Iron is a troublesome component in H2O supplies. Making up at least 5 % of the earths crust, Fe is one of the Earth ‘s resources. Rainwater, as it infiltrates dirt, the underlying geologic formations, dissolves Fe, doing it to ooze into the aquifers that serve as beginning of groundwater for Wellss. However, a small sum i.e. 0.3 ppm can do H2O to turn a ruddy brown colour. Therefore, the remotion of Fe is necessary to avoid wellness hazard.

In the present thesis work, surface assimilation of Iron has been studied for two types of grain sizes of sand in waste H2O. The consequence of contact clip, dose, and pH is studied in column experiment.

It has been found that when initial Fe concentration is 5mg/L, 20gm/L dosage of 0.5 millimeters sand can take 97.6 % Fe at contact clip of 2 hour and 20gm/l dosage of 1.0 millimeters sand can take 95 % Fe contact clip of 2 hour at initial pH is 7.5. On comparing two grain size ( i.e. GMS ( geometric mean size ) equal to 0.5 millimeters and 1 millimeter ) of sand it is observed that 0.5 millimeter sand is much better adsorbent than other grain size of sand for Fe remotion. Finally, it has been concluded that low cost adsorbents has been found successfully remotion of Fe from waste H2O.




Iron ( Fe ) is metal that occur of course in dirts, stones and minerals. In the aquifer, groundwater comes in contact with solid stuff fade outing them, let go ofing their components ( Fe ) to the H2O. At concentrations nearing 0.3 mg/L of Fe, the H2O ‘s utility may go earnestly wedged, for example, there may be a metallic gustatory sensation to the H2O and staining of plumbing fixtures may go common. At these concentrations, nevertheless, the wellness hazard of dissolved Fe in imbibing H2O is undistinguished. The extent to which Fe dissolved in groundwater depends on the sum of O in the H2O and, to a lesser extent, upon its grade of sourness, i.e. , its pH. Iron can happen in two signifiers: as Fe2+ and as Fe3+ . When degrees of dissolved O in groundwater are greater than 1-2 mg/L, Fe occurs as Fe3+ , while at lower dissolved O degrees, the Fe occurs as Fe2+ . Although Fe2+ is really soluble, Fe3+ will non fade out appreciably. If the groundwater contains less oxygen so, Fe will fade out more readily, peculiarly if the pH of the H2O is on the low side ( somewhat more acidic ) . Dissolved O content is typically low in deep aquifers, peculiarly if the aquifer contains organic affair. Decomposition of the organic affair depletes the O in the H2O and the Fe dissolves as Fe2+ . When this H2O is pumped to the surface, the dissolved Fe reacts with the O in the ambiance, alterations to Fe3+ and signifiers rust-colored Fe minerals. Treatment for dissolved Fe takes advantage of the natural procedure of oxidization, through the usage of aeration, i.e. , shooting air into the H2O prior to the pat to precipitate Fe from the H2O. Chlorine is besides an effectual oxidant and will do Fe to precipitate, plus it provides protection from microbic contaminations. Normally a physical filter follows the intervention so that the atoms will non go out through the pat. Additional intervention methods include greensand filters and H2O softeners. Local providers of H2O intervention devices should be consulted in order to choose the best system for a given H2O supply. The sum of dissolved Fe in groundwater may change seasonally for a given good. Normally this is associated with an inflow of oxygenated H2O from the surface during periods of high recharge. This oxygenated H2O will forestall the Fe from fade outing and the H2O pumped from the well will hold low concentrations of these metals. After the O in the recharge H2O has been consumed, Fe will once more be dissolved and the H2O will hold dissolved Fe features.

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A concluding note is that even though handling the H2O for dissolved Fe after it leaves the well will do the H2O more toothsome, high concentrations of dissolved Fe within the good dullard may take to growing of Fe bacteriums. These bacteriums may surface the interior of the shell or any other submersed portion of the plumbing in the well and may do jobs. In countries where elevated Fe is common, it may be deserving while to sporadically disinfect the well to maintain Fe bacterial growing in cheque.

Harmonizing to the W.H.O. imbibing H2O criterion recommended bound for Fe in public H2O supplies is 0.3 mg/L. Even though this bound is non based on physiological consideration, the presence of Fe in domestic and industrial H2O supplies has long plagued the homeowner and the maker. When Fe is present in a H2O supply at concentration transcending 0.3 mg/l, it is unwanted for the undermentioned ground:

Iron precipitates give H2O a ruddy coloring material when exposed to air.

Iron gives H2O a metallic gustatory sensation.

Home softness becomes clogged by Fe precipitates.

