Exploring the Possibility of Using Agave sisalana Perrine, Austrocylindropuntia subulata (Muehlenpf) Backeb and Opuntia ficus- indica (L.) MILL. as a Source of Bio-electrolyte

Abstract

The global search for sustainable and affordable green energy sources has intensified due to escalating environmental concerns, health issues, energy access challenges and fossil fuel depletion. Succulent plants such as Agave sisalana Perrine, Austrocylindropuntia subulata (Muehlenpf) Backeb and Opuntia ficus-indica (L.) Mill are fast-growing, drought-resistant and invasive in nature, thriving in arid and marginal lands where food crops cannot survive. These plants store significant amounts of water, bioinorganic and bio-organic matter, making them promising candidates for bio-electrolyte feedstock in renewable bio-fuel production. Currently, these plants do not have any significant use, yet they are invasive and are rapidly spreading, killing pasture for livestock in rural areas. This study investigated the potential of Agave sisalana Perrine, Austrocylindropuntia subulata (Muehlenpf) and Opuntia ficus-indica (L.) Mill saps as plant-based bio-electrolytes. Sap pH and electrical conductivity were measured at different temperatures and dilution levels, while voltage and current were measured using Zn-Cu, Zn-C, Zn-Fe, Fe-Cu, Fe-C and Cu-C electrode pairs. Pearson correlation and general linear model analyses were used to examine relationships among the measured variables. The results showed that pH and electrical conductivity decreased with an increase in temperature. Voltage showed relatively small changes during the short-term monitoring period but varied among plant species and electrode-pair combinations. Applied voltage had a weak positive correlation with current (r = 0.153, p < 0.001), while the Fe-Cu electrode pair recorded the highest estimated mean current of 3.66 mA. Overall, the results provided preliminary evidence that the three plant saps can function as bio-electrolytes in electrochemical cells.