title: Utilization of natural chabazite and mordenite as a reactive barrier for immobilization of hazardous heavy metals.
abstract: BACKGROUND
  Understanding the sorption process in natural geomedia is necessary for effective utilization of these materials as low-cost adsorbents and consequently as controlled release hazardous elements. This research was oriented to investigate the affinity of two natural zeolite minerals towards cobalt, zinc, and nickel mixture as an important industrial and radioactive waste.
  
  
  METHODS
  The uptake of metal ions as a function of different parameters has been studied using a batch equilibrium technique.
  
  
  RESULTS
  The results revealed that the affinity and adsorption capacity of chabazite and mordenite follow the order: Zn(2+) > Co(2+) > Ni(2+), with good fits being obtained using Langmuir and Freundlich adsorption isotherms. The metal uptake was found to be concentration-dependent and independent of the pH over 3.0 to 8.0 range; this reveals that the adsorption mechanism is controlled mainly by a pure ion-exchange reaction at the experimental conditions used. Kinetic curves showed a rather fast exchange reaction for three cations, as equilibrium was mostly reached within 20 min.
  
  
  CONCLUSIONS
  These materials especially chabazite are recommended to be used as a reactive barrier for hazardous heavy metals control.
authors.affiliation: Department of Analytical Chemistry and Environmental Control, Hot Laboratories Center, Atomic Energy Authority, Cairo, Egypt. aymanseliman@yahoo.com
authors.forename: Ayman F
authors.initials: AF
authors.lastname: Seliman
authors.forename: Emad H
authors.initials: EH
authors.lastname: Borai
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry* / Q000494:pharmacology; D002852:Chromatography, Ion Exchange / Q000379:methods; D003035:Cobalt / Q000302:isolation & purification; D006256:Hazardous Waste; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D019216:Metals, Heavy / Q000302:isolation & purification*; D009532:Nickel / Q000302:isolation & purification; D014865:Waste Disposal, Fluid / Q000379:methods*; D017641:Zeolites / Q000737:chemistry* / Q000494:pharmacology; D015032:Zinc / Q000302:isolation & purification
chemical_list: D000538:Aluminum Silicates; D006256:Hazardous Waste; D007220:Industrial Waste; D019216:Metals, Heavy; C048397:mordenite; D017641:Zeolites; D003035:Cobalt; D009532:Nickel; D015032:Zinc