Deposition of Fe precipitates in the distribution system can cut down the effectual pipe diameter and finally choke off the pipe.

Iron is a substrate for the growing of bacteriums in the H2O brinies, when Fe bacterium dice and gangrene away, bad olfactory properties and unpleasant gustatory sensations may be caused.

In paper industries, Fe causes stain of mush and paper. Iron is responsible for topographic point and stain of leather goods. Distilleries require clear, drinkable H2O free from Fe. Deposits are formed in boiler operating at high force per unit area due to presence of Fe in the provender H2O. Since these sedimentations can do tubing failures, the provender H2O in high – force per unit area boiler system should be free from Fe.

In the present thesis work, surface assimilation of Iron has been studied for two types of grain sizes of sand in waste H2O. The consequence of contact clip, dose, and pH is studied in column experiment.



2.1 Introduction

Iron is a bright, malleable, ductile, silver-grey metal ( group VIII of the periodic tabular array ) . It is known to be in four distinguishable crystalline signifiers. Iron rusts in shit air, but non in dry air. It dissolves readily in dilute acids. Iron is chemically active and signifiers two major series of chemical compounds, the bivalent Fe ( II ) , or ferric, compounds and the trivalent Fe ( III ) , or ferrous, compounds. The chemical belongingss of Fe are given below:

Atomic figure


Atomic mass

55.85 g.mol-1

Electronegativity harmonizing to Pauling



7.8 20 & A ; deg ; C

Melting point

1536 & A ; deg ; C

Boiling point

2861 & A ; deg ; C

Vanderwaals radius

0.126 nanometer

Ionic radius

0.076 nanometer ( +2 ) ; 0.064 nanometer ( +3 )



Electronic shell

[ Ar ] 3d64s2

Energy of first ionization

761 kJ.mol-1

Energy of 2nd ionization

1556.5 kJ.mol-1

Energy of 3rd ionization

2951 kJ.mol-1

Standard potency

– o.44 V ( Fe2+/ Fe ) ; 0.77 V ( Fe3+/ Fe2+ )


Iron is the most used of all the metals, including 95 % of all the metal tunnage produced worldwide. Thankss to the combination of low cost and high strength it is indispensable. Its applications go from nutrient containers to household autos, from screwdrivers to rinsing machines, from cargo ships to paper basics. Steel is the best known metal of Fe, and some of the signifiers that iron takes include: hog Fe, cast Fe, C steel, shaped Fe, metal steels, Fe oxides.

2.1.1 Health effects of Fe

Iron can be found in meat, whole repast merchandises, murphies and veggies. The human organic structure absorbs Fe in carnal merchandises faster than Fe in works merchandises. Iron is an indispensable portion of haemoglobin ; the ruddy coloring agent of the blood that transports O through our organic structures.

Iron may do pinkeye, choroiditis, and retinitis if it contacts and remains in the tissues. Chronic inspiration of inordinate concentrations of Fe oxide exhausts or dusts may ensue in development of a benign pneumonoconiosis, called siderosis, which is discernible as an x-ray alteration. No physical damage of lung map has been associated with siderosis. Inhalation of inordinate concentrations of Fe oxide may heighten the hazard of lung malignant neoplastic disease development in workers exposed to pneumonic carcinogens. LD50 ( unwritten, rat ) =30 gm/kg. ( LD50: Lethal dose 50. Single dosage of a substance that causes the decease of 50 % of an carnal population from exposure to the substance by any path other than inspiration. A more common job for worlds is iron lack, which leads to anaemia. A adult male needs an mean day-to-day consumption 7 milligram of Fe and a adult female 11 milligram ; a normal diet will by and large supply all that is needed.

2.1.2 Iron and H2O

Seawater contains about 1-3 ppb of Fe. The sum varies strongly, and is different in the Atlantic and the Pacific Ocean. Rivers contain about 0.5-1 ppm of Fe, and groundwater contains 100 ppm. Drinking H2O may non incorporate more than 200 ppb of Fe. Most algae contain between 20 and 200 ppm of Fe, and some brown algae may roll up up to 4000 ppm. The bio concentration factor of algae in saltwater is about 104 – 105. Sea fish contain about 10-90 ppm and oyster tissue contains about 195 ppm of Fe ( all are dry mass ) . Dissolved Fe is chiefly present as Fe ( OH ) 2+ under acidic and impersonal, oxygen rich conditions. Under oxygen-poor conditions it chiefly occurs as binary Fe. Iron is portion of many organic and inorganic chelation composites that are by and large H2O soluble.

