Search

Coal fly ash was functionalized and modified with graphene oxide and polyaniline (CFA/GO/PANI nanocomposite) through hydrothermal synthesis, which was used for remediation of hexavalent chromium (Cr(VI)) ions. Batch adsorption experiments were carried out to investigate the effects of adsorbent dosage, pH, and contact time on the removal of Cr(VI). The ideal pH for this work was 2, and it was used for all other studies. The Cr(VI)-loaded spent adsorbent CFA/GO/PANI + Cr(VI) was reused as a photocatalyst for the degradation of bisphenol A (BPA). The CFA/GO/PANI nanocomposite removed Cr(VI) ions rapidly. The adsorption process was best described by pseudo-second-order kinetics and the Freundlich isotherm model. The CFA/GO/PANI nanocomposite demonstrated a high adsorption capacity of 124.72 mg/g for Cr(VI) removal. In addition, the Cr(VI)-loaded spent adsorbent played a significant role in the photocatalytic degradation of BPA with 86% degradation. The reuse of the Cr(VI)-loaded spent adsorbent as a photocatalyst presents a new solution for the reduction of secondary waste from the adsorption process., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Silver nanoparticles decorated on an exfoliated graphitic carbon nitride/carbon sphere (AgNP/Eg-C 3 N 4 /CS) nanocomposites were synthesized by an adsorption method with a self-assembled process. These nanoparticles were characterized by different techniques like UV-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Raman spectroscopy, scanning electron spectroscopy (SEM), transmission electron spectroscopy (TEM), electrochemical impedance spectroscopy (EIS), and ζ potential. AgNP/Eg-C 3 N 4 /CS nanocomposites showed a higher catalytic reduction activity for the conversion of Cr(VI) into Cr(III) with formic acid (FA) at 45 °C when compared to bulk graphitic carbon nitride (Bg-C 3 N 4 , Eg-C 3 N 4 , CS, and Eg-C 3 N 4 /CS). The kinetic rate constants were determined as a function of catalyst dosage, concentration of Cr(VI), pH, and temperature for the AgNP/Eg-C 3 N 4 /CS nanocomposite. This material showed higher reduction efficiency (98.5%, k = 0.0621 min -1 ) with turnover frequency (0.0158 min -1 ) for the reduction of Cr(VI) to Cr(III). It also showed great selectivity and high stability after six repeated cycles (98.5%). Further, the reusability of the Cr(III)-AgNP/Eg-C 3 N 4 /CS nanocomposite was also investigated for the photocatalytic degradation of methylene blue (MB) under visible light irradiation with various time intervals and it showed good degradation efficiency (α = 97.95%). From these results, the AgNP/Eg-C 3 N 4 /CS nanocomposite demonstrated higher catalytic activity, improved environmental friendliness, lower cost for the conversion of toxic Cr(VI) to Cr(III) in solutions, and also good reusability., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Coal fly ash was decorated with a graphene oxide-tungsten oxide nanorods nanocomposite (CFA/GO/WO 3 NRs nanocomposite) via a hydrothermal method and applied for the remediation of lead (Pb 2+ ions). The Pb 2+ ion-loaded spent adsorbent (CFA/GO/WO 3 NRs + Pb 2+ nanocomposite) was reused for the photodegradation of acetaminophen. CFA/GO/WO 3 NRs + Pb 2+ nanocomposite displayed rapid removal of Pb 2+ ions. Pseudo-second-order kinetics and the Langmuir isotherm model described the adsorption data. The adsorption capacity of the CFA/GO/WO 3 NRs nanocomposite was 41.51 mg/g for the removal of Pb 2+ ions. Additionally, the Pb 2+ ion-loaded spent adsorbent significantly influenced the degradation of acetaminophen by photocatalysis where 93% degradation was observed. It is worthy to note the reuse application of Pb 2+ ion-loaded spent adsorbent as a photocatalyst, which will significantly reduce the secondary waste obtained from conventional adsorption methods., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)