11
CHAPTER 2
LITERATURE REVIEW
2.1 INTRODUCTION
In this chapter the literature available within the purview of the
objectives of the present study is reviewed. The need for the proposed work is
also discussed.
2.2 REMOVAL OF CONTAMINANTS USING ORGANIC
ADSORBENTS
Shokoohi et al (2009) have studied the influence of various
experimental parameters such as initial iron concentration, dosage of biomass
and contact time in removing iron from the aqueous solution by using dried
biomass of activated sludge. From the study it was inferred that when the
concentration was 2 mg/L the removal efficiency was 70% and subsequently
it decreased to 56% when the concentration of the solution was increased.
Shokoohi et al (2009) have concluded that the above influence is due to the
driving force of the concentration gradient, and increase in initial iron
concentration.
Rakhi Gopalan (2007) has investigated the adsorption of hexavalent
Chromium from the chrome plating industry effluent using tapioca peel
carbon. Both batch and column experiments were conducted and the optimum
pH and dosage were found to be 3 and 400 mg respectively. The removal
efficiency was found to be 82% based on the experiments. They have
12
concluded that tapioca peel carbon is more effective in removing Chromium
from wastewater.
Tiwari et al (1995) have investigated the removal of Mercury (II)
from the aqueous solution using the rice husk ash. Both batch and column
experiments were conducted and in the column experiment a circular column
was used and the flow rate was varied from 20-45 mL/min and the pH of the
solution was maintained at 5.5. The study revealed that the adsorption
efficiency decreases with increase in particle size.
Mansour et al (2011) have investigated the removal of Cu (II) ion
from wastewater by adsorption onto polyaniline coated on sawdust. The
concentration of the metal solution was ranged from 5 mg/L to 40 mg/L. The
pH range was 2-8. The adsorption capacity was found to be strongly
dependent on the initial pH of the solution. The adsorption of Cu (II) ions was
significant with the slight increase in pH. The optimum pH was found to be 6
and optimum contact time was 20 minutes. It is found that the sorption
capacity is strongly dependent on the initial concentration and initial pH of
the solution.
Tarek Abdel et al (2000) have carried out a research work on
Fluoride removal from drinking water using activated carbon prepared from
naturally occurring zeolites and molecular sieves. Aqueous solution was
prepared from sodium solution. The initial fluoride concentration was 10mg/l
and the dosage of the adsorbent was 4g/l. It was found that the equilibrium
condition was reached within 48 hours for all combination of adsorbent. It
was found that char fines and bentonite exhibit a removal capacity of 38%
and 40% respectively.
Hameed et al (2009) have studied the effect of pH on the adsorbing
capacity of dye using agricultural waste. pH was varied from 2 to 10 and it
13
was found that the adsorbing capacity increased from 13.29 mg/g to
104.50 mg/g when the pH varied between 2 and 10 .The authors used
pineapple stem for removing cationic dye and studied the potentiality of its
usage. The surface texture of the adsorbent was studied using Scanning
Electron Microscope before and after adsorption and Fourier Transform Infra
Red analysis was applied and the spectra was recorded. From the study, the
results indicate that pineapple stem was very effective in its adsorbent
property.
Danica Barlokova et al (2009) have made studies on the removal
of Iron and Manganese from small water sources by passing the raw water
containing Iron and Manganese through the filtration materials namely
Klinopur-Mn, (activated zeolite), Birm (granulated filter medium) and green
sand. From the study it was found that Kilnopur - Mn was effective in
removing both Iron and Manganese, but the other materials showed lower
efficiency in Manganese removal and found to be effective in Iron removal.
Manjeet Bansal et al (2008) studied the removal of Cr (IV) from
aqueous solution using rice husk. He used two forms of rice husk namely
boiled rice husk and formaldehyde treated rice husk. He conducted batch
studies by varying the parameters such as pH, dosage and agitation speed. The
initial concentration of the solution was taken as 100mg/L, the contact time
was fixed as 180 min, pH of the solution was maintained as 2. The removal
efficiency for boiled rice husk was found to increase from 33.2% to 71% with
increase in dosage from 2 g/L to 4 g/L. Similarly for formaldehyde treated
rice husk the removal efficiency increased from 38% to 78.5% with the
increase in dosage from 5 g/L to 4 g/L. The results indicate that the metal
removal was found to be maximum at pH 2. It is also found that there is no
much difference in adsorption capacity of boiled rice husk and formaldehyde
treated rice husk.
14
Veeraputhiran and Alagumuthu (2011) have investigated the
efficiency of activated carbon prepared from Phyllanthus emblica (Indian
Gooseberry) for fluoride removal from groundwater. It was concluded that the
rate of adsorption of fluoride was increased with increase in contact time.
Also the adsorption capacity decreases with increase in concentration. The
removal efficiency at 2 mg/L concentration was found to be 87.95% and at
10 mg/L it was found to decrease to 47.22%. It was concluded that the
removal efficiency is highly dependent upon contact time, adsorption dose
and concentration and fluoride could be successfully removed from
groundwater using Phyllanthus emblica based activated carbon.
