In this article, adsorption modelling was presented to describe the sorption of textile dye, Direct Red 75 (DR75), from coloured wastewater onto the natural and modified adsorbent, Posidonia oceanica. The formulation of the double-layer model with two energy levels was based on statistical physics and theoretical considerations. Thanks to the grand canonical ensemble in statistical physics some physico-chemical parameters related to the adsorption process were introduced in the analytical model expression. Fitting results show that the dye molecules are adsorbed in parallel position to the adsorbent surface. The magnitudes of the calculated adsorption energies show that the DR75 dye is physisorbed onto Posidonia. Both Van der Waals and hydrogen interactions are implicated in the adsorption process. Despite its simplicity, the model fits a wide range of experimental data, thereby supporting the underlying data that the grafted groups facilitate the parallel anchorage of the anionic dye molecule. Thermodynamic parameters, such as adsorption energy, entropy, Gibbs free adsorption energy and internal energy were calculated according to the double-layer model. Results suggested that the DR75 adsorption onto Posidonia was a spontaneous and exothermic process.

In the field of functional polymers, new aromatic polyethers were obtained with good yields by interfacial polycondensation of (EBr 2 ) n and bisphenol A (bis(4-hydroxyphenylether) or catechol (2-hydroxyphenol) with various catalysts (Aliquat, TBAB, and TDA1).The structure of all aromatic polyethers was determined by means of 1 H and 13 C NMR, and infrared spectra. All polyethers had good solubilities and could be soluble in usual solvents such as acetone, chloroform, and dichloromethane. Average molecular weight ranged from 1000 to 11000 g mol −1. Their thermal characteristics were also studied by differential scanning calorimetry. The hydrolysis of these aromatic polyethers esters gives aromatic polyethers acids.