Green Route for Hydrogen Evolution from Real Electroplating Waste Liquids Induced by a Solar Light Responsive Photocatalyst

Real electroplating wastewater/liquid containing disodium ethylenediaminetetraacetate (Na2EDTA) and nickel (Ni), a platinum/nitrogen-doped TiO2/strontium titanate-TiO2 tube (a solar light-responsive material), and simulated sunlight were used as the photogenerated hole scavenger, photocatalyst, and light source, respectively, in the development and evaluation of a waste-to-energy system. Effects of the wastewater/liquid source, pH, EDTA concentration, EDTA/Ni molar ratio, EDTA/photocatalyst weight ratio, and the degree of Ni removal on the photocatalytic hydrogen evolution efficiency are discussed. Our results indicate that the hydrogen evolution efficiency is affected by these factors in the following order: EDTA/Ni molar ratio > EDTA/photocatalyst weight ratio > pH value. When the initial EDTA/Ni molar ratio and EDTA/photocatalyst weight ratios were 30 and 0.7, respectively, economically optimal hydrogen evolution efficiency (480.0 μmol/h/g) was achieved; when the waste liquid was further treated for Ni...