Survive Global Water Shortages
Water is critical to human existence. The lack of a clean water supply not only affects health, but contaminated water from animal and human waste and chemical pollution and runoff is especially harmful. Access to clean water is a bigger problem than hunger in underdeveloped, war-torn, or natural disaster areas. In the United States, drinking water standards have been revised and water treatment methods are being changed to meet stricter contaminant standards. As the planet's population and agriculture needs require greater volumes of potable water, the need for better purification methods have become particularly important. The use of nanomaterials may offer big improvements to existing water purification techniques and materials and may well bring about new ones. They could also supply water treatment and purification in remote areas where electricity is not available.
After the tragedy of Sept. 11, 2001, concern over biological and chemical warfare has led to the development of handheld units with bio- and chemical sensors for the detection of biological germs, chemical or nerve agents, mustard agents, and chemical precursors to protect subways, airports, the water supply, and the population 1.29 .
Yet his manufacturing practices are primitive. Everyone knows that a lot more needs to be done to get closer to nature. For example, no one has reached the efficiency of photosynthesis in storing energy. No one can facilitate energy transfer (or electron transfer) as efficiently as biomolecules. No factory does water purification and storage as efficiently as coconut trees or water melons. The brain of one person can, in principle, store and process more information than today's computer. It is unlikely for any movie camera to capture visuals more vividly than the human eye. The olfactory receptors of the dog are much more sensitive than the sensors we have developed, though single molecule detectors have been reported. Most early warning systems are primitive when compared to the sixth sense
Few studies, however, have investigated the oxidation potential of ZVI. The recently discovered ZVI oxidative process and the further modified process in the presence of ethylenetetraaminediacetic acid (EDTA) are described, and the potential future applications are discussed. The discovered reaction processes can be widely used to treat pesticides, herbicides, and industrial chemicals and purify contaminated water for domestic use. One of the most interesting, and potentially least costly, methods for their degradation involves the use of elemental iron (Fe(0)). While Fe(0) or ZVI has been used principally to degrade contaminants in subsurface environments by placing ZVI barriers across the groundwater flowpath, the possibility also exists of using particulate ZVI, which could be either pumped into a contaminated aquifer or dispersed through contaminated sediments. The focus of the work reported here is on the degradation of agrochemicals, which are widely used worldwide and yet for...
At the same time there is a sector of great economic activity, the construction industry, dealing with coarse components consumed in large amounts seeking necessary innovations. The construction industry is also a great integrator of solutions offered by other industrial sectors i.e. a building integrates water supply, heating, ventilation and communication systems, etc.
To many people, Richard Smalley was the foremost leader in nanotechnol-ogy. He has often been noted as the Father of Nanotechnology. Richard Smalley was a Rice University professor who won the Nobel Prize in chemistry in 1996. Richard Smalley is mostly known for his work with carbon nanotubes, (known as the Buckyballs ). Smalley was hopeful that nanotechnology could solve the global energy problem, which would ultimately solve other worldwide problems such as hunger and water shortages. He believed the potential for nanotechnology to benefit humanity was virtually limitless, and he abided by the mantra Be a scientist save the world.
The feasibility of Fenton's oxidation of methyl ierf-butyl ether (MTBE) using ZVI as the source of catalytic ferrous iron was assessed in a study by Bergendahl and Thies (2004). More than 99 of MTBE-contaminated water was removed at pHs 4 and 7 using a H2O2 MTBE molar ratio of 220 1. Similarly, Lucking et al. (1998) investigated the oxidation of 4-chlorophenol in aqueous solution by hydrogen peroxide in the presence of a variety of additional substrates including iron powder. H2O2 oxidation of 4-chlorophenol in the presence of iron powder proceeded much faster when iron powder was used instead of graphite or activated carbon, presumably via Fenton's oxidation of the 4-chlorophenol. Studies by Tang and Chen (1996) showed the degradation of azo dyes was faster using the H2O2 iron powder system than the Fenton's reagent system, e.g., H2O2 Fe(II). The difference was attributed to the continuous dissolution of Fe(II) from the iron powder and the dye adsorption on the powder.
