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Malachite green is a N-methylated diaminotriphenylmethane dye, which belongs to triphenyl methane class and it contains two amino groups, and is water soluble. It is widely used for the dyeing of leather, cotton, wool and silk, distilleries, jute, paper, as a food-coloring agent, food additive, and in fish industries. It is also used as fungicide and as antiseptic, on the wounds and ulcers. However, its oral consumption is hazardous and carcinogenic. It is highly toxic in nature and when discharged, it mixes with neighboring water receiving bodies, will affect aquatic life ecosystem .Hence adsorption, a high efficient cost effective method is to be employed to remove this toxic dye from wastewater before it released into aquatic environment. Different adsorbents have been carried out for the removal of Malachite Green. Adsorbents include clay based such as HNT, montmorillonite and bentonite , activated carbon based such as acid activated carbon, bamboo based activated carbon, palm flower activated carbon, rubber seed coat based activated carbon, rice husk based activated carbon, sawdust such as neem sawdust and rattan sawdust, waste such as ginger waste, solid agriculture waste and agriculture waste such as Tamarix aphylla leaves, Oil Palm Trunk Fiber, fiber such as waste newspaper fiber and wood fiber, carbon based such as carbon prepared from borrassus bark, mesoporous carbon and coal based such as Akash kinari coal and fly ash.
Despite MG is useful for dyeing silk, leather, cotton, paper, as a medical disinfectant, and as an antiseptic and fungicidal ,it has certain toxic properties, and poses several risk to consumers[1-2]. It also has mutagenic, carcinogenic, and genotoxic characteristics [3-6]. MG when discharged into receiving streams will affect the aquatic life and causes detrimental effects in liver, gill, kidney, intestine, gonads and pituitary gonadotrophic cells . It causes sinusoidal congestion and focal necrosis in liver, damages mitochondria and also causes nuclear alterations .
There is a significant health risk to humans who eat fishes grown in contaminated water having Malachite green dyes and also causes irritation, redness and pain .
When it was inhaled or ingested by human, it may cause irritation to the gastrointestinal tract.
It is highly toxic to flora and fauna. Therefore, it is mandatory to establish an effective method for the removal of this toxic dye MG from water and solutions. Adsorption process has been employed widely for biochemical, chemical, environmental recovery and purification applications . So for performing this process, various adsorbent materials such as bentonite , montmorillonite , halloysite nanotubes, activated carbon, waste, sawdust, coal and flyash have been utilized, and discussed below for the removal of this dye by adsorption.
Montmorillonite clay when used as adsorbent, it shows 95% removal efficiency. The adsorption data were fitted on Langmuir, Freundlich adsorption isotherm equations. But when halloysite nanotubes employed as a adsorbent , the maximum adsorption capacity of 99.6Â mgÂ gâˆ’1 of MG was achieved in pHÂ =Â 9.5.
Adsorption of MG dye onto acid activated carbon was studied by using batch technique and it was observed that more than 84% of dye removal was achieved by using 0.025 g of zea mays dust carbon. Almost 92% removal of dye was observed at pH of 9.0. The adsorption data seems to follow both Langmuir and Freundlich isotherms.
And when chemically prepared activated carbon derived from Borassus aethiopum flower was used as adsorbent and when its carbon dosage increased from 0.001 g/10mLto 0.5 g/10 mL, it was observed that, for 100Î¼m, 600Î¼m and 1000Î¼m particle size, the % adsorption varied from 83 to 99, 33 to 99 and 31 to 98 respectively. Maximum adsorption occurred at the pH range from 6.0 to 8.0.Here Langmuir isotherm model was found to fit best the adsorption data.
The removal % is found to increase from 93.75 to 94.91% by decreasing the initial concentration from 100 to 60 mg/l, when rice husk based activated carbon is used as adsorbent. Equilibrium data were fitted to both Freundlich and Langmuir isotherm equations.
