Ag–Co oxides nanoparticles supported on carbon nanotubes as an effective catalyst for the photodegradation of Congo red dye in aqueous medium

Formulation of silver phosphate/graphene/silica nanocomposite for enhancing the photocatalytic degradation of trypan blue dye in aqueous solution

Photocatalytic degradation of several harmful organic compounds has been presented as a potential approach to detoxify water in recent decades. Trypan Blue (TB) is an acidic azo dye used to distinguish live cells from dead ones and it's classified as a carcinogenic dye. In this study, silver phosphate (Ag3PO4) nanoparticles and novel Ag3PO4/graphene/SiO2 nanocomposite have been successfully prepared via simple precipitation method. Afterward, their physical properties, chemical composition, and morphology have been characterized using SEM, EDS, TEM, SAED, BET, XRD, FTIR and UV-VIS spectroscopy. The specific surface area of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite were reported to be 1.53 and 84.97 m2/g, respectively. The band gap energy of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite was measured to be 2.4 and 2.307 eV, respectively. Photocatalytic degradation of Trypan blue (TB) was studied at different parameters such as pH, catalyst dosage, initial concentration, and contact time. The results showed that, at initial dye concentration of 20 ppm, pH = 2, and using 0.03 g of Ag3PO4/G/SiO2 as a photocatalyst, the degradation percent of TB dye in the aqueous solution was 98.7% within 10 min of light exposure. Several adsorption isotherms such as Langmuir, Freundlich, and Temkin adsorption isotherms have been tested in addition to the photocatalytic degradation kinetics. Both catalysts were found to follow the Langmuir isotherm model and pseudo-second-order kinetic model. Finally, the possible photocatalytic performance mechanism of Ag3PO4/G/SiO2 was proposed.

Enhanced Photocatalytic Degradation of Malachite Green Dye Using Silver-Manganese Oxide Nanoparticles

Efficient and excellent nanoparticles are required for the degradation of organic dyes in photocatalysis. In this study, silver-manganese oxide nanoparticles (Ag-Mn-NPs) were synthesized through a wet chemical precipitation method and characterized as an advanced catalyst that has enhanced photocatalytic activity under sunlight irradiation. The nanoparticles were characterized using scanning electron microscopy (SEM), XRD, UV-vis light spectra, and energy-dispersive X-ray (EDX) spectroscopy, revealing their spherical and agglomerated form. The EDX spectra confirmed the composition of the nanoparticles, indicating their presence in oxide form. These bimetallic oxide nanoparticles were employed as photocatalysts for the degradation of malachite green (MG) dye under sunlight irradiation in an aqueous medium. The study investigated the effects of various parameters, such as irradiation time, catalyst dosage, recovered catalyst dosage, dye concentration, and pH, on the dye's photodegradation. The results showed that Ag-Mn oxide nanoparticles exhibited high photocatalytic activity, degrading 92% of the dye in 100 min. A longer irradiation time led to increased dye degradation. Moreover, a higher catalyst dosage resulted in a higher dye degradation percentage, with 91% degradation achieved using 0.0017 g of the photocatalyst in 60 min. Increasing the pH of the medium also enhanced the dye degradation, with 99% degradation achieved at pH 10 in 60 min. However, the photodegradation rate decreased with increasing dye concentration. The Ag-Mn oxide nanoparticles demonstrate excellent potential as a reliable visible-light-responsive photocatalyst for the efficient degradation of organic pollutants in wastewater treatment.

Green synthesis of magnetic activated carbon from peanut shells functionalized with TiO2 photocatalyst for Batik liquid waste treatment

The composite of magnetic activated carbon derived from peanut shells functionalized titanium dioxide (Fe3O4/TiO2/AC) has been successfully synthesized. The composite was employed to remove indigosol green and Cr(vi) under ultraviolet (UV) and visible light. In this work, the activated carbon was synthesized from a sustainable source of peanut shell by carbonization and activation method employing NaOH as the activating agent. Magnetite was prepared by chemical co-precipitation technique using FeCl3·6H2O and FeSO4·7H2O, and then, the deposition of TiO2 was performed under ultrasonic irradiation. A variety of material characterization, consisting of Fourier transform infrared, X-ray diffraction, and scanning electron microscopy-energy dispersive X-ray, was used to analyze the physicochemical properties of the composite. The effects of pH, irradiation time, and composite mass during optimization performance were investigated. The characterizations represent the dispersed TiO2 in the anatase phase with the existence of magnetic particles. The activity tests revealed the superiority of the composite for applications involving adsorption and photocatalysis under visible light source compared to UV light. It was found that Fe3O4/TiO2/AC yields the efficiency for the removal of indigosol green and Cr(vi) from Batik liquid waste of 92.91 and 76.92%, respectively.

Morphological Studies, Photocatalytic Activity, and Electrochemistry of Platinum Disulfide Nanoparticles from Bis(morpholinyl-4-carbodithioato)-platinum(II)

Bis(morpholinyl-4-carbodithioato)-platinum(II) was synthesized and characterized using spectroscopic techniques and single-crystal X-ray crystallography. The Pt(II) complex crystallized in a monoclinic space group P2₁/n with a Pt(II) ion located on an inversion center coordinated two morpholinyl dithiocarbamate ligands that are coplanar to form a slightly distorted square planar geometry around the Pt(II) ion. The complex was thermolyzed at 120, 180, and 240 °C to prepare PtS₂ nanoparticles. Powder X-ray diffraction patterns confirmed the hexagonal crystalline phase for the as-prepared PtS₂ nanoparticles irrespective of thermolysis temperature. Bead-like shaped PtS₂-120 nanoparticles with a particle size in the range of 12.46-64.97 nm were formed at 120 °C, while PtS₂-180 prepared at 180 °C is quasi-spherical in shape with particles in the range of 24.30-46.87 nm. The PtS₂-240 obtained at 240 °C is spherical with particles in the range of 11.45-46.85 nm. The broad emission maxima of the as-prepared PtS₂ nanoparticles are ascribed to the particles' broad size distributions. The photocatalytic degradation of methylene blue by the PtS₂ nanoparticles shows a maximum efficiency of 87% for PtS₂-240 after 360 min. The effects of photocatalytic dosage, irradiation time, pH medium, and scavengers were also evaluated. Cyclic voltammetry of the PtS₂ nanoparticles showed a reversible redox reaction, while the electrochemistry of the as-prepared PtS₂ indicates that the electron transfer process is diffusion-controlled.