Cadmium removal from aqueous systems using Opuntia albicarpa L. Scheinvar as biosorbent.

The aim of this research was to investigate the use of a natural adsorbent like nopal (Opuntia albicarpa L. Scheinvar) for removing cadmium from aqueous solutions with low concentrations of this metal. Two treatments were applied to the cladodes: a dehydration to get dehydrated nopal (DHN) and heating up to 90C to obtain a thermally treated nopal (TN). After examining the effect of various pH values (2?7), the capacity of each biosorbent was examined in batch sorption tests at different dosages (0, 500, 1000, 1500, 2000, and 3000?mg?L?1). The results indicated that adsorption of cadmium to biomass of DHN and TN was highly dependent on pH and biosorbent dosage. The best removal of cadmium (53.3%, corresponding to of 0.155?mg?g?1) was obtained at pH 4.0 by using the TN sorbent. Infrared and Raman spectra confirmed that cadmium removal occurred via adsorption to ?OH functional groups.