2.1.3 Environmental effects of Fe in H2O

Iron is a dietetic demand for most beings, and plays an of import function in natural procedures in binary and third signifier. Oxidized third Fe can non be applied by beings freely, except at really low pH values. Still, Fe normally occurs in this by and large H2O indissoluble signifier. Adding soluble Fe may quickly increase productiveness in pelagic surface beds. It might than play an of import function in the C rhythm. Iron is indispensable for N binding and nitrate decrease, and it may be a confining factor for phytoplankton growing. Solubility in salt H2O is highly low.The Fe rhythm means decrease of third Fe by organic ligands ( a procedure that is exposure catalysed in surface Waterss ) , and oxidization of binary Fe. Iron forms chelation composites that frequently play an of import function in nature, such as hemoglobin, a ruddy coloring agent in blood that binds and releases oxygen in take a breathing procedures. Organisms take up higher sums of double star Fe than of third Fe, and uptake chiefly depends on the grade of impregnation of physical Fe militias.

Iron is frequently a confining factor for H2O beings in surface beds. When chelation ligands are absent, H2O indissoluble third Fe hydrated oxides precipitate. This is non thought to be risky for aquatic life, because non much is known about jeopardies of H2O borne Fe.

Mollusks have dentitions of magnetic iron-ore of gothite. Green workss apply Fe for energy transmutation processes. Plants that are applied as carnal provender may incorporate up to 1000 ppm of Fe, but this sum is much lower in workss applied for human ingestion. Generally workss contain between 20 and 300 ppm Fe ( dry mass ) , but lichens may dwell up to 5.5 % of Fe. When dirts contain small Fe, or small H2O soluble Fe, workss may see growing jobs. Plant uptake capacity strongly varies, and it does non merely depend on dirt Fe concentrations, but besides upon pH values, phosphate concentrations and competition between Fe and other heavy metals. Limes dirts are frequently iron shortage, even when sufficient sums of Fe are present. This is because of the by and large high pH value, which leads to press precipitation. Iron normally occurs in dirts in third signifier, but in H2O saturated dirts it is converted to binary Fe, thereby enabling works Fe consumption. Plants may take up H2O indissoluble Fe compounds by let go ofing H+ ions, doing it to fade out. Micro organisms release Fe siderochrome, which can be straight taken up by workss.

Iron may be harmful to workss at feed concentrations of between 5 and 200 ppm. These can non be found in nature under normal conditions, when low sums of dirt H2O are present. A figure of bacteriums take up Fe atoms and change over them to magnetite, to use this as a magnetic compass for orientation. Iron compounds may do a much more serious environmental impact than the element itself. A figure of values are known for rats ( unwritten consumption ) : Fe ( III ) acetyl propanone 1872 mg/kg, Fe ( II ) chloride 984 mg/kg, and Fe pent carbonyl 25 mg/kg. There are four of course happening non-radioactive Fe isotopes.

2.1.4 The wellness effects of Fe in H2O

The entire sum of Fe in the human organic structure is about 4 g, of which 70 % is present in ruddy blood coloring agents. Iron is a dietetic demand for worlds, merely as it is for many other beings. Men require about 7 milligrams Fe on a day-to-day footing, whereas adult females require 11 milligram. The difference is determined by catamenial rhythms. When people feed usually these sums can be obtained quickly. The organic structure absorbs about 25 % of all Fe nowadays in nutrient. When person is iron shortage provender Fes intake may be increased by agencies of vitamin C tablets, because this vitamin reduces third Fe to binary Fe. Phosphates and phytates decrease the sum of binary Fe. In nutrient Fe is present as binary Fe edge to haemoglobin and myoglobin, or as third Fe. The organic structure may peculiarly absorb the binary signifier of Fe. Iron is a cardinal constituent of hemoglobin. It binds O and conveyances it from lungs to other organic structure parts. It transports CO2 back to the lungs, where it can be breathed out. Oxygen storage besides requires Fe. Iron is a portion of several indispensable enzymes, and is involved in DNA synthesis. Normal encephalon maps are iron dependant.

In the organic structure Fe is strongly bound to transferring, which enables exchange of the metal between cells. The compound is a strong antibiotic, and it prevents bacteriums from turning on the critical component. When one is infected by bacteriums, the organic structure produces high sums of reassigning. When Fe exceeds the needed sum, it is stored in the liver. The bone marrow contains high sums of Fe, because it produces hemoglobin. Iron shortages lead to anaemia, doing fatigue, concerns and loss of concentration. The immune system is besides affected. In immature kids this negatively affects mental development, leads to crossness, and causes concentration upset. Young kids, pregnant adult females and adult females in their period are frequently treated with Fe ( II ) salts upon Fe shortages.

