The ultrasound assisted extraction of matrix elements and heavy metal fractions associated with Fe, Al and Mn oxyhydroxides from soil

Abstract

The single agent extractions of major and trace metals from soil sample were conducted by means of rotary mixer and ultrasonic bath with sonication time of 10, 20, 30, 40 and 50 min. The sequential extraction according to the BCR scheme was undertaken. The obtained soil extracts were analyzed by ICP-OES and according to the results the rotary mixer assisted extraction was more efficient in the case of alkaline-earth elements. However, by the use of ultrasound several times higher amounts of matrix elements (Fe, Al and Mn) and heavy metals predominantly associated with Fe, Al and Mn oxyhydroxides were extracted. The increase of the sonication time failed to improve extraction yields. The changes of the conductivity, pH, oxidoreduction potential, particle size diameter and zeta potential of colloid particles, with the sonication time increase were measured. The extraction mechanism and expressed selectivity of ultrasound is discussed and explanation is suggested.

Keywords

• soil analysis
• extraction mechanism
• sequential extraction
• soil phases