Synthesis and Characterization of Ca-ALG/MgO/Ag Nanocomposite Beads for Catalytic Degradation of Direct Red Dye

Increased water pollution due to the tremendous increase of dye-containing effluent is still a serious problem which, in turn, adversely affects aquatic life and, consequently, the balance of our ecosystem. The aim of this research was to investigate whether Ca-ALG/MgO/Ag nanocomposite beads successfully prepared from calcium alginate hydrogels with MgO (Ca-ALG/MgO) doped with Ag nanoparticles (Ag NPs) caused effective degradation of Direct Red 83 dye. The formation of nanocomposite beads was confirmed by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Dynamic Light Scattering (DLS), and Energy Dispersive X-ray Analysis (EDX). The results from the EDX analysis proved that both MgO and Ag nanoparticles within the alginate beads network were present. This study also examines the effects of various operating parameters, such as the reducing agent, time of reaction, the concentration of the dye solution, and the catalyst dosage, which were examined and studied carefully to find the optimum degradation conditions. The kinetics and isothermal study revealed that the degradation process using Ca-ALG/MgO/Ag nanocomposite beads as a catalyst in the presence of sodium borohydride (NaBH4) as a reducing agent was the best fit for the pseudo-first-order model and the Temkin isotherm model. The results indicated that the optimum dosage of Ca-ALG/MgO/Ag was 0.3 g for a dye concentration of 50 mg/L, and equilibrium of the degradation process was attained at 340 min. Accordingly, it could be stated that the catalyst, Ca-ALG/MgO/Ag nanocomposite beads, is considered efficient for the degradation of Direct Red 83 dye. The degradation efficiency reached 95% approximately. Furthermore, after four runs of reuse, Ca-ALG/MgO/Ag nanocomposite beads exhibited excellent performance and long-term stability

Impact of Hybrid Fillers on the Properties of High Density Polyethylene Based Composites

The main objective of this work is to develop a variety of hybrid high-density polyethylene (HDPE) micro- and nanocomposites and to investigate their thermal, mechanical, and morphological characteristics as a function of number of fillers and their contents percentage. In this study, 21 formulations of the composites were prepared using fillers with different sizes including micro fillers such as talc, calcium carbonate (CaCO3), as well as nano-filler (fumed silica (FS)) though the melt blending technique. The morphological, mechanical, and thermal properties of the composite samples were evaluated. The morphological study revealed negligible filler agglomerates, good matrix–filler interfacial bonding in case of combined both CaCO3 and FS into the composites. Sequentially, improvements in tensile, flexural and Izod impact strengths as a function of fillers loading in the HDPE matrix have been reported. The maximum enhancement (%) of tensile, flexural and impact strengths were 127%, 86% and 16.6%, respectively, for composites containing 25% CaCO3 and 1% FS without any inclusion of talc filler; this indicates that the types/nature, size, quantity and dispersion status of fillers are playing a major role in the mechanical properties of the prepared composites more than the number of the used fillers