When high concentrations of Fe are absorbed, for illustration by haemochromatose patients, Fe is stored in the pancreas, the liver, the lien and the bosom. This may damage these critical variety meats. Healthy people are by and large non affected by Fe overdose, which is besides by and large rare. It may happen when one drinks H2O with Fe concentrations over 200 ppm.

Iron compounds may hold a more serious consequence upon wellness than the comparatively harmless component itself. Water soluble binary Fe compounds such as FeCl2 and FeSO4 may do toxic effects upon concentrations transcending 200 milligram, and are deadly for grownups upon doses of 10-50 g. A figure of Fe chelates may be toxic, and the nervus toxin Fe penta carbonyl is known for its strong toxic mechanism. Iron dust may do lung disease.

Approximately 80 % of catching diseases in the universe are due to H2O. Various unwanted and of course happening pollutants in H2O such as coli form bacteriums, Fe, fluoride and arsenic are really of import as theses pose terrible wellness jobs ( Joshi and Chaudhuri, 1996 ) . Iron comprises 5 per centum of the Earth ‘s crust. Iron ores include haemetite ( Fe2O4 ) , magnetite ( Fe3O4 ) , limonite ( Fe2O33H2O ) , siderite ( FeCO3 ) and pyrite ( FeS2 ) .Fe+3 minerals are virtually in soluble in H2O, but chalybite has solubility of 65 mg/l. The solubility of chalybite ( FeCO2 ) is extremely increased by the presence of C dioxide or carbonaceous acid ( Das et al. 2007 ) .

Iron is besides present as ferric sulfate in river, lakes or reservoirs incorporating acerb wastes or in land H2O incorporating sulfur peculiarly, H sulfide. Normally referred to as organically bound Fe is found in land and surface supplies. High concentration of Fe+3 occurs in the hypolimniteic zones of entropic lakes and reservoirs when the dissolved O in these section zones is depleted and the bottom clay contain Fe stuffs. When such Waterss are used for H2O supplies, they come in contact with the atmospheric O and Fe+2 is oxidized to Fe+3 organizing xanthous or ruddy precipitates of ferrous hydrated oxide. Iron incorporating colour compound are stable and are non normally regarded as Fe beginnings, though there may be practical or aesthetic expostulation to the usage of colored H2O. Red H2O owes its visual aspect and name to suspended indissoluble ferrous hydrated oxide formed by the corrosion of the ferric metal of brinies, shrieking and toxic and oxidization of ferric carbonate.


Oxidation in Iron Removal

There are several methods for remotion of Fe from imbibing H2O like ion exchange and H2O softening ( Vaaramaa and Lehto, 2003 ) , activated C and other filtration stuffs ( Munter et al. 2005 ) , bioremediation ( Berbenni et al. 2000 ) . Oxidation by aeration, chlorination, ozonation is followed by filtration ( Ellis et al. 2000 ) . However, oxidization procedures are by and large used to take soluble Fe from land H2O. Actually this is a reversal of the natural procedure whereby Fe is rendered soluble. The most normally used oxidising agent is O, which is added to the H2O by agencies of aeration. When H2O is aerated, CO2 is removed from H2O ensuing in an addition in the pH. The rate of oxidization additions quickly at a pH of 7.0 or more. Therefore any factor which tends to displace the equilibrium:

H2O + CO2 H+ + HCO3- 2H+ + CO3-2

May find the class of reactions involved in Fe remotion. The oxidization is normally accomplished by:

( I ) Open devices over which H2O flows by gravitation. With or without antagonistic current

forced bill of exchange, e.g. unfastened bar tray aerator, unfastened salt tray aerator, closed forced

bill of exchange aerator etc.

( two ) Spray devices which spray the H2O in to the air.

( three ) Diffused air aeration.

( four ) Aspiration devices e.g. venture devices. The most common method of aeration

is cake tray aerator.

Ferric Fe can be oxidized by utilizing other oxidising agents besides. It has been reported that Fe in H2O can be removed about wholly by a free residuary Cl of about 0.5 mg/l at normal pH values without utilizing luxuriant intervention installations. Other oxidising agents normally are ozone K permanganate etc.

2.3.2 Unit Processes in Iron Removal

The most common method of Fe remotion from land H2O involve four basic unit processes, viz, surface assimilation, oxidization, settling and filtration. The precipitated Fe is removed partly by deposit and partly by filtration. Rapid sand filter or force per unit area filter are used. Vander Wal ( 1952 ) has reported that Fe and manganese are excessively hard to take from H2O without anterior flock formation. Whatever intervention method is employed, troubles of uncomplete Fe remotion are frequently encountered and in some workss decrease of Fe from the ferrous province to the ferric province during filtration has been reported. This is ever associated with a pronounced depletion of dissolved O and a considerable growing of biological sludge on the filter. It has been postulated that the chemical decrease of Fe is mediated by the bacterial growing in the filter.

