Biosorption of Cr(III) ions from synthetic aqueous solutions and tannery effluent using the macrophyte Pistia stratiotes

ABSTRACT

Chromium is a toxic metal widely used in industrial processes, so the concern with the liquid effluents generated is constant, that once released without proper treatment can compromise the quality of the receiver body. The study aimed at analyzing the process of biosorption in removing Cr(III) ions of synthetic aqueous solutions and tannery effluent using as biosorbent the Pistia stratiotes macrophyte in natura (PN) and chemically modified (PM) with sodium hydroxide and citric acid. The preparation, characterization of the biosorbents and the experiments of biosorption were performed. Equilibrium studies indicated that the maximum biosorption capacity for PM was 58.16 mg g^-1 and 19.80 mg g^-1 for PN. In the tests using raw effluent from tannery, chromium removal was 28.26% for both biosorbents, and in the effluent from biological treatment lagoon, the higher rate of metal removal was obtained by biosorbent PM with 65.44%. The results showed that the use of P. stratiotes as biosorbent may be an effective and low-cost alternative and that additional studies are needed to assess its full-scale application.

Keywords:
toxic metals; chemical modification; wastewater treatment