The reactive surface of Castor leaf [Ricinus communis L.] powder as a green adsorbent for the removal of heavy metals from natural river water

• Published in: Applied surface science 2013-07, Vol.276, p.24-30
• Main Authors: Martins, Amanda E., Pereira, Milene S., Jorgetto, Alexandre O., Martines, Marco A.U., Silva, Rafael I.V., Saeki, Margarida J., Castro, Gustavo R.
• Format: Article
• Language: English
• Subjects: Adsorbent; Aqueous samples; Castor leaf powder; Chemisorption; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Metals ions; Physics
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.02.096

[Display omitted] ► The Castor leaf powder presented a reactive surface which enables metal ions adsorption through chemisorption process. ► The predominance of macroporous enables water diffusion and metal ions may be adsorbed inside the pores. ► The Castor leaf powder was used in the removal of metal species from river water. ► An enrichment factor of 45 enable the determination of Cd(II) and Pd(II) ions. ► Method validation was performed through an analysis of certified water standards. In this study, a green adsorbent was successfully applied to remove toxic metals from aqueous solutions. Dried minced castor leaves were fractionated into 63-μm particles to perform characterization and extraction experiments. Absorption bands in FTIR (Fourier Transform Infrared Spectroscopy) spectra at 1544, 1232 and 1350cm−1 were assigned to nitrogen-containing groups. Elemental analysis showed high nitrogen and sulfur content: 5.76 and 1.93%, respectively. The adsorption kinetics for Cd(II) and Pb(II) followed a pseudo-second-order model, and no difference between the experimental and calculated Nf values (0.094 and 0.05mmolg−1 for Cd(II) and Pb(II), respectively) was observed. The Ns values calculated using the modified Langmuir equation, 0.340 and 0.327mmolg−1 for Cd(II) and Pb(II), respectively, were superior to the results obtained for several materials in the literature. The method proposed in this study was applied to pre-concentrate (45-fold enrichment factor) and used to measure Cd(II) and Pb(II) in freshwater samples from the Paraná River. The method was validated through a comparative analysis with a standard reference material (1643e).