CEHIXM extraction of Pb, Cd, Zn, and Mn from high permeable soils

A new method CEHIXM for extracting heavy metals from high permeable soils under coupled electric-hydraulic gradient was investigated. Spent foundry sand, containing high levels of Pb, Cd, Zn, and Mn, was used as the contaminated source. A suitable ion-exchange resin was used for trapping and recovering the metals from the aqueous medium. Control experiments were conducted using hydraulic gradient alone to assess the leachability of the contaminants. The experiments were repeated with 50 V across the soil sample and without hydraulic gradient to evaluate ion migration under electric gradient. A number of CEHIXM experiments involving both hydraulic and electric gradients were conducted at a constant DC voltage of 50 V and a constant flow velocity of 0.0178 cm/sec. With hydraulic gradient only, 3 to 8% metals were extracted, whereas with electric gradient only the metal removal rate was 0 to 0.7%. When the electric and hydraulic gradients were coupled, as much as 93% of Pb, 97% of Cd, 98% of Zn, and 94% of Mn were extracted, after 100 h of the processing.