Experimental Study on the Effect of Operating Parameters on Hydrogen Production from Alkaline Wastewater Electrolysis

Abstract

This study investigated the influence of three principal operating parameters on hydrogen production from alkaline wastewater electrolysis. Hence the primary objective of this study was to examine the effects of specific operating conditions on hydrogen yield, employing alkaline wastewater as electrolyte. The key parameters examined included temperature variation, effect of electrolyte concentration variation, and applied current variability. The findings indicated that electrolysis performance was significantly influenced by these parameters. Specifically, the volume of hydrogen produced rose with rising current. At the tested currents of 0.3A, 0.5A, 0.7A, and 0.8A, the time needed to reach 10 ml of hydrogen was 664.88s, 349.24s, 244.21s, and 230.08s, In addition efficiency rose with each added current, 41.122%, 46.973%, 50.322%, 47.982%, and 44.562%. Higher applied currents initially enhanced the yield. However, beyond a certain threshold, further increases in current lead to a decline in efficiency owing to limitations in mass transport and bubble formation in and around the cell. Regarding the effect of temperature and electrolyte concentration on the rate of hydrogen production, as the temperature raised at 10 K intervals (303.15, 313.15, 323.15, 333.15, and 343.15 K), the time needed to reach 10 ml of hydrogen by volume reduced in higher order of magnitude (312.61, 267.61, 233.96, 189.72, and 184.18 s, respectively). In addition, the efficiency of the hydrogen production rate improved at each added current: 45.173%, 51.84%, 56.623%, 62.31%, and 67.735%. Although high temperatures improve efficiency, they are not favored because of the higher operating costs. The effect of the electrolyte concentration was also significant in terms of the hydrogen rate. At a current of 0.25 A for all ranges of concentration tested (5, 10 g/l; 15g/l and 20 g/l NaOH), the time(s) to reach 10 ml by volume of hydrogen was 341.58s, 276s, 236.18, and 209.57 s, respectively. This was due to the higher ionic mobility with an enhanced concentration of the electrolyte. Generally, the hydrogen production yield reached approximately 57% efficiency at a temperature of 323.15 K, current of 0.6A, and concentration of 10 g/NaOH from the alkaline wastewater, highlighting the potential of this method for generating hydrogen from an abundant and environmentally friendly resource. Future research should focus on further optimization strategies, long-term stability of electrodes in wastewater electrolysis, and economic feasibility of scaling up this process for practical applications.