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Nanobiotechnology July 2017 Viewpoints

Technology Analyst: Ivona Petrache

Desalination of Waste Brine with Carbon Nanotubes

Why is this topic significant?

A layer of carbon nanotubes on the surface of distillation membranes can recover almost 100% of fresh water from brines with very high salinity. These membranes may be useful for water-treatment plants that produce waste brine and for oil-and-gas-production fields that use hydraulic fracturing.

Description

Researchers at the University of California, Riverside (UCR), have developed porous membranes that recover almost 100% of fresh water from brines with very high salinity during heat-driven membrane-distillation processes. The porous membranes consist of polymer composite and a layer of carbon nanotubes (CNTs) on the surface of the membrane. The layer of CNTs acts as a Joule heater—it produces heat when an electric current passes through it. Therefore, the layer of CNTs allows the heating of brine only at the water-vapor interface of the membrane. The new membrane reduces the heat and improves the performance of the distillation process compared with conventional methods. By applying the frequency of the electric current at high potentials, the researchers used the membrane to directly desalinize brines with high salinity—such as waste brine from reverse-osmosis (RO) processes. The researchers also discovered that maintaining a high-potential current through the membrane during the distillation process prevented the CNTs from degrading. As a result, the scientists could use the membrane for extensive time without fear of decreasing the membrane's performance.

Implications

Typically, manufacturers use high-temperature treatment processes (such as heat-driven membrane distillation) to extract fresh water from high-salinity water (such as seawater, wastewater, and brackish water). These processes tend to rely on the heat capacity of the water and on a constant feed of heated brine over the membrane. In addition, the processes are complex and expensive (because highly corrosive brine gives the system's elements short life) and have low recovery yields (less than 10%). Reverse osmosis is another common choice for the desalination of high-salinity water. However, with RO, manufacturers can treat only water with salinity below 3.5%. The CNT membrane overcomes these limitations.

Impacts/Disruptions

The researchers' CNT membrane may be useful for water-treatment plants that produce waste brine and for oil-and-gas-production fields that use hydraulic fracturing. In countries in the Middle East (the United Arab Emirates, Saudi Arabia, Kuwait, Qatar, Bahrain, and Oman) alone, water-desalination plants have generated about twice as much salty wastewater as they have produced clean water (2 cubic meters of salty wastewater for every cubic meter of fresh water). These countries make up 45% of global desalination capacity.

When building and installing a desalination plant, companies may need to consider appropriate measures that comply with environmental regulations to dispose of brine waste. The appropriate disposal of brine may help the plants and production fields avoid any environmental damage (such as damage to marine life). Choosing a brine-disposal method is no small matter, particularly because of the high costs; brine disposal can cost manufacturers 5% to 33% of the total cost of desalination. This big cost gap is usually dependent on the volume of waste brine, the level of brine treatment before disposal, and the type of disposal. Reuse of water can generate significant savings for producers and manufacturers. The CNT membrane will have the greatest impact on plants with high-salinity flowback and in areas with water shortages.

Scale of Impact

  • Low
  • Medium
  • High
The scale of impact for this topic is: Low

Time of Impact

  • Now
  • 5 Years
  • 10 Years
  • 15 Years
The time of impact for this topic is: 10 Years

Opportunities in the following industry areas:

Desalination systems, waste-brine treatment

Relevant to the following Explorer Technology Areas:

Colorimetric Assay for Authentication of Food

Why is this topic significant?

The needs for food authentication and for tracking of unsafe and fraudulent food drive widespread demand for tools that can profile, tag, and track food ingredients. Recent research reveals a low-cost and rapid colorimetric assay for establishing the authenticity of food products.

Description

Researchers at the Istituto Italiano di Tecnologia, Genoa, and the University of Milano-Bicocca developed a colorimetric assay that enables naked-eye authentication of food content. The assay—NanoTracer—contains gold nanoparticles functionalized with a universal and short sequence of primers. NanoTracer is a simple version of DNA bar coding, which identifies an organism by a specific sequence of mitochondrial DNA—the "barcode." The researchers developed the short sequence of primers to be capable of analyzing all eukaryotes.

When a sample of DNA sequence matches the sequence of the short primers, the NanoTracer amplifies the respective DNA sequence using a polymerase-chain-reaction process. The gold nanoparticles then aggregate, leading to a color change from red to violet. The researchers used their assay to identify the presence of substitutes and diluents in European perch and saffron powder. The assay is somewhat fast (taking less than three hours to complete) and sensitive, and it has low operational costs.

Implications

Using DNA bar coding to identify fraudulent or unsafe food is both labor and cost intensive, because the technology requires complex and expensive tools, extensive operational times, and skilled personnel. Typically, DNA bar coding uses sequence libraries to compare and identify mitochondrial DNA information. Such sequence libraries are scarce for some eukaryote groups. In recent years, research organizations in 25 countries have invested $150 million to advance DNA bar coding and build up a library of DNA information of more than 500,000 species and 5 million individual eukaryotes. Growing sequence libraries may help scientists and food manufacturers to lower the number of occurrences of mislabeled food products.

A key benefit of the NanoTracer is that it uses a universal DNA sequence. The universality of the sequence enables scientists to identify comprehensive DNA information from various eukaryote species—even for samples with low concentrations of DNA or with degraded DNA, such as the DNA in processed foods. Another key benefit of the NanoTracer is that it uses functionalized gold nanoparticles to trigger a color change. Such an assay is essential for rapidly distinguishing between safe and unsafe food with the naked eye.

Impacts/Disruptions

DNA-bar-coding tools such as NanoTracer may appeal to food manufacturers that want to protect consumers from harmful food products. Similarly, because it is easy to use by untrained personnel, supermarkets may adopt the assay to reveal mislabeled food and to safeguard high-value food. Opportunities also exist for food manufacturers to use NanoTracer to detect food prohibited for religious reasons—such as non-halal food—in food products. Outside the food-and-drink industry, the technology may improve environmental monitoring and help scientists evaluate the environmental impacts of human activities.

With sufficient investment, NanoTracer could become commercially available in the next five to ten years. If so, the technology is likely to impact the market for DNA bar coding—as long as it can overcome competition from existing commercial DNA-sequencing assays—for which the costs continue to decline rapidly.

Scale of Impact

  • Low
  • Medium
  • High
The scale of impact for this topic is: Medium

Time of Impact

  • Now
  • 5 Years
  • 10 Years
  • 15 Years
The time of impact for this topic is: 5 Years to 10 Years

Opportunities in the following industry areas:

DNA sequencing, food and drink, agriculture, quality control, process management

Relevant to the following Explorer Technology Areas: