A functional structure of Mn_0.5Zn_0.5Fe₂O₄-on-polyaniline nanocomposites with high dielectric absorbing properties and electromagnetic shielding effectiveness at low frequencies was successfully fabricated through a facile in situ emulsion polymerization. Polyaniline (PANI) was doped with hydrochloric acid to improve its electrical properties and interactions with ferrite nanoparticles. The electrostatic force, paramagnetic force and hydrogen bonding strongly bonded or assembled ferrite nanoparticles on the polyaniline surface and improved the thermal stability of the polyaniline nanostructure. Polyaniline nanofibers were found to have an average diameter of 100 nm and length of 500 nm, consisting of a bundle of smaller individual units, whereas ferrite nanoparticles were of spherical shape with an average diameter 30 nm. The research findings show that ferrite particles overcome the common problem of aggregation and evenly dispersed on the surface of polyaniline. The ferrite-grafted polyaniline nanostructures were demonstrated as a promising functional material for the absorbing of electromagnetic microwaves because of a large amount of dipole polarizations in the polymer backbone and at the interfaces of the ferrite nanoparticles and polyaniline nanofibers. Both the complex permittivity and shielding effectiveness of the ferrite-grafted polyaniline nanocomposites increased with the increasing weight percentage of PANI. There is also a good match of real and imaginary parts of the complex permittivity, giving rise to almost an equal dielectric loss angle tangent in the measured frequency (30 MHz to 1 GHz). This superior property allows the nanocomposites to function within an extended absorbing band.

Thiocarboxylate-functionalized silver nanoparticles (NPs) were synthesized and characterized in terms of their thermal and electrical properties. Thiocarboxylic acids with chain lengths of 3 and 11 carbons were used to functionalize silver NPs, leading to the formation of NPs smaller than 5 nm. We found that silver NPs, functionalized with a short-chain acid, were twice smaller than those with a long-chain acid. Electrical conductivity measurements showed that the short-chain functionalized NPs were electrically conductive while the long-chain functionalized ones were nonconductive. The short-chain functionalized NPs were incorporated into a conventional electrical conductive adhesive (ECA) composite, consisting of micron-sized silver particles and an epoxy matrix to form a hybrid-designed ECA. The electrical conductivity measurements and SEM images of the cross-section of the cured hybrid composite showed that lower contents of the NPs (<20 wt% of the silver microparticles) increased the electrical conductivity due to the filling of NPs into the interstices of the micron-sized particles as well as their low sintering temperature, whereas higher NPs contents reduced the electrical conductivity because they clustered and increased the gaps between the microparticles. We attributed the positive effect of synthesized NPs on the electrical conductivity of the nanocomposite to their small size (<5 nm) and the specific design of the covering layer over the surface of NPs. These research findings provide insights into the relationship between the overall properties of the nanocomposites and the nanoparticles' surface chemistry, size and weight fractions.

Pressure-driven processes have come a long way since they were introduced. These processes, namely Ultra-Filtration (UF), Nano-Filtration (NF), and Reverse-Osmosis (RO), aim to enhance the efficiency of wastewater treatment, thereby aiming at a cleaner production. Membranes may be polymeric, ceramic, metallic, or organo-mineral, and the filtration techniques differ in pore size from dense to porous membrane. The applied pressure varies according to the method used. These are being utilized in many exciting applications in, for example, the food industry, the pharmaceutical industry, and wastewater treatment. This paper attempts to comprehensively review the principle behind the different pressure-driven membrane technologies and their use in the removal of heavy metals from wastewater. The transport mechanism has been elaborated, which helps in the predictive modeling of the membrane system. Fouling of the membrane is perhaps the only barrier to the emergence of membrane technology and its full acceptance. However, with the use of innovative techniques of fabrication, this can be overcome. This review is concluded with perspective recommendations that can be incorporated by researchers worldwide as a new problem statement for their work.