Bhargava et al (2008) have studied the removal of fluoride by
adsorption using fish bone charcoal. The concentration of the solution was
maintained as 6.5 mg/L and pH of the solution was varied from 6 - 9 and the
agitation speed was maintained at 100 rpm to perform batch studies. It was
found that fluoride removal was efficient for pH values less than 9. With
respect to contact time it was found that the fluoride removal increases with
increase in time and it has reached its equilibrium condition in about
540 minutes.
Veeraputhiran and Alagumuthu et al (2011) have studied the
fluoride adsorption capacity using Cynodon dactylon (Bermuda grass) based
activated carbon. The concentration of fluoride solution was varied from
2 mg/L to 10 mg/L with dosage of adsorbent as 1.25 g and the contact time
was maintained at 105 minutes. The adsorption of fluoride decreased from
84% to 51% with increase in fluoride concentration from 2 mg/L to 10 mg/L.
Along with the batch study the effect of coexisting anions such as sulfate,
nitrate, chloride and bicarbonate on fluoride adsorption was studied using
Cynodon dactylon adsorbent. It was found that chloride and nitrate ions did
15
not interfere with fluoride removal upto the concentration of 500 mg/L, while
the sulphate ion showed some adverse effects in the removal process.
Lalhruaitluanga et al (2011) have carried out a research to study the
feasibility of chemically activated raw charcoals of Melacanna baccifera
(bamboo) for the removal of Ni (II) and Zn (II) from aqueous solution. Batch
adsorption studies were conducted by varying the adsorbent quantity from 0.1
g to 0.5 g. The concentration was kept constant at 50 mg/L and 30 mg/L. It
was found that beyond 0.4g, the adsorption capacity decreases which is due to
the overlapping and aggregation of adsorption sites resulting in the decrease
of the surface area available for the metal ions. Lalhruaitluanga et al (2011)
have concluded that chemically activated charcoal of Melacanna baccifera has
higher adsorption capacity than the raw charcoal.
Anjali Gupta et al (2010) have evaluated the effect of novel space
granular chitosin impregnated with molybdate for the removal of arsenite and
arsenate from contaminated water by conducting column studies. Fixed bed
column reactor was employed with a flow rate of 10ml/min. Batch adsorption
experiments were carried out by varying the pH from 4 to 10.The maximum
adsorption was obtained for a pH of 7 for both AS (III) and AS (V). It is
proved that chitosin impregnated with molybdate has been very effective in
both AS (III) and AS (V) in complete removal.
Senthil Kumar et al (2010) have made an attempt to study the
feasibility of Bengal gram husk (BGH) for the removal of ion Fe(III) . The pH
of the aqueous solution was varied from 0.5 to 3 and it was observed that the
removal efficiency increases with increased pH. The dosage of the adsorbent
was varied from 5 to 30 mg/L and significant increase in uptake was observed
when the dosage was increased and the maximum removal of 77.35% was
observed at adsorbent dosage of 20 g/L. The increased contact time raised the
iron adsorption and it remains constant after equilibrium in 30 minutes. From
16
the above results it can be concluded that Bengal gram husk powder has high
potential in removing iron from aqueous solution.
Mohd Rafatullah et al (2010) reviewed the adsorption of methylene
blue on low cost adsorbents such as agricultural wastes, industrial solid
wastes, biomass, clay minerals and Zeolites. Among the various adsorbents
used for removal of methylene blue dye, the fly ash was found to be an
effective adsorbent. The adsorption capacity of fly ash was found to be 6.46
mg/g. The authors have concluded that a number of inexpensive, locally
available materials can be employed in place of commercial activated carbon
in removing the contaminants.
Kailash Daga and Pallav (2009) have made an attempt on the
adsorption of Zinc (II) onto polyvinyl alcohol coated datura stramonium and
by varying the dose from 3-6 g/L. The adsorption capacity was found to be
17.24 mg/g for a pH of 8 for a removal efficiency of 74.3%. Kailash Daga and
Pallav (2009) concluded that polyvinyl alcohol coated with datura
stramonium available cheaply and widely in Thar Desert can be used for
preparation of adsorbent with high adsorption capacity.
Karthikeyan et al (2005) used chitin for iron (III) removal by
adsorption study. The initial concentration of the iron (III) solution was
maintained at 10 mg/L. The dosage was varied from 10 – 30 mg. Maximum
adsorption occurs at the 8th minute after which the adsorption remains
uniform. The time variation curve was smooth with the formation of
monolayer coverage on the outer interface of the absorbent. It was found that
sorption of iron increased at higher concentrations and dosages.
Munavallin et al (2010) have made comparitive studies of
defluoridation techniques. Various adsorbents such as activated alumina,
activated carbon, brick powder of used tea powder were used as absorbents.
