Study of Langmuir and Freundlich Isotherms for Cr(III) and Cu(II) using Polyalthia Longifolia (ulta ashok) as an adsorbent

ABSTRACT

This research work is based on the adsorption of toxic metals Cr(III) & Cu(II) using leaves of plant (Polyalthia longifolia) as an adsorbent. Batch Adsorption Process was applied relying upon analytical technique i.e Atomic Absorption Spectroscopy. Different parameters e.g. adsorbent dosage, time of contact, pH, agitation speed and temperature were studied. Langumir & Freundlich isotherms were used to describe the observed sorption phenomenon. The maximum adsorption of chromium was at 3g of adsorbent in 50ml of 50ppm solution at 20^oC, at the agitation speed of 150 rpm for 15 minutes. And the maximum adsorption of copper was at 1.5g of adsorbent in 50ml of 50ppm solution at 60^oC, at the agitation speed of 125 rpm for 20 minutes.

Importance of Water

Our earth seems to be unique among the other known celestial bodies. It has water, which covers three-fourths of its surface and constitutes 60-70 percent by weight of the living world. Water regenerates and is redistributed through evaporation, making it seem endlessly renewable by hydrological cycle. Clean, fresh drinking water is essential to human and other life. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. ⁽¹⁾ 

Water is the most precious natural source and covers 71% of earth’s surface. It is known as "blood of earth". It can dissolve many of the body's solutes and is an essential part of metabolic processes in the body. Waste water is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industries, agricultural activities and can encompass a wide range of potential contaminants and concentrations.
Water is indispensable to life on this planet. It is said that water is the most valuable of nature^,s unlimited bounties for human service. The quality of water is of vital concern for the mankind.  Since it is directly linked with human welfare.

97% of world^, water is found in oceans. Only 2.5% of the world^,water is non saline fresh water. However 68.5% of all the fresh water is bound up in glaciers and ice-caps. Only less than 1% of fresh water is found in lakes, river and 30% as ground.⁽²⁾⁽³⁾

Water Pollution

Water is typically referred to as polluted when it is impaired by anthropogenic contaminants and either does not support a human use, like serving as drinking water or undergoes a marked shift in its ability to support its constituent biotic communities such as fish. Natural phenomena such as volcanoes, algae blooms, storms and earthquakes also cause major changes in water quality and the ecological status of water.

Water pollution categories

Water pollution is of two types.

·         Surface water pollution.

·         Ground water pollution.  

Surface water and ground water have often been studied and managed as separate resources, although they are interrelated. ⁽⁴⁾

Sources of surface water pollution are generally grouped into two categories based on their origin.

a) Point source pollution

Point source pollution refers to contaminants that enter a waterway through a discrete conveyance, such as a pipe or ditch. Examples of sources in this category include discharges from a sewage treatment plant or a factory or a leaking underground storage tank. The U.S. Clean Water Act (CWA) defines point source for regulatory enforcement purposes. ⁽⁵⁾

b) Non point source pollution

Non-point source (NPS) pollution refers to diffuse contamination that does not originate from a single discrete source. Nutrient runoff in storm water from "sheet flow" over an agricultural field or metals and hydrocarbons from an area with highly impervious surfaces and vehicular traffic are sometimes cited as an example of NPS pollution.

The primary focus of legislation and efforts to curb water pollution for the past several decades was first aimed at point sources. As point sources have been effectively regulated, greater attention has been placed on NPS contributions, especially in rapidly urbanizing or developing areas.⁽⁶⁾

Heavy Metals

Heavy metals are chemical elements with specific gravity that is at least five times the specific gravity of water.⁽⁷⁾ Heavy metal is a member of an ill-defined subset of elements that exhibit metallic properties, which would mainly include the transition metals, some metalloids, lanthanides and actinides.

Many different definitions have been proposed—some based on density, some on atomic number or atomic weight and some on chemical properties or toxicity. Term heavy metal has been called "meaningless and misleading" in an IUPAC technical report due to the contradictory definitions and its lack of a "coherent scientific basis"⁽⁸⁾  Heavy metal can include elements lighter than carbon and can exclude some of the heaviest metals. One source defines heavy metal as one of the common transition metals, such as copper, lead and zinc.

