Water treatment is important for human consumption and environmental protection. Non-trivial purification of water involves removal of toxic ions, organic impurities, microbes and their by-products as well as scooping oil spills. The removal of organic contaminants from water is a major industrial concern. The challenging goal here is to detect, decompose and remove contaminants present usually in low concentrations. Towards this end, different types of sorbent materials have been developed to date, the most common being activated carbon. Though the use of activated carbon is still considered to be one of the best method, the disposal of adsorbed contaminants along with the adsorbent is a major concern. Researchers in India have recently come up with an innovative method for organic pollutant removal from waste water.
Several manufacturers are incorporating nano-sized particles of silver into, among other things, garments like socks and shirts to kill bacteria that cause odor. But does the silver stay in the socks or T-shirts? And what happens to it if it washes out? Also, what is the climate footprint of producing the required nanosilver? To answer these questions, a group of researchers have performed a cradle-to-grave life cycle assessment to compare nanosilver T-shirts with conventional T-shirts with and without biocidal treatment. For their assessment, the team used conventional T-shirts treated with triclosan, a commonly applied biocide to prevent textiles from emitting undesirable odors. The results show significant differences in environmental burdens between nanoparticle production technologies.
In the wake of the BP oil spill in the Gulf of Mexico we published a general overview of the wide variety of nanomaterials and nanotechnologies that offer significant promise for oil spill cleanup and recovery. One problem with many existing solutions though is that they are one-offs, i.e. one they absorb oil they can't be re-used and need to be disposed of (which could in turn create secondary pollution effects). Ideally, any oil absorbent material used during ocean oil spills should be reusable and with special wettability that could controllably capture and release oil pollution repeatedly. Addressing this issue, researchers have now created an underwater water/solid interface inspired by fish scales. The surface of this new material shows superamphiphobicity in air and superoleophilicity under water, allowing it to be repeatedly used to capture and collect oil droplets in water.
There is a general perception that nanotechnologies will have a significant impact on developing 'green' and 'clean' technologies with considerable environmental benefits. However, the environmental footprint created by today's nanomanufacturing technologies are conflicting with the general perception that nanotechnology environmentally benign. It actually appears that certain nanomaterial production technologies are quite dirty and also have a considerable energy footprint. Determining the full environmental impact of nanomaterials requires a full life cycle assessment. A recent paper takes a look at the material and energy intensity of fullerene production. It finds that the embodied energy of all fullerenes are an order of magnitude higher than most common chemicals.
The recent oil spill in the Gulf of Mexico is widely acknowledged to be among the worst ocean oil spills in world history. Inevitably, the spill has once again raised serious concerns worldwide about the likely environmental impact of such catastrophic oil spills caused by oil tanker accidents at sea or mishaps during loading and unloading of oil from tankers at seaports. Numerous solutions have been proposed for dealing with the problem of oil spills. Conventional techniques are not adequate to solve the problem of massive oil spills. In recent years, nanotechnology has emerged as a potential source of novel solutions to many of the world's outstanding problems. Although the application of nanotechnology for oil spill cleanup is still in its nascent stage, there has been particularly growing interest in exploring ways of finding suitable solutions to clean up oil spills through use of nanomaterials.
Global warming, caused by a build-up of greenhouse gases, in particular carbon dioxide, in the atmosphere, has led to numerous proposals on how to capture and store CO2 in order to mitigate the damaging emissions from fossil fuels. Today we take a look at carbon sequestration and subsequent storage in geological formations (geosequestration) - a proposal that is already being tested on a large scale. The idea behind coal-bed geosequestration is that you inject a huge amount of carbon dioxide into deep unmined coal seams. Due to strong adsorption forces, the carbon dioxide will be adsorbed in coal. It will not be desorbed and gradually transform to solid rocks. Moreover the technology is already developed and in use for oil and gas mining. However, the fundamental problem is so-called adsorption-induced deformation of coal or any other porous material.
Friends of the Earth have just published a new report titled 'Nanotechnology, climate and energy: over-heated promises and hot air?' As usual, the 'good cop, bad cop' team that writes this kind of document was at its best again. On one hand, there is a lot of really good information in this report, well researched and referenced, and it provides a very useful overview of what's going on in nanotechnology research and development in the climate/renewables fields - albeit with a very negative spin on it. On the other hand, there seems to be a monkey sitting on each FoE editor's shoulder that constantly whispers 'Are you kidding me? Boooring! Too positive! Too balanced! Not scary enough! Traitor - think of all the drowning polar bears!' We look at some of the misconceptions in FoE's report.
A relatively new method of purifying brackish water is capacitive deionization (CDI) technology. The advantages of CDI are that it has no secondary pollution, is cost-effective and energy efficient. The basic concept of CDI, as well as electrosorption, is to force charged ions toward oppositely polarized electrodes through imposing a direct electric field: brackish water flows between pairs of high surface area carbon electrodes that are held at a potential difference of about 1-2 volts. The ions and other charged particles, such as microorganisms, are attracted to and held on the electrode of opposite charge. A research team has now developed a CDI application that uses graphene-like nanoflakes as electrodes for capacitive deionization. They found that the graphene electrodes resulted in a better CDI performance than the conventionally used activated carbon materials.