When carbon prepared from borassus bark activated by sulphuric acid is used as an adsorbent, the uptake of MG ions was minimum at pH 7.5 and maximum at pH 5.75. However, when the pH of the solution was increased (more than pH 7), the uptake of malachite green ions was increased . On the other hand, adsorption onto mesoporous carbon resulted in more than 99% removal at the optimum pH value of 8.5. The experimental data correlated reasonably well by the Langmuir and Freundlich adsorption isotherms in the case of borassus bark activated carbon as adsorbent while Langmuir equation showed higher conformity than Freundlich equation in the case of mesoporous carbon as adsorbent.
Different adsorbent materials :-
Clay based adsorbents:-
Clay is a combination of one or more clay minerals with traces of metal oxides and organic matter. Clay minerals are typically formed by the gradual chemical weathering of rocks over long periods of time. An important property of the clays is that the layers are negatively charged and this negative charge is normally balanced by hydrated cations placed in the interlayer spaces. Cationic dyes, can be attracted toward the anionic layers and are, therefore, quite suitable for investigating the properties of these minerals in aqueous suspensions. Clays when mixed with water exhibits plasticity in certain proportions. When dry, it becomes firm and when fired in a kiln, permanent physical and chemical changes occur. These changes cause the clay to be converted into a ceramic material.
Naturally occurring clay minerals offer a great potential and are widely applied in many fields such as polymer nano-composites, adsorbents for heavy metal ions ,catalysts , photochemical reaction fields , ceramics, paper filling and coating , sensors and biosensors, because of their high specific surface area , high mechanical stability ,and three-dimensional structure. The most-used clays as nano-adsorbents are montmorillonite/smectite group and kaolinite group clays.
Bentonite is a hydrated aluminosilicate clay primarily composed of the smectite-class mineral montmorillonite. Among different natural clays, bentonite has been considered to be an efficient adsorbent for dye removal since it is having negative charge on its surface. It is estimated to have 22 million tons of natural bentonite in Miles, Queensland, Australia and 40 to 70 million tons of bentonite exists in Arumpo, New South Wale, Australia.
Montmorillonite is a very soft group of minerals , which comes under category of phyllosilicate that typically forms in microscopic crystals, forming a clay. Chemically it is hydrated sodium calcium aluminum magnesium silicate hydroxide (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2Â·nH2O. It is a 2:1 clay since a central octahedral sheet is sandwiched between 2 tetrahedral sheets.
Montmorillonite swells and expands more than other clays when water is penetrated to the interlayer molecular spaces.
Montmorillonite has been used to treat contact dermatitis. They are also used for adsorption of heavy metals.
Halloysite is a 1:1 aluminosilicate clay mineral that is chemically similar to kaolin, but differs in having a hollow microtubular rather than a stacked plate-like structure, and its chemical formula is Al2Si2O5(OH)4. It consists of aluminum, silicon and hydrogen.
Halloysite nanotubes are ultra-tiny hollow tubes with diameters typically smaller than 100 nanometres, with lengths typically ranging from about 500 nanometres to over 1.2 microns. It possesses a regular nanotubular morphology, bulk structure and rich mesopores and nanopores. Recently, it was used as adsorbents and nanotemplates or nanoscale reaction vessels instead of carbon nanotubes .
Halloysite has found application in the automotive industry to form the support material for catalytic converters in exhaust systems. It can also be used as additive in paints, protective agents, in personal care, and as a skin cleanser agent by removing unwanted toxins which leaves you stay fresh. They are capable of entrapping both hydrophilic and hydrophobic agents.
Activated carbon based:-
Activated carbon, also called activated charcoal, is a form of carbon with small, low-volume pores that increase the surface area availability and can be used for removal of organic chemicals, chlorine, lead, unpleasant tastes and odors in effluent or coloured substances from gas or liquid streams by the mechanism of adsorption.
Due to its high degree of microporosity , just one gram of activated carbon has a surface area in excess of 500Â m2.
Activated carbon properties are determined by its porosity, the specific surface area, texture characteristics.
