Siliceous adsorbent for heavy metals.
Carnahan-TG; Flynn-CM Jr.
U S Pat 4 256 587 1981 Mar; :
Heavy metals are removed from wastewater by ion exchange on a low-cost, porous, high surface-to-weight ratio siliceous material, preferably a kaolinitic clay leach residue, which has been activated with an alkali. The heavy metal ion-loaded exchanger can be regenerated for subsequent reuse or utilized for flux in base-metal smelting and the like. For example, 200 g of minus 10-mesh kaolin leach residue (surface/weight ratio 325 m2/g) was treated with 0.1M Na2SiO3 and then washed with water. A solution containing 640 mg/l cu ions was passed through the ion-exchange resin to give an effluent containing 0.05 Mg/l cu. The ion-exchange resin was regenerated by treatment with 0.2M H2SO4, rinsing with water, and treatment with 1.0M NaOH.
U.S. Pat. 4,256,587, Mar. 17, 1981; Chem. Abstr. 93:191,601Z