Carbon nanotubes (CNT) have high surface area and absorption capabilities and the absorption capacity of multi-walled CNTs (MWNTs) enables paramagnetic nanotubes to be obtained by absorbing iron salts. Characterization of paramagnetic MWNTs was performed with TEM, FTIR, DSC, and VSM. Paramagnetic CNTs are used for the purification of water from heavy metals and plastic originated compounds. Most of the PVC-based materials contain phthalate acid esters (PAE) which have considerable effects on human health. In this study, MWNTs were used for removing diethyl phthalate (DEP) from methanol after their toxicity evaluation. Concentration-dependent absorption of 494, 1461, and 2950 ppm, respectively, were measured from the mixture containing 13.3, 33.3, and 66.6% DEP in 40 mg paramagnetic MWNT solution. Although it was concluded that magnetic nanotubes would exhibit significant toxic effects compared to untreated MWNTs, GC-MS results were showed a reliable absorption capacity of magnetic nanotubes for purification applications. The results demonstrated that the use of magnetic MWNTs for the extraction of PAEs is an efficient way from liquids.