A Ag nanoparticle functionalized Sg-C3N4/Bi2O3 2D nanohybrid: a promising visible light harnessing photocatalyst towards degradation of rhodamine B and tetracycline

Efficient degradation of tetracycline antibiotics using a novel rGO/Ag/g-C3N4 photocatalyst for hospital wastewater treatment

This study focuses on the development of an efficient photocatalyst for degrading hospital wastewater, specifically targeting the degradation of the antibiotic tetracycline (TC). We introduce a novel 2D/2D heterostructure photocatalyst composed of graphitic carbon nitride (g-CN), functionalized with silver nanoparticles (Ag NPs) and reduced graphene oxide (rGO). The primary aim is to enhance the photocatalytic performance of g-CN through the synergistic effects of Ag NPs and rGO. The rGO/Ag/g-CN nanocomposites demonstrated remarkable photocatalytic activity, achieving over 97% TC degradation within 60 min under commercial LED light irradiation. Additionally, these photocatalysts were used to remove other antibiotics, such as doxycycline hydrochloride and ofloxacin, and it was observed that the nanocomposite effectively removed these antibiotics as well. This enhanced performance is attributed to the surface plasmon resonance (SPR) effects of Ag NPs and the electron sink properties of rGO, which were confirmed through comprehensive physicochemical characterization. Various concentrations of Ag NPs and rGO were tested to optimize the nanocomposite synthesis, with optical and electrical characterizations, including photoluminescence (PL), electrochemical impedance spectroscopy (EIS), and Mott-Schottky (M-S) measurements, revealing higher electron-hole pair generation rates and carrier concentrations in the rGO/Ag/g-CN nanocomposites compared to pristine g-CN, Ag/g-CN, and rGO/g-CN. The results demonstrate the potential of the rGO/Ag/g-CN photocatalyst as a cost-effective and scalable solution for the treatment of medical pollutants in wastewater.

Polyacrylonitrile support impregnated with amine-functionalized graphitic carbon nitride/magnetite composite nanofibers towards enhanced arsenic remediation: A mechanistic approach

Recently, novel composite materials are rapidly being explored for water treatment applications. However, their physicochemical behavior and mechanistic investigations are still a mystery. Therefore, our key prospect is to develop a highly stable mixed-matrix adsorbent system using polyacrylonitrile (PAN) support impregnated with amine-functionalized graphitic carbon nitride/magnetite (gCN-NH₂/Fe₃O₄) composite nanofibers (PAN/gCN-NH₂/Fe₃O₄: PCNFe) by simple electrospinning techniques. Various instrumental techniques were used to explore the structural, physicochemical, and mechanical behavior of the synthesized nanofiber. The developed PCNFe with a specific surface area of 39.0 m²/g was found to be non-aggregated and to have outstanding water dispersibility, abundant surface functionality, greater hydrophilicity, superior magnetic property, and higher thermal & mechanical characteristics making it favorable for rapid As removal. Based on the experimental findings from the batch study, 97.0 and 99.0 % of arsenite (As(III)) and arsenate (As(V)), respectively, could be adsorbed by utilizing0.02 g of adsorbent dosage within 60 min of contact time at pH 7 and 4, with an initial concentration of 10 mg/L. Adsorption of As(III) and As(V) followed the pseudo-second-order kinetic and Langmuir isotherm models with an sorption capacities of 32.26 and 33.22 mg/g, respectively, at ambient temperature. The adsorption was endothermic and spontaneous, in accordance with the thermodynamic study. Furthermore, the addition of co-anions in a competitive environment did not affect As adsorption except for PO₄^3-. Moreover, PCNFe preserves its adsorption efficiency above 80 % after five regeneration cycles. The combined results of FTIR and XPS after adsorption further support the adsorption mechanism. Also, the composite nanostructures retain their morphological and structural integrity after the adsorption process. The facile synthesis protocol, high As adsorption capacity, and enhanced mechanical integrity of PCNFe foreshadow its huge prospects for real wastewater treatment.

Double Z-scheme Co3O4/Bi4O7/Bi2O3 composite activated peroxymonosulfate to efficiently degrade tetracycline under visible light

Co₃O₄/Bi₄O₇/Bi₂O₃ (CBB) composites were prepared, in which Co₃O₄ was synthesized from Co-MOF as precursor. The peroxymonosulfate (PMS) activated by CBB catalyst under visible light was used to degrade tetracycline (TC). Owing to the synergistic effect of photocatalysis and PMS activation, 98.4% of TC was removed within 60 min. The optimal loading of Co₃O₄ was determined, and the influence of PMS dosage, initial pH, and disturbing anions on the degradation effect were investigated. The "CBB + Vis + PMS" system showed good reusability, and the degradation was only reduced by 1.7% after 5 cycles. This system also had a good degradation of other five pollutants. The quenching experiment showed that holes (h⁺), superoxide radicals (·O₂^-), and singlet oxygen (¹O₂) were the main active species. The degradation products of TC were determined by liquid chromatography-mass spectrometry, and the degradation pathway was proposed. Finally, a double Z-scheme degradation mechanism was proposed in the "CBB + Vis + PMS" system. The peroxymonosulfate activated by CBB under visible light to degrade organic pollutants has widespread application prospects in environmental remediation.

Hematite nanoparticles decorated nitrogen-doped reduced graphene oxide/graphitic carbon nitride multifunctional heterostructure photocatalyst towards environmental applications

The carcinogenic heavy metals and aromatic organic compounds linger as wastewater pollutants implying great menace to the ecological balance. To solve these environmental pollution problems, the photocatalytic process is an...

Green and controllable synthesis of one-dimensional Bi2O3/BiOI heterojunction for highly efficient visible-light-driven photocatalytic reduction of Cr(VI)

BiOI nanosheets have been successfully deposited on the porous Bi₂O₃ nanorobs via a one-pot precipitation method. The physicochemical features of the as-prepared materials were characterized in detail by a series of techniques, and the results revealed that BiOI nanosheets were evenly distributed on the porous Bi₂O₃ nanorobs. Because of higher photogenerated electron-hole pairs separation efficiency and the larger specific surface area compared to the pristine Bi₂O₃ and BiOI, the 50%Bi₂O₃/BiOI composite exhibited significantly enhanced photocatalytic activity for Cr(VI) reduction under visible light irradiation, and the reduction rate constant was 0.02002 min^-1, which was about 27.4 and 2.6 times higher than that of pure Bi₂O₃ (0.00073 min^-1) and BiOI (0.00769 min^-1), respectively. Moreover, the 50%Bi₂O₃/BiOI composite also possessed the excellent photochemical stability and recyclability, thereby facilitating its wastewater treatment application.