This paper describes the preparation and use of a low cost biosorbent made of castor leaves for the extraction of Cu(II) from an
aqueous medium. The biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR), surface area and pore
diameter measurements. The results showed absorption bands of carboxylic and amide groups at 1738 and 1540 cm-1,
respectively, and the measured surface area was 1.3728 ± 0.0160 m2 g-1, with predominance of microporous < 10.51 Å.
Quantitative extraction was achieved at pH above 4 and kinetic equilibrium was reached within 10 minutes. Isotherm adsorption
data were adjusted to a modified Langmuir equation, yielding a Ns value of 0.321 mmol g-1. The continuous flow system showed,
after the optimization parameters, a 47-fold enrichment factor (preconcentration factor) when applied to standard and real water
samples (Paraná River and Tap water). The developed preconcentration method was validated against the certified reference
material (CRM 1643e).