Catalytic pyrolysis of the Eupatorium adenophorum to prepare photocatalyst-adsorbent composite for dye removal

Eupatorium adenophorum, a kind of pernicious weed, is used to produce a photocatalyst-adsorbent composite, consisting of ZnO[sbnd]Fe ₃ O ₄ particles on the surface of activated carbon, and bio-gas via catalytic pyrolysis. The photocatalyst-adsorbent composite was characterized by several characterization methods. The results show that the photocatalyst-adsorbent composite possesses adsorptive, photocatalytic degradative and magnetic properties. Methylene blue, a kind of dye, is used to evaluate the adsorption and photocatalytic degradation performance of photocatalyst-adsorbent composite. The maximum amount of methylene blue adsorption in photocatalyst-adsorbent composite was as high as 330.03 mg/g based on the adsorption experiment in dark conditions. The photocatalyst-adsorbent composite had good degradation performance with methylene blue, which was found to be 20.78% more efficient than the ZnO catalyst and 205% more efficient than the adsorption under ultra violet light irradiation. Photocatalyst-adsorbent composite could be conveniently separated from the aqueous solution by using an external magnetic field. The bio-gas was collected from the pyrolysis process, which mainly consisted of H ₂ and CO. The production cost of the photocatalyst-adsorbent composite is US$ 1,361/t based on the preliminary economic analysis.