17
For all the absorbents it was found that the removal of fluoride increased with
increase in dose of adsorbent till equilibrium is reached. It is also observed
that the adsorption of fluoride increased with time and there is no significant
change beyond a contact time of 60 minutes. The minimum contact time
required for adsorption is independent of initial concentration of fluoride.
Tonni Agustiono Kurniawan et al (2006) compared the effects of
low cost adsorbents for treating waste waters laden with heavy metals, it was
found that low cost adsorbents prepared from agricultural waste have
demonstrated outstanding removal capacity for Cr (VI). The adsorption
capacity was 170 mg/g of hazelnut shell activated carbon, for Ni (II), it was
158mg/g of orange peel, for Cu (II), it was 154.9mg/g of chemically modified
soybean hull, for Cu (II), it was 52.08 mg/g of jackfruit.
Emine Malkoc et al (2006) conducted batch and column studies to
find the adsorption capacity of Chromium (VI) on pomale an olive oil indenty
waste. The effect of pH on the Cr (VI) was investigated by varying the pH
value as 2, 3, 4 and 5 by fixing the contact time as 180 min. The adsorption
capacity of Cr (Vl) at pH 2 was 8.4mg/g which reduced to 2.7 mg/g at pH 5.
In the column study influent flow rate were varied from 5 mL/min to
20 mL/min with bed depth as 10 cm. It was found that breakthrough curve
becomes steeper when the flow rate was increased.
Adeniyi Ogunlaja et al (2010) conducted activity tests using Co-Mo
catalysts prepared from egg shell based activated carbon using silicon dioxide
as supporting element for the hydrogenation of methyl orange. The catalysts
were prepared from leached and unleached carbon. It was found that Co is
more efficient in hydrogenating methyl orange than Mo.
Subramanyan Vasudevan et al (2009) have carried out a research
on the removal of iron from drinking water by electro coagulation. The
18
parameters such as pH, temperature and current density were considered.
Langmuir and Freundlich isotherms were plotted. The results revealed that the
removal efficiency of 98.8% was achieved at pH 6.5.The temperature studies
also showed that the adsorption was endothermic and spontaneous.
Olayinka Kehinde et al (2009) have compared the efficiencies of
two low cost adsorbents in the removal of chromium and nickel from aqueous
solution. Coconut husk and teak tree bark based adsorbents were employed
for the removal of chromium and nickel. The influence of pH, dosage, contact
time and temperature were studied. The coconut husk adsorbents gave better
results the teak tree bark adsorbents at the increased contact time it was also
found that the percentage of adsorption of the adsorbents increased with
increasing adsorbent dosage. From the results it is found that coconut husk
adsorbent was more efficient in removing the metals when compared with
teak tree bark adsorbent.
Kadirvelu and Namasivayam (2001) have made studies on the
removal of Nickel (II) from aqueous solution onto the activated carbon
prepared from coirpith. The batch experiments were conducted and the
concentration of the solution was varied from 10-40 mg/L and the removal
efficiency was found to be 100% for the concentration of 20 mg/L solution.
The results indicate that the removal of metals was strongly dependent on the
pH of the solution. The removal efficiency was increased from 0% to 100%
for a concentration of 20 mg/L and 80% for 40 mg/L with the pH range of
2 to 7. The authors have also made the desorption studies by using HCl, and it
indicated that ion exchange is an important process in the adsorption of metal
ion by carbon.
Vishwanath (1974) has investigated the effect of Lignite in the
removal of Nickel from the aqueous solution and conducted batch
experiments. The effect of the parameters such as sorbent particle size, pH,
19
sorbent/sorbent ratio, retention time, temperature and carbonate ion
concentration was varied. The removal efficiency was found to be 98% at the
retention time of 30 minutes and the optimum pH was found to be 12.6.
Ramesh et al (2009) have prepared activated carbon from green pea
peels for treating dyeing industry wastewater. Wastewaters from textile
industry were collected. 100 ml of the sample was collected and agitated with
0.5 g of adsorbent at 120 rpm. The adsorbent dose was varied from 0.5 g to
3.5 g and pH was varied from 3 to 10. The results revealed that the removal
efficiency increases with agitation time and attains equilibrium after
60 minutes and remains constant thereafter.
Belgin Bayat (2002) has studied the properties of turkish fly ashes
and made a comparative study for the adsorption of copper, nickel and zinc
ashes such as Afsin-Elbistan fly ash and Seyitomer fly ash. The pH was
varied from 3 to 6 and it was found that pH had a greater influence in the
removal efficiency. Equilibrium time was maintained as for minutes. The
effect of concentration, pH and contact time was studied and the results
revealed that the adsorption efficiency for copper was found to be more than
that of zinc and nickel.
Kermit Wilson et al (2006) have carried out research on select
metal adsorption by using activated carbon made from peanut shell. The
metals considered were cadmium, copper, lead, nickel and zinc. The activated
carbon was prepared by different methods such as pyrolysis steam activation,
oxidation and ash removal. It was found that carbons with higher titratable
functional groups are better at binding metal ions than those carbons with
fewer amounts of titratable functional groups.
