Question: What is the latest in Water purification?

Nanotechnology for water purification









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Nanotechnology and Nanomaterials commercialized for water purification
Water is the most essential element to every life on this Earth. It’s a substance composed of the chemical elements hydrogen and oxygen. Water has always played a prominent role in human civilization. A sufficient supply of safe drinking water is one of the important requirement for a healthy life, but waterborne diseases plays a deadly role in creating large numbers of deaths in many parts of the world. All living things require water to grow and reproduce their own kind. Water is a tasteless and odorless liquid at room temperature. Water is the only substance that occurs naturally as a solid in the form of ice, a liquid and a gas which is in the form of water vapor. Water covers 71% of the entire Earth surface. The amount of water in this world isn't diminishing, but the demand is steadily increasing. Scientists believe that the world's population, will double by 2050. In addition to this, the amount of fresh water that is clean and safe to drink is steadily decreasing because of pollutants. So, people are in need of drinking water in its purest form. There are plenty of water purifiers available in the market which use different techniques like boiling, filtration, distillation, chlorination, sedimentation and oxidation. Currently nanotechnology plays a vital role in water purification techniques. In nanotechnology, nano membranes are used with the purpose of softening the water and removal of contaminants such as physical, biological and chemical contaminants. There are variety of techniques in nanotechnology which uses nano particles for providing safe drinking water with a high level of effectiveness. Some techniques have become commercialized.
For better water purification or treatment processes nanotechnology is preferred. Many different types of nanomaterials or nanoparticles are used in water treatment processes. Nanotechnology holds great promise in remediation, desalination, filtration, purification and water treatment.
The main features that make nanoparticles effective for water treatment are 
More surface area
Small volume
The higher the surface area and volume, the particles become stronger, more stable and durable
Materials may change electrical, optical, physical, chemical, or biological properties at the nano level
Makes chemical and biological reactions easier
Water Purifiers using nanotechnology
Lifesaver Bottle

This LifeSaver Bottle is designed so that it is very simple for its user to get clean water. It's a microbiological water filter that uses nanotechnology to filter out bacteria, viruses, cysts and parasites from contaminated water sources. Based on recommendations of the U.S. Environmental Protection Agency (EPA) It filters out bacteria to a minimum level of Log 6 (99.9999%), cysts to a minimum level of Log 3 (99.9%) and viruses to a minimum level of Log 4 (99.99%) as specified by NSF Protocol 231. It can be used to Collect water from the source we want and then the bottom of the bottle is uncapped in order to fill it up.  The bottle consists of a pump at its bottom. So, once the bottle is full, it should be tightly closed and then pumped.  The pressure that builds up by pumping will make the water to pass through the filter by purifying it.The bottle's interchangeable filter can purify between 4,000 and 6,000 litres, but once it stops working, the filter should be replaced. It filters out objects bigger than 15nm, including viruses, bacteria etc. For 0.71 litres of water to be filtered, 20sec is all it takes. Soldiers use this Lifesaver bottle for drinking water. With a capacity of 750ml and a filter life of up to 6,000 litres, this advanced personal purifier will ensure us to have fresh, pure water when we need it. The principle of a lifesaver bottle is a nanofiltration technology. This is highly effective against all forms of pathogen as well as suspended particles. It is effective against bacteria to a minimum of 99.999% removal and viruses up to 99.99%.[1]
Lifesaver Jerrycan

Lifesaver Jerrycan is a portable water purification system. It is commonly used for storage and purification purpose. The capacity of lifesaver jerrycan is 18.5L. It can process up to 10,000-20,000L. It can filter out particle up to 0.015 microns. The minimum and maximum operating temperature is about 32°F and 140°F. The minimum and maximum storage temperature is 14°F and 140°F. The initial flow rate is 2 l/min. Molecular weight cutoff is 200 KDa. The largest version of lifesaver bottle is called as lifesaver jerrycan. It consists of an air pump that creates pressure inside the can so that the water enters through the filtration membrane and gets filtered. Dirty water is carried inside the can itself while the filtered water is obtained from the filtered spout. Activated carbon filter removes chlorine, bad odour and taste. It also removes heavy metals, medical residues and chemical pesticides that include pesticides endocrine disrupting compounds. It also removes suspended particle in the water. The main purpose of lifesaver jerrycan is to remove the biological impurities. It includes the removal of bacteria, viruses, parasites and various forms of cysts. It can remove viruses greater than 99.999% (log 4) and cysts up to 99.99% (log 3).Here the bacteria reduction is greater than 99.999995% (log 7.5).One jerrycan filter can provide water for four people over a three-year span[2]
Lifesaver Cube