Wars have been fought, and will continue to be fought, over access and control of clean water. Drinking water has two major classes of contamination biological contamination and chemical contamination. Bacterial contamination can be dealt with by a number of well-established technologies e.g., chlorination, ozone, ultraviolet (UV), etc. , but chemical contamination is a somewhat more challenging target. Organic contaminants, such as pesticides, agricultural chemicals, industrial solvents, and fuels, can be removed by treatment with UV ozone, activated carbon, or plasma technologies. Toxic heavy metals such as mercury, lead, and cadmium can be partially addressed by using traditional sorbent materials such as alumina, but these materials bind metal ions non-specifically and can be saturated with harmless, ubiquitous species such as calcium, magnesium, and zinc (which are actually nutrients, and do not need to be removed). Another weakness of these traditional sorbent...
Clearly, all these toxic metals form a significant threat to the water supplies of the world. How can nanoscience address this problem A chemically specific sorbent material capable of permanently sequestering these toxic metal ions from groundwater supplies is needed to purify contaminated drinking water. Because we consume vast quantities of drinking water every day, the kinetics of heavy metal sorption need to be fast, allowing for high throughput in the process stream. A high binding capacity for the target heavy metal is clearly of value. In addition, as acceptable drinking water contamination limits becomes
X-ray fluorescence coupled with SAMMS SPME enable the rapid detection of trace levels of toxic metals. Table 1 shows the concentration of trace metals in an SPME thiol SAMMS column (15 mg) after only 200 mL of river water (pH 8) spiked with of 1 ppb of selected metals was pumped through at 1mL min. The difference in the preconcentration of the metals in the SPME SAMMS column is a result of the competitive equilibrium processes between the sample solution and monolayer surface. However, the SAMMS SPME clearly preconcentrated all the metals from a level (1 ppb) well below their EPA drinking water limits (listed in the right column) to a range easily measurable by the XRF. Using Cu-EDA SAMMS, we have obtained similar results for the toxic chromate and arsenate anions. The actual limit of detection for metals in environmental samples with this approach will depend upon a number of variables including the target metal, the sample matrix, the type of SAMMS,
Membrane interfaces are unsung heroes of the modern world. They permeate its every aspect, yet they rarely get the spotlight. The basic concept is deceptively simple a membrane barrier allows some molecules to pass through it while stopping others. Membranes provide one of the most energy-efficient ways to separate chemical species on the basis of size, charge or chemical properties. Modern industrial membrane technology, dominated by polymer membranes, is used in applications as diverse as dialysis for kidney patients and the supply of clean drinking water. The market for membranes is worth billions of dollars per year, but there is still plenty of scope for
The herbicide molinate S-ethyl hexahydro-1 H-azepine-1-carbothioate is used extensively to control germinating broad-leaved and grass weeds during rice production. It is a moderately persistent (t 1 2 21 days) (Weber, 1994) and highly soluble (solubility 880 ppm (Hartley and Kidd, 1983)) herbicide that is often detected as a contaminant in rainwater (Charizopoulos and Papadopoulou-Mourkidou, 1999 Sakai, 2003 Suzuki et al., 2003), lakes (Nohara et al., 1997 Sudo et al., 2002), rivers (Cerejeira et al., 2003 Coupe et al., 1998 Crepeau and Kuivila, 2000 Paune et al., 1998), and estuaries (Oros et al., 2003) worldwide. Molinate is one of the most frequently detected pesticides herbicides exceeding drinking water guidelines and guidelines for the protection of aquatic ecosystems in southern Australian irrigation networks and rivers (Australian State of the Environment Committee, 2001). Molinate has a high cancer hazard factor (Gunier et al., 2001 Kelly and Reed, 1996), primarily as a...
Because of its health threat, the EPA has lowered the arsenic standard for drinking water to 10 ppb, a number that can be tough to reach in most water treatment plants. Globally, arsenic poisoning is a huge problem. In the nations of Bangladesh, India, Mexico, Chile, Argentina, Taiwan, and Thailand, an estimated 10 to 40 percent of the population is afflicted with arsenic poisoning. Although arsenic contamination is generally associated with third-world countries, many drinking water supplies in America exceed the recommended 10 ppb level. New technologies that can target and remove heavy metals such as arsenic from drinking water are critical.
