Almond shell waste (Prunus dulcis): Functionalization with [dimethy-diallyl-ammonium-chloride-diallylamin-co-polymer] and chitosan polymer and its investigation in dye adsorption

The current paper reports on the chemical modification of Almond Shell (Prunus dulcis) waste (AS) with either [PolyDimethy-Diallyl-Ammonium-Chloride-Diallylamin-co-polymer] (PDDACD) or Chitosan polymer (CS) to improve its reactivity. The characteristics of the products were achieved using Whiteness Index, FT-IR spectroscopy and SEM features. The surface of shell powders is found to be rough with macroporous and microporous structure. Adsorption process was investigated using Acid Blue 25 (AB25) and Methylene Blue (MB) with respect to the change in pH value, initial dye concentration, contact time and temperature. The optimum doses of cationic reagents for the removal of AB25 are to be 0.5% and 5%, respectively, for CS and PDDACD. The equilibrium ofAB25 is attained at about 60 and 30 min, respectively, for [AS-CS] and [AS-PDDACD]. However, it was reached at 60 min for MB. At 25 degrees C and after equilibrium, the adsorbed capacity (q(t)) of MB on AS was 84.9 mg.g(-1). The modeling of kinetic data reveals that the adsorption ofAB25 on [AS-CS] shows a good adjustment to the pseudo-second-order model. The equilibrium data, globally, best fit the Freundlich model. The studied products are moderate and sometimes good sorbents for AB25 (n > 2). The Energy values (E) are higher than 40 kJ mol(-1) confirming that the adsorption of AB25 and MB is chemical. Based on the advantages offered and registered sorption results, Almond shell waste could be selected as adsorbent of both anionic and cationic dyes in its raw and functionalized form. (C) 2017 Elsevier B.V. All rights reserved.