Effect of cationic surfactants on the modification of esparto grass for removal of diclofenac from aqueous solutions

The aim of this investigation was the adsorption of the diclofenac sodium (DS) from aqueous solution using its adsorption onto esparto grass (EG) modified with cationic surfactants such as Dodecyltrimethylammonium bromide, Cetyltrimethylammonium bromide and Benzyldimethylhexadecyl ammonium chloride to get DEG, CEG and BEG, respectively. The potentiality of these modified EG for the DS adsorption was studied. Batch mode analyses were conducted and the results showed that the maximum adsorption loading (q_max) was 3.31 mg/g for DEF, 6.45 mg/g for CEG, and 10.30 mg/g for BEG. Based on the results of the isotherm models and the calculated error of each model, Langmuir isotherm model demonstrated the best agreement with the adsorption data. Kinetic studies showed that the data have the highest fitting to the pseudo-second-order model. Adsorption mechanism mainly involves electrostatic interactions, hydrophobic interactions and π–π interactions. Finally, the exhausted MEG_s can be regenerated by diluted NaOH solution and reused.