Arsenic (V) adsorption from aqueous solution onto goethite, hematite, magnetite and zero-valent iron: Effects of pH, concentration and reversibility Original Research Article

In this paper, adsorption of arsenic (V) was studied under different physico-chemical conditions onto four commercial adsorbents: hematite, goethite, magnetite and zero-valent iron (ZVI). The reversibility of adsorption process was also studied using chlorides and phosphates as competing ions. Results show that arsenate adsorption is related to the iron content of adsorbents, and adsorption rate increases in the following order: goethite < hematite < magnetite < ZVI. The modeling of adsorption isotherms by empirical models show that arsenate adsorption is fitted by the Langmuir model for almost all adsorbents, suggesting a monolayer adsorption of arsenic onto adsorbents. Desorption experiments show that arsenic is strongly adsorbed onto hematite and ZVI. Among adsorbents, hematite appears to be the most suitable for removing arsenate in natural medium since it is effective over large ranges of pH and arsenic concentration.