Human and livestock pressure on the land has created worsening desertification in China, land of 1.3 billion people, and soil erosion is reducing arable land and affecting water supplies in many other areas of the world. About one third of the world's population lives in nations experiencing water shortages, and the proportion is rising. The recent intensive and comprehensive Millennium Ecosystem Assessment concludes that about 60 per cent of the planet's 'ecosystem services' are being degraded or used unsustainably. It catalogues a destabilizing loss of fish-stocks, forests, mangroves, coral reefs, natural water cycles and so on (Graham-Rowe and Holmes, 2005). The general On the negative side, nanotechnology will cumulatively be appropriated by the existing forces of consumer production, advertising and marketing. Unless there is coordinated scrutiny and regulation, nanotechnologies may be introduced with the old mistake of ignoring or neglecting any potential external costs they may...
One direction being looked at for cleaning water involves production of nanoparticles that use less expensive materials than palladium, the current industry standard. One idea Inject iron nanoparticles into a contaminated body of water, as illustrated in Figure 9-4. The particles would then spread throughout the water, cleaning it in the process. This would be much faster and cheaper than conventional methods that involve pumping the contaminated water out of the ground before treating it.
By 2015, approximately 3 billion people will live in countries where it will be difficult to get enough water for basic needs. More than 1 billion people will lack access to clean drinking water, while others will die from contaminated water. The Environmental Protection Agency (EPA) estimates that at least 500,000 cases of illnesses annually can be attributed to contaminated drinking water in the United States.
TCE can be absorbed through the lungs, mucous membranes, gastrointestinal tract, and the skin. Exposure to TCE happens mostly from breathing contaminated air and drinking contaminated water. Short-term exposure to high levels of this chemical can result in toxic effects on a number of organs and systems, including the liver, kidney, blood, skin, immune system, reproductive system, nervous system, and cardiovascular system. In humans, acute inhalation exposure to TCE causes central nervous system symptoms such as headache, dizziness, nausea, and unconsciousness. TCE has been linked to liver damage, impaired pregnancies, and cancer.
The constant daily pumping operation is costly. Ex situ process can also be tied up in legal and regulatory issues because once the contaminated water is pumped up to the surface you cannot just dump it back on the ground again because it is hazardous waste, so you need to go through regulatory and legal requirements to remove it. The iron wall or permeable reactive barriers (PRBs) has two main characteristics it is in situ and it is passive. In situ means that you apply iron particles by placing them into the ground and treat the contamination there. You do not have to pump the contaminated water up to the surface. The other advantage is that this method is passive. Pump and treat is active because you have to constantly keep the pumps working. Ideally passive technologies mean that once the treatment is in place you can cover it up, plant grass, and then you can leave the area there is nothing else to do.
Discoloration of sugar, air purification, removal of odor or toxic gases, water purification, gas separation, solvent recovery, etc. have been the traditional application areas of porous carbons. Most of these applications are based on the superior adsorption properties. Of course, the pore sizes of the activated carbons are different among the various applications by controlled production of activated carbons. Because the readers may find a suitable book for activated carbons that describes these historical usages of the activated carbons 132 , we will review contemporary applications of porous carbons.
Chiefly related to the absorption of nanoparticles by the human body and their distribution as well as the risk of accumulation in organs. It is also unknown, as to how the human (and animal) metabolism will react to the intake of nano-engineered food and nanoparticles, which once introduced in the ecosystem, will enter the food chain. This necessitates research into the possible negative impacts of bio-nanotech, and transparency in the results in view of the credibility and plausibility of green nanotechnology. However, recent results obtained suggest that the benefits far outweigh the risks (e.g., applied nanotech techniques for water purification systems).
As an example of federal laboratory activities, consider technology transfer efforts at one of the leading nanotechnology laboratories at NASA Ames Research Center. The research focus at NASA Ames is on nanomaterials such as carbon nanotubes, inorganic nanowires, conducting organic molecules, and protein nanotubes. The applications focus for these nanomaterials is diverse nanoelectronics, computing, data storage, nanoscale lasers, chemical sensors and biosensors, ultraviolet and infrared detectors, and advanced life-support systems that address waste remediation, air purification, and water purification as well as instrumentation for planetary exploration and astronaut health monitoring devices.