Activated carbon is carbon produced from carbonaceous source materials such as nutshells, peat, wood, coir, lignite, and coal. It can be produced by one of the following processes:
The precursor is developed into activated carbons using gases. This is generally done by using one or a combination of the following processes:
Carbonization: Material with carbon content is pyrolyzed at temperatures in the range 600-900 Â°C, in absence of oxygen (usually in inert atmosphere with gases like argon or nitrogen)
Activation/Oxidation: Raw material or carbonized material is exposed to oxidizing atmospheres (carbon dioxide, oxygen, or steam) at temperatures above 250 Â°C, usually in the temperature range of 600-1200Â Â°C.
Prior to carbonization, the raw material is impregnated with certain chemicals. The chemical is typically an acid, strong base, or a salt (phosphoric acid, potassium hydroxide, sodium hydroxide, calcium chloride, and zinc chloride 25%). Then, the raw material is carbonized at lower temperatures (450-900Â Â°C). It is believed that the carbonization / activation step proceeds simultaneously with the chemical activation. Chemical activation is preferred over physical activation owing to the lower temperatures and shorter time needed for activating material.
Based on their physical characteristics activated carbon is classified into following-
Powdered activated carbon
Granular activated carbon.
Extruded activated carbon
Bead activated carbon
Acid activated carbon (Zea mays dust carbon):-
Here Zea mays dust carbon as adsorbent is activated with sulphuric acid. Zea mays is binomial name of maize.
Maize is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. Maize kernels are used in cooking as a starch. The word maize derives from the Spanish form of the indigenous Taino word for the plant, maiz. Maize belongs to family Poaceae and subfamily Panicoideae.
Maize is the most widely grown grain crop in the Americas, with 332 million metric tons grown in the United States alone annually.
Maize stems superficially resemble bamboo canes. Maize has a distinct growth form, with the lower leaves being like broad flags, generally 50-100 Â centimeters long and 5-10Â centimeters wide (2-4Â ft by 2-4Â in), the stems are erect, conventionally 2-3Â meters (7-10Â ft) in height, with many nodes, casting off flag-leaves at every node. Under these leaves and close to the stem grow the ears. They grow about 3Â millimeters a day.
Maize is widely used for the production of biofuels ie. ethanol fuel. Ethanol is used at low concentrations as an additive in gasoline and octane rating increases, decreases the amount of pollutants emitted when used to fuel motor vehicles. Maize is increasingly used as a feedstock for biogas plants in Germany as well.
Activated carbon derived from Borassus aethiopum flower:-
Dried Palm flower (Borassus aethiopum) is activated with sulphuric acid and used as an adsorbent.
Borassus aethiopum is an unbranched palm growing up to 20 m tall, characterized by a crown up to 8 m wide; young palms are covered with dry leaf stalks, showing gradually fading leaf scars; trees over 25 years old have a swelling of the trunk at 12-15 m above the ground (at 2/3 of the height); bark is pale grey in older palms and is more or less smooth. Leaves are very large, fan shaped, bluish-green, 15-30, up to 3.5 m long, including petiole which is marked with sharp, black thorns; leaflets symmetric at the base. Flowers dioecious, yellowish; male flowers clustered in a branched spadix, 0.8-1.8 m long. Female flowers with unbranched and shorter spadix, 1.3-2.6 m long. The fruit a large drupe, diameter about 15 cm, ovoid, orange to brown when ripe; fibrous pulp contains 3 woody kernels with an albumen that becomes hard when ripe. This genus is probably the only tropical species that bears a generic name so old that its meaning has been lost in time. The name 'flabellifer' means 'fan shaped' and refers to the shape of the leaves.
B. aethiopum grows in tropical Africa and in the east. It was described from India in 1753 and only later in Africa.
B. aethiopum is dioecious. Flowering and fruiting take place whole year round. Pollination is largely done by insects.
Durian peel activated carbon:-
Durian , a widely known fruit in Southeast Asia belongs to family Malvaceae and many people regarded it as "King of fruits." Durian fruit is used to flavor a wide variety of sweet edibles such as traditional Malay candy,Â ice kacang,Â dodol,Â lempuk. Durian fruit contains a high amount ofÂ sugar,Â vitamin C,Â potassium and theÂ amino acidÂ tryptophan,Â and is a good source of proteins, andÂ fats. DurianÂ trees Â are large, growing to 25-50Â metres (80-164Â ft) in height depending on the species. The durian is native toÂ Brunei,Â IndonesiaÂ andÂ Malaysia.