Ramesh et al (2008) have made studies on COD removal using
cement kiln dust based adsorbents. The adsorbent dose of 4 g was mixed with
20
100 ml sample and it was stirred at 150 rpm in an orbital shaker. It was found
that the removal efficiency of COD increased gradually from 5 minutes and
attained its optimum level at 90 minutes. In this optimum time removal
efficiency of 82% was achieved. Finally it can be concluded that the
maximum adsorption capacity of cement kiln dust based adsorbent was
19.56 mg/g.
Sreenivasulu et al (2010), have conducted experiments on the
adsorption of chromium on acid treated soapnut tree stem bark carbon. The
concentration of chromium was varied from 1.25 mg/L to 50 mg/L. The
stirring speed was maintained as 120 rpm. Equilibrium time was maintained
at 5 hours. The experiment data show 68.4% removal for chromium ion at
pH 3.7 and adsorbent dose of 6 g/L.
Halil Hazar (2003) has investigated the removal of Nickel (II) from
aqueous solution using activated carbon prepared from almond husk and
found that the removal efficiency at 25 mg/L concentration was 97.8% and at
250 mg/L concentration was 68.6%. The data reveal that activated carbon
prepared from almond husk could be used effectively as a potential adsorbent
for the removal of Nickel ions from aqueous solution.
Demirbas (2002) has made equilibrium studies on the removal of
Nickel (II) from aqueous solution by adsorption onto hazelnut shell activated
carbon by varying the parameters such as pH, contact time, temperature,
agitation speed, concentration and the particle size of the adsorbent and pH
was varied from 3 to 8. The studies were carried out at equilibrium contact
time of 180 minutes. Initial metal ion concentration was varied from
15-200 mg/L. It was found that the adsorption efficiency increased as the pH
of the solution was increased.
21
Malathy and Rajkumar (2008) have investigated the use of fly ash
for the removal of colour from the textile factory effluent. The effect of pH,
dosage and concentration of the solution were studied and the maximum
adsorption was found to take place when the pH of the solution was 8. The
retention time was kept for 3 hours. The results showed that fly ash could be
used as an alternative to other adsorbents to reduce the pollution
concentration discharged from dying industries.
Xin Huang et al (2009) have made studies on the adsorption
removal of phosphate in industrial wastewater using metal – loaded skin split
waste taken from the tannery industries. The adsorbent dose taken was 0.1g
and the pH of the solution was adjusted to 7 and the column studies were also
conducted with a constant flow rate of 40 mL/h. Studies revealed that skin
split waste loaded with Fe (III) exhibit good results when compared to skin
split waste loaded with Al (III).
Xiaotian Xu et al (2011) have prepared magnesia loaded fly ash
cenospheres for fluoride removal from aqueous solution. Coal fly ash has
been employed by impregnating it at wet condition with magnesium chloride.
The physiochemical properties were analysed using Scanning Electron
Microscopy and Fourier Transform Infrared Spectrometry. The maximum
adsorption capacity was about 6.0 mg/g with the concentration of the solution
as 100 mg/L with pH 3. It has been concluded that magnesia loaded fly ash is
low cost and found to be more effective in removing fluoride from aqueous
solution.
Raju and Saseetharan (2010) have carried out research on the
removal of lead from metal plating industries using sludge based activated
carbon. The parameters such as pH, contact time and dosage were varied. The
contact time was varied from 0 to 30 minutes with an interval of 5 minutes
and the dosage was varied from 0.25 g to 2g. It was observed that the
22
optimum contact time was 20 minutes with the adsorbent dosage of 1g. The
pH of the solution was varied from 2 to 9. It is clearly understood that the
lead removal was 96% at optimum contact time of 20 minutes and optimum
pH of 5.3, and these results show that sugar mill sludge based carbon can be
an effective alternative to commercial activated carbon for lead removal.
Kalpana et al (2010) have determined the efficiency of eggshell
powder in removing cadmium ions from aqueous solution. Batch studies were
performed to optimize the experimental conditions. The parameters such as
concentration, contact time, dosage and partical size were varied. The results
revealed that percentage biosorption of cadmium decreased with increase in
metal ion concentration. Dosage of the adsorbent was varied from 0.1 g to
0.5 g. At pH 6 and at optimum contact time of 90 minutes the adsorption
capacity of the eggshell powder was found to be 34.38 mg/g.
Ajmal et al (2000) employed orange peel for Ni (II) removal from
simulated wastewater. They found out that the maximum metal removal from
simulated wastewater. They also found out that the maximum metal removal
occurred at pH 6.0 and that the adsorption followed Langmuir isotherm,
indicating that Ni (II) uptake might occur on a homogeneous surface by
mono-layer adsorption. A metal adsorption capacity of 158 mg/g was
achieved at 323 K.
