Grantee Research Project Results
1997 Progress Report: Development and Characterization of a New Heavy-Metal Selective Inorganic Ion Exchanger
EPA Grant Number: R825422Title: Development and Characterization of a New Heavy-Metal Selective Inorganic Ion Exchanger
Investigators: Sengupta, Arup K.
Current Investigators: Sengupta, Arup K. , Kney, Arthur D. , Leun, David , Greenleaf, John , DeMarco, Matthew
Institution: Lehigh University
EPA Project Officer: Aja, Hayley
Project Period: November 1, 1996 through October 31, 1998 (Extended to December 31, 2000)
Project Period Covered by this Report: November 1, 1996 through October 31, 1997
Project Amount: $218,643
RFA: Exploratory Research - Water Engineering (1996) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Safer Chemicals
Objective:
To synthesize granular inorganic ion exchanger particles which can be used in fixed-bed columns to remove dissolved heavy metals; To benchmark the performance of this new ion exchanger in comparison with other commercially available chelating exchangers; To elucidate the stoichiometry and underlying sorption mechanism responsible for high heavy-metal-ion affinity.Personnel: Two masters students, namely, Duk Shin and David Leun and one doctoral student, Arthur Kney, have worked on this project so far. While Duk has completed his M.S. in Spring, 1998, David and Arthur are presently working on the project.
Progress Summary:
We have synthesized primarily two classes of Synthetic Inorganic Sorbent, referred to as SISORB1 and SISORB2. Photographs and scanning electron micrographs (SEM) of these particles are available at the NCER-EPA office. Iron oxide is the primary constituent for both but SISORB1 was synthesized by fusing iron oxides with calcium magnesium silicates while SISORB2 was synthesized by fusing iron oxides with silicon dioxide (SiO2). Granular SISORB particles with sizes ranging from 0.1 - 0.4 mm were used in fixed-bed columns without any hydraulic or operational problems.SISORB1 showed much higher affinity for environmentally regulated dissolved heavy metals, namely, Zn2+ and Cu2+, compared to competing non-toxic calcium, magnesium and sodium ions. At the influent acidic pH of 4.0 and in the presence of citrate as a ligand, SISORB1 removed dissolved zinc very efficiently in the presence of competing calcium and sodium ions.
SISORB1 is amenable to efficient regeneration with ammonia. After regeneration, SISORB1 has also been reused in fixed-bed column operation for removals of dissolved zinc and copper.
SISORB2 is very selective toward As(V) oxyanion and removes As(V) in the presence of competing sulfate, chloride and bicarbonate ions. In a laboratory fixed-bed column, SISORB2 performed significantly better than commercially available anion exchangers. SISORB2 is amenable to efficient regeneration with sodium hydroxide.
Future Activities:
It is postulated that ion exchange and Lewis acid base interactions are concurrently operative for selective sorption of heavy metals onto SISORB1. We will carry out appropriate experiments to confirm that precipitation plays a rather insignificant role in heavy metals removal by SISORB1.Although precipitated ferric hydroxides are non-magnetic, both SISORB1 and SISORB2 possess strong magnetic properties. Our preliminary experimental studies provide evidence that such magnetic characteristics are retained over sorption/desorption cycles. A more in-depth study is currently underway to utilize this particular characteristic of SISORB in removing dissolved heavy metals from the background of sludge with high suspended solids content.
Journal Articles:
No journal articles submitted with this report: View all 15 publications for this projectSupplemental Keywords:
Heavy Metals Removal, Ion Exchanger, Metal-Ligand Interaction., RFA, Scientific Discipline, Water, POLLUTANTS/TOXICS, Environmental Chemistry, Chemistry, Chemicals, Arsenic, Water Pollutants, Drinking Water, Engineering, Chemistry, & Physics, metal-chelate complexes, chelating exchanger, chemical composition, chemical detection techniques, metal speciation, treatment, physicochemical, other - risk management, drinking water contaminants, heavy metals, ion exchangeProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.