Final 2013 Sde Report

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PROJECT REPORT

ON

Study of Adsorption and Desorption of m-Cresol using activated

charcoal

BY

MUDIT JAJODIAClass Roll No. 095660

Examination Roll No. 09126004051

Registration No. 091260110250

UNDER THE GUIDANCE OF

Ms. Sudipta DeyProfessor

Department of Biotechnology

Heritage Institute of Technology, Kolkata

HERITAGE INSTITUTE OF TECHNOLOGY

Kolkata 700 107, INDIA

Affiliated To:WEST BENGAL UNIVERSITY OF TECHNOLOGY

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INDEX

Serial no. Topic Page no.

1. Abstract 4.

2. Chapter1:Introduction 6.-13.

3. Chapter2:Experiment 14.-20.

4. Chapter3:Results and

Discussions

21.-41.

5. Future Prospects 42.

6. References 42.-45.

ACKNOWLEDGEMENT

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It is a pleasure to acknowledge the assistance received from several individuals during

the preparation of this project report. First of all, I would like to convey my heartfelt

gratefulness to my respected teacher and research supervisor Mrs. Sudipta Dey,Department of

Biotechnology, of Heritage Institute of Technology, Kolkata, who introduced me to the world

of research and development with great enthusiasm and patience.

I am greatly indebted to Ms.Deepa Hariharan,Technical Assistant,Department of

Biotechnology, Heritage Institute of Technology, Kolkata for her kind guidance, valuable

suggestions and constant encouragement from the very beginning without which this project

would have been an impossible task.

I am also thankful to all faculty members, technical and non technical staff of the same

department of their help whenever I needed it.

I find no words to express my feelings for my parents and my brother whose moral

support, love and constant encouragements have helped me to complete this journey. Their

patience and sacrifice have always been a main source of my inspiration motivating me to

pursue higher goals. I wish to extend my sincere gratitude to my all relatives for their

blessings.

Place:Kolkata Mudit Jajodia

Date:

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ABSTRACT

Fresh water crisis has been emerged as one of the most acute issues in the current global

scenario, forcing the waste water reutilization concept a must. The reutilization of waste wateragain demands proper yet effective treatment. Among organic contaminants of waste water m-

Cresolic compounds are the principal components, which due to its toxic and carcinogenic

nature forces people for its removal from waste water. Adsorption being the highly efficient,

simple, cost effectiveness and the availability of a wide range of adsorbents is used as one of

the most indispensable method for treatment of m-Cresolic waste water.

In the present study,different types of activated carbons can be used as adsorbants available

from different sources. For batch adsorption process, operating variables studied were

adsorbent dose, contact time, initial m-Cresol concentration, and different shaker speed.

Sorption experiments indicated that the sorption capacity was dependent on operatingvariables.Kinetic measurements showed that the process was uniform and rapid. In order to

investigate the mechanism of sorption, kinetic data were fitted in pseudo-first-order and

pseudo-second-order kinetic equations. Among the kinetic models studied, the pseudo-second-

order equation was the best applicable model to describe the adsorption process of m-Cresol

onto the adsorbent. Equilibrium isotherm data were analyzed using the Langmuir, isotherms.

Isotherm parameters can also be used to obtain the thermodynamic parameters such as free

energy, enthalpy, and entropy of sorption.Desorbtion of m-cresol from the activated charcoal

was also done acid and alkaline solution.

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INTRODUCTION5

This chapter presents the general framework of investigation on m-Cresol.


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Classification of Activated Carbon:-

Powdered activated carbon (PAC)

Traditionally, active carbons are made in particulate form as powders or fine granules less than 1.0 mm in size

with an average diameter between .15 and .25 mm. Thus they present a large surface to volume ratio with a

small diffusion distance. PAC is made up of crushed or ground carbon particles, 95100% of which will pass

through a designated mesh sieve. Granular activated carbon is defined as the activated carbon retained on a50-mesh sieve (0.297 mm) and PAC material as finer material, while ASTM classifies particle sizes

corresponding to an 80-mesh sieve (0.177 mm) and smaller as PAC.