Babel and Kurniawan (2004) investigated the applicability of
Coconut Shell Charcoal (CSC) modified with oxidising agents or chitosan for
Cr (VI) removal. They found out that CSC oxidised with nitric acid had
higher Cr adsorption capacities (10.88 mg/g) than that oxidised with sulphuric
acid (4.05 mg/g) or coated with Citosan (3.65 mg/g). The results suggest that
surface modification of CSC with a strong oxidising agent generated more
adsorption sites on its solid surface for metal adsorption.
23
Bansode et al (2003) made studies on Cu (II) and Zn (II) removal
from real wastewater using pecan shells activated carbon. Some treated pecan
shells used are: PSA (phosphoric acid – activated pecan shell carbon), PSC
(carbon dioxide – activated pecan shell carbon), PSS (steam – activated pecan
shell carbon). PSA and PSS had good removal capacities for both ions. The
Freundlich isotherm was applicable for the equilibrium sorption of PSA,
suggesting that metal uptakes ions took place on a heterogeneous surface by
multilayer adsorption.
Demirbas et al (2002) investigated Ni (II) removal from simulated
solution using hazelnut shell activated carbon. They found out that metal
adsorption improved with an increasing temperature, suggesting that the
adsorption was endothermic as indicated by all thermodynamic parameters.
With an initial metal concentration of 15 mg/L, the optimum Ni (II) removal
took place at pH 3.0 with metal adsorption capacity of 10.11 mg/g.
Bishnoi et al (2003) conducted a study on Cr (VI) removal by rice
husk activated carbon from aqueous solution. They found out that the
maximum metal removal by rice husk took place at pH 2.0 and multilayer
adsorption might occur on the surface of the adsorbent, as indicated by the
applicability of the Freundlich isotherm for the equilibrium data.
Kadirvelu et al (2001) studied the uptake of Cd (II), Ni (II) and Cu
(II) ions from real industrial wastewater using coirpith activated carbon. They
reported that the maximum metal removal occurred at pH ranging from
4.0 – 5.0. Since coirpith was made up of homogeneous adsorption patches,
monolayer adsorption may occur on the surface, as indicated by the
applicability of Langmiur isotherm for equilibrium adsorption.
Halil Hasar (2003) studied Ni (II) adsorption from simulated
solution using almond husk activated carbon. The author found out that the
24
maximum metal removal of 37.17 mg/g occurred at pH 5.0. Monolayer
adsorption might occur on the adsorbent surface as indicated by the
applicability of the Langmuir isotherm for the equilibrium adsorption.
Abia et al (2003) explored thioglycolic acid cassava waste for the
removal of Cd (II), Zn (II) and Cu (II) from simulated solution. After
chemical modification, adsorption kinetics was rapid and equilibrium was
obtained within 20 minutes. The adsorption capacities of the adsorbent were
18.05, 11.06 and 56.82 mg/g for Cd (II), Zn (II) and Cu (II) ions respectively,
thus suggesting that the surface modification of cassava waste with
thio- glycolic acid improved the metal performance.
Periyasami and Namasivayam (1995) investigated the removal of
Ni (II) from synthetic solution using peanut hulls. Maximum Ni (II) removal
of 53.65 mg/g took place at pH ranging from 4 -5. In another column studies,
Periasamy and Namasivayam (1996) explored Cu (II) removal from synthetic
solution using peanut hull. Maximum Cu (II) removal of 65.57 mg/g occurred
at pH ranging from 6 – 10.
Zouboulis and Kydros (1993) investigated red mud, a solid by –
product from alumina production, for Ni (II) removal from wastewater. Red
mud has high cation exchange capacity and cation exchange sites. With an
initial Ni (II) concentration of 400 mg/L, the maximum Ni (II) uptake of
160 mg/g occurred at pH 9.0.
Lee et al (2004) studied green sands, another by – product from the
iron industry, for Zn (II) removal from synthetic solution. Kinetic studies
showed that the adsorbent was effective for the metal removal with an
adsorbent capacity of 32.46 mg/g. Clay and iron in the green sands played
major roles for Zn (II) sorption via sorption and precipitation. The adsorption
reaction was andothermic.
25
Feng et al (2004) investigated Cu (II) and Pb (II) removal from
simulated wastewater using iron slag or steel slag. A pH range from 3.5 to 8.5
for Cu (II) and from 5.2 to 8.5 for Pb (II) was optimum for both iron and
steels slags to maximise metal removal.
Dimitrova (1996) studied the adsorption of Cu (II), Ni (II) and Zn
(II) ions from simulated wastewater using blast – furnace slag. Its sorption
capacities on Cu (II), Ni (II) and Zn (II) were 133.55, 55.76 and 103.33 mg/g,
respectively. The metal sorption was in the form of hydro – oxo complexes
and the high sorption capacity was due to the formation of soluble compounds
on the internal surface of the adsorbent.
Manju and Anirudhan (1997) conducted experiments to determine
the ability of coconut fibre pith carbon to remove Cr+6 from aqueous solution
by adsorption. The extent of removal was found to be dependent on sorbent
dose, initial concentration, pH and temperature. The adsorption process was
exothermic with a maximum adsorption of 99.20% at 30 ºC for an initial
concentration of 50 mg/L at pH 2.0 with an optimum dosage of 2.0 g/L.
