Valorization of Waste Tungsten Filament into mpg-C₃N₄–WO₃ Photocatalyst: A Sustainable e-Waste Management and Wastewater Treatment

Abstract

The waste of tungsten filament materials in the environment is one of the reasons for environmental pollution, and it is very dangerous to animals and plants. To date, not much attention has been given to its utility or recyclability. Herein, the present work reported the synthesis of tungsten trioxide nanoparticles (WO3 NPs) by the utilization of cost-free waste tungsten filament by a simple calcination method. A mesoporous graphitic carbon nitride–tungsten trioxide (mpg-C3N4–WO3) composite designed from the WO3 NPs produced from tungsten filament waste and thiourea as a carbon and nitrogen precursor by a one-step calcination method. The synthesized samples were characterized and confirmed by different characterization techniques. The photocatalytic behavior of the synthesized mpg-C3N4–WO3 composite was assessed, with respect to the effect of initial pH, amount of photocatalyst, dye concentration, and reaction time, as well for the degradation of Methylene Blue (MB) dye under sunlight. The best photocatalytic performance (92%) was achieved using mpg-C3N4–WO3 with experimental condition ([photocatalyst] = 100 mg/L, [MB]0 = 10 mg/L, pH 8, and time = 120 min) under sunlight irradiation with excellent photostability than that of isolated mpg-C3N4 and WO3 NPs. The histotoxicological studies also showed that the photodegraded products of MB were found to be nontoxic and did not structurally changes in the gill architecture as well as brain tissues of freshwater fish Labeo rohita.

Economic Feasibility Evaluation of Bioleaching-Based Tungsten Recycling of Semiconductor Industry Waste

“…The extraction process for tungsten requires significant energy, and the complexity of the process results in costs that are approximately 8–20 times higher than those for aluminum, zinc, and copper. − Recycling technologies that are environmentally friendly and efficient in resource recovery within regulatory frameworks are expected to provide a solution to these challenges . Compared to various types of E-waste, wastewater from semiconductor production contains target metals at concentrations 2–40 times lower. − This characteristic enables the pretreatment of heavy metals, such as tungsten, in a powdered form, rendering bioleaching an advantageous area in recycling technology compared to other methods, as highlighted in previous studies. , …”

Preparation of Oxygen-Doping Nongraphitic Carbon Nitride via Efficiency Exfoliation for the Application of Photocatalytic Degradation

“…The conversion of solar energy into value-added chemical energy is attracting worldwide attention for its potential to address growing energy needs and environmental crises. , Photocatalysis has great potential in the degradation of organic pollutants due to its advantages of environmental friendliness and good reusability. , Among them, semiconductor photocatalysis is effective for removing organic pollutants from water . Since the discovery of metal-free graphitic phase carbon nitride (g-C 3 N 4 ) with visible photocatalytic decomposition of water by Wang et al in 2008, g-C 3 N 4 has been playing an increasingly important role in photocatalytic hydrogen production, organic pollutant degradation, , and environmental pollution remediation due to its low cost, nontoxicity, good visible light response, and suitable electron energy band structure .…”

“…3,4 Among them, semiconductor photocatalysis is effective for removing organic pollutants from water. 5 Since the discovery of metal-free graphitic phase carbon nitride (g-C 3 N 4 ) with visible photocatalytic decomposition of water by Wang et al in 2008, 6 g-C 3 N 4 has been playing an increasingly important role in photocatalytic hydrogen production, organic pollutant degradation, 7,8 and environmental pollution remediation 9 due to its low cost, nontoxicity, good visible light response, and suitable electron energy band structure. 10 However, the bulk g-C 3 N 4 synthesized by conventional methods still suffers from small specific surface area, poor visible light utilization, and rapid photogenerated charge carrier complexation.…”