Grapefruit peels as biosorbent: characterization and use in batch and fixed bed column for Cu(II) uptake from wastewater

Abstract

BACKGROUND A 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. RESULTS Mercury 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. CONCLUSION Based 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. © 2016 Society of Chemical Industry

Amino‐functionalized material from a bio‐template for silver adsorption: process evaluation in batch and fixed bed

“…As shown, all properties are modified by the applied treatment. The DIC process modifies the structure of the adsorbent by increasing the area of the grapefruit peel from 5.24 to 9.55 m 2 g −1 ; this effect has previously been discussed . This phenomenon is the result of formation of mesoporosity in the surface, as the volume of the mesopores considerably increases after DIC treatment.…”

“…The second peak at 285.6 eV is related to C–OH bonds, whereas the signal at 287.3 eV corresponds to the O=C‐OH and COO − . Finally, the peak at 288.79 eV corresponds to carbonyl group bonded to oxygen and nitrogen atoms (R‐NH‐COO‐R) …”

“…Pseudo‐first and second‐order models were fitted to the experimental data . To obtain Ag(I) adsorption isotherms, it was assumed that the experiments reached equilibrium when the adsorption capacity remained constant.…”

“…To obtain Ag(I) adsorption isotherms, it was assumed that the experiments reached equilibrium when the adsorption capacity remained constant. Once experimental data were obtained, Langmuir and Freundlich models were fitted to determine the maximum adsorption capacities of the adsorbents . All models were tested by performing adjustment of the experimental data to the nonlinear equations using as an estimation method the algorithm of Levenberg–Marquardt.…”

“…Adsorption studies in continuous mode were carried out using the adsorbent that in previous studies had presented best adsorption capacity in batch mode. For this purpose, the experimental system consisted of a 2 L capacity recipient, a peristaltic pump, a glass column and an auto‐sampler installed at the column outlet . The column had a height of 14 cm and an internal diameter of 1 cm; it was filled with a fixed amount of adsorbent, and using a peristaltic pump (GILSON Minipuls 3) the flow rate was fixed at 1 mL min −1 .…”