Desorption of arsenic from soil, goethite and zerovalent iron using some extractants under different pH values [electronic resource].

Includes references.

Arsenic is a toxic element that can occurs in the environment as a result of either natural processes or anthropogenic activities. The accumulation of arsenic in form of arsenate As(V) in soils and sediments threatens the health of plants, wildlife and human. Goethite (ɑ-FeOOH), zerovalent iron (fine powder of iron metal) and clay minerals play an important role in controlling the concentration of soluble arsenic in pure water due to it is formed inner sphere surface complexes. Extraction of arsenic using phosphate, sulphate, molybdate and DTPA had been suggested as a procedure to assess its amounts. Arsenate was equilibrated with soils at 10-100 µg As ml-1 surface coverage and extracted by 0.005M DTPA. On the other hand, it was equilibrated with goethite and zero valent iron at 10 µg As ml-1 and pH values of 5 and 9 as well as it was extracted by phosphate, sulphate and molybdate solutions at a ratio of I : 100 ≈ As: each solution and pH values ranging from 3 to 12. Regarding soils, desorbed As (µg g-1) from both the studied loamy and clay loam soils by DTPA gradually increased with increasing initial As (V) concentration. A slight increase in the desorbed As from the loamy soil was observed with increasing its initial concentration from 30 to 40, 50 to 60 and 60 to 100 µg As ml-1, Whereas, a relatively high increase in the desorbed As(V) from the clay loam soil was noticed with increasing the initial concentration of As(V) from 20 to 30,70 to 80 and 90 to 100 µg As ml-1. Key words: Desorption process, arsenate, goethite, zerovelant iron, phosphate, sulphate, molybdate and variable pH values.

Summary in Arabic.

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