Efficient Visible-Light Photocatalysis and Antibacterial Activity of TiO₂-Fe₃C-Fe-Fe₃O₄/Graphitic Carbon Composites Fabricated by Catalytic Graphitization of Sucrose Using Natural Ilmenite

Abstract

Dyes in wastewater are a serious problem that needs to be resolved. Adsorption coupled photocatalysis is an innovative technique used to remove dyes from contaminated water. Novel composites of TiO 2 -Fe 3 C-Fe-Fe 3 O 4 dispersed on graphitic carbon were fabricated using natural ilmenite sand as the source of iron and titanium, and sucrose as the carbon source, which were available at no cost. Synthesized composites were characterized by X-ray diffractometry (XRD), Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF), and diffuse reflectance UV–visible spectroscopy (DRS). Arrangement of nanoribbons of graphitic carbon with respect to the nanomaterials was observed in TEM images, revealing the occurrence of catalytic graphitization. Variations in the intensity ratio ( I D / I G ), L a and L D , calculated from data obtained from Raman spectroscopy suggested that the level of graphitization increased with an increased loading of the catalysts. SEM images show the immobilization of nanoplate microballs and nanoparticles on the graphitic carbon matrix. The catalyst surface consists of Fe 3+ and Ti 4+ as the metal species, with V, Mn, and Zr being the main impurities. According to DRS spectra, the synthesized composites absorb light in the visible region efficiently. Fabricated composites effectively adsorb methylene blue via π–π interactions, with the absorption capacities ranging from 21.18 to 45.87 mg/g. They were effective in photodegrading methylene blue under sunlight, where the rate constants varied in the 0.003–0.007 min –1 range. Photogenerated electrons produced by photocatalysts captured by graphitic carbon produce O 2 •– radicals, while holes generate OH • radicals, which effectively degrade methylene blue molecules. TiO 2 -Fe 3 C-Fe-Fe 3 O 4 /graphitic carbon composites inhibited the growth of Escherichia coli (69%) and Staphylococcus aureus (92%) under visible light. Synthesized novel composites using natural materials comprise an ecofriendly, cost-effective solution to remove dyes, and they were effective in inhibiting the growth of Gram-negative and Gram-positive bacteria.

Fabrication of Naturally Derived Chitosan and Ilmenite Sand-Based TiO2/Fe2O3/Fe-N-Doped Graphitic Carbon Composite for Photocatalytic Degradation of Methylene Blue under Sunlight

“…Similar behavior was observed in the higher-resolution spectra of C 1s of CIL (1:1) and CIL (3:4) composites ( Supplementary Figure S2c,d , respectively). The higher resolution spectrum of C 1s of CIL (1:2) ( Figure 6 c) was deconvoluted into five peaks at 283.39, 284.5, 285.21, 286.32 and 288.35 eV, which are assigned to Fe-C in Fe 3 C, sp 2 -hybridized C-C, C-O, C=O, C-N and O-C=O, respectively [ 56 , 57 , 58 ]. The higher resolution spectrum of C 1s of CIL (1:4) ( Supplementary Figure S2e ) was deconvoluted into four peaks appearing at 283, 284.5, 285.87 and 287.96 eV, which can be attributed to the Fe-C in Fe 3 C, sp 2 -hybridized C-C, C-O and N-C=N, respectively.…”

Kinetics and Thermodynamics Study of Methylene Blue Adsorption to Sucrose- and Urea-Derived Nitrogen-Enriched, Hierarchically Porous Carbon Activated by KOH and H3PO4

“…The Raman spectrum of SU was obtained (Figure b). The D band at 1346.4 cm –1 is attributed to the breathing modes of sp 2 atoms in hexagons and the G band at 1557.9 cm –1 corresponds to the bond stretching of all pairs of sp 2 atoms in both rings and chains. , The intensity ratio of the D band to the G band is 0.90, indicating that the sp 2 atoms in hexagons are higher than those in both rings and chains, suggesting that SU is more amorphous.…”

“…Hence, it is vital to remove dyes from water reservoirs. There are many methods available for such purposes including membrane filtration, nanofiltration, adsorption, remediation by microorganisms, ion exchange, ozonation, photooxidation, − chemical reduction, etc. These methods possess disadvantages such as sludge production, use of expensive chemicals, poor efficiency, short half-life, formation of byproducts, regeneration difficulties, etc.…”

Ilmenite-derived titanic acid species: exploring their outstanding light-independent antibacterial activity

“…Although MTA and potassium titanate have not been explored in antimicrobial applications under dark conditions by previous studies, the mechanism of light-independent action of the two species against bacteria can be assessed under similar compounds reported in the literature. [45][46][47][48][49][50] The electroncapturing ability of the Schottky junction created between Fe and titanium oxide has been attributed to the cause of oxidation damage to S. aureus under dark conditions. 45 A similar study reports the light-independent antibacterial action of ZnO nanoparticles against S. aureus and Klebsiella pneumoniae, as its attachment to bacterial cell wall.…”

“…Adsorption of bacteria on the antimicrobial material is expected to improve the extent of interactions with the cell wall and, therefore, alters the cell membrane integrity even without photon energy. 27,46,48 Moreover, being titanium-based catalytic materials, the bactericidal potential of MTA and potassium titanate can be related to their super-hydrophilic properties as well as to their defect sites, which is predicted to possess a greater oxidation tendency due to the presence of oxygen vacancies and Ti 4+ in higher concentrations. The presence of such defects causes the generation of ROS upon contact with O 2 , and ROS generated can profoundly have a detrimental impact on pathogens.…”