Polyaniline as an On−Off−On bright green fluorescent probe: Solvent directed synthesis, characterization and recognition of chromium through the inner filter effect

Fluorescence sensing of water in various organic solvents based on a novel cyclic polymer

A sensor capable of sensing of water in various organic solvents ranging from water-soluble to water-miscible solvents is still a challenging task. In this research, a cyclic polymer fluorescence chemosensor (CPFC) has been developed for sensing of water by turn-on model in 9 organic solvents and turn-off model in DMA, where the broadest concentration range and the lowest detection limit was obtained for water in DMA (10 %-90 %) and dioxane (0.011 %), respectively. The sensing mechanism is explored by theory calculation and experimental investigation. The amphiphilic nature endows the polymer probe with great potential for measuring various contaminants from aqueous and nonaqueous mediums. Furthermore, the present search highlights the potential applications of cyclic polymer as fluorescence probes in the field of sensing.

Characterizing graphene oxide waste stream and assessing its impact on anaerobic co-digestion with municipal sludge

This study evaluated anaerobic co-digestion as a promising strategy for managing organic-contaminated waste streams generated from nanomaterial synthesis. The novel approach enabled precise quantification of organic content, efficient biomethane recovery, and a sustainable redirection of ethanol-contaminated graphene oxide (GO) dispersions. The proposed method achieved high accuracy (93-97%) in detecting organic content in ethanol-contaminated GO dispersions, significantly outperforming the conventional total chemical oxygen demand (tCOD) method, which only reached 75-77% accuracy. Additionally, co-digestion of trace ethanol content in GO dispersions with municipal sludge substantially enhanced methane production kinetics, resulting in a 17.6% increase in specific methane yield (per tCOD added) and a 284% increase in total methane production. Parallel anaerobic digestion (AD) experiments using conductive GO nanosheets (without ethanol) revealed the synergistic impact of GO nanosheets and trace ethanol content as a key mechanism driving these improvements. Furthermore, the study provided evidence of the biological reduction of GO and its magnetite-decorated counterpart, magnetic GO, as indicated by a shift in the ID/IG ratio from 1.06 to 0.77 and a G-band shift from 1606 cm⁻1-1565 cm⁻1. This reduction decreased the stability of nanosheets in the AD liquid phase, promoting their partitioning into the solid phase. This process facilitates the adsorption of the GO phase within the digestate and allows for the slow release of micronutrients when used as soil amendments.

Polyaniline/Ag nanoparticles/graphene oxide nanocomposite fluorescent sensor for recognition of chromium (VI) ions

Selective determination of toxic hexavalent chromium (Cr(VI)) is a stringent important due to its huge negative impact on the health and environment. Recently, the high sensitivity, rapidness, and cost-effectiveness of the fluorescent sensors for Cr(VI) have been developed. A fluorescent nanocomposite (NC) has been synthesized based on doped polyaniline (PANI), 2-acrylamido-2-methylpropanesulfonic acid (AMPSA) capped Ag nanoparticles (NPs) and graphene oxide (GO) quantum dots (QDs) via in situ reaction for highly selective sensing of Cr(VI) ions based on the luminescent quenching in the range from 0.01 to 7.5 mg/L. This NC showed an emission peak at 348 nm with a linear range from 0.01 to 0.05 mg/L and the low limit of detection (LOD) was 0.0065 mg/L (~ 6 µg/L). PANI/Ag (AMPSA) GO QDs NC displayed high selectivity for Cr(VI) over other common metal ions. Notably, the PANI/Ag (AMPSA) GO QDs NC can be used for distinguishing Cr(VI) and Cr(III) in solutions. The sensitive determination of Cr(VI) in real surface water samples was also confirmed and demonstrated recoveries in the range 95.3-99.2%. This NC will emerge as a new class of fluorescence materials that could be suitable for practical applications.