Abstract: A method for the removal of arsenic in a positive oxidation stage from an aqueous liquid comprising the steps of: i) providing a porous adsorbent which comprises a solid phase carrying a metal ion in a form (I) which is capable of binding the arsenic to give a metal ion form (II) comprising the metal ion and the arsenic; ii) contacting the aqueous liquid with the adsorbent for formation of form (II), iii) separating the aqueous liquid from the adsorbent, iv) optionally regenerating the adsorbent, and reusing it in cycles comprising steps (i)-(iv), The characterizing feature is that A) form (I) is a metal chelate (I), which •comprises a metal ion and a multidentate chelating group, •comprises three or more amino nitrogens which are directly attached to sp3 carbon and in an at least triplet wise manner can coordinate a metal ion, and, •can be transformed to form (II), and/or B) step (ii) prior to the formation of form (II) comprises the substeps of: •oxidising As (+III) to As(+V), and •securing zero amounts of