done by subjecting the optimized beads to batch adsorption of MO confirmed good predicting capability of the model with an experimental MO removal of 96.20%. Characterization of the beads was performed using Fourier Transform Infrared Spectroscopy (FTIR) analysis and Scanning Electron Microscope (SEM). The beads were found to contain multiple functional groups and have a coarse surface with a porous structure which are ideal attributes for good adsorbents.the beads was performed using Fourier Transform Infrared Spectroscopy (FTIR) analysis and Scanning Electron Microscope (SEM). The beads were found to contain multiple functional groups and have a coarse surface with a porous structure which are ideal attributes for good adsorbents.

Abstract: Detection of heavy metals in water has long been a key area of study due to the adverse health effects these substances may bring. Multiple methods of detecting heavy metals have already been established. Though these methods are highly selective and can detect heavy metals in trace amounts, they commonly require specialized equipment. Thus, producing an inexpensive, reliable, and convenient sensor that could be used for point-of-need applications is of great interest. This study focuses on fabricating paper-based silver nanoparticle (AgNP) sensors for the smartphone-based colorimetric detection of Cu²⁺ ions in water. Polymer-decorated AgNPs functionalized by chitosan, glutaraldehyde, and polyethyleneimine were used as the main sensing mechanism for the paper-based sensors. Various fabrication methods were tested, and the optimal fabrication method was through the rectangular soak method with a total of 5 coatings as it produced the most uniform sensors. The calibration curve was studied over concentrations from 0.5 mM to 50 mM of Cu²⁺ across multiple parameters. It was found that there was a linear correlation between the Euclidean distance measured in reference to the blank filter paper against the concentration of copper in the analyte. The calibration curve exhibited a dynamic linear range between 2 mM to 28 mM of Cu²⁺ with R² = 0.99789. The LOD and LOQ were reported at 94.9438 ppm and 316.4793 ppm, respectively. Lastly, selectivity studies were also performed to determine the sensor’s response to other metal ions. It was found that the response of the sensor to Cu²⁺ was significantly different from those elicited by Ni²⁺, Cd⁺, Mn²⁺, Ca²⁺, Mg²⁺, Sn²⁺, K⁺, Cr³⁺, Al³⁺, Ba²⁺, Na⁺, Zn²⁺, Fe³⁺, and Fe²⁺. The study demonstrated its strong potential as rapid on-site detection method for Cu (II) in industrial wastewater.

Abstract: The present study applied low-temperature atmospheric plasma (LTAPP) jets to modify polymer substrates used in chip packaging. These substrates include bismaleimide triazine (BT), polyimide (PI) and PTFE materials. All these materials play important roles in modern semiconductor packaging. During the study, focuses were aimed the effects of reactive species (mainly OH and atomic oxygen) generated by atmospheric plasma jets on surface energy, water contact angle (WCA) and surface composition of these three substrates. In order to better understand and apply LTAPP jets, another focus will be on the understanding of the relationship among (1) the generation and distribution of various reactive species, (2) parameters for generating LTAPP jet, and (3) plasma characteristics. The plasma activation mechanism of these substrates was also discussed. In addition to plasma generation using AC high-voltage supplies, plasma characterization using optical emission spectroscopy (i.e., analysis of electron density, electron temperature, plasma temperature, and reactive species), XPS and water WCA analysis were used to understand surface activation mechanisms. In sum, Ar and Ar-O₂ plasma jets can be used to modify the surfaces of these three substrates, although the latter relies on the generation of O radicals, while the former relies on OH radicals more. According to the results obtained by XPS analysis, the formation of C-O and C=O bond after plasma treatment is the main reason for surface activation in this study.

Abstract: In this study, a simple combustion synthesis was utilized to obtain the SrLaAlO₄ (SLAO) host sample and SrLaAlO₄: Ce (SLAO:Ce) phosphors with different Ce concentrations (1.0, 3.0, 5.0 and 7.0 mol.%). Also, the as-synthesized samples were subjected to a post-annealing treatment at 1200 °C in air. X-ray diffraction (XRD) patterns for the SLAO and SLAO:Ce phosphors correspond to pure tetragonal phase (JCPDS No 24-1125). The photoluminescence spectra of the SLAO:Ce phosphors (under 254 nm excitation) showed a blue emission peak at 470 nm attributed to the 5d → 4f Ce³⁺ transition. The SLAO:Ce phosphors doped with 1 mol.% of Ce showed the highest emission and quenching of photoluminescence was produced when the Ce dopant concentration increases (3.0-7.0 mol.%). The CCT and color purity are in the range of 6456 -8276 K and 49.1 -55.9 % respectively. Due to its strong blue emission, the SLAO:Ce phosphor could be a good candidate for UV phosphor converted LED or for solid state lighting applications.

