Modified Grape Seeds: A Promising Alternative for Nitrate Removal from Water

Abstract

The aim of this work was to investigate grape seeds as a potential adsorbent for nitrate removal from water. Grape seeds were modified by quaternization and the applicability of the modified grape seeds (MGS) was evaluated in batch adsorption experiments. Fixed bed adsorption and regeneration studies were carried out to determine the regeneration capacity of MGS. The maximum adsorption capacity of 25.626 mg g−1 at native pH (6.3) for nitrate removal by MSG was comparable to that of the commercial anion exchange resin Relite A490 under similar conditions. The percent removal of nitrate from model nitrate solution was 86.47% and 93.25% for MGS, and Relite A490, respectively, and in synthetic wastewater 57.54% and 78.37%. Analysis of the batch adsorption data using isotherm models revealed that the Freundlich model provided a better fit to the data obtained than the Langmuir model, indicating multilayer adsorption. In kinetic terms, the results showed that the adsorption followed the pseudo-first order model. By investigating the adsorption mechanism, the results suggest that the intraparticle diffusion model was not the only process controlling the adsorption of nitrate on MGS. In column experiments (adsorption/desorption studies), three adsorption cycles were tested with minimal decrease in adsorption capacities, implying that this alternative adsorbent can be successfully regenerated and reused.

Modified Hazelnut Shells as a Novel Adsorbent for the Removal of Nitrate from Wastewater

“…Triethylamine-functionalized polystyrene microsphere 47.27 [37] Modified brewers' spent grain 24.16 [57] Modified grape seeds 27.47 [44] Modified hazelnut shells 26.51 This study…”

“…Similar results were reported by Keränen et al [34] using modified pine sawdust and [43] who studied the adsorption of nitrate onto quaternary starch derivatives. In addition, Stjepanović et al [44] reported that ETM-modified grape seeds could be considered as an alternative for the commercial ion exchanger Relite A490. The lower percent removal from wastewater samples is to be expected and could be explained by the fact that such a complex matrix contains other ions, which prevent nitrates from adsorbing by competing for the same adsorption sites.…”