Granular activated carbon (GAC)

Granular activated carbon has a relatively larger particle size compared to powdered activated carbon and

consequently, presents a smaller external surface. Diffusion of the adsorbate is thus an important factor. These

carbons are therefore preferred for all absorption of gases and vapors as their rate of diffusion are faster.

Granulated carbons are used forwater treatment, deodorization and separation of components of flow system

and is also used in rapid mix basins. GAC can be either in granular or extruded form. GAC is designated bysizes such as 820, 2040, or 830 for liquid phase applications and 46, 48 or 410 for vapor phase

applications. A 2040 carbon is made of particles that will pass through a U.S. Standard Mesh Size No. 20

sieve (0.84 mm) (generally specified as 85% passing) but be retained on a U.S. Standard Mesh Size No. 40

sieve (0.42 mm) (generally specified as 95% retained). AWWA (1992) B604 uses the 50-mesh sieve

(0.297 mm) as the minimum GAC size. The most popular aqueous phase carbons are the 1240 and 830

sizes because they have a good balance of size, surface area, and head loss characteristics.

Extruded activated carbon (EAC)

Extruded activated carbon combines powdered activated carbon with a binder, which are fused together andextruded into a cylindrical shaped activated carbon block with diameters from 0.8 to 130 mm. These are

mainly used for gas phase applications because of their low pressure drop, high mechanical strength and low

dust content.

Bead activated carbon (BAC)

Bead activated carbon is made from petroleum pitch and supplied in diameters from approximately 0.35 to

0.80 mm. Similar to EAC, it is also noted for its low pressure drop, high mechanical strength and low dust

content, but with a smaller grain size. Its spherical shape makes it preferred for fluidized bed applications such

as water filtration.

Polymer coated carbon

This is a process by which a porous carbon can be coated with a biocompatiblepolymerto give a smooth and

permeable coat without blocking the pores. The resulting carbon is useful forhemoperfusion. Hemoperfusion

is a treatment technique in which large volumes of the patient's blood are passed over an adsorbent substance

in order to remove toxic substances from the blood.

Other

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http://en.wikipedia.org/wiki/Mesh_(scale)http://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/Absorption_(chemistry)http://en.wikipedia.org/wiki/Water_treatmenthttp://en.wikipedia.org/wiki/Hydraulic_head#Head_losshttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Hemoperfusionhttp://en.wikipedia.org/wiki/Mesh_(scale)http://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/Absorption_(chemistry)http://en.wikipedia.org/wiki/Water_treatmenthttp://en.wikipedia.org/wiki/Hydraulic_head#Head_losshttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Hemoperfusion


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Activated carbon is also available in special forms such as cloths and fibres. The "carbon cloth" for instance is

used in personnel protection for the military.

Properties of Activated Carbon:

A gram of activated carbon can have a surface area in excess of 500 m 2, with 1500 m2 being readily

achievable.Individual particles are intensely convoluted and display various kinds ofporosity; there may be many areas

where flat surfaces ofgraphite-like material run parallel to each other, separated by only a few nanometers or

so. These microporesprovide superb conditions foradsorption to occur, since adsorbing material can interact

with many surfaces simultaneously.

Physically, activated carbon binds materials by van der Waals forceorLondon dispersion force.

Activated carbon does not bind well to certain chemicals, including alcohols, glycols,

strong acids andbases, metalsand most inorganics such as lithium, sodium, iron,lead,arsenic,fluorine, and

boric acid.

Activated carbon does adsorb iodine very well and in fact the iodine number, mg/g, (ASTM D28 StandardMethod test) is used as an indication of total surface area.

Carbon monoxide is not well adsorbed by activated carbon. This should be of particular concern to those using

the material in filters for respirators, fume hoods or other gas control systems as the gas is undetectable to the

human senses, toxic to metabolism and neurotoxic.

Substantial lists of the common industrial and agricultural gases absorbed by activated carbon can be found

online.

Activated carbon can be used as a substrate for the application of various chemicals to improve the adsorptive

capacity for some inorganic (and problematic organic) compounds such ashydrogen sulfide (H2S), ammonia

(NH3), formaldehyde (HCOH), radioisotopesiodine-131(131I) and mercury(Hg). This property is knownas chemisorption.

