Advancing bio-filter materials for enhanced desalination in agricultural applications†

The global scarcity of irrigation-grade water poses severe concerns in the agricultural sector. Desalination techniques including reverse osmosis, electrodialysis, capacitive deionization, membrane filtration, and multi-stage flash are some dynamic solutions to mitigate this challenge. In this study, novel bio-filter materials were explored and developed for the application of membrane-based electrodialysis. Firstly, a series of composites were synthesized comprising different compositions of carboxymethyl cellulose (CMC), graphene oxide (GO), and Aloe vera to serve as cationic-selective membranes. Then desalination abilities of the composite series were assessed through permselectivity and ion exchange capacity (IEC) studies. Membrane matrix developed by integrating all the above three materials exhibited the highest permselectivity and IEC. The composites were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). It was determined that the designed composites can function effectively as cationic-selective membranes, while dried banana leaves can serve directly as an anionic-exchanger in an electrodialysis apparatus. Optimal performance was achieved when the pH of the system was maintained between 4.5 and 8.1. This system successfully desalinated a 3.5% (w/v) sodium chloride solution, achieving ∼75% desalination within 20 minutes. The potential to use banana leaves as a bio-filter material was explored in a parallel study. The results revealed that banana leaves dried for over 28 days at room temperature have high potential to function as anionic-selective membranes effectively in the electrodialysis desalination process. Altogether, this innovative approach offers a sustainable, eco-friendly and cost-effective solution for electrodialysis based water desalination.