Comparative study of the adsorption of phenol and salicylic acid from aqueous solution onto nonionic polymeric resins

Phenolic compounds are undesirable pollutants in the environment, specifically in aquatic media. Salicylic acid is a phenolic compound, and, together with phenol, which is its precursor, it is present in wastewaters from different industries. Adsorption being one of the most common ways for these wastewaters treatment, the comparison of the adsorption on these compounds onto two different polymeric resins (Amberlite XAD16 and Duolite S861) was the aim of this work. The adsorptive behavior of these resins has been compared in batch and fixed bed operation. Langmuir isotherm model was used to fit equilibrium data. In order to ascertain the fixed bed implementation of the adsorbents, adsorption runs were carried out at laboratory scale and the effects of temperature and flow-rate were addressed. For modelling, the adsorption kinetics a linear driving force (LDF) approximation was used. The LDF rate constant accounting for macropore diffusion and adsorption and the film mass transfer resistance were grouped in an overall mass transfer coefficient. According to the results, the capacity of Duolite S861 for phenol adsorption (96.13 mg g−1) was slightly higher than for Amberlite XAD (81.68 mg g−1). On the contrary, Amberlite XAD salicylic acid adsorptive capacity (85.06 mg g−1) was nearly double than that of Duolite S861 (43.01 mg g−1). From a kinetic point of view, for both the resins the overall mass transfer coefficient was higher when adsorbing phenol than salicylic acid. Nevertheless, in the temperature range studied (293-333 K), the separation parameter for thermal parametric pumping purification is larger for Amberlite XAD16 for both phenol and salicylic acid.