Durian peel is efficient oil absorbent that can aid in the recovery of spilled oil at coastal areas. The durian peel is considered as an agricultural waste but it helps to remove oil from water.
Bamboo activated carbon:-
Activated carbon prepared from bamboo is used as adsorbent for the MG dye removal by chemical activation with K2CO3 and physical activation with CO2. Also known as "Black Diamond", bamboo activated carbon or charcoal is produced when plants, five years or older, are burned inside an oven at temperatures over 800ËšC. Bamboo charcoal has countless small cavities. Compared with wood charcoal, bamboo charcoal has about four times more cavities and its surface area of 300m2/gram is 10 ten times more. Bamboo activated carbon comes with more cavities than charcoal and has specific surface are>1000m2/gram.
Bamboo charcoal or activated carbon packs can be kept in car, shoe rack and kitchen in order to remove odours, absorb moisture.
Rubber seed coat based activated carbon:-
The adsorbent used to remove MG dye was the activated carbon of seed coat of the rubber tree(Hevea brasiliensis). H. brasiliensis belongs to the family Euphorbiaceae. It is economically important because a significant amount of milky latex, which is the primary source of natural rubber, can be extracted from this tree. Rubber seed oil is extracted from the rubber seed. In plantations, the trees are kept smaller, up to 78 feet (24Â m) tall, so as to use most of the available carbon dioxide for latex production. The tree requires a climate with heavy rainfall and without frost. Recently, it was reported that activated carbon, prepared form rubber seed coat is used for the sorption of phenol from aqueous solution.
Rice husk activated carbon:-
The outermost layer of the paddy grain is the rice husk, also called rice hull. It is separated from the brown rice in rice milling. Burning rice husk produced Rice Husk Ash (RHA), if the burning process is incomplete Carbonized Rice Husk (CRH) is produced.
Around 20% of the paddy weight is husk. In 2008, the world paddy production was 661 million tons and consequently 132 million tons of rice husk were also produced. While there are some uses for rice husk it is still often considered a waste product in the rice mill and therefore often either burned in the open or dumped on wasteland. HuskÂ has a high calorific value and therefore can be used as a renewable fuel.
Characteristics of rice husk and RHA
Rice husk is difficult to ignite and it does not burn easily with open flame unless air is blown through the husk. It is highly resistant to moisture penetration and fungal decomposition. Husk therefore makes a good insulation material.
Rice husk has a high silica (SiO2) contents which means that it decomposes slowly when brought back to the field. It also makes it a poor fodder
Handling of rice husk is difficult because it is bulky and dusty. It has angle of repose is about 40-45Â° which means that it's flow ability, e.g. in feed hoppers is very poor.
Rice husk has low bulk density of only 70-110 kg/mÂ³,Â 145 kg/mÂ³ when vibrated or 180kg/mÂ³Â in form of brickets or pellets. It thus requires large volumes for storage and transport, which makes transport over long distances un-economical.
When burned, the ash content is 17-26%, a lot higher than fuels (wood 0.2-2%, coal 12.2%). This means when used for energy generation large amounts of ash need to be handled.
Rice husk has a high average calorific value of a 3410 kcal/kg and therefore is a good, renewable energy source.
Because of the high silica contents rice husk is very abrasive and wears conveying elements very quickly.
Rice husk is not an easy fuel. One concern in rice husk firing is the behavior of the ash, i.e., its slagging and fouling tendency caused by a low melting point of the rice husk ash.
Rice husk is sometimes used as animal feed stuffÂ and as litter material for pet animals . Untreated hull is low in protein and digestible energy. Husk can be pretreated with 12% NaOH to reduce the silica content from 19 to 3-4% to improve digestibility and used as animal feed.
Waste is the residual matter left after processing. Wastes can be classified as biological waste, solid waste, hazardous waste and on hazardous waste. It is important to identify and manage these wastes properly in order to protect yourself and others in the community as well as environment. Different type of wastes that are used as adsorbent for the removal of MG dye including ginger waste, agricultural wastes such as ginger waste, Tamarix aphylla, oil palm trunk fibre etc.