Liquid-solid and gas-solid are two representative heterogeneous photocatalysis reactions for pollutant remediation in water and air, respectively. Vast amounts of photocatalysis research have dealt with the liquid phase 2, 5, 7 , with relatively less work carried out on gas-phase systems 7, 140145 . For gas-phase reactions, O2, which is adsorbed with H2O molecules on the catalyst surface, can largely improve the oxidation reaction. Although O2 molecules are not only electron scavengers but also the main radicals with oxygen-derived formations ( O- and HO2, etc.) that oxidize organic molecules, the existence of O2 alone is found to be inefficient for oxidation. H2O is necessary to improve photooxi-dation reactions in gas-phase systems. The role of H2O in the gas-phase reaction is complicated and still not very clear. Fourier transform infrared studies revealed that the photodegradation rate of 4-CP was dramatically enhanced in the presence of water, but the action of water was not...
Are there any risks in using iron nanoparticles for groundwater remediation and if so what would some of these risks be
Different situations pose different risks. If you are in the business of manufacturing these particles then you have occupational health issues that you need to worry about. However, once you inject these particles into the ground for remediation there is very little chance that anyone will be exposed to those iron particles. It is quite clear that these particles are not very mobile in groundwater because they tend to stick onto anything available for them to attach to. A general rule is once you inject these particles into the ground they may move only a few feet from where you have injected them. So there is little likelihood that the nanoparticles will show up in the neighbor's drinking water well that is 300 feet away.
Poly(s-caprolactone) (PCL) is another biodegradable polymer that has been used to encapsulate hydrophobic drugs. Using this polymer, nanoparticles were prepared by solvent displacement in an acetone-water system in the presence of Pluronic . The solvent displacement technique used for the preparation of PCL nanoparticles facilitates instant adsorption of PPO-PEO groups when the organic solution of the polymer is introduced into aqueous solution containing the stabilizer.51 In addition, it also favors the encapsulation of hydrophobic drugs such as tamoxifen that could be dissolved along with the polymer in the organic phase, resulting in a high entrapment efficiency of greater than 90 at loading levels of 20 of the weight of the drug. The intracellular uptake of these nanoparticles in MCF-7 estrogen receptor-positive breast cancer cells and MDA-MB231 human breast adenocarcinoma cells was monitored at different time points using tritiated 3H -tamoxifen. The results showed that the cell...
The second subset of the challenge to develop instruments to assess exposure to engineered nanomaterials is to develop instruments that can track the release, concentration and transformation of engineered nanoparticles in water systems 41 . Measurements of natural nanoparticles in environmental waters have been reported by a variety of techniques, but there are few reports at this time of field studies designed to detect engineered nanoparticles
The Environmental Protection Agency was created in 1970 and was established in response to growing public concern about unhealthy air, polluted rivers and groundwater, unsafe drinking water, endangered species, and hazardous waste disposal. The agency's mission is to protect public health and to safeguard the natural environment air, water, and land upon which human life depends. Its areas of responsibility include control of air pollution and water pollution, solid waste management, protection of the drinking water supply, and pesticide regulation. The EPA is aware that
Generally, nanoparticles do not move very far, in fact they do not move far enough. You want the nanoparticles to move farther. Researchers are working on ways to make nanoparticles go farther, but if they get too good at this the particles might move to places we don't want them (drinking water supplies, for example). So, we need to do more research to try to figure out if this PRB process poses a potential problem.
Role of Fullerenelike Structures in the Reactivity of Shungite Carbon as Used in New Materials with Advanced Properties
The work highlights a source of unusual high reactivity of shungite carbon (ShC) as a catalyst in modeling coal-treatment reactions, a filler for polymeric matrices, an adsorbent and filter for a water-purification process, and a reagent in melting of siliceous iron and in the production of silica carbide. The structural pattern of ShC was shown to be connected with fullerene-like structures which could be released under different conditions, providing its activation and determining reactivity of ShC containing materials. Fullerenes are likely to be present in ShC as chemical derivatives and strong molecular complexes. It was proposed to liberate fullerenes and fullerene-like structures while processing the ShC. Artificial fullerenes display an effect similar to that of ShC in modeling the reaction of coal treatment. Fullerene-like structures, both synthetic and those liberated from natural carbon, are capable of acting as a hydro-genated catalyst at low temperatures. Owing to the...