Effects of m-Cresol:

m-Cresol ,leads to serious environmental contamination due to its toxicity towards aquatic biota.Short-termeffects reported include respiratory irritation, headaches, and burning eyes. Chronic effects of high exposures

included weakness, muscle pain, anorexia, weight loss, and fatigue; effects of long-term low-level exposures

included increases in respiratory cancer, heart disease, and effects on the immune system. Virtually all of the

workplace exposures associated with these effects involved exposures to other chemicals; thus, it is difficult to

determine whether these are solely due to m-Cresol, or are the result of mixed, multiple, or other chemical

exposures.

Health hazards caused by m-Cresol:

Exposure mode Effects due to exposure

8
http://en.wikipedia.org/wiki/Porosityhttp://en.wikipedia.org/wiki/Porosityhttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Microporehttp://en.wikipedia.org/wiki/Microporehttp://en.wikipedia.org/wiki/Adsorptionhttp://en.wikipedia.org/wiki/Van_der_Waals_forcehttp://en.wikipedia.org/wiki/Van_der_Waals_forcehttp://en.wikipedia.org/wiki/London_dispersion_forcehttp://en.wikipedia.org/wiki/Alcoholhttp://en.wikipedia.org/wiki/Glycolhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Inorganichttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Arsenichttp://en.wikipedia.org/wiki/Arsenichttp://en.wikipedia.org/wiki/Fluorinehttp://en.wikipedia.org/wiki/Fluorinehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Iodine_valuehttp://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Iodine-131http://en.wikipedia.org/wiki/Iodine-131http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Chemisorptionhttp://en.wikipedia.org/wiki/Porosityhttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Microporehttp://en.wikipedia.org/wiki/Adsorptionhttp://en.wikipedia.org/wiki/Van_der_Waals_forcehttp://en.wikipedia.org/wiki/London_dispersion_forcehttp://en.wikipedia.org/wiki/Alcoholhttp://en.wikipedia.org/wiki/Glycolhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Inorganichttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Arsenichttp://en.wikipedia.org/wiki/Fluorinehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Iodine_valuehttp://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Iodine-131http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Chemisorption


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Inhalation Can irritate the nose, throat, and lungs.

Higher exposures may cause a build-up of fluid in the lungs.

Oral Ingestion of as little as 1 gram can be fatal to humans.

Eyes Can also cause blindness.

Skin Irritating and corrosive to the skin. Little or no pain may be felt on initial contact due to its local

anaesthetic effect.

Skin contact will cause the skin to turn white; later severe burns

may develop.

Rapidly absorbed through the skin; toxic or fatal amounts can

be absorbed through relatively small areas.

Chronic exposure prolonged exposure causes dizziness, vomiting.

Exposure to m-Cresol:

Populations residing near m-Cresol spills, waste disposal sites, or landfill sites may be at risk for higher

exposure to m-Cresol than other populations. If m-Cresol is present at a waste site near homes that have wells

as a source of water, it is possible that the well water could be contaminated. If m-Cresol is spilled at a waste

site, it is possible for a person, such as a child playing in dirt containing m-Cresol, to have skin contact or to

swallow soil or water contaminated with m-Cresol. Skin contact with m-Cresol or swallowing products

containing m-Cresol may lead to increased exposure. This type of exposure is expected to occur infrequently

and generally occurs over a short time period.

Adsorption:

By definition adsorption is the phenomenon of concentration or assimilation of gas (or liquid) at the surface

of a solid (or liquid) with which it is in close proximity or contact called adsorption. Adsorption arises as a

result of the unsaturated and unbalanced molecular forces that are present on every solid surface. Thus, when a

solid surface is brought into contact with a liquid or gas, there is an interaction between the fields of forces of

the surface and that of the liquid or the gas. The solid surface tends to satisfy these residual forces by

attracting and retaining on its surface the molecules, atoms, or ions of the gas or liquid, adsorption is

associated with decrease in residual surface energy. The molecules which are adsorbed are called adsorbates

and the surface is called as adsorbent. This process creates a film of the adsorbate (the molecules or atoms

being accumulated) on the surface of the adsorbent. The process of adsorption of gases into the solid surface is

called occlusion. The adsorption involves two types of forces: physical forces that may be dipole moments,

polarizationforces, dispersive forces, or short range repulsive interactions and chemical forces are valency forces arising