Owing to the increased demand for better quality H2O, assorted alterations for the conventional method have been suggested. The utilizations of diatomaceous Earth filter for Fe remotion have been found executable both practically and economically. The usage of precipitators relieves the sand filter of the enormous burden they have to transport in Fe remotion workss of the aeration, surface assimilation, and deposit and filtration type. Approximately 95 % Fe can be removed by the Precipitators, when proper pH is maintained. Iron can besides be removed during ion exchange softening procedures. A Na zeolite bed or a manganese zeolite bed can be used.


2.4.1 Mechanism of Filtration

The development of the sand filter for H2O purification took topographic point in England in the mid-nineteenth century. Those filters were developed in the United States to run at higher filtration rates. The higher rate agencies less filter country and less capital investing to accomplish the coveted capacity. A batch of probes have been conducted to analyze the mechanism of filtration. Harmonizing to Cleasby et Al. ( 1963 ) a really delicate balance exists between those forces be givening to lodge and keep to atoms. The remotion of suspended atoms in a filter is believed to be achieved in two stairss, transport measure followed by an attachment measure O’Melia and Stumm, 1967 ) . Particle conveyance is a physico hydraulic procedure and is chiefly affected by those parametric quantities which govern mass transportation. Particle fond regard is fundamentally physicochemical procedure and is influenced by both physical and chemical parametric quantities. In existent filtration pattern, removal consequences from a combination of these mechanisms ( Cleasby, 1969 ) . The major conveyance mechanisms include striving, majority flow or convective flux ( which promotes interception ) , gravitation subsiding, Brownian diffusion and hydrodynamic action ( Ives, 1971 ) and are affected by such physical features as medium size, filtration rate, fluid temperature and the denseness and size of the suspended atom. As the atom approaches the surface of the medium or antecedently deposited solids on the medium fond regard mechanisms are required to retain the atom which are believed to be dependent upon London forces, electrical dual bed interaction ( electrokinetic ‘s forces ) and chemical bridging or specific surface assimilation. The fond regard forces are affected by the coagulators applied in the pre-treatment, and the chemical features of the H2O and the filter medium. Harmonizing to Conley Hsiung ( 1969 ) flocculation within filter pores may play an of import function and the consequence of these demands to be re-evaluated.

A assortment of stuffs can be used as effectual filtering media. The most lasting and possibly, the cheapest stuff available is sand, Rapid sand filter are normally operated at filtration rate 94lpm/m2. Other stuffs like hard coal besides are used as filter medium in states like United State. These filters can be operated at rate much higher than the sand filter.


Many probes have been made to analyze the usage of stuffs others than sand as filter media. These probes have been necessitated due to the relatively low flow rate in rapid sand filter and increased demand of H2O. Anthrathracively is used as a filter medium in the United States. Coal is besides used the filter medium. One of the most valuable belongingss of coal is its ability to adsorb from solution many of the dissolved contaminations. Gr. Eskenazy ( 1970 ) has reported that Be can be adsorbed on peat and coal. It is stated that selected type of dissolved inorganic affair can be removed from H2O solution by coal either by surface assimilation or by mechanisms yet to be defined.

The stopping point relationship between the composing of coal and active C would bespeak that a mean for utilizing coals as an adsorbent, though possibly in greater measure, might economically supply comparable consequences with active C. Use of coal has advantages over usage of active C because of their handiness, lower cost and recovery of fuel value after exhaustion.


2.6.1 Adsorption

Adsorption is recognized as a important phenomenon in most natural physical, biological and chemical procedures. Sorption has widely used operation for purification of Waterss and waste Waterss. Some of import definition used in surface assimilation is given as ( Weber, 1972 ) :

Adsorbate: It is material acquiring adsorbed or being concentrated ( or being removed from one stage ) .

Adsorbent: It is the adsorbing stage on which the stuff is acquiring adsorbed.

Sorption: Include both surface assimilation and soaking up and it is general look for a procedure in which a constituent moves from one stage to be accumulated in another stage, peculiarly for the instances when 2nd stage is liquid.

Adsorption Equilibrium: In a solid liquid system during surface assimilation procedure, the solute from the solution is adsorbed at the surface of solid. This positive surface assimilation continues till the clip, when the concentration of solute staying in the solution achieves a dynamic equilibrium with the solute concentrated at the surface. However equilibrium is a map of many factor unrecorded concentration of solute of nature of solution, temperature of the solution.


