Arsenic (As) is a naturally occurring (geogenic) carcinogenic metalloid present in groundwater. Excess arsenic (>10 μg/L) in drinking water is a major public health concern across the globe by affecting more than 200 million people and the number is increasing rapidly. The goal of this research has been to develop a new class of iron-based nanomaterials for arsenic removal which will be an ideal adsorbent and fabricate a sustainable point-of-use water treatment unit for household and small community arsenic removal.

Research progress

We reported a novel graphene oxide iron nanohybrid (GFeN) that achieved removal capacities of 306 mg/g for As(III) and 431 mg/g  for As(V) and fast reaction kinetics (remove >99% in less than 10 min). Graphene oxide sheets plays important role in the removal process, we proposed an arsenic removal mechanism where graphene oxide sheets used in the nanohybrid work as electron storage units and the stored electrons help in reactivating the iron as well as reducing the arsenic species to the final zero-valent state. There were negligible interferences by co-existing ions, pH, temperature and organic matters on arsenic removal efficiency at environmentally relevant level. High adsorbing GFeN possess a risk of release of adsorbed arsenic, we evaluated the reliability and stability of arsenic loaded GFeN.  In the presence of competing anions and variable pH at environmentally relevant concentration, these nanohybrids showed the release of only < 0.5 % adsorbed arsenic in 24 hr. The adsorbed arsenic on the monohybrid surface remained stable, only ~6% of the adsorbed arsenic was released over  ~2 years period. Ultra-high arsenic adsorption capacities, quick removal, and stabilization of adsorbed arsenic for a long period made our nanohybrid a reliable and robust candidate as a filter medium. To ease the application of powder nanomaterial in point of use treatment system we have synthesized polyethersulfone (PES) and cellulose nanofiber (CNF) based composite droplet size spherical beads which successfully entrap the GFeN and recorded efficient arsenic removal. This research is developing a feasible and sustainable arsenic treatment system that will be able to supply millions of people with safe drinking water.

Peer-reviewed Journal Papers

     Das, T.K.,and Bezbaruah, A.N. 2021 Comparative Study of Arsenic Removal by Iron-based Nanomaterials: Potential Candidates for Field Applications. Science of the Total Environment. 142914.

     Das, T.K., Sakthivel T.S., Jeyaranjan A., Seal S., Bezbaruah, A.N. 2020 Ultra-high arsenic adsorption by graphene oxide iron nanohybrid: Removal mechanisms and potential applications. Chemosphere. 126702.

Conference presentations and seminars

     Das, T.K., Sakthivel T.S., Seal S, Bezbaruah A.N. 2019. Mechanism(s) of arsenic desorption from graphene oxide-metal oxide nanohybrids. 8th Sustainable Nanotechnology Conference (San Diego, CA, USA) from November 7-10, (Oral Presentation).

     Das, T.K., Bezbaruah, A.N. 2019. Practical relevance of Graphene oxide supported iron nanohybrid in arsenic remediation. Association of Environmental Engineering and Science Professors (AEESP) Distinguished Lecture. (University of Minnesota, MN, USA) November 1 (Poster Presentation)

     Das, T.K., Bezbaruah, A.N. 2019. Arsenic Removal by Graphene-oxide Iron Nanohybrid: Spectroscopic and Microscopic Studies. NDEPSCoR Conference, Fargo, ND, USA (Poster).