Pectin-based hydrogels produced from banana and mango peels as a potential approach to removing heavy metal Ions from contaminated water

Abstract

The release of harmful compounds from manufacturing processes into the environment causes a variety of environmental problems. In the low concentration range, conventional removal methods are frequently either too costly or insufficiently successful. On the other hand, hydrogel-based biosorption demonstrated to be economical and effective. Biohydrogels suitable to adsorb heavy metal contaminants from water were prepared using pectin obtained from a mixture of banana and mango peels and combined with carboxymethyl cellulose using calcium chloride as a crosslinker. The hydrogel’s internal structure and surface morphology as well as their swelling behavior, swelling-shrinking cycles, and water adsorption capacity under different external pressures were evaluated. The adsorption capacity and the influence of pH and temperature were assessed using Pb(II), Cu(II), Cd(II), and Ni(II). The reusability was investigated by adsorption-desorption cycles. The findings demonstrated a porous structure, more than 80% swelling at pH higher than 5 and within 30 min in contact with the medium, and the capacity to retain water at pressures of up to 400 kPa. With a reusability of five adsorption-desorption cycles, and the ability to adsorb more than 70 mg of each heavy metal ion per gram of dried hydrogel in the resulting order; Cu(II)>Pb(II)>Cd(II)>Ni(II).