Surface tenseness of liquid is a major factor causation, surface assimilation of solute solid because surface assimilations take topographic point at boundary of liquid stage. Hence is caused as an consequence of increased concentration of solute at the surface of liquid. The phases in the surface assimilation procedure are:

Film Diffusion: In this procedure the conveyance of surface assimilation molecules/ions through a surface movie to the outside of adsorbent takes topographic point.

Pore Diffusion: In this procedure the molecules diffuse in to and through pore infinites of the adsorbent.

Interparticle Transport: It is surface assimilation of active sites on surface jumping the inner pore infinite of the adsorbent. The slowest of these transport/reaction stairss controls the overall rate of consumption by adsorbate and depends on the method of contact. For ‘Batch Process ‘ pore diffusion controls the rate of reaction more. Besides for sufficient turbulency, conveyance of adsorbate within the pores is likely to command the overall dynamicss.


Adsorption capacity of an adsorbent is a complex map of many variables. Some known variables are being discussed here:

Nature of Adsorbate: Adsorption equilibrium is affected by solubility of solute. Decrease in the solubility of solute consequences in increased in surface assimilation. For effectual surface assimilation solute solvent bond must be broken.

A polar solute is strongly adsorbed from a nonionic dissolver by a polar adsorbent ( polar of an inorganic compound is a map of charge separation within the molecules ) . Water solubility is expected to increase with increasing mutual opposition, hence surface assimilation decreases as mutual opposition additions.

Molecular size of the solute influences the rate of surface assimilation and can be generalized with peculiar chemical category. This rate dependance on size is expected merely for quickly agitated batch reactors as it affects interparticle conveyance. Geometry of molecules may hold merely smaller consequence on equilibrium conditions. Adsorption rate is decreased with increasing molecular weight.

Ionization affects the surface assimilation rate. Maximum surface assimilation capacity is for impersonal species and structurally simple compounds. More compact molecules of a related brace are adsorbed more quickly.

Nature of Adsorbent: Pore size distribution governs the rate of conveyance of adsorbed species from exterior surface to interior surface. It is besides related to come up country, as the size distribution of molecular pores may find what part of the entire surface country will be eventually available for the surface assimilation of solute.

Adsorption capacity does increase with addition in pore size.

Particle size is another characteristic impacting the rate of surface assimilation, for surface assimilation on exterior surface of adsorbent.

Chemical nature of surface adsorbent has some consequence on adsorptive surface of C can be considered as non-polar but normally is somewhat polar due to interaction of O with C. This causes so called surface sourness of C.

Concentration of Solute in Solution: Adsorption capacity depend on concentration of solute in solution stage at changeless temperature and in a given system rate and capacity of surface assimilation additions with increasing with concentration of solute in solution stage.

Dose of Adsorbent: Rate and extent of surface assimilation vary with doses of adsorbent for a rangs so that no great difference in concentration of solute remains in bulk solution. Second variable is the concentration of adsorbate in the majority and is created for big differences in concentration of residuary solute.

Type of Control and Time of Contact: Batch commixture or uninterrupted flow system may be adopted. Rate of surface assimilation may differ in the two instances. Blending additions surface assimilation rate, but does non change the surface assimilation capacity.

Temperature: Adsorption reactions are usually exothermal. Extent of surface assimilation additions with decreasing temperature but rate of surface assimilation lessenings.

Competitive Interactions: Degree of common suppression of packing adsorbates is related to the comparative sizes of molecules, comparative surface assimilation affinities and comparative concentration of solute Total surface assimilation capacity may increase with assorted solutes due to competitory inter factors.



3.1 Materials and method

Sand with geometric mean size, GMS 0.5 millimeter and 1.0 millimeter, has been used in surface assimilation survey.

Preparation of Sample: Appropriate measures of FeSO47H2O solution are added to tap H2O to do man-made natural Waterss. Initial Fe concentration has been taken as mean of 0, 1, 2 hour. concentration.

Table – 4: Analysis of Tap Water

pH 7.5

Entire Iron nothing

Alkalinity 378 mg/l

Entire Hardness 194 mg/l

Calcium 128 mg/l

Dissolved Oxygen 7. mg/l

Sulphate 320 mg/l

Chlorides 210 mg/l

Conductivity 430. micromoh/cm

3.2 IRON DETERMINATION: Entire Fe, ferric Fe and dissolved Fe were determined by phenanthroline method ( APHA et al. 1981 ) as explained below:

Entire Iron:

Mix sample exhaustively and mensurate 50 milliliter in to a 125 milliliter volumetric flask.

Add 2 ml dressed ore HCL and 1.0 milliliters hydroxylamine solution

Add a few glass beads and heat to boiling until volume is reduced to 15 to 20 milliliters.