out of the redistribution of electrons between the solid surface and the adsorbed atoms. Depending upon the

nature of the forces involved, the adsorption is of two types: physical adsorption and chemisorption. In the

case of physical adsorption, the adsorbate is bound to the surface by relatively weak van der Walls forces,

which are similar to the molecular forces of cohesion and are involved in the condensation of vapours into

liquids. Chemisorption, on the other hand, involves exchange or sharing of electrons between the adsorbate

molecules and the surface of the adsorbent resulting in a chemical reaction. The bond formed between the

adsorbate and the adsorbent is essentially a chemical bond and is thus much stronger than in the

physiosorption. Physiosorption and chemisorption again differ from each other due to following two

differences namely, magnitude of the enthalpy of adsorption , in physical adsorption the enthalpy ofadsorption is of the same order as the heat of liquefaction and does not usually exceed 10 to 20 KJ per mol.,

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whereas in chemisorptions the enthalpy change is generally of the order of 40 to 400 KJ per mol. Taking into

account specificity physical adsorption is nonspecific and occurs between any adsorbate-adsorbentsystems, but chemisorption is specific. Another important point of difference between physiosorption and

chemisorption is the thickness of the adsorbed phase although it is multimolecular in physiosorption and isunimolecular in chemisorptions.Some of the potent adsorbents are charcoal, silica gel, clay, fuller s earth,alumina gel,zeolites .

Desorption:

The ability of activated carbon to adsorb compounds at low concentrations has made it common adsorbent in

wastewater treatment and other industrial applications. However, the economics of the carbon adsorption

process depends very much on the method of regeneration. The reverse process of adsorption is called

desorption in which the adsorbed substances are removed from the surface. In case of spent carbon with a

large quantity of adsorbate, regeneration by chemical treatment is economically more attractive then

commonly employed thermal method.

Desorption is a phenomenon whereby a substance is released from or through a surface. The process is the

opposite ofsorption (that is, either adsorption or absorption). Although adsorption of phenolic compounds

onto adsorbents such as granular activated carbon (GAC) and polymeric resins is relatively simple, the process

of regenerating the adsorbent by desorption of the organic adsorbate still poses a major challenge to workers

in this field, notably because of the high affinity of the compounds to the sorbent surface. The high initial cost

of these adsorbents adds to the importance of the problem of sorbent regeneration. The most common

techniques for desorption of phenol from activated carbon are thermal regeneration .The thermal regeneration

method suffers from severe drawbacks, such as the requirement of high temperatures of the order of 300-

500C and excessive burnout of the carbon, resulting in capacity losses of 5-15%.Chemical regeneration, the

other most common method. Chemical treatment is also more attractive because of its cost effectiveness. In

this study, we treated the spent activated carbon with mainly two chemicals i.e. sodium hydroxide solution

(NaOH) and hydrochloric acid (HCl).

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Figure showing the process of adsorption and desorption

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Materials Required in carrying out the process:

m-Cresol.

4-Aminoantipyrene.

Liquour Ammonia.

Potassium Ferricyanide.

Spectrophotometer.

Shaker-set at different speed.

pH paper.

Sample Preparations:

1)Reagents:

(i)4-Aminoantipyrene=0.4gm in 20ml of water(20%).

(ii)Ammonium hydroxide=1.0ml in 49.0ml of water.(iii)Potassium ferricyanide=1.6gm in 20ml of water(8%).

(iv)Stock solution=0.2gm of m-Cresol in 100ml of water.

2)Solutions:

(ii)Basic solution(NaOH solution):Stock solution was prepared using 2gm of NaOH pellets in 100gm of water.

(iii)Acidic solution(HCl solution):

Stock solution was prepared using 0.8ml of HCl mixed with 99.2ml of water.

Standard for whole experiment:

Concn. Water Stock solution of m-Cresol100ppm 95.0ml 5.0ml

200ppm 90.0ml 10.0ml

300ppm 85.0ml 15.0ml

400ppm 80.0ml 20.0ml

500ppm 75.0ml 25.0ml

600ppm 70.0ml 30.0ml700ppm 65.0ml 35.0ml

800ppm 60.0ml 40.0ml

900ppm 55.0ml 45.0ml

1000ppm 50.0ml 50.0ml

Reagents addition: 1.25ml of Sodium hydroxide.

