Green synthesis of gold nanoparticles by phycoerythrin extracted from Solieria tenuis as an efficient catalyst for 4-nitrophenol reduction and degradation of dyes in wastewater

Advances in 4-Nitrophenol Detection and Reduction Methods and Mechanisms: An Updated Review

This review emphasizes the progress in identifying and eliminating para-nitrophenol (4-NP), a toxic organic compound. It covers various strategical methods and materials, including organic and inorganic nanomaterials, for detecting and reducing 4-NP. Detection techniques such as electrochemical methods. Optical fiber-based surface plasmon resonance and photoluminescence, as well as the mechanisms of Förster Resonance Energy Transfer (FRET) and Inner Filter Effect (IFE) in fluorescence detection, are presented. Removal techniques for this contaminant include homogeneous catalysis, electrocatalysis, photocatalysis, and thermocatalysis, and their reaction mechanisms are also discussed. Further, the theoretical perspectives of 4-NP detection and reduction, parameters influencing the activities, and future perspectives are also reviewed in detail.

Novel approach for green synthesis of stable gold nanoparticles with dried turmeric root extract: investigations on sensor and catalytic applications

In this study, we present the synthesis of gold nanoparticles (AuNPs) using a completely green synthesis method without the use of any additional functionalizing agent, except dried turmeric root extract. The significant synthesis parameters were optimized, and the applicability of AuNPs was investigated in areas such as plasmonic and fluorescent sensing of aluminum (Al3⁺) and chromium (Cr3⁺) ions, reduction of 4-nitrophenol (4-NP), and degradation of methylene blue (MB) and methyl orange (MO) dyes. Characterization studies were performed using UV-Vis spectroscopy, TEM, FTIR, and XRD, revealing that the AuNPs predominantly had a spherical morphology and a very small particle size of 8.5 nm, with stability maintained up to 120 days. The developed AuNP-based plasmonic sensors relied on aggregation-induced decreases in absorption, along with a red shift in the spectra. Fluorescence sensing demonstrated a linear increase in intensity with increasing concentrations of Al3⁺ and Cr3⁺, with detection limits of 0.83 and 1.19 nM, respectively. The catalytic activities of AuNPs were tested in reducing 4-NP and degradations of MB and MO dyes (binary system) in tap water and wastewater, with the reactions following pseudo-first-order kinetics. This study highlights the potential of AuNPs synthesized from turmeric roots for various environmental and sensing applications.