The optimum contact time was 3 hours.
Swamy et al (1997) have investigated the possibility of utilizing the
bagasse fly ash and activated carbon for the removal of resorcinol from
aqueous solution. They have concluded that equilibrium data of various
systems at 30 0.5oC and pH 6.5 fit well to the Freundlich equation and the
removal of resorcinol increases with pH of the solution and is maximum at
pH 6.5. The column studies carried out indicate that the absorbed amount of
resorcinol decreased with increasing flow rate and decreasing bed height.
Selvaraj et al (1997) observed the ability of photo film sludge to
adsorb Cr (VI) from synthetic wastewater by adsorption process. Authors
reported that optimal conditions for the maximum removal for Cr(VI) was
26
95% at pH 5.0, adsorbent dosage 750 mg/50 mL, agitation time 90 min,
initial Cr(VI) concentration 10 mg/L, with particle size 0.1 - 0.2 mm.
Selvapathy et al (1998) studied the removal of Cd, Cu, Mn, Ni and
Zn from wastewater using water lettuce a small floating stoliferrous aquatic
herb in its original herbal form. Efficiency of removal has been measured
when the metals were present separately and also in the combined form.
Results indicated that removal efficiency from individual solutions was more
compared to the metals present together. Also it was concluded that water
lettuce plants can be effectively used to remove metal concentration of
10 mg/L or less.
Sulochana et al (1998) conducted a study on the removal efficiency
of Copper and Nickel by wood powder of Phyllanthus embilica (nelli),
Lannea grandis (Odi) and Cicca disticha (Arunelli). It was reported that the
plant substrate of commonly available Indian plant species to be an alternative
for the removal of heavy metal ion.
Samantaroy et al (1998) made a comparative study on the removal
of chromium (VI) by different adsorbents namely Kendu fruit Gum Dust
(KGD), Drumstick Gum Dust (DGD) and Green Peas Skin Dust (GPSD). It
was found that KGD is the most effective one and concluded that the removal
of Cr (VI) upto 100% was observed with KGD, DGD and GPSD whereas
other conventional adsorbents showed lower percentages.
Jayasankar et al (1999) found that tamarind nut, a waste product
from agricultural sector, when processed under suitable conditions to achieve
the required porosity, bulkiness and adsorption capacity, could be used to
remove Lead (II) ions effectively. The results are compared with
commercially available granular activated carbon. The authors discussed the
27
advantages of using this type of locally available activated carbon from
indigenous sources for removal of Lead (II) ions.
Cormick and Fred (1999) studied that Enhanced Copper removal
from Activated Sludge using Bio Ferric / Selectors. Effluent copper
concentrations from a pilot – scale conventional activated – sludge system
(control) was compared with those from a conventional pilot treatment
process that also integrated bio ferric / selector units.
Orhan Altin et al (1999) have studied the effect of pH, flow rate
and concentration on the sorption of Pb and Cd on montmorillonite.
Continuous column adsorption of Lead (II) and Cadmium (II) was studied
using pH adjustment and calcium-saturated montmorillonite in a short
stainless steel column. At intermediate pH (4-6), ionic size played the major
role in adsorption and ion exchange. At low flow rates, sorption of both Lead
(II) and Cadmium (II) increased due to the long retention time in the column.
It was found that, when both Lead (II) and Cadmium (II) ions were present in
the feed, adsorption remained the same while that of Cadmium (II) decreased
compared with single ion experiments.
Rai and Surendrakumar (1999) conducted experiments on
Treatment of Chromium bearing wastewater by adsorption on brick kiln and
fly ash. Suitability of brick kiln ash and fly ash for removing Chromium (VI)
exhibited good sorption at a pH of 1.3 and particle size 124 – 853 µm. The
author reported that fly ash adsorbent was more effective than brick kiln ash
due to smaller particle size.
Reed et al (2000) made investigations on the removal of As(III),
As (V), Hg(II) and Pb(II) by virgin and Fe(III) impregnated Activated
Carbons (FeAC). Observations made indicate that iron oxide impregnation
increased the pH of the carbon from 7.5 to about 8.2 - 8.7, but had no change
28
in the surface area or pore volume. Results indicated that metal removal was a
function of pH with removal increasing with pH for Hg(II) and Pb(II) and
decreasing with pH for As(V). As(III) removal was not a strong function of
pH below 5. It was concluded that As(III) and As(V) removal were about one
and two orders of magnitude higher, respectively, for the FeAC compared
with the non-impregnated carbon, while for Hg(II) and Pb(II) removal, it was
only slightly higher.
Verma et al (2000) investigated the removal of Nickel (II) from
Electro Plating Industry Effluent by Agrowaste Carbons, prepared by using
wheat stem and spent Babul bark as the raw materials and the data were
compared with a commercially available activated carbon. Almost 100 %
removal of Ni (II) was observed at a pH value of 4.0.The Nickel removal
increased with carbon dose, adsorption period, pH and decrease with increase
in Nickel concentration.