Life Saver cube is a novel and portable water purifier which filters the contaminated water and provides clean water instantly and thus making it fit for drinking purpose. It is predominantly used as a household water purifier. It consists of a cube of 5 litre capacity and dirty water can be stored inside the cube. Also, there is an internal membrane through which the dirty water is forced to pass through it, in order to remove the contaminants present in it. The contaminants may be bacteria, viruses or some other pathogens. The pore size of the membrane filter is 15nm and it can remove the biological contaminants efficiently and provide clean drinking water. This means that the filter is capable of removing 99.9% contaminants. The pressure necessary for forcing the water through the nano filter membrane is provided by a small pump. The weight of the Life Saver Cube is 1.2kg which makes it easy to transport or carry the system from one place to another and hence forth clean water can be obtained anywhere, anytime. This can be used to filter nearly 5,000 litres of dirty water in its lifetime and the flow rate of the filter is 1 litre/minute.[3]
Nanoceram

Nanoceram family of pleated filter cartridges are another type of sediment filters. They are designed in such a way that it could satisfy the difficulties in water treatment. When multilayer is used, it is capable of retaining 99.9999% of microbes (includes viruses, bacteria, and protozoa which are cryptosporidium, Giardia intestinalis, Legionella pseudomonas, salmonella, E.coli, Mycobacteria, Aspergillus, Endotoxins and DNA, all at flow rates hundreds of times greater than virus rated ultrafiltration membrane. The water turbidity which comes through the nanoceram media remains below 0.01NTU. Nanoceram filters use a highly electropositive filter media that absorbs particles quickly even it is too small. Each nanoceram electropositive water filter has a high capacity for particles ranging from tens of microns to few nanometers. The main advantage of this filter is that it uses a media for adsorptive removal process that has 42,000 square meters of nanofiber surface area per square meter of filter media of loading capacity. Sub-micron particles are electronegative due to the double layer effect. At a pH of 7.2, this particles are attracted due to the high zeta potential between the particle or hydrocarbon droplet and the media.[4]
NanoH2O

Desalination is a viable solution for a water scarcity. But it has economical effect in society. So, we need a cost-effective alternative method for desalination. Nano H2O is next level of reverse osmosis (RO) and membrane technology. And also it is one of the cost-effective technique. The University of California discovers a lot of these membrane technologies. In recent days Nano H2O membrane is commercially available in a market. This membrane contains 9 nanoparticles in a non-woven polyester fabric and a layer of porous polysulfone film followed by proprietary Nanocomposite material to form a quantum flux membrane. It increases membrane permeability by 50-100 % over conventional methods. This layer gives higher throughput and best salt rejection. It is folded and packed by a Nanocomposite material and prepared to 4 to 8-inch tube vessel. This technology gives higher flux than the thin film composite so that we get more water with less energy. In quantum flux membrane technology, energy consumption is 20 to 70% less than the other conventional method. For the supply of more water, this technology developed for reverse osmosis with Nano H2o membrane. It produces higher yield with low cost. So, it has high-level customer services in a global network.[5]
Nanocellulose based water purification system

