Photocatalytic Removal of Cyanide from Cassava Processing Wastewater with Simultaneous Generation of H2 and C2H4 Using Ni-modified TiO2

The present work reports the photocatalytic treatment of the wastewater from cassava processing in an inert atmosphere aiming to degrade cyanide species with the simultaneous generation of sustainable fuels. Nickel-modified TiO2 was used as a photocatalyst with a wide range of Ni content, varying from 0.5 to 4%. The materials were also treated under reducing and oxidizing atmospheres to improve the photocatalytic activity. XRD analysis revealed anatase as the main phase in all samples with the rutile phase present in some of them and the exchange of some Ti atoms by Ni atoms in the crystal lattice. Although no segregated phase associated with Ni has been identified, the presence of nickel dramatically changes the bandgap energies of the photocatalysts, from 3.2 eV for pure TiO2 to 2.3 for Ni(4.0%)-TiO2. Both Ni content and heat treatment influenced the photocatalytic activity. The photocatalyst with the highest Ni content and thermally treated in a reducing atmosphere followed by an oxidizing atmosphere, called O-Ni(4%)-TiO2, was the most active photocatalyst, with mitigation of 98% of total cyanide and simultaneous generation of H-2 and C2H4.

Automated summary

This study presents the photocatalytic treatment of cassava processing wastewater in an inert atmosphere using nickel-modified TiO2 as a catalyst to degrade cyanide species and generate sustainable fuels. The photocatalytic activity was influenced by the nickel content and heat treatment, with the O-Ni(4%)-TiO2 catalyst showing the highest activity. XRD analysis revealed the presence of anatase and rutile phases in the samples, and the exchange of Ti atoms by Ni atoms in the crystal lattice.