In the study made by Ortiz et al (2001) the main component of
converter slag (magnetite) in the steel industry was used as an adsorbent for
the removal of Ni(II) from aqueous solutions over a range of conditions,
initial metal concentration (10 – 100 mg/L), stirring times (2 - 240 min)
adsorbent dosage (1 g for 0.5 L of metal solutions) and temperature (20, 30
and 38oC). The adsorption process was found to obey the Freundlich isotherm
model.
Li et al (2001) developed and studied a mathematical model to
describe the mass transfer kinetics in a fixed – bed adsorber packed with
activated carbon fibers. Experiments were carried out to remove phenolic
compounds from an aqueous solution. A simpler model, based solely on a
liquid phase mass balance and incorporating local equilibrium with axial
dispersion with a good description of the adsorption process.
29
Aksu and Yener (2001) examined a comparative adsorption /
bio sorption study of mono – chlorinated phenols onto various sorbents. The
potential use of dried activated sludge and fly ash as a substitute for granular
activated carbon for removing mono – chlorinated phenols were found out.
The suitability of the Freundlich and Langmuir models to the equilibrium data
were investigated.
Chen et al (2002) studied the removal of phenol and carbon
tetrachloride by activated carbon prepared from sewage sludge. The results
indicate that activated carbon prepared from sewage sludge had remarkable
micropore and mesopore surface areas which aided notable phenol and carbon
tetrachloride removal.
Appel and Ma (2002) focused on the Concentration, pH, and
Surface Charge Effects on Cadmium (II) and Lead (II) sorption in Three
Tropical Soils. Sorption characteristics of two heavy metals, Cd and Pb, in
three tropical soils (Mollisol, Oxisol, and Ultisol) were assessed at varying
metal concentrations and pH values. Sorption appeared to depend more on
soil mineralogy than organic matter content. Metal sorption depended more on
metal type than soil composition. Cadmium (II) sorption displayed greater pH
dependence than Pb. It was concluded that the Lead (II) was adsorbed more
strongly than Cd in the three tropics soils.
Li et al (2009) studied the feasibility of preparation of activated
carbon from coconut shell chars in pilot – scale microwave heating
equipment. Experiments conducted to prepare activated carbon by microwave
heating indicated that microwave energy decreases the reaction temperature,
saving the energy and shortening processing time remarkably compared to the
conventional heating.
30
Wang et al (2008) investigated the removal of Cr (VI) from
aqueous solutions using Alligator weed, a freshwater macrophyte, was
investigated in batch studies. Various factors including solution pH, Cr (VI)
concentrations, agitation time, and temperature were taken into account and
promising results obtained. An initial solution pH of 1.0 was most favorable
for Cr (VI) removal. The results suggested that the Cr (VI) adsorption at all
temperatures was best represented by the pseudo-second-order equation.
Oke et al (2008) investigated that Adsorption kinetics for arsenic
removal from aqueous solutions by untreated powdered eggshell. The batch
removal of arsenic aqueous solution using low – cost adsorbent (powdered
eggshell) under the influences of initial arsenic ion concentration (0.5 to
1.50 mg/L), pH (3.2 to 11.5) and particle size of eggshells (63 to 150 µm)
were investigated.. The study revealed that there was a slight reduction in the
rate of adsorption of arsenic ion onto the larger particle size, but adsorption
capacity and parameters were unaffected. Powdered eggshells with particle
size of 63 µm removed up to 99.6 % of the 1.5 mg/L of arsenic ion in
synthetic water within the first 6 hours but decreased to 98.4 % and 97.4 %
when the powdered eggshell particle sizes were increased to 75 and 150 µm
respectively.
Marin et al (2008) investigated that adsorption of mercury from a
single and multicomponent metal systems on activated carbon developed
from cherry stones. The adsorption of mercury from a single / multi solute
aqueous solution by Activated Carbon (AC) prepared from cherry stones by
chemical activation with H3PO4, ZnCl2 or KOH is studied. Three series of AC
were prepared by controlling the impregnation ratio and carbonization
temperature. The textural characterization of AC was carried out by gas
adsorption, mercury porosimetry and density measurements. Experiments of
31
mercury adsorption were conducted by the batch method, using aqueous
solutions of mercury, cadmium and zinc without pH adjustment.
Lua et al (2007) investigated that adsorption of phenol by oil –
palm – shell activated carbons. The adsorption isotherms could be described
by both the Langmuir Freundlich and the Langmuir equations. A multipore
model is proposed that akes into account of a concentration dependent surface
diffusion coefficient within the particle. This model is an improvement to the
traditional branched pore model. The theoretical concentration versus time
curve generated by the proposed model fitted the experimental data for phenol
adsorption reasonably well.