Nanocellulose based renewable material has a combination of high surface area with high material strength. It is chemically inert and possesses versatile hydrophilic surface chemistry. These properties make them a most promising nanomaterial for usage membrane and filter in water purification system to remove bacterial and chemical contaminants from polluted water. It is noted that nanocellulose material has high potential in water purification technology. Different types of nanocellulose materials available for water purification system includes Cellulose nanocrystals (CNC) and Cellulose nanofibrils (CNF). These are the rod-like nanomaterials whose size ranges from 100 to 2000nm with the diameter of 2 to 20nm. Those length and diameter are mostly based on origin and preparation route for the synthesis of nanocellulose. Those nanocellulose materials are used to remove organic pollutants in water such as dyes, oils and pesticides traces present in water. Presently fully biobased membrane using nanocellulose are fabricated which is used to remove metal ions such as Cu2+, Fe2+ etc, sulfates, fluorides and other organic compounds. This bio-based nanocellulose filter has more advantage to conventional filters. Nanocellulose is prepared by various methods such as sulphuric acid hydrolysis and mechanical grinding method. Water purification system is mainly based on the principle of absorption. For the absorption of anionic metal species, the nanocellulose materials are functionalized with a positive charged cationic group. Similarly, for the absorption of cationic metal species, the nanocellulose material is functionalized with the negatively charged anionic group. Nanocellulose based materials have limitation in cost for large-scale production and its specificity. Presently research is based on the synthesis of hybrid nanocellulose material in combination with several other nanomaterials for the improvement of adsorption capacity.[6]
Graphene coated nanofilter

Graphene is chemically dormant, mechanically sturdy, and non-permeable to gas or liquid. So, carbon plays a major role for fabrication of nanomaterials with porous nature. Graphene membranes that are formed by graphene oxide molecules or chemically converted graphene that is adhered with 2D nano mediated arrays have the ability to efficiently separate molecules in a gas or in a liquid phase. Graphene-coated nanomembranes are said to be more applicable in water treatment due to its unique properties. Graphene membranes are obtained from vacuum filtration or coating of graphene oxide solution as Graphene oxide sheets. The graphene coated nanofiltration membrane showed a higher water flux range. The graphene embedded with carbon nanotubes to serve as nanofilters is more useful for dye rejection in water effluent, removal of salt ions, and also acts as antifouling agent. Graphene nanofilter membranes possess effective antifouling agent due to its strong bond between graphene sheets and proteins. Also, graphene oxide coated nanofilter membranes helps in dechlorination of water.In addition to this, ultrathin nanofilter coated with graphene is the most potent filter that could be commercialized for water purification. Graphene oxide membranes can be used in various forms such as free, surface modified, and graphene cast in membranes in the range of micro, nano, or ultrafilters. Among which nanofilters is more efficient for water desalination due to its mechanical strength and physiochemical properties of the membrane. Moreover, there are some challenges in fabricating and applying graphene oxide based nanofilters for water desalination. The challenges include mechanical instability if nanofilters are in the form of nanosheets, cost strategy, surface flaws, and assembly.Therefore, there are more scopes in this area of research to be worked on for the betterment of the society.[7]
Electrochemical Carbon nanotube filter

Carbon nanotubes have gained much attention for its use as wastewater and water filter. Carbon nanotube’s mechanical, electrical and chemical properties made it unique and an ideal candidate for research since 1990. Carbon nanotube combined with electrochemistry proved to be the best method for water and wastewater purification. Electrochemistry helps in reducing the fouling rate of the CNT. In case of CNT based ultra-filters modified with electrochemistry, helps in reducing the energy by two folds comparing to an unmodified CNT based filters. Thus electrochemical carbon nanotubes have been developed due to the advanced studies in nanotechnology and electrochemistry. Here the electrochemical activity of the CNT is exploited. Very first electrochemical CNT was developed by P.J.Britto etal and the results were first recognized in 1996. An electrochemical CNT filter contains electrodes and CNT in a systematic setup such that the electrodes can attract the wastes that clog the CNT based on its charges, thus resulting in high efficiency of filtering and extension of the lifetime of the CNT in the process. The electrochemical carbon nanotubes can be easily used for removing amino group based dyes from wastewater. Chen etal first reported the absorption of dyes to the CNT walls by strong covalent bonds. These electrochemical CNT can be typically used for filtering, and recycling wastewater. Currently, there are many unannounced advancements in CNT based electrochemical sensors and these are highly under research to bring its applications into biomedical systems.[8]
Health and safety

See also

Nanostructure
Nanotopography
LifeStraw
Nanofiltration
Tata Swach
Slingshot (water vapor distillation system)
Millbank bag
Nanoremediation
List of nanotechnology applications
Nanomaterials
Nanotechnology
Ultrafiltration
Reverse Osmosis




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