Frank Antolasic

Fabrication of a GNP/Fe–Mg Binary Oxide Composite for Effective Removal of Arsenic from Aqueous Solution

Graphene nanoplates (GNPs) can be used as a platform for homogeneous distribution of adsorbent nanoparticles to improve electron exchange and ion transport for heavy-metal adsorption. In this study, we report a facile thermal decomposition route to fabricate a graphene-supported Fe–Mg oxide composite. The prepared composite was characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Batch experiments were carried out to evaluate the arsenic adsorption behavior of the GNP/Fe–Mg oxide composite. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, in which the sorption kinetics of the arsenic adsorption process by the composite was found to be pseudo-second-order. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled-column filter test. The GNP/Fe–Mg oxide composite exhibited significant fast adsorption of arsenic over a wide range of solution pHs, with exceptional durability and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solutions.

Infrared Spectroscopy-Based Metabolomic Analysis for the Detection of Preharvest Sprouting in Grain

Preharvest sprouting of grains causes significant losses to growers and buyers. The problem occurs throughout the world, and economic losses can be millions of dollars. Visual assessment of germination is ineffective because even grains showing no external signs (e.g., having a visible shoot) may still have germinated sufficiently so that it is no longer possible for high-quality products to be made from them. Current procedures to determine whether a grain has germinated are based around measuring enzyme or starch levels. However, despite protracted efforts to develop enhanced ways to measure germination over the last 50 years, there are currently no sufficiently accurate or reliable approaches available. The present work assesses the potential for infrared spectroscopy-based metabolomic profiling to assess the germination of barley and wheat. The results indicate that mid- and near-infrared spectroscopy are able to determine if the grain has germinated and give an indication of how long the germination ...

Tuning the oxygen functional groups in reduced graphene oxide papers to enhance the electromechanical actuation

The superior mechanical flexibility, mechanical strength, electrical conductivity, high specific surface area, and a special two-dimensional crystalline structure make graphene a very promising building block material for flexible electromechanical actuators. However, graphene papers have exhibited limited electromechanical actuation strain in aqueous electrolyte solution. In this paper, we show an easy approach to significantly improve the electromechanical actuation of reduced graphene oxide (rGO) papers via fine tuning the oxygen functional groups in rGO sheets, which was achieved by careful control of quantity of the reduction agent used in the chemical reduction process of graphene oxide. The actuation strains are enhanced up to 0.2% at an applied voltage of −1 V, which is more than a 2 fold increase compared to the regular pristine rGO paper. Further theoretical and experimental analyses reveal that the change of the capacitance and the stiffness of the rGO papers are two key factors responsible for the observed improvement.

Stereochemistry and miscibility of epoxy resin–poly(trimethylene terephthalate) blends

Stereochemistry is proposed to contribute to the miscibility of poly(trimethylene terephthalate) (PTT) and bisphenol-A diglycidyl ether (BADGE), since molecular conformation is one of the determinants of the close packing ability and hence the interactions of such a system. Polymer blends were prepared by the conventional melt mixing technique using a HAAKE mixer. The influence of the stereochemistries of the mixing polymers on the miscibility has been poorly investigated in the literature. The amorphous fraction of PTT was found to be miscible with BADGE, while the crystalline fraction was found to be immiscible with BADGE. This is an interesting situation where one fraction of the polymer is miscible while another fraction is immiscible. The stereochemistries of the glycol residues of PTT are different in the crystalline and the amorphous fractions, and therefore the miscibility of the amorphous fraction of PTT with BADGE could be due to the π–π and n–π interactions between the phenyl and carbonyl groups of PTT with the aromatic rings of BADGE. Fourier transform infra-red microscopy (FTIR microscopy), wide angle X-ray scattering (WAXS) and thermogravimetric analyses show that PTT and BADGE retain their identities in the blend, eliminating the possibility that any trans reactions occur between the blend components.

The sensitivity of donor – acceptor charge transfer to molecular geometry in DAN – NDI based supramolecular flower-like self-assemblies

A charge-transfer (CT) complex self-assembled from an electron acceptor (NDI-EA: naphthalene diimide with appended diamine) and an electron donor (DAN: phosphonic acid-appended dialkoxynapthalene) in aqueous medium. The aromatic core of the NDI and the structure of DAN1 were designed to optimize the dispersive interactions (π-π and van der Waals interactions) in the DAN1–NDI-EA self-assembly, while the amino groups of NDI also interact with the phosphonic acid of DAN1 via electrostatic forces. This arrangement prevented crystallization and favored the directional growth of 3D flower nanostructures. This molecular geometry that is necessary for charge transfer to occur was further evidenced by using a mismatching DAN2 structure. The flower-shaped assembly was visualized by scanning electron and transmission electron microscopy. The formation of the CT complex was determined by UV-vis and cyclic voltammetry and the photoinduced electron transfer to produce the radical ion pair was examined by femtosecond laser transient absorption spectroscopic measurements.

Pyrene-Phosphonate Conjugate: Aggregation-Induced Enhanced Emission, and Selective Fe3+ Ions Sensing Properties

A new pyrene-phosphonate colorimetric receptor 1 has been designed and synthesized in a one-step process via amide bond formation between pyrene butyric acid chloride and phosphonate-appended aniline. The pyrene-phosphonate receptor 1 showed aggregation-induced enhanced emission (AIEE) properties in water/acetonitrile (ACN) solutions. Dynamic light scattering (DLS) characterization revealed that the aggregates of receptor 1 at 80% water fraction have an average size of ≈142 nm. Field emission scanning electron microscopy (FE-SEM) analysis confirmed the formation of spherical aggregates upon solvent evaporation. The sensing properties of receptor 1 were investigated by UV-vis, fluorescence emission spectroscopy, and other optical methods. Among the tested metal ions, receptor 1 is capable of recognizing the Fe3+ ion selectively. The changes in spectral measurements were explained on the basis of complex formation. The composition of receptor 1 and Fe3+ ions was determined by using Job’s plot and found to be 1:1. The receptor 1–Fe3+ complex showed a reversible UV-vis response in the presence of EDTA.