Patents by Inventor Nadim R. Khandaker

Nadim R. Khandaker has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method of removing arsenic and other anionic contaminants from contaminated water using enhanced coagulation
    Patent number: 7138063
    Abstract: An improved water decontamination process comprising contacting water containing anionic contaminants with an enhanced coagulant to form an enhanced floc, which more efficiently binds anionic species (e.g., arsenate, arsenite, chromate, fluoride, selenate, and borate, and combinations thereof) predominantly through the formation of surface complexes. The enhanced coagulant comprises a trivalent metal cation coagulant (e.g., ferric chloride or aluminum sulfate) mixed with a divalent metal cation modifier (e.g., copper sulfate or zinc sulfate).
    Type: Grant
    Filed: February 10, 2006
    Date of Patent: November 21, 2006
    Assignee: Sandia Corporation
    Inventors: David M. Teter, Patrick V. Brady, James L. Krumhansl, Nadim R. Khandaker
  • In situ remediation process using divalent metal cations
    Patent number: 6830695
    Abstract: An in situ process for treating ambient solid materials (e.g., soils, aquifer solids, sludges) by adding one or more divalent metal cations to the ambient solid material. The added divalent metal cations, such as Cu2+ or Zn2+, combine with metal oxide/hydroxides (e.g., ferric oxide/hydroxide or aluminum oxide/hydroxide) already present in the ambient solid material to form an effective sorbent material having a large number of positively-charged surface complexes that binds and immobilizes anionic contaminant species (e.g., arsenic or chromate). Divalent metal cations can be added, for example, by injecting an aqueous solution of CuSO4 into an aquifer contaminated with arsenic or chromate. Also, sludges can be stabilized against leaching of anionic contaminants through the addition of divalent metal cations. Also, an inexpensive sorbent material can be easily formed by mixing divalent metal cations with soil that has been removed from the ground.
    Type: Grant
    Filed: January 31, 2003
    Date of Patent: December 14, 2004
    Assignee: Sandia Corporation
    Inventors: Patrick V. Brady, Nadim R. Khandaker, James L. Krumhansl, David M. Teter
  • Arsenic removal in conjunction with lime softening
    Patent number: 6802980
    Abstract: A method for removing dissolved arsenic from an aqueous medium comprising adding lime to the aqueous medium, and adding one or more sources of divalent metal ions other than calcium and magnesium to the aqueous medium, whereby dissolved arsenic in the aqueous medium is reduced to a lower level than possible if only the step of adding lime were performed. Also a composition of matter for removing dissolved arsenic from an aqueous medium comprising lime and one or more sources of divalent copper and/or zinc metal ions.
    Type: Grant
    Filed: August 30, 2002
    Date of Patent: October 12, 2004
    Assignee: Sandia Corporation
    Inventors: Nadim R. Khandaker, Patrick V. Brady, David M. Teter, James L. Krumhansl