Water Treatment

Charge dependent separation of organic molecules from water. Ultramicroporous fluoropolymer network (COP-99) was developed from a self-condensation reaction of perfluoro hydroquinone and shown to separate water-soluble organics by their size and charges (Nature Commun. 2016, 7, 13377). This nanoporous material is the first to selectively pull dyes and other compounds from water based on their charge and size. The fluorine-cation interaction was found to be the main driving force for this unusual behavior.

Nano-magnetic separations for water treatment. A new method for making magnetite (Fe3O4) nanocrystals was developed (Chem. Comm., 2004, 2306) and these were used to show size dependent magnetic behavior and enhanced arsenic affinity (Science, 2006, 314, 964). Unprecedented low temperature phase transition (Nature Mater., 2007, 7, 130), magnetic separations (Chem. Eng. Sci., 2009, 64, 2510) and analytical ultracentrifugations (ACS Nano, 2008, 2, 311) were also made possible by these uniform magnetite nanocrystals. An affordable and accessible arsenic removal technology that is based on magnetic nanoparticles and an open source concept to produce them was introduced through the use of household items such as edible oils, rust, vinegar (Environ. Geochem. Health, 2010, 32, 327). We then synthesized barium hexaferrite (BHF) nanoparticles and tested them for the arsenic removal (J. Nanopart. Res. 2012, 14, 881). Subsequently, we developed an inexpensive method to synthesize BHF nanofibers. The BHF fibers are the thinnest ever in the literature and the goal is to make a mesh out of these in solving the leaching problem for magnetic nanoparticle based water treatment procedures (J. Nanopart. Res. 2014, 16, 2787).

Shape controlled synthesis of nanoparticles in porous polymeric frameworks for water treatment. Shape and size variation for nanoparticles is limited to surfactant-controlled synthesis. We developed one of the first methods to control nanoparticle growth by locking them into the pores of porous polymers (J. Mater. Chem. A 2015, 3, 15489). Using same approach we installed nanoscale zero valent iron (nZVI) into COP networks for effective degradation of organic pollutants (J. Mater. Chem. A 2016, 4, 632-639).

Uranium capture from seawater. Oceans contain vast amounts of fissile uranium but there is no economically feasible sorbent to extract them. Our amidoxime based sorbents showed the fastest and the highest Uranium uptake with multiple cycles of regeneration and reuse (RSC Adv. 2016, 6, 45968-45976).

Precious metal capture from electronic waste. Phenazine COPs are designed for capturing gold and platinum from electronic waste. High selectivity and low cost of the sorbent enables commercial development.