0.5ml of 4-Aminoantipyrene. 0.5ml of Potassium ferricyanide.

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Methods:

1.For standard curve of m-cresol:

Stock solutions of 4-aminoantipyrene(20%),m-Cresol(2%),liquid ammonia,Potassium

ferrocyanide(8%) was prepared.

m-Cresol of 100ml is prepared.

3 flasks are taken separately in which-0.3gm,0.6gm and 0.9gm of activated charcoal are added.

The mouth of the flasks are covered and they are kept on the shaker.

After 15 minutes on the shaker,5ml of the samples is taken out by pipette.Whatman paper is used to

filter out the charcoal deposits.

45 ml of Water is added to the sample.

To each sample,first 1.25ml of ammonia solution is added.

Then solution of antipyrene is added,0.5ml.

Then to them is Potassium Ferricyanide is added.

A reddish tinge is obtained.

O.D. value is measured at 490nm.

2.For Adsorbtion process:

In conical flasks,stock solution of m-Cresol and water was added(according to the

required concetration).

Then charcoal was added according to the required concentration.The whole setup is

then kept on a shaker for 15 minutes and rpm is set.

After 15minutes,5ml of that sample is filtered out.To that clear solution,1.25ml of liquid

Ammonia,0.5ml 0f 4-Aminoantipyrene and 0.5ml of Potassium ferricyanide was added.A red coloured tinge is obtained which is dependent and proportional to the concentration of m-Cresol

being added.

Meanwhile,a Blank is also prepared which should not have a red tinge.Then the O.D.

Value is calculated on a spectrophotometer at 490nm.

This experiment is repeated for every batch until the equilibrium or steady state is occurred.

Varying m-cresol conc.-300,500,600,700 ppm

Variyng Charcoal conc.-0.3 gm and 0.6 gm

Variyng shaker speed-48 and 76 rpm

3.For Desorption process:

For alkaline pH- Different m-Cresol solution was prepared and 0.3 gm charcoal was added.

The conical flask was kept in shaker at constant speed until maximum adsorbtion is achieved.

The solution was filtered in another flask with the help of whatmann filter paper.

The filter paper used for adsorption was dipped in alkaline solution at pH 10.

Than OD was measured at 280nm in uv spectrophotometer.

The same process was repeated for different m-cresol solution of concentration -300,500,600,700 ppm

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For Basic pH-

The step was same as that of alkaline pH except that the adsorbed whatmann paper was

dipped in a basic solution at pH 2.

Results:

Table.1:To plot the standard curve for m-Cresol,the following datas were obtained:

Sl no. Concn. of m-

Cresol

Vol. of m-

Cresol

Vol. of water O.D.

1 5ppm 0.01ml 50.0ml 0.01

2 10ppm 0.25ml 49.75ml 0.24

3 20ppm 0.50ml 49.50ml 0.374 30ppm 0.75ml 49.25ml 0.74

5 40ppm 1.00ml 49.00ml 1.30

From the standard curve,the following results were obtained:

Charcoal

concn.

OD

15

Concn.

of

m-

cresol

O.D.

30

Concn.

of

m-

cresol

O.D.

45

Concn.

of

m-

cresol

O.D.

60

Concn.

of

m-

cresol

0.3gm 0.20 0.19 0.07 0.02 0.01 0 0.01 0

0.6gm 0.08 0.04 0.02 0.01 0.03 0.01 0.03 0.01

0.9gm 0.10 0.08 0.09 0.06 0.00 0 0.00 0

After doing the assay of m-Cresol,the activity of adsorption of m-Cresol at different concentrations and at

different speed were studied.The results which were obtained were as follows:

Table.2:

(i) 0.3gm of charcoal at 48rpm

Concn. OD at 15 OD at 30 OD at 45 OD at 60

300ppm 0.48 0.00 - -

500ppm 0.65 0.00 - -

600ppm 0.58 0.58 0.61 0.58

700ppm 0.84 0.78 0.73 0.73

(ii)0.3gm of charcoal at 76rpm

Concn. OD at15 OD at 30 OD at 45 OD at 60

300ppm 0.00 - - -

500ppm 0.08 - - -

600ppm 0.16 0.18 0.09 0.00

700ppm 0.54 0.19 0.15 0.06

(iii)0.6gm of charcoal at 48rpmConcn. OD at15 OD at 30 OD at 45 OD at 60

300ppm 0.11 0.31-0.30=0.01

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500ppm 0.78 0.32 0.09 0.22 0.04

