Hydrogen generation from wastewater using Aluminium scraps

The hydrolysis reaction of water–Al scraps was catalysed by KOH to produce hydrogen (H2). Reject water generated in the reverse osmosis (RO) process from domestic RO filters and the common effluent treatment plant (CETP) RO unit; CETP inlet and outlet; car wash wastewater; and tap water was used to generate H2. The optimum pH for maximum H2 production was 14. The addition of 1 g of Al scraps was enough to generate H2, equivalent to the theoretical values of the pure Al–water reaction (1,360 mL/g). The hydrolysis reaction depends on the size of the Al particles; the reaction accelerates with the decreased particle size and the increased surface area. Similarly, the H2 production increases with the increased reaction temperature up to 45 °C. The activation energy was comparable to the literature-reported studies. Within 30 min of the reaction, 94% H2 was generated utilising RO rejects as the water source, while 98.6% H2 was produced using car wash water. The precipitate generated during the hydrolysis reaction was characterised using Fourier transform infrared spectroscopy and X-ray diffractometer and may be used to make useful items. Thus, waste materials and wastewater have the potential to generate H2. The cost of 1 m3 of H2 production is estimated as Rs. 100.