Removal of diphenhydramine from water by swelling clay minerals

► Montmorillonite is a good adsorbent for diphenhydramine (DPH) in aqueous solution. ► Cation exchange is the dominant mechanism for DPH adsorption. ► At high adsorption DPH intercalated into the interlayer of montmorillonite. ► Adsorption of DPH resulted in interlayer dehydration of montmorillonite.