Research Projects
I have worked on a variety of projects which have provided me expertise in electrochemical separation techniques for nutrient recovery, Biogeochemical cycles in natural systems, adsorption of REEs on minerals, and synthesis and application of nanoparticles.
Membrane fouling in electrochemical separations techniques
Electrochemical methods hold the potential to sustainably transform nutrients and CO2 into value-added products. However, the fouling of ion-exchange membranes (IEMs) used for the selective transport of ions in electrochemical separations poses a barrier to their integration into wastewater treatment processes. My postdoctoral research has been focused on understanding and preventing membrane fouling during electrochemical stripping (ECS) of ammonia from wastewaters. I currently use advanced synchrotron-based (micro-X-ray fluorescence (µ-XRF) and X-ray absorption spectroscopy (µ-XAS)) techniques to determine the speciation and distribution of the moieties deteriorating membrane performance over time. With this information, I have tested and identified suitable additives (chelating agents and antiscalants) that can prevent Ca-based IEM fouling during ECS operation.
Trace metal role in biogeochemical processes
Trace metals serve as essential micronutrients for microorganisms involved in biogeochemical processes and may regulate the greenhouse gases emitted via these processes in natural environments. With the aid of field studies and modeling techniques, I established that natural aquatic systems lack sufficient available trace metals to carry out these biogeochemical processes. My work on the role of copper in denitrification, as described in preprint found at https://eartharxiv.org/repository/view/2949/ provides evidence that the presence of adequate copper can decrease the amount of nitrous oxide emissions from wetland soils.
Response of natural systems to fluctuating redox conditions
Natural aquatic systems undergo fluctuating redox conditions due to microbial activity, varying water saturation levels, and nutrients dynamics. With fluctuating oxic and anoxic conditions, trace metals can be mobilized or sequestered in response to changes in iron and sulfur speciation and the concentrations and lability of organic carbon. With the help of lab-based microcosm study, I illustrated that different trace metals display distinct bioavailability patterns during oxic-anoxic fluctuations in natural environments. The biogeochemical cycling of carbon and nitrogen in systems with redox fluctuations may be influenced by these patterns in trace metal availability in addition to the availability of electron donors and acceptors.
Synthesis of rhamnolipid-coated magnetite nanoparticles for U(VI) sorption
Based on tunable properties, engineered nanoparticles (NPs) hold significant promise for water treatment technologies. Motivated by concerns regarding toxicity and non-biodegradability of some nanoparticles, we explored engineered magnetite nanoparticles with a biocompatible coating. These were prepared with a coating of rhamnolipid, a biosurfactant primarily obtained from Pseudomonas aeruginosa. By optimizing synthesis and phase transfer conditions, particles were observed to be monodispersed and stable in water under environmentally relevant pH and ionic strength values. These materials were evaluated for U(VI) removal from water at varying dissolved inorganic carbon and pH conditions.
Structural and Interfacial Geochemistry of Rare Earth Elements
Critical elements are essential to key technologies that underlie energy storage and generation, transportation, communications, and computing. The availability of the rare earth elements (REEs) are of particular concern because of the lack of adequate U.S. domestic production and their overall low abundance in Earth’s crust. Our overall objective is to elucidate the roles of mineral surfaces and
structures in controlling the migration and enrichment of REEs in weathering environments.