600ppm 0.22 0.36-0.30=0.06

700ppm 0.88 0.66 0.25 0.33 0.15

(iv)0.6gm of charcoal at 76rpm

Concn. OD at15 OD at 30 OD at 45 OD at 60

300ppm 0.00 - - -

500ppm 0.05 - - -600ppm 0.04 0.00 0.00 0.00

700ppm 0.02 0.00 0.00 0.00

Table.3:

Standard curve for Desorption study:

Concn. Of m-cresol Water Stock of m-cresol O.D. value

10ppm 99.5ml 0.5ml 0.05

20ppm 99.0ml 1.0ml 0.11

30ppm 98.5ml 1.5ml 0.20

40ppm 98.0ml 2.0ml 0.26

50ppm 97.5ml 2.5ml 0.32

Table.4:

Study of desorption using NaOH solution at pH=10 and charcoal taken was 0.3gm at 76rpm

Concentration O.D after 1hour O.D. at 24hrs

after 50%

dilution300ppm 0.742 0.451

500ppm 0.566 0.772

600ppm 0.885 0.973

700ppm 0.914 0.552

Table.5:

Study Of desorption using acidic solution ( HCl solution) at pH=1.5 and charcoal taken was 0.3gm at 76rpm.

Concentration O.D. at 1hour O.D.value after 24hrs

300ppm 0.075 0.094

500ppm 0.224 0.245

600ppm 0.373 0.391

700ppm 0.068 0.129

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The standard curve :

A standard curve is a general method for determining the concentration of a substance in an unknown sample

by comparing the unknown to a set of standard samples of known concentration.

For adsorption:

For desorption:

The percentage removal of m-cresol was calculated by the following equation,

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%R=((C0-Ct))*100

C0where,

C0=initial m-Cresol concentration.

Ct=final m-Cresol concentration.

%R=percentage of adsorption.

For Adsorption:

Study of various parametric effects on adsorption of m-cresol onto activated charcoal

A: Effect of phenol concentration on its own adsorption:

Percentage(%)recovery:

(i)0.3gm of charcoal at 48rpm:

Initial concentration Final concentration % adsorption

300ppm 20ppm 93.33%

500ppm 27ppm 94.60%

600ppm 24ppm 96.00%

700ppm 30ppm 95.71%

% adsorption

80

85

90

95

100

300 500 600 700

m-cresol conc.(ppm)

%a

dso

rpti

From the graph it is otained that at 600 ppm maxium adsorption of m-cresol take place i.e 96%.for 600ppm

and 700 ppm the adsorbtion was nearly equal.as conc of m-cresol increase adsorption process is also increase.

ii)0.6gm of charcoal at 48rpm:


300ppm 1ppm 99.60%500ppm 4ppm 99.20%

600ppm 4ppm 99.30%

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700ppm 7ppm 99.00%

% adsorption

80

85

90

95

100

300 500 600 700

m-cresol conc.(ppm)

%a

dso

rp

For 0.6 gm charcoal conc at 48rpm,the %adsorption of m-cresol was almost same for the diff. m-cresol

conc.the maximum %adsorbtion was take place for 300ppm m-cresol conc.further increase in conc. The

%adsorbtion of m-cresol was decrease .

(iii)0.3gm of charcoal at 76rpm:


300ppm 0ppm 100.00%

500ppm 4ppm 99.20%

600ppm 5ppm 99.17%

700ppm 4ppm 99.43%

% adsorption

80

85

90

95

100

300 500 600 700

m-cresol conc.(ppm)

%a

dsorpt

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For 0.3 gm charcoal at 76 rpm,adsorbtion of m-cresol is 100% for 300ppm of m-cresol,,further increase in

concentration the adsorbtion of m-cresol was decrease very minutely.