These metals are a cause of environmental pollution (heavy-metal pollution) from a number of sources, including lead in petrol, industrial effluents and leaching of metal ions from the soil into lakes and rivers by acid rain" ⁽⁹⁾

Heavy Metals and Living Organisms

Living organisms require varying amounts of "heavy metals" Iron, cobalt, copper, manganese, molybdenum and zinc are required by humans. Excessive levels can be damaging to the organism. Other heavy metals such as mercury, plutonium and lead are toxic metals that have no known vital or beneficial effect on organisms and their accumulation over time in the bodies of animals can cause serious illness. Certain elements that are normally toxic for certain organisms, are beneficial under certain conditions. Examples include vanadium, tungsten and even cadmium.⁽¹⁰⁾

Chromium

Chromium exists primarily in Trivalent [Cr(III)] or Hexavalent [Cr(VI)] oxidation states. Cr (VI) is a notorious environmental pollutant because it is a strong oxidant and much more toxic than Cr(III). Cr(VI) exists as the chromate ion in basic solution and as dichromate in acidic solutions. Chromium has been found in at least 115 to 1300 national priorities list sites identfied by EPA (environmental pollution agency).⁽¹¹⁾

Chromium is a lustrous, brittle & hard metal. Its colour is silver-grey and it can be highly polished. It does not tarnish in air, when heated it burns and forms the green chromic oxide.

Properties

General:

Name, Symbol, Number	Chromium, Cr, 24
Atomic Weight	565.99g/mole
Atomic Radius	140 pm
Crystal Structure	Cubic body centered
Oxidation States	6,5 (12) 4,3,2,1

Physical:

Melting Point	1907 Celsius
Boiling Point	2617 Celsius
Density	7.19 g/mole
Electronegativity	1.66 (Pauling Scale)
Ionization Energies	652.9 kJ/mol
Heat of fusion	21.0 kJ /mole
Heat of Vaporization	339.5 kJ /mole
Heat Capacity	23.33 J/mol/K

Sources of Chromium Exposure

The environmental and occupational sources of chromium exposure include the following ⁽¹³⁾

·         Airborne emissions from chemical plants and incineration facilities

·         Effluents from chemical plants

·         Contaminated landfill

·         Cement dust

·         Road dust from catalytic converter erosion and asbestos brake lining erosion

·         Tobacco smoke

·         Topsoil and rocks

Sources of emissions

·         Industrial sources

·         Diffuse sources and industry sources included in diffuse emissions data

·         Natural sources

·         Transport sources

·         Consumer products that may contain chromium(III) compounds

a) Industrial sources

Emissions to air and water may result from leather tanning industries, chemical manufacturing industries (e.g dyes for paints, rubber and plastic products), metal finishing industries (e.g chrome plating), manufacturers of pharmaceuticals, wood, stone, clay and glass products, electrical & aircraft manufacturers, steam & air conditioning supply services, cement producing plants (cement contains chromium), incineration of council refuse & sewage sludge and combustion of oil & coal.

b) Natural sources

Chromium is a relatively common element, naturally occurring in rocks, soil, plants, animals and in volcanic dust and gases. Oil and coal contain traces of chromium(III). Chromium is chiefly found as the chromium(III) form in nature and rarely as chromium(VI) compounds.

Exposure to chromium

People expose to chromium by following ways

a) Breathing

People can be exposed to chromium by breathing chromium dust or fumes. This is the route of exposure that is of greatest concern.

b) Drinking/Eating

Most human exposure to chromium occurs when people eat fresh vegetables, meats, fish and poultry. Drinking water is not normally a major source of exposure. Plants can absorb chromium and enters the food chain.

c) Touching

Contact with contaminated soils can result in exposure to chromium. Exposure can be reduced by thorough washing of exposed skin and clothing to remove soil residues. Chromium can pass through the skin but this is probably not a major route of exposure.

Toxicity of Chromium

The following health effects may occur immediately or shortly after exposure to high levels of chromium.

a) Acute Toxicity

Irritation to mouth, throat, lungs and nose following inhalation of hexavalent                                                             chromium particles.

Skin irritation and allergic reactions.

Digestive problems, kidney damage and liver damage after eating food or drinking water contaminated with hexavalent chromium.

b) Chronic Toxicity

The following health effects can occur after several years of exposure to chromium:

Cancer

 Lung cancer can develop after exposure to hexavalent chromium vapors or fumes.

Respiratory

 Lung irritation resulting in asthma can be caused by hexavalent chromium.

Organ Systems

Chromium exposure can cause liver and kidney damage.

Immune System

Animal studies show changes in immune system function.

Reproductive Effects

 Animal studies show damage to developing fetuses and lowered sperm production in males.

In general, chemicals affect the same organ systems in all people who are exposed. However, the seriousness of the effects may vary from person to person.

