Practical and mechanistic aspects of the removal of cadmium from aqueous systems using peat.
A sphagnum peat moss removed Cd from aqueous solutions very efficiently, and its effectiveness in taking up the metal was significantly enhanced by exposure to a 1N NaOH solution. The capacity of the untreated peat for Cd reached 300 g/kg and that of the NaOH-activated peat was over 400 g/kg. Although saturation was rarely reached, the Cd uptake from concentrated solutions often exceeded 200 g/kg. In column experiments, 1g of the NaOH-activated peat completely removed the metal from over 0.2L of a 200-mg/L Cd solution (final Cd concentration<0.1mg/L), while 1g of non-activated peat cleared Cd from less than 25% of that volume. The cation exchange capacity measured for the peat depended on the time of contact with the exchanging solution. After 72 h contact, the value for the NaOH-activated peat was 135 cmol(c)/kg. In addition to uptake by exchange, a significant amount of Cd was sorbed by non-exchange mechanisms. FTIR spectroscopy revealed the importance of carboxyl groups in the uptake.
Fine
Pinchas
P
Institute of Soils, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, P.O.B. 6, Bet Dagan 50250, Israel. finep@volcani.agri.gov.il
Scagnossi
Alessandra
A
Chen
Yona
Y
Mingelgrin
Uri
U
D002104:Cadmium / Q000032:analysis*; D007220:Industrial Waste; D012972:Sodium Hydroxide; D012987:Soil; D017550:Spectroscopy, Fourier Transform Infrared; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
D007220:Industrial Waste; D012987:Soil; D014874:Water Pollutants, Chemical; D002104:Cadmium; D012972:Sodium Hydroxide