Cool to room temperature and transportation to a 50 or 100 milliliters nessler tubing.

Add 10 ml ammonium ethanoate buffer solution and 4 milliliters phenanthroline solution and dilute to tag with H2O.

Mix exhaustively and let at least 10 to 15 min. for maximal coloring material development.

Ferric Iron: Add 2.0 ml concentration HCL/100 milliliter sample at clip of aggregation instantly with pull a 50 ml part of acidified sample and add 20 ml phenanthroline solution and 10 milliliter ammonium ethanoate buffer solution with vigorous stirring. Dilute to 100 milliliter and step colour strength within 5 to 10 minute.


3.3.1 Adsorption:

The surface assimilation surveies along with the consequence of certain parametric quantities like initial Fe concentration, initial pH, contact clip, dosage of surface assimilation etc. For these surveies, 0.5 millimeter and 1.0 millimeter geometric mean size i.e. GMS of sand are used of adsorbents preselected sum of adsorbent has been contacted with 100 ml solution of Fe at assorted concentrations in a flask and agitated by stirred for coveted clip. After coveted agitation, solution are allowed to settle for 30 proceedingss and so passed through the filter paper prior to press finding.

3.3.2 Column Study:

The experiment has been conducted utilizing a 5.0 centimeter diameter column as shown in Figure 3.1. A pierced glass home base fixed in place is used as the support for the filter media. The overhead influent reservoir had a capacity of about 100 litres and provided about 100 centimeter of available caput.

Input solution


Output solution

Figure 3.1 Experimental set-up of column experiment.

All glass ware washed with concentration hydrochloric acid followed by lifting in pat and distilled H2O. Appropriate measure of the stock Fe solutions is added to tap H2O and assorted to do the man-made Fe bearing H2O. The conduction and pH of the H2O before and after adding the ferric sulfate solution are noted. The filtration rate was adjusted manually and maintained changeless during a tally. Effluent and inflowing sample are taken at coveted intervals and analyzed for Fe.



Some of the of import parametric quantities which have great consequence on the rate of surface assimilation, nature of adsorbent and adsorbate, contact clip, adsorbent dose initial Fe concentration, pH etc. The consequences of present work are presented in item. Similarly, for happening the consequence of contact clip, grain size, and pH at different flow rates are besides studied.


To happen out the Fe concentration at each phase of experiment, standardization of Fe solution is necessary. A secret plan between Fe concentration and optical density at wave length of 500 nanometer is shown in Table 4.1 and Figure 4.1.

TABLE – 4.1

Calibration of Iron Solution: Optical density Vs. Concentration of Iron ( Wavelength = 500 nanometer and pH = 7. 5 )

Sample Concentration ( mg/L )

Optical density

% Transmittance



















Figure 4.1. Plot between optical density and concentration of Fe.

The equation of line is

X = 7.57 y – 0.35 …………………… ……………… ( 4.1 )

Where ten = concentration of Fe in mg/l,

Y = optical density


The consequence of adsorbent dosage on Fe remotion efficiency changing from 1 gm/l to 20 gm/l has been shown in Tables 4.2 and 4.3 and Figures 4.2, 4.3 and 4.4.

Table – 4.2

Adsorption by 0.5 millimeter sand at initial Iron Concentration of 5 mg/l, initial pH = 7.5,

Contact clip = 2 hour and sample value = 100 milliliter

S. No.

Doses ( gm/l )

Iron Conc. after Adsorption ( Ce ) ( mg/l

Sum Adsorbed ( mg/l )

Percentage remotion of Fe




































Figure 4.2. Plot between adsorbent dosage and adsorbed Fe.

Figure 4.3. Plot between adsorbent dosage and per centum remotion of Fe.

Figure 4.2 indicates that as a dosage additions, the surface assimilation efficiency increases really quickly up to 8 gm/l but becomes slow beyond this dose. Figure 4.3 represents per centum remotion of Fe with regard to adsorbent dose. This may be attributed to the fact that with addition in adsorptive dosage, more and more adsorptive surface is available for solute to adsorb and this increases the per centum remotion. At higher dosage, nevertheless the surface assimilation becomes slow, as the big figure of atoms on stirring had more contact with each other, where the adsorbed Fe is partly removed.

It can be farther observed from the Figure 4.3 and 4.4 that at an initial concentration 5 mg/l of Fe, the maximal efficiency of remotion lessenings with the geometric mean size ( GMS ) of sand as at 0.5 millimeter, it is 97.6 % , at 1.0 millimeter GMS it is 95 % . The ground for this behaviour can be explained as an addition in geometric mean size, GMS of the sand for the same mass leads to diminish in surface country available for surface assimilation and hence lessening in per centum remotion.