(iv)0.6gm of charcoal at 76rpm:Initial concentration Final concentration % adsoption

300ppm 0ppm 100.00%

500ppm 2ppm 99.60%

600ppm 4ppm 99.33%

700ppm 1ppm 99.86%

% adsorption

80

85

90

95

100

300 500 600 700

m-cresol conc.(ppm)

%a

dsorp

For 0.6 gm charcoal conc at 76rpm,the %adsorption of m-cresol was almost equal for the diff. m-cresol

conc.the maximum %adsorbtion was take place for 300ppm m-cresol conc.

: Effect of Contact time for adsorption of m-cresol onto activated charcoal :

Adsorption of 0.3 gm charcoal at 46 rpm-

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adsorption of 500ppm m-crersol

0

100

200

300

400

500

600

o 15 30 45 60

adsoption 0f 600ppm m-cresol

0

100

200

300

400

500

600

700

o 15 30 45 60

time(min)

adsorbedconc.ofm-cresol(ppm)

adsorption of 700ppm m-cresol

0

100

200

300

400

500

600

700

800

o 15 30 45 60

time(min)

adsorbedconc.ofm-cresol(ppm)

The results showed that equilibrium time required for the adsorption of m-cresol onto activated charcoal was

30min . However, the results also indicated that up to 95% of the total amount of phenol uptake was found to

occur in the first 15.

22


0

50

100

150

200

250

300

350

o 15 30 45 60

time(min)

adsorbedm-cres

ol

conc.(

ppm

)


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Adsorption of 0.3 gm charcoal at 76 rpm:

adsorption of300ppmm-cresol

0

50

100

150

200

250

300

350

o 15 30 45 60

time(min)


0

100

200

300

400

500

600

o 15 30 45 60

time(min)

adsorbedconc.

ofm-cresol(ppm

)


0

100

200

300

400

500

600

700

o 15 30 45 60

time(min)

adsorbedconc.o

fm-cresol(ppm)


0

100

200

300

400

500

600

700

800

o 15 30 45 60

time(min)

adsorbedconc.

ofm-cresol(ppm)

The results showed that equilibrium time required for the adsorption of m-cresol onto activated charcoal was

15min. The result also showed that upto 600ppm ,100%(approx) adsorption take place.

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For Desorption:

(i)Using Basic Solution(pH=10) (ii)Using Alkaline solution(pH=2)

Initial

concentration

% recovery

after 1hr

% recovery

after 24hrs.

300ppm 4.33% 5.67%

500ppm 7.20% 8.0%

600ppm 10.00% 10.9%

700ppm 10.2% 11.4%

Fig.7:desorption of m-cresol in basic solution fig.8:desorption of m-cresol in acidic solution

26

Initial

concentation

% recovery

after 1hr

% recovery

after 24hrs.

300ppm 28% 39%

500ppm 18% 24.8%

600ppm 22% 26%

700ppm 20.7% 25%


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As we see from the above graph the desorption process of m-cresol is maximum in case of basic solution.

As the concn. of m-cresol is increase,the % desorption is decrease in basic solution. But for desorption study

in acidic solution it was found that with increase in initial m-cresol concentration, % desorption increased and

became steady at 500 and 700 ppm.

Langmuir isotherm model:

The most widely used isotherm equation for modelling of the adsorption data is the Langmuir

equation, which is valid for monolayer sorption onto a surface with a finite number identicalsite and is given by following equation,

qe=qoKLCe1+KLCe

Where ,

qo and Kl = Langmuir parameters related to maximum adsorption capacity and free

energy of adsorption, respectively.

C =equilibrium concentration in the aqueous solution and

x =equilibrium adsorption capacity of adsorbent.

The linearized form of Langmuir equation can be written as,

1/x=1/ q0+(1/qoKL).1/C

The Langmuir constant q0 and KL can be calculated by plotting 1/qe versus 1/Ce.

