“…Its outer surface is mostly composed of SiO 2 and the inner surface of Al 2 O 3 , and, hence, those surfaces are oppositely charged [ 119 ]. The external siloxane and internal aluminol surface of halloysite is efficient as an absorbent (described above) or could be used as a carrier for drugs [ 120 , 121 , 122 , 123 ], nucleic acids [ 124 ], antibacterial agents [ 125 ], and antioxidants [ 119 , 126 , 127 , 128 , 129 , 130 ]. Therefore, halloysite is an efficient adsorbent both for cations and anions.…”