A person's reaction depends on several things including individual health, heredity and previous exposure to chemicals including chromium and medicines and personal habits such as smoking or drinking. It is also important to consider the time of exposure to the chemical, the amount of chemical exposure and whether the chemical was inhaled, touched or eaten.

Chromium plays a role in glucose and cholesterol metabolism and is thus an essential element to man and animals. Non-occupational exposure to the metal occurs via the ingestion of chromium containing food and water, whereas occupational exposure occurs via inhalation. Workers in the chromate industry have been exposed to estimated chromium levels of 10-50µg/m³ for Cr(III) and 5-1000µg/m³for Cr(VI) however improvements in the newer chrome-plating plants have reduced the Cr(VI) concentrations 10 to 40 folds.

Chromium(III) is poorly absorbed, regardless of the route of exposure whereas chromium(VI) is more readily absorbed by humans and animals localize chromium in the lung, liver, kidney, spleen, adrenals, plasma, bone marrow and red blood cells (RBC). There is no evidence that chromium is biotransformed but Cr(VI) does undergo enzymatic reduction, resulting in the formation of reactive intermediates and Cr(III).  The main routes for the excretion of chromium are via the kidneys/urine and the bile/feces.

Copper

Copper is an essential trace nutrient to all high plant and animal life. In animals including humans it is found primarily in the bloodstreamas a co-factor in various enzymesand in copper-based pigments. However, in sufficient amounts copper can be poisonous and even fatal to organisms.

Properties

General:

Name, symbol, number	Copper, Cu, 29
Element category	Transition metal
transition metal	11, 4, d
Appearance	Metallic copper
Standard atomic weight	63.546(3)g·mol−1
Electron configuration	[Ar] 3d10 4s1
Electrons per shell	2, 8, 18, 1 (Image)

Physical:

Phase	Solid
Density	8.96g/cm3
Liquid density at m.p.	8.02g/cm3
Melting point	1357.77K (1084.62 °C, 1984.32 °F)
Boiling point	2835K (2562 °C, 4643 °F)
Heat of fusion	13.26 kJ mol1
Heat of vaporization	300.4 kJ mol−1
Specific heat capacity	(25 °C) 24.440 J·mol−1K−1

Copper is essential in all plants and animals

Copper is carried mostly in the bloodstream on a plasma protein called ceruloplasmin. When copper is first absorbed in the gut, it is transported to the liver bound to albumin. Copper is found in a variety of enzymes including the copper centers of cytochrome c oxidase and the enzyme superoxide dismutase (containing copper and zinc). In addition to its enzymatic roles, copper is used for biological electron transport. The blue copper proteins that participate in electron transport include azurinand plastocyanin. The name "blue copper" comes from their intense blue color arising from a ligand-to-metal charge transfer (LMCT) absorption band around 600nm.

It is believed that zinc and copper compete for absorption in the digestive tract so that a diet that is excessive in one of these minerals, may result in a deficiency in the other. Professional research on this subject recommends 3.0mg/day.⁽¹⁴⁾ Because of its role in facilitating iron uptake, copper deficiency can often produce anemia-like symptoms. In humans, the symptoms of Wilson's disease are caused by an accumulation of copper in body tissues.

Chronic copper depletion leads to abnormalities in metabolism of fats, high triglycerides, non-alcoholic steatohepatitis (NASH) fatty liver disease and poor melanin and dopamine synthesis causing depression and sunburn. Food rich in copper should be eaten away from any milk or egg proteins as they block absorption.

Toxicity

Copper toxicity refers to the consequences of an excess of copper in the body. Copper toxicity can occur from eating acid food that has been cooked in un-coated copper cookware or from exposure to excess copper in drinking water or other environmental sources.^{(15) (16)}

Symptoms and presentation

Symptoms of copper poisoning are very similar to those produced by arsenic. Fatal cases are generally terminated by convulsions, palsy and insensibility. In toxicity, copper can inhibit the enzyme dihydrophil hydratase, an enzyme involved in haemopoiesis and homeostasis.

The lethal dose for copper may be as low as 3.5 grams. Short periods of exposure can cause gastrointestinal disturbance. Use of water that exceeds the action level over many years could cause liver or kidney damage. Copper build up can result in a tendency for hyperactivity in autistic children. It can cause stuttering, insomnia and hypertension. An excess of copper can cause oily skin, loss of skin tone (due to its ability to block vitamin C) and can cause a dark pigmentation of the skin, usually around the face. Copper can cause nails to be brittle and thin. It can contribute to hair loss, especially in women.

