Treatment of Industrial Wastewater using Zeolitite and Sepiolite, Natural Microporous Materials

This work investigates the ability of natural microporous materials, such as a zeolite-rich tuff (zeolitite) and a modulated phyllosilicate (sepiolite), to remove heavy-metal ions from simulated inorganic polluted industrial wastewater. Fixed beds of sepiolite and zeolitite were percolated by a solution of Co 2+, Cu 2+, Zn 2+, Cd 2+, and Pb 2+ (concentration of each cation, 2 x 10 -3 N; total concentration, 10 -2 N) and were regenerated with a 2 x 10 -3 N Na + solution. The order of decreasing affinity was, for sepiolite: Cu 2+ > Zn 2+ > Cd 2+ > Pb 2+ ? Co 2+, and, for zeolite: Pb 2+ >> Cd 2+ > Cu 2+ > Zn 2+ > Co 2+. After regeneration with Na + solution, a fraction of the retained heavy metals was quickly released by the beds as follows: sepiolite, Co 2+ ? Pb 2+ > Cd 2+ > Zn 2+ > Cu 2+; zeolitite, Cd 2+ > Cu 2+ >? Zn 2+ > Co 2+ > Pb 2+. XRD and DTA-TGA analyses examined structural changes in the natural and final materials. This work investigates the ability of natural microporous materials, such as a zeolite-rich tuff (zeolitite) and a modulated phyllosilicate (sepiolite), to remove heavy-metal ions from simulated inorganic polluted industrial wastewater. Fixed beds of sepiolite and zeolitite were percolated by a solution of Co 2+, Cu 2+, Zn 2+, Cd 2+, and Pb 2+ (concentration of each cation, 2×10 -3 N; total concentration, 10 -2 N) and were regenerated with a 2×10 -3 N Na + solution. The order of decreasing affinity was, for sepiolite: Cu 2+>Zn 2+>Cd 2+>Pb 2+?Co 2+ , and, for zeolitite: Pb 2+>>Cd 2+>Cu 2+>Zn 2+>Co 2+ . After regeneration with Na + solution, a fraction of the retained heavy metals was quickly released by the beds as follows: sepiolite, Co 2+?Pb 2+>Cd 2+>Zn 2+>Cu 2+ ; zeolitite, Cd 2+>Cu 2+?Zn 2+>Co 2+>Pb 2+ . XRD and DTA-TGA analyses examined structural changes in the natural and final materials.