Category: October 2017

Stephanie Richins, an undergrad sophomore majoring in chemical engineering at NMSU, in conjunction with her faculty advisor, Dr. Hongmei Luo, also in the chemical engineering department at NMSU, have explored the route of mitigation through chemical conversion, enhanced by the use of a suitable catalyst and energy source. The research was supported in part by an NM WRRI Student Water Research Grant, and is summarized in a report titled: Oxidation of Arsenite by a Carbon Nitride Photocatalyst with Graphitized Polyacrylonitrile.

The methodology employed in this study has included the synthesis and analysis of a suitable catalyst, graphitic carbon nitride, and the use of a solar simulator to provide ultraviolet light to speed up the oxidation of Arsenic III to Arsenic V in the presence of the catalyst. Properties of the synthesized catalyst were established and confirmed using an array of instrumental techniques including X-ray diffractometer, infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy combined with energy-dispersive X-ray analysis. These techniques permitted the identification of phase and structure of nanomaterials, as well as their morphology and particle size distributions, and the identification of elemental composition. More specifically, it revealed the concentration of active sites on the photocatalyst material, and confirmed, through the detected ratio of carbon to nitrogen in the material, that the synthesis of the catalyst was carried through to completion successfully.

Having established the properties of the catalyst, experiments were carried out to test the efficiency of conversion of arsenite to arsenate in water in the presence of the catalyst and ultraviolet light. The tracking of this chemical reaction as a function of time was accomplished using an inductively coupled plasma mass spectrometer. This device produces a very hot plasma that can ionize a small sample of solution, which then absorbs and emits light that is analyzed by the mass spectrometer; as a result the information in the light spectrum can be used to estimate the ratio of arsenic species in the water solution. It was found that roughly one half of the Arsenic III could be converted to Arsenic V within two hours of reaction time.

These results are very encouraging, and Stephanie hopes there will be an opportunity to pursue follow-on research, such as graphitic carbon nitride with modification or functionalization for large surface area and more active catalytic sites. As she notes, water agencies that work on arsenic contamination problems should be able to make use of this research. For example, the U.S. Environmental Protection Agency has restrictions on the amount of arsenic in water, and this research could help find a cost effective way to better control that contamination.

The final report for the project is on the NM WRRI website by clicking here.

The three-year project, funded by the New Mexico Department of Health (NMDOH), provided free laboratory tests to the owners of private, domestic wells. Some 521 individual households participated in the study. Water from incorporated cities, towns, and villages was not included in the study because those systems are routinely treated and tested for contaminants already. The study ended June 30.

Ward said an estimated 17,500 people living in New Mexico’s border region obtain their water supply from their own wells. Due to the high cost of lab testing, most well owners are reluctant to ship their water to laboratories for testing. “It’s a gap in our knowledge of water quality in this area,” said Ward. “We don’t have the income base to press well owners to test their water. So, they do without.”

Ward said the project proved a win-win for both the well owners and the NMDOH. “The Health Department remains particularly interested in understanding the quality of our groundwater. However, the department three years ago didn’t have a good picture of the groundwater quality down here in southern New Mexico,” she said. “As for the well owners, they jumped at the opportunity to save $200 to $300 for a laboratory analysis of their water.”

During the course of the project, water samples were collected once each week and shipped overnight to the state-authorized drinking water lab in Albuquerque. Staff members at Cooperative Extension Offices in Deming, Las Cruces, Lordsburg, or Silver City assisted with collections and shipments.

“I can’t thank the Cooperative Extension Service enough for their help and support of this project,” said Ward. “The project would have gone nowhere without the enthusiastic support of the Extension staff.”

A report on the three-year study can be found in the Miscellaneous Reports section of NM WRRI’s website by clicking here. Upon request, NM WRRI can email a copy of the Excel database of laboratory results. Please email coklett@nmsu.edu or erinward@nmsu.edu for a copy.

The cooperative agreement’s annual community learning meeting was held on October 24 at the Las Cruces Convention Center and began with a poster session that highlighted diverse water-related research projects by New Mexico State University students and faculty. Following the poster session, Dr. Sam Fernald, Director of New Mexico Water Resources Research Institute, welcomed the 83 attendees and shared background information on the cooperative agreement between NMSU and the U.S. Bureau of Reclamation.

NM Representative Bill Gomez, NM Representative Nathan Small, and NM Senator Ron Griggs, and Mayor Javier Perea of the City of Sunland Park, spoke about water issues that affect their constituents and the development efforts to remediate some of those challenges as they plan for the future.

One of the highlights of the meeting was brief summary presentations on research projects by researchers who have received funding through the cooperative agreement. The group heard about exciting new and innovative technologies and research projects underway that may well have positive impacts on the ability to use and develop brackish and marginal quality water.

The lunch speakers, John Balliew, Director and CEO of El Paso Water Utilities, and Fernando Barrera, Senior Project Closing Specialist from the North American Development Bank, both gave firsthand accounts of desalination projects that they have worked on and provided valuable insight.

Following lunch, a community small group discussion was held, which gave vital feedback on concerns, challenges, and opportunities that desalination presents for the participants and their communities. The feedback they provided will be available on the cooperative agreement website, which is in progress and should go live in mid-November.