Copper(II) adsorption by Opuntia ficus-indica biochar fiber–MnO2 composites

Abstract

The adsorption efficiency of biochar fibers obtained from Opuntia ficus-indica cactus regarding the removal of Cu(II) ions from aqueous solutions has been investigated prior and after MnO2 surface-deposition. The removal efficiency has been studied as a function of pH, Cu(II) concentration, ionic strength, temperature and contact time. In addition, the biochar fibers have been characterized by Fourier transform infrared spectroscopy studies to elucidate the adsorption mechanism. Evaluation of the experimental data indicated that the MnO2-composite product presents higher adsorption capacity, which is attributed to the formation of inner-sphere surface complexes, and that the adsorption reaction is a relatively fast and endothermic process. The results of the present study reveal that MnO2–biochar composites could be used as very effective adsorbents for the removal of bivalent metal-ions from contaminated waters.