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Heavy metal removal from aqueous solutions by tobermorites and zeolites

Nuclear and Chemical Waste Management
Publication Date
DOI: 10.1016/0191-815x(85)90001-4


Abstract The specific removal of Pb 2+, Cd2 2+, Co 2+, Ni 2+ and Cr 6+ from 0.02 N NaCl solution by tobermorite and zeolite cation exchangers was investigated using a batch method. Tobermorites, both synthetic and natural were extremely efficient in the removal of all the heavy metals except Cr 6+ and are superior to zeolites. For example, a natural tobermorite from Crestmore, CA removed 99.9% of Pb2 2+, 90% of Cd 2+, 95.8% Co 2+ and 96.6% of Ni 2+ from 0.02 NNaC1 solution containing 0.002 N of the heavy metal. Based on the percentage of metal ions removed by tobermorites from solutions, the order of removal for the different ions is as follows: Pb 2+ > Cd 2+ > Co 2+ > Ni 2+. The removal of heavy metals by tobermorites appears to be related to the exchange of structural Ca 2+ by Pb 2+, Cd 2+, etc., analogous to the exchange of these metals in hydroxyapatites. These results suggest that tobermorites may serve as useful scavengers for trace heavy metals in waste solutions.

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