Combination of electrocoagulation and photocatalysis for hydrogen production and decolorization of tartrazine dyes using CuO-TiO2 nanotubes photocatalysts

Abstract

Tartrazine dyes contained in various types of industrial waste need to be processed first before being discharged into the waters because it is dangerous for the environment and human beings. Therefore tartrazine processing is needed before being discharged into the waters. Meanwhile, with the increasing energy needs, the development of environmentally friendly renewable energy sources such as hydrogen (H2) is needed. The decolorization process of dye waste by electrocoagulation has the potential to produce H2 gas at once in abundant quantities. However, the decolorization process is less effective because it is only through adsorption by the coagulant produced. The photocatalysis process also has the potential to degrade organic waste (including decolorization) more effectively, while producing H2 gas, although it is less effective. In this study, it is proposed to combine the electrocoagulation and photocatalysis processes and see the effect of CuO dopant in TiO2−Nanotubes to decolorize the dye waste and simultaneously produce H2. Decolorization and hydrogen production simultaneously were carried out in a reactor made of acrylic which is equipped with a power supply and UV lamps. H2 was produced from the reduction of H+ ions in solution on stainless steel cathodes and water splitting by photocatalysis simultaneously. Decolorization of tartrazine is obtained from a combination of adsorption by electrocoagulation and degradation by photocatalysis. TiO2 Nanotubes was synthesized by anodizing method, then modified with Cu dopant by the SILAR method. The SEM results confirm that the Nanotubes structure is still formed with an average diameter of 166 nm and an average tube thickness of 52 nm. The presence of Cu was detected by analysis with EDX, which amounted to 1.68% wt. The XRD results showed that TiO2 Nanotubes was in the anatase phase with a crystal size of 27 nm. Bandgap energy is calculated using the Kubelka-Munk equation from the results of UV-Vis DRS characterization. The calculation results show that the energy band gap of CuO-TiO2 Nanotubes decreases from a bandgap of pure TiO2 Nanotubes. The hydrogen production test shows that the combination of the electrocoagulation-photocatalysis process produces more hydrogen than the electrocoagulation process alone. Modification of TiO2 Nanotubes with CuO dopant in the electrocoagulation-photocatalyst system can increase 44% hydrogen concentration and degrade tartrazine solution 10.5% better than using pure TiO2 Nanotubes in that system.