Table – 4.3

Adsorption by 1.0 millimeter sand at initial concentration of 5 mg/l, initial pH = 7.5,

Contact clip = 2 hour, sample value = 100 milliliter.

S. No.

Doses ( gm/l )

Iron Conc. after Adsorption ( mg/L )

Sum Adsorbed ( mg/L )

Percentage remotion of Fe




































Figure 4.4. Plot between adsorbent dosage and per centum remotion of Fe.


The consequence of contact clip on Fe remotion efficiency has been shown in Tables 4.6, 4.7 and 4.8:

Table – 4.4

Consequence of contact clip on Percentage Fe remotion with pH = 7.5 ; GMS of sand = 0.5 millimeter, Initial conc. = 5 mg/l and Dose = 20gm/l

Time ( min. )

( 1 )

Iron conc. after surface assimilation ( mg/L )

( 2 )

% Removal ( P ) =

100* ( initial conc.- ( 2 ) ) /initial conc

























Figure 4.5 Plot between clip and per centum remotion of Fe.

Table – 4.5

Consequence of contact clip on per centum Iron remotion with pH = 7.5, GMS of sand = 1.0 millimeter, Initial concentration = 5 mg/l and Dose = 20gmsl

Time ( min. )

( 1 )

Iron conc. after surface assimilation ( mg/L )

( 2 )

% Removal ( P ) =

100* ( initial conc.- ( 2 ) ) /initial conc

























Figure 4.6 Plot between clip and per centum of Fe remotion

Table – 4.6

Consequence of concentration of contact clip on per centum Fe remotion with pH =7.5 ; GMS of Sand = 2.0 millimeter ; Initial concentration = 5 mg/l and Dose = 20gms/l

Time ( min. )

( 1 )

Iron conc. after surface assimilation ( mg/L )

( 2 )

% Removal ( P ) =

100* ( initial conc.- ( 2 ) ) /initial conc.




























Figure 4.7 Plot between clip and per centum of Fe remotion.

Tables 4.4 to 4.6 and matching Figures 4.5 to 4.7 indicate that as the contact clip additions, the surface assimilation efficiency besides increases really quickly upto clip of 60 proceedingss, but it become slow beyond this clip for all grain sizes of sand. The ground for this behaviour can be expressed as an addition in contact clip up to 60 minute Fe remotion is faster but after 60 proceedingss contact clip, surface assimilation and desorption becomes equal doing Fe remotion to be really slow. Besides the surface country available for surface assimilation reduces as most of the surface assimilation sites are saturated.


The consequence of pH changing from 4 to 10 has been shown in Table 4.7nand 4.8.

Table – 4.7

Consequence of Ph per centum Iron Removal Using Sand as Adsorbent In Removal Using Sand as per centum Iron Removal Using Sand As Adsorbent Initial Contact = 5 Mg/l, Contact clip = 2 hour. , DOSE = 10 mg/l GMS of sand = 0.5 millimeter


After surface assimilation concentration ( mg/L )

% Removal of Iron













Table 4.8

Geometric mean size, GMS of sand = 1.0 millimeter


After surface assimilation conc. Mg/l

% remotion













Table 4.7 and 4.8 indicate that as the pH is increased, the surface assimilation efficiency besides increases. This may be attributed to the fact that at lower pH below 4, the entire Fe in the initial Fe concentration of 5 mg/l may be expected to be in the soluble province and the remotion at lower pH become slow. Above pH 4 a portion of the Fe is oxides in the presence of dissolved O and the higher per centum remotion of Fe is obtained. However, per centum remotion of Fe is higher in instance of sand of GMS 0.5mm than compared to sand of GMS 1 millimeter.



Following decisions are drawn from the present work.

Two types of geometrical mean size ( GMS ) of sand, 0.5 millimeter and 1.0 millimeter adsorb Fe rather significantly but it has been seen that 0.5 millimeter sand is a better adsorbent.

At lower pH values of the Fe solution, the surface assimilation is slower, while with addition in pH value up to 10 surface assimilation additions.

Contact clip is besides one of of import parametric quantity. After a peculiar contact clip Fe remotion occurs at slower rate and smaller in measure. It is different for different grain size of adsorbents.

On increasing the adsorbent dosage, ab initio iron remotion is faster, it becomes about steady after a certain optimal dosage.

Finally, adsorptive stuff ( i.e. sand of geometric average size 0.5 millimeter ) is found successful for remotion of Fe up to 97.6 % from waste H2O without utilizing intervention works.

The present method is really simple and economical.


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