Bioremediation Using Fruit Waste to Remove Lead From Water

The application of biomaterials in the remediation of contaminated water requires studies that support their use, involving physical, chemical, and/or biological treatments. This study aimed to physicochemically characterize the adsorption process of biomaterials created from orange peels, tamarind seeds, and avocado seeds when they interact with lead to remove it from water. Additionally, we compared the adsorption efficiency between materials subjected to physical processes and chemical processes (polymerized with polyanilines). Our results indicate that orange peel is the best option for Pb(II) concentrations lower than 100 mg L-1, whereas avocado seeds offer better adsorption results for higher concentrations, followed by tamarind seeds. The results show that Freundlich isotherms best describe the adsorption process. The Fourier Transform Infrared spectra indicate that chemisorption is the dominant mechanism. This is supported by comparing the adsorption capacity of the biomaterial with that of the biomaterial polymerized with polyanilines; this process reduces adsorption by up to 40% due to the diminution of active sites. The optimal pH for orange peel and tamarind seeds is 4.5, whereas for avocado it is 6.0, which coincides with the pKa of carboxyl groups. The infrared spectra suggest that the interaction occurs in the carboxyl groups.