Table: Study Of Langmuir Isotherm

O.3gm charcoal at 48rpm

X 1/X C 1/C93.33 0.01 20 0.05

157.6 0.006 27 0.04

192 0.005 24 0.04

223 0.004 30 0.03

0.3gm charcoal at 76rpm:

X 1/X C 1/C

100.0 0.01 1 1.00

165.3 0.006 4 0.25

198.3 0.005 5 0.2

232 0.004 4 0.25

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0.6gm charcoal at 48rpm:

X 1/X C 1/C

49.83 0.02 1 1.0

82.6 0.01 4 0.25

99.3 0.01 4 0.25

115.5 0.008 7 0.18

0.6gm of charcoal at 76rpm:

X 1/X C 1/C50 0.02 1 1

83.0 0.01 2 0.5

99.3 0.01 4 0.25

116.5 0.008 5 0.2

Graphs for Langmuir Isotherm:

1. Varying The rpm(48rpm and 76rpm) at constant amount of charcoal(0.3 gm)

Datas obtained:

qo KL

232 0.8

2.Varying the rpm(48rpm and 76rpm) at constant amount of charcoal(0.6gm)

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Datas obtained:

qo KL200 0.3848

Study of reaction kinetics:

Adsorption kinetics study for m-cresol on activated charcoal:

0.3 gm at 48 rpm:

y = 0.005x + 0.0277R2 = 0.7101

y = 0.006x + 0.0018

R2 = 0.9987

y = 0.0052x + 0.0001

R2 = 1

y = 0.0045x + 0.0003

R2 = 1

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 10 20 30 40 50 60 70

t

t/q

300 PPM

500 PPM

600 PPM

700 PPM

Linear (300 PPM)

Linear (500 PPM)

Linear (600 PPM)

Linear (700 PPM)

Data obtained:

C qe,exp qe,cal R 2 K

300 100 200 0.7101 0.0009500 166.7 166.7 0.9987 0.019

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600 192 192.3 1 0.027

700 223.3 222.3 1 0.067

From the above graph and calculated data it is obtain that qe,exp and qe,cal value are almost same except for

300ppm m-cresol conc. And value of R2 is obtained 1 for all other conc. except for 300ppm.So for 0.3 gm

charcoal conc. at 48 rpm the reaction kinetic follow second order kinetic.

0.3gm at 76 rpm:

y = 0.01x + 0.0028

R2 = 0.9998

y = 0.0101x + 0.0048

R2 = 0.9997

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 20 40 60 80

t

t/q

600

700

Linear

(600)

Linear

(700)

Data obtained:


600 100 100 0.9998 0.035

700 99 99 0.9997 0.021

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From the graph and obtained data it is clear that for 0.3 gm charcoal conc. at 76 rpm,adsorbtion process follow

second order kinetic and the value of R2 is 1.

0.6 gm at 48 rpm:

y = 0.0201x + 0.0013

R2 = 0.9999

y = 0.0201x + 0.0169

R2 = 0.9993y = 0.0202x + 0.0003

R2 = 1

y = 0.0189x + 0.0554

R2 = 0.9463

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 10 20 30 40 50 60 70 80

t

t/q

300

500600

700

Linear (300)

Linear (500)

Linear (600)

Linear (700)

Datas obtained:


300 49.83 49.75 0.3108 0.9999

500 49.66 49.75 0.0239 0.9993

600 49.5 49.5 1.36 1

700 49 0.006 0.9463

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From the above graph and obtained data,it is seen that for 0.6gm charcoal conc at 48 rpm,the value of q e,exp

and the value of qe,cal is almost equal and the value of k is 1.hence for 0.6 gm charcoal conc. At 48 rpm,the

adsorbtion process follow second order kinetic.

Conclusions

As the shaker speed increase,the adsorption of m-cresol on activated charcoal was

increased and the time required for maximum adsorbtion is decrease.

Adsorbant conc. also effect the adsorbtion process.

As m-cresol conc. increase,the % adsorbance is also increase.

With the lower charcoal concentration and higher speed of rotation, % adsorption is

more.

With the higher charcoal concentration and lower speed of rotation, % adsorption is

less.

With the higher charcoal concentration and higher speed, % adsorption is more.

The kinetics studies confirmed that Phenol-GAC adsorption system can be described bypseudo- second-order kinetics model.

Over all analysis of equilibrium model analysis indicates the fitness of Langmuir

isotherm model to Phenol-GAC adsorption system, suggesting a monolayer adsorption

of phenol on the surface of GAC.

Desorption is very less at acidic pH activity and moderate in alkaline solution.

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