A facile method for synthesis rGO/Ag nanocomposite and its uses for enhancing photocatalytic degradation of Congo red dye

Green Synthesis, Characterization and Application of Silver Nanoparticles Using Bioflocculant: A Review

Nanotechnology has emerged as an effective means of removing contaminants from water. Traditional techniques for producing nanoparticles, such as physical methods (condensation and evaporation) and chemical methods (oxidation and reduction), have demonstrated high efficiency. However, these methods come with certain drawbacks, including the significant energy requirement and the use of costly and hazardous chemicals that may cause nanoparticles to adhere to surfaces. To address these limitations, researchers are actively developing alternative procedures that are cost-effective, environmentally safe, and user-friendly. One promising approach involves biological synthesis, which utilizes plants or microorganisms as reducing and capping agents. This review discusses various methods of nanoparticle synthesis, with a focus on biological synthesis using naturally occurring bioflocculants from microorganisms. Bioflocculants offer several advantages, including harmlessness, biodegradability, and minimal secondary pollution. Furthermore, the review covers the characterization of synthesized nanoparticles, their antimicrobial activity, and cytotoxicity. Additionally, it explores the utilization of these NPs in water purification and dye removal processes.

Bioinspired Synthesis of Silver Nanoparticles for the Remediation of Toxic Pollutants and Enhanced Antibacterial Activity

This research presents a novel and environmentally friendly approach for the synthesis of multifunctional nanobiocomposites for the efficient removal of toxic heavy metal and dye, as well as the disinfection of wastewater microorganisms. The nanobiocomposites (KAC-CS-AgNPs) were prepared by incorporating photochemically generated silver nanoparticles (AgNPs) within a chitosan (CS)-modified, high-surface-area activated carbon derived from kenaf (KAC), using a unique self-activation method. The even distribution of AgNPs was visible in the scanning electron microscopy images and a Fourier transform infra red study demonstrated major absorption peaks. The experimental results revealed that KA-CS-AgNPs exhibited exceptional adsorption efficiency for copper (Cu²⁺), lead (Pb²⁺), and Congo Red dye (CR), and showed potent antibacterial activity against Staphylococcus aureus and Escherichia coli. The maximum adsorption capacity (mg g^-1) of KAC-CS-AgNPs was 71.5 for Cu²⁺, 72.3 for Pb²⁺, and 75.9 for CR, and the adsorption phenomena followed on the Freundlich and Langmuir isotherm models and the second-order kinetic model (R² > 0.99). KAC-CS-AgNPs also exhibited excellent reusability of up to four consecutive cycles with minor losses in adsorption ability. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic in nature. The bacterial inactivation tests demonstrated that KAC-CS-AgNPs had a strong bactericidal effect on both E. coli and S. aureus, with MIC calculated for E. coli and S. aureus as 32 µg mL^-1 and 44 µg mL^-1, respectively. The synthesized bioinspired nanocomposite KAC-CS-AgNPs could be an innovative solution for effective and sustainable wastewater treatment and has great potential for commercial applications.

Development of silver oxide-loaded reduced graphene oxide nanohybrids for enhanced photocatalytic activity under visible light in aqueous solutions

We report on the synthesis of silver oxide/reduced graphene oxide nanocomposites (Ag/rGO NCs) using a hydrothermal technique. This paper presents a simple method for synthesizing Ag/rGO hybrid nanocomposites, which can be used for environmentally treating hazardous organic pollutants. The photocatalytic degradation of model artificial Rhodamine B dye and bisphenol A was assessed under visible light illumination. The crystallinity, binding energy, and surface morphologies of the synthesized samples were determined. The silver oxide loading sample resulted in a decrease in the rGO crystallite size. SEM and TEM images demonstrate strong adhesion of the Ag NPs to the rGO sheets. XPS analysis validated the binding energy and elemental composition of the Ag/rGO hybrid nanocomposites. The objective of the experiment was to enhance the photocatalytic efficiency of rGO in the visible region using Ag nanoparticles. The synthesized nanocomposites in the visible region exhibited good photodegradation percentages of approximately 97.5% and 98.6% after 120 min of irradiation for pure rGO, Ag NPs, and Ag/rGO nanohybrid, respectively. Furthermore, the Ag/rGO nanohybrid maintained their degradation ability for up to three cycles. The synthesized Ag/rGO nanohybrid demonstrated enhanced photocatalytic activity, expanding their potential for environmental remediation. Based on the investigations, Ag/rGO nanohybrid proved to be an effective photocatalyst and holds promise as an ideal material for future applications in preventing water pollution.