Ginger or ginger root is the rhizome of the plant Zingiber officinale, consumed as a delicacy, medicine, or spice. The adsorption properties of ginger waste material is treated with zinc
chloride and sulfuric acid for the removal of malachite green(MG) from aqueous solution. The ginger waste was treated in order to increase its adsorption capacity. Ginger cultivation began in South Asia and has since spread to East Africa and the Caribbean. Mature ginger rhizomes are fibrous and nearly dry. The juice from old ginger roots is extremely potent. Ginger act as useful food preservative.
Agricultural solid waste :-
Solid waste means any garbage or refuse; sludge from a wastewater treatment plant, water supply treatment plant, or air pollution control facility; and other discarded material, including solid, liquid, semi-solid, or contained gaseous material resulting from industrial, commercial, mining, and agricultural operations, and from community activities.
Oil palm trunk fibre (OPTF):-
Oil palm trunk fibre (OPTF) - an agricultural solid waste - was used as low-cost adsorbent to remove malachite green (MG) from aqueous solutions. Oil Palm is a monocotyledonous species and does not have cambium, secondary growth, sapwood, and heartwood. Looking to anatomical structure, Oil Palm Trunk Fibres are present in vascular bundles and parenchyma cells.
Oil palm trunk is a major lignocellulosic-rich, solid waste material generated from palm-oil upstream industry . The chemical composition of the oil palm trunk fibre (% dry weight, w/w) is the following: cellulose 41.2%, hemicelluloses 34.4%, lignin 17.1%, ash 3.4%, extractives 0.5%, and ethanol solubles 2.3%.,which is different from hardwood/softwood species.
Oil palm trunk fiber was found to possess high tensile strength (300-600 N/mm2), high density (1200 kg/mm3) and high content of lignin (23.03%). Hence OPTF is suitable as reinforcement. The high density indicates that the fiber is strong. The high content of lignin in OPTF (23.03%) also gives extra merit to the fiber because lignified cellulose fibers retain their strength better than delignified fibers when exposed to moisture.
The value-added products made from Oil Palm Trunk can be used as particleboard, laminated board, plywood, fireboard, and furniture. It can be used as nutrient in plantations, as erosion control measure, and as animal feed.
Tamarix aphylla leaves:-
A new agriculture waste (Tamarix aphylla leaves) was treated with sulfuric acid, sodium hydroxide and acetone and used as adsorbent.
Tamarix aphylla is a fast growing, moderate sized evergreen tree, up to 18 m high with erect tapering trunk, 60-80 cm dbh with many stout spreading purplish brown and smooth branches. The species is monoecious. This species has a variety of common names, including Athel pine, Athel tree, Athel tamarisk, and saltcedar. It belongs to family Tamaricaceae. Twigs drooping, wiry or needle-like, up to 1.5 mm diameter, jointed, older twigs greenish-brown, hairless, mostly shedding. The tiny leaves are alternately arranged along the branches, and excrete salt. Leaves bluish-green, alternate, reduced to tiny scales ensheathing wiry twigs and ending in points, hairless, often with epidermal salt glands each forming a joint along the twig. These leaves are shed during the cold season, the new shoots and leaves appear about May. Flowers many, nearly stalkless, tiny, whitish-pink, in racemes 3-6 mm long, 4-5 mm broad at end of twigs, drooping. Fruit a small capsule, many, narrow, pointed, 5 mm long, splitting into 3 parts. Seeds many, 0.5 mm long, brown, each with tuft of whitish hairs 3 mm long.
Sawdust or wood dust is a by-product of cutting, grinding, drilling, sanding, or otherwise pulverizing wood with a saw or other tool; it is composed of fine particles of wood. It is also the byproduct of certain animals, birds and insects which live in wood. It is used in the manufacture of charcoal briquettes. A major use of sawdust is for particleboard; coarse sawdust may be used for wood pulp. Cellulose, an indigestible fiber starch can be made from sawdust. Sawdust accumulations present a number of health and safety hazards. Wood dust becomes a potential health problem when, for example, the wood particles, from processes such as sanding, become airborne and are inhaled. Wood dust is a known human carcinogen. Certain woods and their dust contain toxins that can produce severe allergic reactions. Sawdust is flammable and accumulations provide a ready source of fuel.