Abstract: The present work reviews the results of the photoluminescence study of erbium-doped ZnO nanostructures synthesized by physical and chemical methods. ZnO is a semiconductor compound composed of zinc and oxygen atoms. It possesses a wide bandgap (3.37 eV) and is optically and electrically active. When ZnO is synthesized in the form of nanostructures, such as nanoparticles, nanowires, nanorods, nanotubes, or nanosheets, it exhibits enhanced properties compared to its bulk counterpart due to quantum confinement effects and a high surface-to-volume ratio. By controlling different parameters in the growth processes of erbium-doped ZnO nanostructures, materials can be synthesized for different applications such as sensors, optoelectronics, and energy harvesting.

Abstract: Crystal size disribution is a parameter used to indicate the quality of sugar crystals obtained from the crystallization process. The better the crystal size distribution, the better the quality of the sugar crystals produced. The good quality of sugar crystals has an impact on the easier separation process that will occur in the centrifugal machine and can reduce sugar loss both in the centrifugal machine and in the sugar grader. The purpose of this study is to determine the effect of the number of sugar seeds, the quality of the mother liquor and the length of time used in the crystallization process on the quality of white sugar crystals produced in the Batch Vacuum Pan and to obtain the best interaction from several levels used for each factor, which can be used as a reference for producing sugar products that have crystal size distribution values according to the desired standard. Each treatment was carried out twice. Observations were made on material characteristics (brix, pol, and purity) and product sugar characteristics (average crystal size and coefficient of variation of crystal size). Measurement of the characteristics of sugar using a sieving (granulometer) which is then calculated using the ICUMSA GS2-37 method. The influence of factor’s main effect and interaction were analyzed using analysis of variance at the level of p value ≤ 0.05. Further tests for each factor’s main effect and interaction with p values ≤ 0.05 were carried out using the Duncan Multiple Range Test (DMRT). The best distribution of sugar crystal size was obtained from the interaction of sugar seed factors with levels of 3 m³, 5 m³, or 10 m³ which interacted with the quality factor of mother liquor (fine liquor + 0 m3 molasses), and 2 hours of cooking time, Where the results of the interaction of this factor produce a percentage of sugar with a size larger than 0.8 mm as much as 80%.

Abstract: For deep insight into complex reaction system of diesel hydrotreating, the monolayer adsorption and competitive adsorption of typical reactant molecules (phenanthrene, naphthalene, acridine, quinoline, dibenzothiophene, 4,6-dimethyldibenzothiophene and H₂) on MoS₂ and NiMoS catalyst models with different structures were investigated. The basal plane is discovered to be the best physical adsorption position for all molecules in MoS₂ series catalysts. Following saturation of the basal plane, reactant molecules will be adsorbed at Mo edge first, and Mo edge is more prone to bimolecular or multimolecular adsorption than S-edge, implying that Mo edge active sites play an important role in diesel hydrotreating. Naphthalene has a higher adsorption capacity in the partial pressure system that simulates the actual reaction atmosphere, and it is the most likely reactant molecule to predominately occupy active sites, but 4,6-dimethyl dibenzothiophene still exhibits good competition adsorption performance due to its high adsorption capacity and heat release. Interestingly, after phenanthrene adsorption, the secondary adsorption of hydrogen decreases in all of the catalyst models studied, indicating that phenanthrene is one of the most important molecules influencing hydrogen adsorption. Furthermore, the secondary adsorption of hydrogen after phenanthrene adsorption decreased the most on Tri-S50 catalyst. It shed light on that the activity and stability of Tri-S50 catalyst was most likely to decrease during diesel hydrotreating because of the notable inhibition on adsorption of hydrogen molecules brought by phenanthrene adsorption. It presents a theoretical basis for the design and development of highly efficient diesel hydrotreating catalysts.