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(338k) Adsorptive Removal of Cationic Surfactants From Water: Intensification of Adsorbent Regeneration

Authors: 
Sainio, T., Lappeenranta University of Technology
Turku, I., Lappeenranta University of Technology


Adsorptive removal of cationic surfactants from water by using a hydrophobic polymer adsorbent was investigated. In particular, the possibility to intensify the regeneration of the adsorbent with an aqueous solution of an organic solvent was studied. Equilibrium and kinetics of benzalkonium chloride (BKC) adsorption on Amberlite XAD?16 were investigated in a batch adsorber. Since commercial BKC products are mixtures of C12 and C14 homologues, these data were measured for each homologue.

Adsorption isotherms were correlated with the competitive Langmuir model, and intraparticle mass transfer kinetics with a Fickian pore diffusion model assuming local equilibrium in the pores. Fixed-bed adsorption experiments were used to determine the dynamic loading capacity of adsorbent.

Saturation capacity was found to be large (200 BV), but dynamic capacity was smaller (80 BV) due to high mass transfer resistance. It was shown that regeneration of loaded adsorbent can be intensified by using an organic co-solvent (ethanol). With 50 wt-% ethanol in the desorbent, the regeneration of the column was completed a hundred times faster than with pure water.

A mathematical model was derived to describe the influence of ethanol on the adsorption of the BKC homologues. When applied in the column simulation, the proposed model yielded a very good prediction of column performance over a wide range of desorbent concentrations. Process performance aspects, such as the influence of the desired surfactant removal percentage on productivity, were discussed based on simulation results.