Hydrogen production by photovoltaic-electrolysis using aqueous waste from ornamental stones industries

Researchers are currently focused on cost reduction (economic and environmental) in the production of hydrogen by coupling the electrochemical system to photovoltaic (PV) panels and using alternative electrolytes, mainly pollutants. The present work aims to use an electrochemical system coupled to PV panels to convert the energy coming from the sun into hydrogen gas, by residual water electrolysis from ornamental stones industries. This study designed a cylindrical electrolytic cell made of acrylic and 304 stainless steel electrodes to hydrogen production. Of tested residues, conventional loom granite electrolyte presented better accumulated hydrogen production, reaching 329 mL after 2 h of experiment, with an average irradiance of 1332 W m2. Cut diamond multiwire granite residue generated 54% less than conventional loom granite electrolyte, due to lower solution electrical conductivity. During experiments, iron ions precipitation in hydroxide form was observed. Overall efficiency for conventional loom granite electrolyte was approximately half the NaOH 2 mol L−1 however; it was 2.7 times larger than diamond multiwire granite electrolyte. It is noteworthy that use of NaOH, for electrolysis is a problem, given high corrosivity and cost of operation.