Adsorption envelopes for arsenic and cadmium versus variable pH values on soil, goethite and zerovalent iron [electronic resource].

Includes references.

Due to arsenic (As) and cadmium (Cd) are considered of human carcinogenic elements, hence a knowledge about their reaction kinetics at the solid-liquid interface under variable pH values is extremely important for understanding the adsorption/desorption processes which controlling As and/or Cd soil-water system. Thus, the objective of this study was to identify adsorption envelopes for As (as arsenate) and Cd versus variable pH values (3-12) on soil (calcareous in nature), synthetic goethite (colloidal system of iron hydroxide) and zerovalent iron (fine powder of iron metal). Therefore, series of well-controlled laboratory experiments were carried out on the adsorption/desorption processes for As and Cd to achieve the previous objective. The obtained data show that the greatest As adsorption by soil (59.5. µg As g-1 soil) was recorded at pH 5, then it was tended to gradually decrease with increasing the pH value more than 5. The lowest value of As adsorbed by soil (16.5 µg As g-1 soil≈ 6.4 % of total added As) was occurred at pH 12. Adsorption of Cd showed an opposite trend to As, where its adsorbed percent tended to increase with increasing the pH values. The greatest Cd adsorption (98 µg Cd g-1 soil≈ 40 % of total added Cd) was noticed at pH 7, with a constant trend for its adsorbed values with increasing pH value more than 7.

Summary in Arabic.

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