Numerous nanomaterials are in various stages of research and development, each possessing unique functionalities that are potentially applicable to the remediation of polluted industrial wastewater, groundwater, surface water, and drinking-water. The main goal of most of this research is to develop cheap and environmentally friendly materials for removal of heavy metals from water. One example is a novel, low-cost magnetic sorbent material for the removal of heavy metal ions from water, developed by scientists in China, who coated iron oxide magnetic nanoparticles (Fe3O4, magnetite) with humic acid (HA). The coating greatly enhanced material stability and heavy metal removal efficiency of the nanoparticles.
The mixture flows through modules, where it passes along the membranes. The component to be removed is vaporized through the membranes and collected at very low pressure in a vacuum vessel. It is then condensed and purged out. A vacuum pump extracts the noncondensables and maintains the required vacuum. This vaporization cools down the processed mixture, which must be reheated to maintain the highest flux through membranes. Main applications are wine and beer dealcoholization, removal of organic solvents from aqueous streams, aroma recovery and concentration, and waste water purification.
The feasibility of bioremediation depends on the specific contaminant and its suitability as a substrate for microbial degradation. The planned future use of the site is also an important consideration (Arthur and Coats, 1998). Detailed site characterization and preliminary feasibility studies are required for the design and optimization of any biostimulation approach. Remediation also depends on the site-specific nature of each contaminated matrix (Zablotowicz et al., 1998). A bioactive soil barrier technique, known as the Filter technique, which combines the use of contaminated water with filtration through the soil to a subsurface drainage, has been found to reduce pesticide loads by up to 99 (Jayawardane et al., 2001). However, field studies have shown that the concentration of pesticides in the discharge, particularly mobile ones such as molinate, are often found above accepted environmental limits (Biswas et al., 2000).
On the negative side, nanotechnology will cumulatively be appropriated by the existing forces of consumer production, advertising and marketing. For example, if nanotechniques are incorporated into existing built-in obsolescence (or 'disposable') consumer goods, then there is no real advance. Such techniques will simply be grafted onto current consumption patterns, possibly consolidating and deepening them. Thus major development efforts in nano-technological applications at the moment (such as nano-encapsulation techniques) include cosmetics, skin creams and perfumes. Here, one may readily understand the socio-economic context in which nanotechnology is emerging if one makes some comparisons. Recent reports on annual expenditure on make-up show that about US 18 billion is being spent, while a reasonable estimate of the cost of eliminating global hunger and malnutrition is about US 19 billion needed in additional annual investment. Similarly, US 15 billion goes annually on perfumes,...
Safe Drinking Water Among the numerous possible applications of nanotechnology, the most widespread impact as far as the developing world is concerned may be in the area of water purification. Access to safe drinking water is one of the major concerns in the developing world since almost half of the world population has no access to safe drinking water and basic sanitation. Water purification systems, equipped with nanomaterials and using new kinds of membrane technologies with variable pore sizes as filters, could provide people in any area with safe drinking water. These are easy in application and maintenance, and are already available in the market the forward-osmosis membrane technology of Hydration Technologies (Ref. 19) is one technique utilising nanotechnology. Thus a combination of nanotechnologies will be useful in providing safe drinking water through cost-effective measures, which will be less dependent on energy resources. Although the product is currently marketed only...
Nanotechnology has tremendous potential to improve human health and the environment however, it could also have unintended impacts. The ability of nanoparticles ability to penetrate into living cells could be exploited to produce a new drug, or it could result in toxicity. Nanomaterials could be used to produce cheap, energy efficient filters that improve drinking water quality, or they could become environmental contaminants. Given the breadth of materials and devices that fall under the broad umbrella of nanotechnology, all of these outcomes may result to one extent or another. Despite the massive amount of money that supports nanotechnology research and development, for example the development of new applications, little research has been done on potential implications. The National Science Foundation signalled its support of implications research in 2001 by funding the Center for Biological and Environmental Nanotechnology (CBEN) at Rice University, whose mission is to develop...