Pathophysiology

A significant portion of the toxicity of copper comes from its ability to accept and donate single electrons as it changes oxidation state. This catalyzes the production of very reactive radical ions such as hydroxyl radical.⁽¹⁷⁾  This catalytic activity of copper is used by the enzymes that it is associated with and is thus only toxic when unsequestered and unmediated. This increase in unmediated reactive radicals is generally termed oxidative stressand is an active area of research in a variety of diseases where copper may play an important but more subtle role than in acute toxicity.

It has been suggested that some of the effects of aging may be associated with excess copper.⁽¹⁸⁾ In addition, studies have found that people with mental illnesses such as schizophrenia had heightened levels of copper in their systems.

Indian Childhood Cirrhosis

One manifestation of copper toxicity, cirrhosis of the liver in children (Indian Childhood Cirrhosis) has been linked to boiling milk in copper cookware. The Merck Manual states that recent studies suggest that a genetic defect is associated with this particular cirrhosis.⁽¹⁹⁾

Wilsons Disease

An inherited condition called Wilson's disease causes the body to retain copper since it is not excreted by the liverinto the bile. This disease if untreated can lead to brainand liver damage.

Marine life

Too much copper in water has also been found to damage marine life.⁽²⁰⁾ The observed effect of these higher concentrations on fish and other creatures is damage to gills, liver, kidneys and the nervous system. It also interferes with the sense of smell in fish, thus preventing them from choosing good mates or finding their way to mating areas. ⁽²¹⁾

Exposure to copper

Humans may be exposed to copper from breathing air, drinking water, eating foods or have skin contact with copper, particulates attached to copper or copper containing compounds. Drinking water may have high levels of copper if house is equipped with copper pipes containing acidic water. Lakes and rivers that have been treated with copper compounds to control algae or that receive cooling water plants can have high levels of copper. Soil can also contain high levels of copper, especially if they are near copper smelting plants.

Humans beings may be exposed to copper by ingesting copper containing fungicides or if live near a copper mine or where a copper is processed into bronze or brass. They may be exposed to copper if work in copper mines or if grind metal containing copper. Copper is released into the environment by mining, farming, manufacturing operations and through waste water releases into rivers and lakes. Copper is also released from natural sources like volcanoes, windblown dust, decaying vegetation and forest fires. Copper released into the environment usually attaches to particles concerned with organic matter, clay, soil or sand. Copper doesn’t break down in the environment. Copper compounds can break down and release free copper into the air, water and food. ⁽²²⁾  

Copper in drinking water

Concentrations in drinking water are generally low with an astringment taste caused by copper at concentrations in excess of 2 mg/L. Above this concentration the consumer will reject the water due to an astringent taste and so copper rarely causes health problems. Water should not be drunk from hot water taps as the water which is heated in the copper cylinder will have been in contact with copper for sometime at elevated temperatures allowing maximum corrosion to occur and resulting in high levels of copper enough to cause nausea.⁽²³⁾

Techniques for the Removal of  Heavy Metals

The discharge of heavy metals into aquatic ecosystems has become a matter of concern over the last few decades. These pollutants are introduced into the aquatic systems significantly as a result of various industrial operations. The pollutants of concern include lead, chromium, mercury, uranium, selenium, zinc, arsenic, cadmium, gold, silver, copper and nickel. Heavy metals such as zinc, lead and chromium have a number of applications in basic engineering works, paper and pulp industries, leather tanning, organochemicals and petrochemicals fertilizers etc. For zinc and chromium the major application is in leather tanning. Over the few decades, several methods have been devised for the treatment and removal of heavy metals. The commonly used procedures for removing metal ions from aqueous streams include chemical precipitation, lime coagulation, ion exchange,⁽²⁴⁾ reverse osmosis ⁽²⁵⁾ and solvent extraction . The process description of each method is presented below.

a) Reverse Osmosis

 It is a process in which heavy metals are separated by a semi-permeable membrane at a pressure greater than osmotic pressure caused by the dissolved solids in wastewater. The disadvantage of this method is that it is expensive.

b) Electro dialysis

 In this process, the ionic components (heavy metals) are separated through the use of semi-permeable ion selective membranes. Application of an electrical potential between the two electrodes causes a migration of cations and anions towards respective electrodes. Because of the alternate spacing of cation and anion permeable membranes, cells of concentrated and dilute salts are formed. The disadvantage is the formation of metal hydroxides which clog the membrane.

