Effect of humic acid on pharmaceuticals adsorption using sulfonic acid grafted chitosan

A modified polymer (chitosan grafted with sulfonic acid and cross-linked with glutaraldehyde) was synthesized in order to examine the effect of humic acid (HA) on the adsorption equilibrium of a model pharmaceutical compound (pramipexole). The presence of humic acid in water intended for potable or industrial use can have a significant impact on the treatability of that water and the success of chemical disinfection processes. Therefore, industrial effluents are even mis-treatable. The results showed that increasing the concentration of HA (0, 2.5, 5.0, and 20 mg/L), the maximum adsorption capacity decreases. However, in both materials, it seems that there is a crucial concentration of humic acid (5.0 mg/L), which results the higher reduction of adsorption capacity (Qm. found after fitting to Langmuir and Langmuir-Freundlich models). The presence of 5 mg/L of HA in solution causes slightly different Qm than that of 20 mg/L. Also, techniques as BET analysis, SEM images and swelling experiments were applied for the characterization of the material.