THWRC Awarded Proposal 513LUB0024H

Project number:    513LUB0024H

Title:                      Novel Adsorbents: Carbon Nanocomposites towards Toxic Cr(VI) Removal

Lead PI:                  Zhanhu Guo

Awarded amount: $25,000


Project Abstract

Hexavalent Chromium, Cr(VI), recognized as a human carcinogen, is able to transport into cells via the sulfate transport mechanisms, taking advantage of the similarity of sulfate and chromate with respect to their structure and charge. Due to its widely usage in modern industry, over concentrated Cr(VI) are penetrating in our living environmental, especially through water. US EPA sets up maximum limit of total chromium in drinking water as 100 ppb with and Cr(VI) as low as 0.06 ppb. The current Cr(VI) removal technologies, including cyanide treatment, electrochemical precipitation, reverse osmosis, ion exchange and adsorption, are either exhibiting low Cr(VI) removal efficiency or requiring a high manufacturing and operational cost. Until now, at least 74 million Americans in 42 states drink chromium-polluted tap water, most of which are likely in the cancer-causing Cr(VI) form. Nanostructure adsorbents have shown great Cr(VI) removal from polluted water, while the challenge comes from the very difficult separation process after adsorption. To the best of the PIs’ knowledge, there is no report on the study of carbon nanocomposite fibers/fabrics for Cr(VI) treatment from polluted water yet.

To date, we have successfully completed THWRC-funded research to remove Cr(VI) from polluted water by using magnetic polyaniline hybrid nanostructures. This was accomplished by the high surface area and redox reactions between polyaniline and Cr(VI). The major advantage of this material is that we can recycle these nanostructures by using a permanent magnet which is an economic and energy saving process from industry point. However, these nanoparticles need to be dispersed during adsorption and separated afterwards that restricts the process to be continuous. The explicit purpose of this project is to chart a new direction for our research: grow functional nano-adsorbents on flexible electrospun fiber or cotton fabric substrates and to use these materials in filtration column units for continuous, fast and complete Cr(VI) removal. The carbon nanocomposite fibers/fabrics, consisting of carbon substrate and iron oxide nanoparticles, will be fabricated using the dip-coating and subsequent thermal annealing method developed recently by the PIs. The nanocomposite fibers/fabrics packing length, density and assembling configuration in the filtration column as well as flow rate and circulation time of polluted water will be systematically studied by using real industry polluted water. The open structure of the nanocomposite fiber/fabric is projected to remain high fluid flux during filtration. The decorated nanoparticles are expected to enlarge the Cr(VI) removal efficiency and capability. The Cr(VI) removal mechanisms will be exploited by studying the Cr valence state change on the carbon nanocomposites surface with X-ray photoelectron spectroscopy and magnetization change before and after treatment. This project has great potential to be successful within the proposed two-year period. Two assistant professors, one postdoctoral researcher and two undergraduate students will be involved in this project. The unique research team is positioned to advance the nanotechnology in the hazardous treatment field.