In recent years, drinking water regulations have continued to lower the maximum contaminant level (MCL) for pollutants. For instance, in 2002, the World Health Organization (WHO) decided to reduce the arsenic standard for drinking water from 50 g L to 10 g L. The stiffening of regulations generates strong demands to improve methods for removing pollutants from the water and controlling water-treatment residuals. Currently, a wide range of physico-chemical and biological methods are used and studied for the removal of organic and or inorganic contaminants from polluted waters (Sheoran and Sheoran, 2006). Coagulation-flocculation, membrane processes, and adsorption are the most common methods of contaminant removal. The most efficient and low cost process for the removal of colloids and organics in water treatment is the use of inorganic salts as coagulation-flocculation agents such as Al13 (Bottero et al., 1980 Bottero et al., 1982) and Fe24 (Bottero et al., 1993 Bottero et al., 1994)...
Developing near-term commercially viable products is of vital importance for the development of the nanofield. Near-term opportunities of nanomaterials lie in functional nano-materials such as tougher and harder cutting tools, the superplasticity of ceramics during processing, high performance parts for the aerospace and the building industry, energy and filter technologies (novel solar cells and water purification), the automobile industry, optical and catalytic applications, and sensors. On a longer term, and dependent on the developments in the electronic industry, (opto)electronic applications of nanomaterials such as photonics may find a big market. Interdisciplinary cooperation in research and development is important for the realization of scientific breakthroughs and for new products such as hybrid coatings or nanoelectronic devices. Currently, the preparation technology of nanomaterials plays an important
Finally, there is an information deficit on the degree humans will be exposed to different nanomaterials. The most hazardous chemicals may not have toxic effects if the exposure is minimal, and relatively inert chemicals may be highly toxic at certain levels.56 Chemicals can enter the human body through oral ingestion, inhalation, or dermal absorption. Direct exposure involves nanomaterials entering humans during manufacturing or life cycles of the products in which they are used. An example of direct exposure would be workers at manufacturing plants inhaling carbon nanotubes. It is difficult to estimate direct exposure levels. Even when nanomaterials enter the environment, they may not form respirable particles. For example, two recent exposure assessment studies found that individuals working with nanotubes are exposed to very low levels of nanotube dust.57 Indirect exposure to nano-materials would take place if nanomaterials got into the water supply or food chain. There are also...
Silver has long been recognized as an antibacterial agent. Cyrus the Great, King of Persia, reportedly kept water fresh in the sixth century B .C . by boiling the water and then storing it in silver flagons 19 . Pliny the Elder, writing in 78 A . D . , said that silver slag has healing properties as an ingredient in plasters, being extremely effective in causing wounds to close up. In modern time, silver has been used to purify drinking water, sanitize swimming pools, and prevent sepsis in wounds 17, 18 . Silver's antibacterial function results from its ability to disturb the multiplication function of bacteria 17
The integration of nanocatalysts into water treatment provides improved options. Nanocatalysts are substances materials with catalytic properties that have at least one nanoscale dimension. Since their greater surface area provides more contact with reactants, they are more efficient than larger materials. These materials could be used in specific applications where contaminated groundwater is already being treated. Nanocatalysts could be activated by common water purification methods, used as treatment additives, and recovered by nanomembranes. Figure 7-2 shows a portion of a nanostructured membrane created from particle templating.
Although nanofiltration membranes are important in water purification, nanoparti-cles either in solution or attached to membranes can help ensure that pollutants chemically degrade and don't just travel somewhere else. Nanocatalysts are currently being studied for their environmental applications. Catalytic treatments can lower polluted water treatment costs by making it possible for purification methods to be specifically designed to treat chemicals at a particular site.
Scientists have known for centuries that material properties depend just as much on processing conditions as on chemical composition. Now Accelrys' MesoDyn code provides a method to predict micro-phase separation in complex liquids in externally applied flow fields. The strong effect of the applied flow on structure is demostrated in a study by researchers at University of Groningen who used the MesoDyn mesoscale modeling code to calculate the global ordering effects in polymer melts and solutions under simple steady shear. Both for a model system of A-B diblock copolymers and for the hexagonal phase of the specific Pluronic L64-water system, the experimentally observed most stable phase was found.