Rattan saw dust:-
Rattan is the name for the roughly 600 species of palms that belongs to family Arecaceae and subfamily Calamoideae, native to tropical areas of Africa and Asia. Most rattans have slender stems, 2-5Â cm diameter, with long internodes between the leaves; also, they are not trees but are vine-like, scrambling through and over other vegetation. Rattans are also superficially similar to bamboo. Unlike bamboo, rattan stems are solid, and most species need structural support and cannot stand on their own. Many rattans have spines which act as hooks to aid climbing over other plants, and to deter herbivores. Rattans have been known to grow up to hundreds of meters long. Generally, raw rattan is processed into several products to be used as materials in furniture making.
Neem saw dust:-
Neem (Azadirachta indica) tree will grow to heights of up to 30 meters with branching limbs extending 10 to 18 meters. A. indica tree is native to parts of India and Burma.Â It is an evergreen tree that must grow in tropical regions. It can grow with minimal rainfall and extreme heat. It was introduced to Africa and Asia and then in the late 19th century, it was introduced to some areas of Central America. A. indica is widely used throughout Africa as to treat malaria. It is also used to treat fever as well as to treat numerous skin disorders.
Different chemicals present in neem tree include liminoids, and triterpenoids, coumarins, fatty acids and their derivatives, flavonoids, steroids, sulfur compounds and hydrocarbonsÂ .
Fibre type adsorbents:-
Fiber is a string used as a component of composite materials, or matted into sheets to make products such as paper or felt. Carbon fiber is a strong engineering material.
A variety of fiber types, including man-made fibers or synthetic fibers such as steel, glass, polypropylene and natural cellulose fibers are available. Cellulose based fibers are of two types:- pure cellulose and modified cellulose.
Cotton is the purest natural form of cellulose. Commercially, cellulose acetate is made from processed wood pulp.
Natural fibers like jute, coir, bamboo and sisal have already been used as reinforcement materials in cement matrices for many years, especially in developing countries. Natural fibers can be used to reinforce plastics, which increases strength as well as stiffness. Plant fibers are employed in the manufacture of paper and textile. They are biodegradable over time. Wood fiber is under classification of natural fiber.
Phoenix tree (Firmiana simplex) wood fiber:-
The wood fiber obtained from Phoenix tree can be utilized as a good adsorbent for the removal of MG dye. Wood fiber is derived from recycled pallets as hardwood chips. The chips were reduced in size by a hammer mill. The resulting chips were reduced to fibers using a laboratory-scale pressurized refiner and screened through a 40-mesh screen. The wood fiber that is obtained from this tree has highest aspect ratio and thus increases strength as enhanced stress transfer across the matrix to the fiber. The scientific name of Chinese Parasol tree is Firmiana simplex. This tree is a deciduous tree, having green stems and bark and extremely large, three to five-lobed bright green leaves. Chinese Parasol tree has a dense, upright, oval canopy and reaches 35 to 50 feet in height, spreading 15 to 20 feet. It belongs to family Sterculiaceae. Its bark is thin and easily damaged from mechanical impact. Tree grows in full sun exposure.
Deinked waste newspaper fiber:-
Waste newspaper is a kind of domestic waste. Recycling waste newspaper can save resources and avoid pollution. Paper fiber from newspaper can be recycled up to four times and this recycled newspaper is used to create cereal boxes, egg cartons, pencil barrels, grocery bags, cellulose insulation materials, tissue paper.Â
Waste newspaper fiber is a low-cost cellulosic material. It is chemically modified and can be utilized as an adsorbent for the adsorption of zinc. Waste paper is the main material used to make new paper such as newsprint for newspapers and cardboard for boxes. According to the Swindon-based Confederation of Paper Industries, it was reported that 8.0 million tonnes of waste paper was collected for recycling in 2011.
Deinking is the industrial process of removing printing ink from paper fibers of recycled paper to make deinked pulp.
