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Magnetic Fe2CuO4/rGO nanocomposite as an efficient recyclable catalyst to convert discard tire into diesel fuel and as an effective mercury adsorbent from wastewater
- Zandi-Atashbar, N., Ensafi, Ali A., Ahoor, Amir Hooshmand
- Journal of cleaner production 2018 v.172 pp. 68-80
- magnetism, surface area, heavy metals, tires, liquids, diesel fuel, rubber, sulfur, combustion, sorption isotherms, metal ions, gasification, humans, models, nanocomposites, adsorbents, temperature, adsorption, activated carbon, experimental design, mercury, exposure duration, catalysts, pH, wastewater
- Nowadays, abundance of wastes, like discard tires, and heavy metal ions contaminants, like Hg (II) ions, in water sources are big challenges for mankind. In this research, magnetic spinel Fe2CuO4/rGO nanocomposite was successfully prepared, instrumentally characterized and subsequently used as a catalyst to pyrolyze discard tires. This pyrolytic process was conducted, modeled and optimized using experimental design method when the process parameters, including temperature, time, particles size of tire rubber, the flow rate of inert gas (Ar), and amount of Fe2CuO4/rGO nanocomposite as the catalyst were controlled. In the optimized condition (401.2 °C, 20.0 mL min⁻¹ Ar, 12.6 mm, 1.1 g Fe2CuO4/rGO, and 58.9 min), the pyrolytic products included liquid (43.3 wt%), gas (16.6 wt%) and char (40.1 wt%). These products were practically evaluated as pyrolytic fuel, combustion gas and activated carbon, respectively. As the result of this research, the pyrolytic fuel represented comparable physiochemical properties, including flash point of 47 °C, the cetane number of 49, the sulfur content of 0.09 wt%, and remaining ash of 0.01 wt%, to the commercial and Euro 5 diesel fuels. Moreover, the resulted char was activated as activated carbon by gasification process since its specific surface area (SSA) was increased from 62.0 to 1184.0 m²g–¹. Moreover, the catalyst was further applied as an effective mercury adsorbent after its inefficiency with poisoning by sulfur compounds resulted from 17 repeated pyrolyses. Accordingly, the relevant conditions for pH of waste water, temperature, the catalyst amount, and exposure time were optimized as pH 7.0, 24 °C, 0.8 mg mL⁻¹ and 60 min, respectively. Mercury (II) removal was modeled based on Langmuir and Freundlich isotherms models, which Langmuir isotherm was a more fitted model. Hence, mercury (II) ions could be acceptable adsorbed as a monolayer on the catalyst surface by the maximum adsorption capacity of 1250 mg g⁻¹, the affinity constant of 0.0186 L mg⁻¹, and adsorption constant of 50.074 mg⁻⁰.⁵ L–⁰.⁵ g–¹. In conclusion, the successful prepared magnetic nanocomposite indicated high efficient performance to pyrolyze waste tires into valuable products and subsequently to adsorb mercury ions from aqueous wastes.