On the removal of some phenolic compounds from aqueous solutions by using a sporopollenin-based ligand-exchange fixed bed — Isotherm analysis

Single component adsorption of phenol and 2-, 3- and 4-nitrophenol from water was studied under dynamic column conditions by using a carboxymethyl diaminoethane sporopollenin in a cobalt ion-loaded form, Co(II)-CDAE-S, as solid phase. Adsorption isotherm data were acquired by frontal analysis for five plateau concentrations ranged from 1.25×10− 5 to 2.00×10− 4 mol l− 1. The studied ligand-exchange sporopollenin resin showed a selective adsorptive nature within the group of studied nitrophenols, and the nature of phenols' adsorption on the Co(II)-CDAE-S was analyzed in terms of specific bindings by using Scatchard plot analysis. In light of the Scatchard plot analysis, the adsorption of examined compounds was mainly attributed to the specific bindings based on the ligand-exchange matrix of the studied adsorbent. The nitro-substituted phenols were found to be less strongly adsorbed than the phenol, and both binding strength and theoretical saturation capacity had an obvious relationship with the position of nitro substituent: The theoretical saturation capacities calculated from applied isotherm models exhibited an increase in the order of phenol < 4-nitrophenol < 3-nitrophenol < 2-nitrophenol, whereas a reverse order was showed for binding strengths.