The key in the deinking process is the ability to detach ink from the fibers. This is achieved by a combination of mechanical action and chemical means. The most common process in Europe is froth flotation deinking.
Carbon based adsorbents:-
In recent times, carbon has been one of the magnificent elements which have revolutionized
materials science. Carbon provides materials with excellent properties for a large spectrum of
industrial applications. From carbon we obtain the strongest fibres (carbon fibres), one of the best solid lubricants (graphite), one of the best electrically conducting materials (graphite electrodes), the best structural material for high temperature tribological application (carbon-carbon composites), one of the best porous gas adsorbers (activated carbon), an essentially non-crystalline impermeable material (vitreous carbon), the hardest material (diamond), and now the most fascinating material, the fullerenes.
Porous carbons can be grouped into two categories: (i) Carbon foams with desired architecture
of pores for structural and thermal applications; recently, these have been used as
templates for making ceramics, (ii) activated carbons consisting of porous carbons with added
active surface chemical groups. Porous carbons, especially activated porous carbons, constitute one of the most important types of industrial carbons and have been in use for thousands of years. Their use in water purification can be dated back to 2000 BC when ancient Egyptians used charcoal to purify water for medicinal purposes.
The pores in activated carbons are scattered over a wide range of size and shape. The
pores are classified by their sizes usually into three groups: (i) macropores having average
diameter more than 50 nm, (ii) mesopores with diameter 2-50 nm, and (iii) micropores
having average diameter less than 2 nm. These are further divided into supermicropores
(0_7-2_0 nm) and ultramicropores of diameter less than 0.7 nm. Basically these consist of slit-like voids and macropores. In some woods like pine, these are of similar shape and size and are
equally distributed, whereas in bagasse, Babool, castor oil wood etc., pores are of very
different shapes and sizes and are organised in circular fashion. These macropores are in
turn connected to mesopores and micropores.
Different techniques have been used to determine pore size distribution in porous carbons.
These are mercury porosimetry and gas adsorption isotherms and recently, the scanning tunneling microscopy
Coal (Akash kinari):-
Coal is one of the world's major sources of energy. Coal is used to produce more than half of all the electrical energy that is generated and used in the United States. In the United States, coal provides approximately 23% of all the energy consumed. The porosity, surface area, mean particle diameter and density of Akash kinari coal is 0.43, 12.34 m2/g, 49x 10-2 cm and 3.31 g/cm3 respectively. Major chemical constituents include carbon (47.11%), silica (61.11%), and alumina (22.57%).
Coal is a very complex and diverse energy resource that can vary greatly, even within the same deposit. In general, there are four basic varieties of coal, which are the result of geologic forces having altered plant material in different ways.
Lignite:- Lignite is a brownish-black coal with generally high moisture and ash content and lower heating value. However, it is an important form of energy for generating electricity
Sub bituminous coal:- This is a dull black coal with a higher heating value than lignite that is used primarily for generating electricity and for space heating. Most sub bituminous reserves are located in Montana, Wyoming, Colorado, New Mexico, Washington and Alaska.
Bituminous:-This is the type most commonly used for electric power generation in the U.S. It has a higher heating value than either lignite or sub bituminous, but less than that of anthracite. Bituminous coal is mined chiefly in Appalachia and the Midwest. Also used to make coke.
Anthracite:- Sometimes also called "hard coal," anthracite forms from bituminous coal when great pressures developed in folded rock strata during the creation of mountain ranges. This occurs only in limited geographic areas - primarily the Appalachian region of Pennsylvania. Anthracite has the highest energy content of all coals and is used for space heating and generating electricity.
Fly ash is the ash that is produced during combustion of coal.
These minute particles of ash generated by thermal power stations through coal combustion causes serious environmental problems.
These ash particles consist of silica, alumina, oxides of iron, calcium, and magnesium and toxic heavy metals like lead, arsenic, cobalt, and copper.
The 80-odd utility thermal power stations in India use bituminous coal and produce large quantities of fly ash. According to one estimate, up to 150 million tonnes of fly ash will be produced in India in the year 2000, primarily by thermal power plants .This poses problems in the form of land use, health hazards, and environmental dangers. Utmost care has to be taken while utilizing and disposing this fly ash. At present about 2 % of the total fly ash is gainfully utilized.
