Novel Material and Applications for Water Disinfection
Physical Sciences : Materials and Compounds
Available for licensing
- Navid Saleh, Ph.D. , Civil, Architectural and Environmental Engineering
- Jaime Plazas-Tuttle , Civil Engineering
Ensuring water safety via disinfection has largely relied on the use of oxidants since the early 1900s. Common oxidants include chlorine, chloride compounds, and ammonia. However, chemical disinfectants lead to the production of disinfection by-products (DBPs), which have raised public health concerns since the early 1970s.
Alternative non-chemical based disinfection technologies became necessary, and ultraviolet (UV) irradiation has been developed as an effective disinfection alternative. Disadvantages of UV technology are the absence of disinfection residual beyond treatment facility, its need for a clear optical pathway to enable UV ray penetration, and maintenance and replacement of lamps. Furthermore, UV technology is not commonly available at every household, but rather needs to be custom-made with the purpose of disinfecting water. An alternative irradiation-based disinfection technology that can take advantage of an already adopted, affordable, and available device, while overcoming most of the limitations of available disinfection processes, can be greatly beneficial.
Researchers at The University of Texas at Austin have developed a new nanomaterial that amplifies microwave radiation and has demonstrated its effectiveness to disinfect water. The complex nanomaterial combines carbon nanotubes’ microwave absorption abilities with lanthanide series metal (e.g., erbium) oxides’ up-conversion capabilities to generate reactive oxygen species that can eventually inactivate bacteria. Thus far, the material synthesized has been irradiated with a kitchen microwave at 110W power for 20 seconds to attain one log reduction of Pseudomonas aeruginosa, an opportunistic pathogen. Further development will focus on optimal design of a system incorporating the new material that will allow for rapid, high-efficiency disinfection of bacteria-laden water streams.
This new material can use microwave radiation to disinfect water rapidly and inexpensively. The time of microwave irradiation is exceptionally low compared to other radiation-based techniques. Since microwave is a radiative energy and does not require a clear optical path to function (e.g., our food is warmed in a dark bowl with microwaves), turbid water can be disinfected effectively.
The invention includes a new material that can upconvert microwave radiation, the weakest radiation in the electromagnetic spectrum. Thus far, the state-of-the-art upconversion science could achieve near infrared upconversion (which has orders of magnitude higher energy potency). The material can effectively concentrate radiative microwave energy at a small footprint and then transfer the concentrated energy over to lanthanide series metal erbium oxide, which energizes electrons at its exterior shells and enables hydrogen peroxide production. Produced hydrogen peroxide radicals then inactivate bacteria. Preliminary testing shows only 0.0006 kWh energy is required to generate the H2O2 in situ.
Drinking water scarcity is a growing problem worldwide. The high energy consumption and low operating efficiency of typical UV sterilization systems and the high cost of chemical treatments effectively limit access to safe drinking water in many countries. Applications such as hydroponics and aquaculture continue to expand, driven by human population growth pressuring the fixed arable land resources. Additional growth markets like hospital disinfection, dental disinfection, cruise ship and personal drinking water disinfection will all create demand for technology that efficiently and effectively kill waterborne bacteria.
The Freedonia Group reports worldwide demand for water treatment chemicals will grow 5.8% per year to $30B from 2014 to 2017, indicative of the growing demand for water purification.
Proof of concept
- 1 U.S. patent application filed