Pressure-driven filtration by porous membranes is widely used in the production of drinking water from ground and surface water1-3. Permeation theory predicts that filtration rate is proportional to the pressure difference across the filtration membrane and inversely proportional to the thickness of the membrane4. However, these membranes need to be able to withstand high water fluxes and pressures, which means that the active separation layers in commercial filtration systems typically have a thickness of a few tens to several hundreds of nanometres5. Filtration performance might be improved by the use of ultrathin porous silicon membranes6 or carbon nanotubes immobilized in silicon nitride7 or polymer films8,9, but these structures are difficult to fabricate. Here, we report a new type of filtration membrane made of crosslinked proteins that are mechanically robust and contain channels with diameters of less than 2.2 nm. We find that a 60-nm-thick membrane can concentrate aqueous...
The element arsenic is a steel grey metal-like material. Arsenic is a natural part of our environment and widely distributed in Earth's crust. So living organisms are often exposed to some amount of it. Very low levels of it are always present in soil, water, food, and air. Most arsenic compounds have no smell or special taste, even when present in drinking water. Arsenic has been used in pesticides, poisons, chicken-feed supplements, and wood preservatives. However, the naturally occurring arsenic in the soil can make the water toxic to humans.
Scientists are now developing strategies to clean up the arsenic, a carcinogen, in the water. Scientists at Rice University's Center for Biological and Environmental Nanotechnology (CBEN) have developed a low-cost technology for cleaning arsenic from drinking water. The technology holds promise for millions of people not only in India but also in Bangladesh and in other developing countries where thousands of cases of arsenic poisoning are linked to poisoned wells each year.
On a more f1undamental level, such a smart device could have a tremendous impact on the most disadvantaged people around the world, those who lack clean drinking water, adequate food supplies, and so on. Despite the lack of physical infrastructure like telephone cables, wireless Communicator technology could offer them the world of information in a form they can immediately use. Such knowledge will improve their agricultural production, health, nutrition, and economic status. No longer isolated from the global economic and cultural system, they will become full and valued participants.
Contamination of water and soil with agrochemicals is a global environmental problem. Pesticide residues have been detected in various natural waters in many countries and the presence of agrochemicals in drinking water supplies is of particular concern. It is an emerging problem in developing countries, and there is a genuine need for efficient and cost-effective remedial technologies. Thus, the
The strong dependence of the SPR absorption band on the degree of aggregation of gold nanoparticles has also been exploited to detect heavy metals. Various metal ions like zinc, manganese, nickel, lead, cadmium, and mercury may be present in water at parts per million concentrations or higher. Some of these are toxic metal ions that pose significant public health hazards when present in drinking water. For absolute identification and total concentration assessment, ion-coupled-plasma spectroscopy is commonly used as a characterization method. However, more efficient detection can be implemented using colloidal gold.
The greenhouse effect covers a wide range of effects that result from the warming of the earth's atmosphere. Among these are not only the rising mean sea level, but also the increase in extreme climatic weather conditions such as hurricanes, storm floods, catastrophic drought, etc. Changes in the composition and the range of flora and fauna are also already being looked at.
The simplest method to introduce ligands is by blending ligand molecules into the polymer solution and then electrospinning the polymer solution. For example, an attempt 35 was made to incorporate chemically modified p-CD onto the surface of the nanofiber to target potential applications in organic waste treatment for water purification. Phenylcarbomylated or azido phenylcarbomy-lated p-CD was successfully blended with polymethyl methacrylate (PMMA) and electrospun into nanofibrous membrane, respectively. The presence of the p-CD derivatives on the surface of the nanofibers was confirmed by attenuated total reflectance fourier transform infrared spectrometry (ATR-FTIR) and X-ray photo-electron spectroscopy (XPS). To determine the functionalized membranes' ability to capture small organic molecules, a solution containing phenolphthalein (PHP), a small organic molecule, was used. Results obtained showed that the functional-ized nanofibrous membranes were able to capture the PHP...
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