Carbon prepared from Borassuss bark :-
An activated carbon prepared from Borassus bark, a low-cost source, by sulphuric acid activation has its ability to remove malachite green in aqueous solution. The binomial name of sugar palm is "Borassus flabellifer" .This palm tree is found from Indonesia to Pakistan.
Borassus flabellifer is a robust tree and can live more than 100 years and reach a height of 30 m (98 ft), with a canopy of green-bluish, leaves several dozen fronds spreading 3 meters (9.8 ft) across. The very large trunk resembles that of the coconut tree and is ringed with leaf scars.
Their roots have lateral characteristics and no main root. The bunch of leaves is a fan form and clustered on the top of the tree. Midrib of palm tree is thick and smooth; has yellow-green color when it is young; yellow-brown color when it is older; and has thorns along both edges in the form of chainsaw teeth .
Used in cements, adhesives, as a binding agent in industries, in pyrotechnics to make rocket engine nozzles.
Used to treat contact dermatitis
Used for adsorption of heavy metals
Use to capture circulating tumor cells in blood.
HNT coatings promote increased captured of leukemic cells.
Sustained delivery for certain agents, act as template or nanoreactor for biocatalyst, used in personal care and cosmetics, used as nano-adsorbents for the removal of the cationic dye and Zn(II) from aqueous solutions.
Activated Zea mays dust
Rubber Seed Coat
Used as replacement for wheat flour to make cornbread and other baked products, starch source for beer, feedstock for the production of biofuel, feedstock for biogas plants.
B. aethiopum trees are cut and hollowed out to make beehives. Firewood and charcoal can be obtained from B. aethiopum. The fibre extracted from the base of the leaf stalk has qualities of resistance to chemicals, termites and water. Young leaves, before unfolding, can be split into strips and woven into thin mats, baskets and other household objects. The leaf midribs are used to make brooms, fish traps and nets.
Helps to remove oil from water, leaf juice is used for the remedy of fever.
Used in car, shoe rack, kitchen to remove odours, absorb moisture, to maintain freshness of food, and for water purification.
Activated carbon from rubber seed coat is used for sorption of phenol from aqueous solution.
Bio-fertilizer additive, Animal husbandry
Sorbent material in environmental remediation, Pest control agent
Rice Husk Ash is used in manufacturing of refractory bricks, as partial cement replacement material for high-strength concrete, and as insulators.
Waste Treated ginger waste
Agricultural Solid Waste
Oil Palm Trunk Fiber
Tamarix aphylla leaves
Oil palm tree
Athel tree, saltcedar
Ginger is used mainly in sweet foods such as gingerbread, ginger biscuits and ginger snaps. Ginger is added to hot coffee and tea as a spice.
Sorbent material in environmental remediation.
Used in laminated products, such as laminated veneer lumber and both interior and exterior plywood. Several value added products such as particleboard, laminated board, plywood, fibreboard and furniture. Used for making papers, as animal feed.
Used as a windbreak and shade tree in agriculture and horticulture, as a barrier to fire.
Saw dust Rattan
Neem (Azadirachta indica)
Rattan is used for making furniture and baskets, for handicraft and art pieces, and for other decorative works.
Nimbidin, a major crude bitter principle extracted from the oil of seed kernels of A. indica has anti inflammatory effect.
Neem oil and bark have been used to control leprosy, intestinal helminthiasis, respiratory disorders, constipation and also as a general health promoter
Fiber Firmiana Simplex wood
Chinese Parasol tree, phoenix
Recommended for buffer strips around parking
lots, shading tree
Avoid pollution and save resources
Carbon Mesoporous carbon
Borassuss bark carbon
Water purification, gas storage.
Also used as catalyst support, as efficient adsorbent
Used to cure malaria, sexual diseases, anesthesia of hand and leg, and for the construction of houses and boats.
Used for electric power generation.
Fly Ash bricks can be used as building material, as a part replacement of cement in mortar.