c) Ultra filtration

They are pressure driven membrane operations that use porous membranes for the removal of heavy metals. The main disadvantage of this process is the generation of sludge.

d) Ion-exchange

In this process, metal ions from dilute solutions are exchanged with ions held by electrostatic forces on the exchange resin. The disadvantages include high cost and partial removal of certain ions.

e) Chemical Precipitation

Precipitation of metals is achieved by the addition of coagulants such as alum, lime, iron salts and other organic polymers. The large amount of sludge containing toxic compounds produced during the process is the main disadvantage.

f) Phytoremediation

Phytoremediation is the use of certain plants to clean up soil, sediment and water contaminated with metals. The disadvantages include that it takes a long time for the removal of metals and the regeneration of the plant for further biosorption is difficult.

Hence the disadvantages like incomplete metal removal, high reagent and energy requirements, generation of toxic sludge or other waste products that require careful disposal has made it imperative for a cost-effective treatment method that is capable of removing heavy metals from aqueous effluents.

An Efficient Technique for the Removal of Heavy Metals

Adsorption

Adsorption is a process that occurs when a gas or liquid solute accumulates on the surface of a solid or a liquid (adsorbent) forming a film of molecules or atoms (the adsorbate). It is different from absorption, in which a substance diffuses into a liquid or solid to form a solution. The term sorption encompasses both processes, while desorption is the reverse process.

Adsorption is present in many natural physical, biological and chemical systems and is widely used in industrial applications such as activated charcoal, synthetic resins and water purification. Adsorption, ion exchange and chromatography are sorption processes in which certain adsorbates are selectively transferred from the fluid phase to the surface of insoluble rigid particles suspended in a vessel or packed in a column.

Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (ionic, covalent or metallic) of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates.

Biosorption

The search for new technologies involving the removal of toxic metals from wastewater has directed attention to biosorption based on metal binding capacities of various biological materials. Biosorption can be defined as the ability of biological materials to accumulate heavy metals from wastewater through metabolically mediated or physico-chemical pathways of uptake Algae, bacteria, fungi and yeasts have proved to be potential metal biosorbents.⁽²⁶⁾  The major advantages of biosorption over conventional treatment methods include ⁽²⁷⁾

• Low cost

• High efficiency

• Minimization of chemical or biological sludge

• No, additional nutrient requirement

• Regeneration of biosorbent

• Possibility of metal recovery

Cellulosic agricultural waste materials are an abundant source of significant metal biosorption. The functional groups present in agricultural biomass viz. acetoamide, alcoholic, carbonyl, phenolic, amido and amino groups have affinity for heavy metal ions to form metal complexes or chelates. The mechanism of biosorption process includes chemisorpion, complexation, adsorption on surface, diffusion through pores and ion exchange.⁽²⁸⁾

Types of Adsorption

The exact nature of the bonding depends on the details of the species involved but the adsorption process is generally classified as:

a) Physical adsorption

  The adsorption in which the atoms or the molecules are held to the solid and liquid surface by Vander Wall's attraction forces is called physical adsorption. For example, the adsorption of toxic metals on clay. It provides information about the structure of solids and its surface area.

b) Chemical adsorption

 The adsorption of a substance at the surface involving the formation of bond between the adsorbate and the adsorbent which may be covalent or ionic is called chemical adsorption. It is of fundamental importance in heterogeneous catalysis.

c) Polar adsorption

Adsorption may be polar when the material adsorbed consist of possitive or negative ions. The term adsorption is cheifly attributable to attraction between the polar groups of adsorbate and adsorbent.

d) Specific adsorption

 It is preferential adsorption of one substance over another or the quality of adsorbate held per unit area of adsorbant.

Factors affecting Adsorption

a) Surface Area

 The extent of adsorption is proportional to specific area. Specific area can be defined as that portion of the total area that is available for adsorption.

b) Nature of the Adsorbate

Adsorption of a solute is inversely proportional to its solubility in the solvent. The greater the solubility, the stronger the solute-solvent interaction and the small the extent of adsorption.

