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Aqueous adsorption of anions onto oxides at pH levels above the point of zero charge

1984; Elsevier BV; Volume: 100; Issue: 1 Linguagem: Inglês

10.1016/0021-9797(84)90418-1

1095-7103

William H. Morrison,

Diatoms and Algae Research

The adsorption of most simple anions and anionic polyelectrolytes from water onto oxides occurs by electrostatic (hydrogen) bonding to positive surface sites. Surface site density is governed by pH and acid-base character of the oxide. Certain anions continue to adsorb at pHs significantly above those where positive surface site density falls to approximately zero. These anions include phosphate, phosphate esters, and organic acids containing hydroxyl functionality. A mechanism for this involves hydrogen bonding of the residual hydroxy groups to negatively charged surface oxide ions. Past work on adsorption of phosphate, arsenate, etc., onto oxides will be discussed in terms of the present model.