Construction of hybrid sulfur-doped MOF-235@g-C3N4 photocatalyst for the efficient removal of nicotine

Abstract

Nicotine has inevitably been discharged into the environment either directly or as industrial effluent due to the widespread use of nicotine-based products worldwide. Its potential toxicity and irreversible impact on human health have made it a massive global issue. Presently, magnetic sulfur doped metal–organic framework-235 has been synthesized with iron terephthalate using the solvothermal approach and successfully applied as a photocatalyst for the elimination of nicotine. An array of techniques, including X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM) were performed to evaluate the photocatalyst Ni-Mo.S2/MOF-235@g-C3N4, Mo.S2/MOF-235@g-C3N4, Ni.S2/MOF-235@g-C3N4, Ni-Mo.S2/MOF-235 nanocomposites. Studies also showed that Ni.S2 and Mo.S2 overlaid on the main precursor MOF-235@g-C3N4 produced a greater number of active sites and an appreciable rise in photocatalytic activity when exposed to visible light. A noticeable increase in absorbance was seen at the heterojunction of MOF-235@g-C3N4 and bimetallic sulfides (Ni.S2, Mo.S2) as compared to simple MOF-235. The experimental results proved that Ni-Mo.S2/MOF-235@g-C3N4 had the maximum level of catalytic activity while eliminating 98 % of the sample in 60 min. It was significantly greater than the corresponding value of pure Ni-Mo.S2@MOF-235 bimetallic sulfide photocatalyst. Additionally, first-order kinetics is evident according to kinetic studies, where R2 = 0.920. The enhancement of photocatalytic activity by Ni-Mo.S2/MOF-235@g-C3N4 was attributed to an increased surface area and porosity, enhanced absorption of light and a narrowing of band gap from 2.26 to 2.16 eV. A significant amount of stability and recyclability were also displayed by the composite during the course of three consecutive cycles of photocatalytic nicotine degradation. Only a minor change occurred during the fourth and fifth cycles, with a negligible weight loss. The experimental findings demonstrated that a sustainable rise in the quantity of photo generated electron/hole pairs (e−/h+) was likewise associated with enrichment in light absorption intensity. A photo-catalytic mechanism for accelerated nicotine photodegradation has actually been linked to the active species (O2•−) and (OH•). This study expands the application of MOF-235@g-C3N4, which exhibits tremendous capacity for environmental purification and serves as a reference when creating composites of g-C3N4 photocatalyst.