Nanocomposite electrospun nanofiber membranes for environmental remediation

Rapid worldwide industrialization and population growth is going to lead to an extensive environmental pollution. Therefore, so many people are currently suffering from the water shortage induced by the respective pollution, as well as poor air quality and a huge fund is wasted in the world each year due to the relevant problems. Environmental remediation necessitates implementation of novel materials and technologies, which are cost and energy efficient. Nanomaterials, with their unique chemical and physical properties, are an optimum solution. Accordingly, there is a strong motivation in seeking nano-based approaches for alleviation of environmental problems in an energy efficient, thereby, inexpensive manner. Thanks to a high porosity and surface area presenting an extraordinary permeability (thereby an energy efficiency) and selectivity, respectively, nanofibrous membranes are a desirable candidate. Their functionality and applicability is even promoted when adopting a nanocomposite strategy. In this case, specific nanofillers, such as metal oxides, carbon nanotubes, precious metals, and smart biological agents, are incorporated either during electrospinning or in the post-processing. Moreover, to meet operational requirements, e.g., to enhance mechanical stability, decrease of pressure drop, etc., nanofibrous membranes are backed by a microfibrous non-woven forming a hybrid membrane. The novel generation of nanocomposite/hybrid nanofibrous membranes can perform extraordinarily well in environmental remediation and control. This reality justifies authoring of this review paper

Structural Characteristics and Bonding Environment of Ag Nanoparticles Synthesized by Gamma Irradiation Within Thermo-Responsive Poly(N-isopropylacrylamide) Hydrogel

To produce well-defined metal clusters stabilized in protective matrix, poly(N-isopropylacrylamide) (PNi-PAAm) hydrogel with different initial concentration of polymer was used as nanoreactor. The in situ synthesis of well dispersed silver nanoparticles (AgNPs) was performed by gamma irradiation. The obtained AgNPs are spherical in shape with the diameter less than 20 nm. Crystalline properties of nanoparticles such as size, texture coefficient, strain, stress, lattice parameter, d-spacing, and dislocation density have been calculated using XRD data. Results confirm that the changes of lattice parameter of crystalline AgNPs sensitively reflect their state of strain and stress depending on the formation conditions (i.e., on the concentration of PNiPAAm) and on the diameter of AgNPs. The negative lattice strain and compression stress were observed for the smaller AgNPs (lattice contraction), while for the larger AgNPs are positively strained and under tensile stress (lattice expansion). XPS spectra revealed the donor-acceptor type of interaction between carbonyl oxygen from PNiPAAm and AgNPs (positive shift of high BE component of O 1s and negative shift of Ag 3d BE). The greater dislocation density of smaller AgNPs incorporated in more concentrated PNiPAAm, resulted in more binding sites and stronger interaction with polymer