BACKGROUNDA study of copper adsorption onto biosorbents prepared from grapefruit peels (GP) is presented. The objectives of the present analysis were: (1) to evaluate the use of Instant Controlled Pressure Drop (DIC) as a treatment of biosorbents preparation; (2) to assay the modified biosorbents in fixed-bed columns; and (3) to elucidate an adsorption mechanism of the metal on the modified biosorbents. RESULTSMercury intrusion porosimetry studies showed that the use of DIC increases the porosity of material 11.3-fold. Adsorption capacity of GP biosorbents indicate that those prepared using a DIC process had an increase of 32% and by using a subsequent chemical treatment, an enhancement of 69%, compared with simple dried GP peel. In fixed bed adsorption studies, the maximum adsorption capacity of the bed and the minimum adsorbent rate were 52.48 mg g(-1) and 24 g L-1, respectively. CONCLUSIONBased on the results from the adsorption and characterization studies performed by SEM-EDS, FTIR and XPS, it is proposed that the adsorption mechanism was a physisorption phenomenon, between oxygen-containing groups and Cu(II) from water. High adsorption capacity can be achieved using modified GP peels in fixed-bed columns; therefore, it is feasible to use it as a non-conventional adsorbent. (c) 2016 Society of Chemical Industry