In general, the solubility of any organic compound in water decreases with increasing chain length because the compound becomes more hydrocarbon-like as the number of carbon atoms becomes greater. Adsorption of aliphatic series of organic acids increases in the order formic-acetic-propionic-butyric, whereas the order is reversed for adsorption from toluene.

c) Molecular size

If the rate is controlled by intra-particle transport, the reaction generally will precede more rapidly for the smaller adsorbate molecule, within a given class of compound.

d) Charge (Ionic species)

Adsorption is at minimum for the charged species and at a maximum for the neutral species. As compounds become more complex, the effect of ionization becomes of decreasing important.⁽²⁹⁾

Adsorption is studied as maximum at the isoelectric point or that pH at which both the acidic and the basic end of  the compound are ionized and the compound bears a net charge of zero.

e) pH

Hydrogen and hydroxide ions are adsorbed quite strongly, the adsorption of other ions is influence by the pH of the solution.

f) Temperature

 Adsorption reactions are normally exothermic, thus the extent of adsorption generally increases with decreasing temperature.

Nature of the Adsorbent

The physicochemical nature of the adsorbent can have profound effects on both rate and capacity for adsorption. For a given adsorbent, the adsorbability of different substances may vary widely so that in the presence of mixture of substances selective adsorption will occur. Although at the beginning of the run, several substances may be adsorbed simultaneously the less, clear cut suggestion will be obtained according to the relative densities of the substance in the mixture.

Isotherms

Adsorption is usually described through isotherms i.e. the amount of adsorbate on the adsorbent as a function of its pressure (if gas) or concentration (if liquid) at constant temperature. The quantity adsorbed is nearly normalized by the mass of the adsorbent to allow comparison of different materials.

The first mathematical fit to an isotherm was published by Freundlich and Küster (1894) and is a purely empirical formula for gaseous adsorbates.

Adsorption isotherms included in our study are:

a) The Langmuir Adsorption Isotherm

This isotherm is described by following equations:

                                               q = Qmax bCe/(1+bCe)

or

1/q = 1/bQmax.1/Ce+1/Qmax

Where

qmax = Max. amount (adsorption capacity) of metal ion forming a

complete monolayer on the  biomass surface(mg/g)

q = The adsorption density (mg of adsorbate per g of biosorbent)

b = Langmuir constant related to energy of adsorption.

Ce = Equilibrium conc. of adsorbate in solution (mg/L)

b) The Freundlich Adsorption Isotherm

The Freundlich model was chosen to estimate the adsorption intensity of the adsorbate on the adsorbent surface. The Freundlich equation is an empirical equation based in adsorption on heterogeneous surface and is given by:

                                                        q = Kf (Ce)1/n

log q  = log Kf +1/n log Ce

Where                                                                          

q = Adsorption density (mg of adsorbate per g of biosorbent)

Ce = Equlibrium conc.of adsorbate in solution (mg/L)

n = Empirical constant (Freundich exponent)

Kf = Max.adsorption capacity (Freundlich adsorption constant)

Plant  Used as an Adsorbent (Polyalthia Longifolia)

Polyalthia longifolia is a lofty evergreen tree, native to India, commonly planted due to its effectiveness in alleviating noise pollution. It exhibits symmetrical pyramidal growth with willowy weeping pendulous branches and long narrow lanceolate leaves with undulate margins. The tree is known to grow over 30 ft in height.

High percentage of medicinal plants used by Indian industries today are collected, Polyalthia longifolia is one of Indian plant.⁽³⁰⁾

Common names

Asopalav (Gujarati),  false ashoka,  green champa,  Indian mast tree,  Indian fir tree.

                

  Polyalthia Longifolia (Leaves)                              Polyalthia Longifolia (Plant)

Uses

a) Food

The large, edible, pulpy fruits of some members typically called Anona by Spanish and Portuguese speaking people who lived where they grew natively, include species of Annona (custard apple, cherimoya and soursop), Asimina (papaw), Rollinia (the biriba).

b) Medicinal Properties

The bark, leaves and roots of some species are used in folk medicines. Pharmaceutic research has found antifungal, bacteriostatic and especially cytostatic capability of some chemical constituents of the leaves and bark. A large number of chemical compounds including flavonoids, alkaloids and acetogenins have been extracted from the seeds and many other parts of these plants. Flavonoids and alkaloids have shown antibacterial properties and have been used for treatment of medical conditions such as skin disease, intestinal worms and inflammation of the eye. Many species are used in traditional folk medicine, however pharmaceutical products have been developed for the international market. Acetogenins are thought to have anti-HIV and anti-cancer effects. A wide variety of products have been developed and are available for cancer treatment.

c) Insecticidal Properties

Flavonoids and alkaloids contained in the leaves and bark of several species of the family have shown insecticidal properties.

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Introduction

Literature Review

Analytical Techniques

Experimental Work

Results and Discussion

Conclusion

References