Assessment of Cu(II), Zn(II) Cr(III) and Cd(II) removal from aqueous samples using Typha sp as biosorbent

Full text: The use of biomass for environmental remediation and effluent treatment by means of the removal of toxic substances has been extensively investigated. The reason for the interest in such materials can be attributed to their low cost, high availability and removal capacity similar to that of synthetic materials. Thus, the present work describes the use of Thypa sp in the removal of Cu(II), Zn(II), Cr(III) and Cd(II) from aqueous samples. Through simple preparation processes, the raw material was converted into a powder (63 - 105μm Ø), which was characterized through different techniques prior to its application in solid phase extraction procedure. SEM micrographs allowed to identify particles of heterogeneous sizes with elongated shape, which probably is related to the adopted preparation steps. Through FTIR and ¹³C-NMR, several important groups, such as amine and carboxylic acids, were identified. Elemental analysis enabled the quantification of N and S, yielding 13 and 0.8 g Kg^-1, respectively. Groups containing such elements are the main responsible for metal removal, which may occur through sharing non-bonding electron pairs (covalent bond) or ion exchange process. The material had its pH_PZC determined (6.14), and the kinetics and influence of pH on metal ion adsorption were also investigated. Adsorption equilibrium was reached after 15 minutes of contact for all metallic species under investigation and the obtained data demonstrated good agreement with the pseudo-second order kinetic model. The most efficient pH for metal adsorption was found to be between 5 and 7. The maximum adsorption capacity, calculated by the modified Langmuir equation, for Cr(III), Cu(II), Zn(II) and Cd(II) was 0.182, 0.103, 0.046 and 0.085 mmol g^-1, respectively. These results are similar to those available in the literature where synthetic materials were employed, demonstrating that Typha sp could also be applied as adsorbent for the removal of toxic metal species from aqueous samples. (author)