Babu et al (2008) investigated that adsorption of Cr (VI) using
activated neem leaves using kinetic studies. The adsorption of Cr (VI) is
found to be maximum (99 %) at low values of pH in the range of 1 – 3. A
small amount of the neem leaves adsorbent (10 g/L) could remove as much as
99 % of Cr (VI) from a solution of initial concentration 50 mg/L. The
adsorption process of Cr (VI) is tested with Langmuir isotherm model.
Malik et al (2007) made studies on adsorption of malachite green
by groundnut shell waste based powdered activated carbon. In the study,
groundnut shell an agricultural waste, was used for the preparation of
adsorbent and comparative characterization was conducted with commercially
available powdered activated carbon. It was found that Groundnut shell
Powdered Activated Carbon (GSPAC) has a higher surface area compared to
Commercially Prepared Activated Carbon (CPAC).
Kubilay et al (2007) investigated that the removal of Cu (II), Zn (II)
and Co(II) ions from aqueous solutions by adsorption on to natural bentonite
as a function of initial metal concentration, pH and temperature. Results
showed that bentonitic clay hold great potential to remove the relevant heavy
32
metal cations from industrial waste water. It was evident that the adsorption
phenomena depend on the solution pH.
Konstantinou et al (2007) investigated that Sorption of Cu (II) and
Eu (III) ions from aqueous solution by olive cake. Evaluation of the
potentiometric data obtained from competition experiments indicates on a ion
exchange mechanism. The formation constant of the Eu(III) species sorbed on
olive cake is found to be log = 5.4 ± 0.9. This result of this study are of
particular interest with respect to waste water treatment technologies using
biomass products as adsorbent material and environmental impact
assessments regarding disposal of biomass by products in the geosphere.
Vasanthkumar (2003) investigated the treatment of Dye bearing
waste water by Adsorption Technique using boiler bottom Ash as an
adsorbent. Author carried out the experiments in batch process for removing
color of methylene blue a basic dye, from its aqueous solution and achieved
100% color removal at lower initial concentration of less than 15 mg/L Young
– Sook Shim et al (2003) investigated the adsorption characteristics of heavy
metals by various particle sizes of MSWI bottom ash. The adsorption rate
increased with decreasing particle size and with increasing liquid / solid ratio;
however, the removal efficiency of Cu was higher than that of Ni. In the case
of plating rinse water, the adsorption rate decreased sharply at high liquid /
solid ratio and it showed over 80 % of adsorption rates for Cu and Ni at an
initial pH of 3.
Revathi et al (2005) studied that the removal of Nickel Ions from
Industrial Plating Effluents using activated Alumina as adsorbent. The effect
of various factors, such as initial concentration of nickel, contact time, dose of
adsorbent and pH of the solution were investigated. The results showed that
activated alumina was more efficient in removing nickel ions from aqueous
solution.
33
Ayawei et al (2005) studied the ability of the biomass of
Rhizophora mangle waste in removing Cu2+, Cd2+, Zn2+, Ni2+ and Ag+ from
aqueous solution using batch sorption techniques as a function of pH, contact
time, initial concentration of metal ions and temperature variations. The
optimum pH values for the metal ions Cu2+, Cd2+, Zn2+, Ni2+ and Ag+ were
found. The maximum adsorption capacity of the biomass was evaluated by
the Langmuir adsorption isotherm. Comparative examination of the
adsorption capacity of Rhizophora mangle waste with other biomasses
indicated that, Rhizophora mangle waste is also an excellent sorbent for most
of the metals investigated.
Caramuscio et al (2003) investigated the Preparation of activated
carbons from heavy – oil fly ashes. The use of heavy oil fly ash with high ash
content (45 Wt %) as a precursor for the preparation of activated carbons. The
activated carbons have been characterized with regard to the surface area and
the pore volume.
Ayub et al (2003) evaluated Chromium removal by Adsorption on
coconut Shell. The effect of pH, contact time, adsorbent dose, and
concentration of metal, particle size and temperature were studied. The
coconut shell exhibits good adsorption characteristics and the data follow both
Freundlich and Longmuir models.
Rengaraj et al (2002) made investigations on phenol removal from
aqueous solutions using activated Palm Seed Coat Carbon (PSCC) for varying
experimental condition of contact time, phenol concentration, adsorption dose
and pH. Adsorption equilibrium was reached within 3 h for phenolic
concentration 10 - 60 mg/L. The percent removal remained constant over the
pH range 4-9 for phenolic concentration of 25 mg/L. The adsorption of
phenol on PSCC followed the film diffusion process and the equilibrium data
obeyed Freundlich isotherm equation. Moreover, the comparative study with
34
commercial activated carbon showed that PSCC is two times more effective
than commercial activated carbon.
Altundogam et al (2002) investigated that Arsenic adsorption from
aqueous solutions by activated red mud. Author concluded that red mud an
abundant waste product of the aluminium industry, can be used as an
adsorbent for Arsenic in aqueous solutions. The adsorption data obtained
follow a first order kinetics and fit for Langmuir Isotherm.
Baisakh and Patnaik (2002) studied “Removal of Hexavalent
Chromium from Aqueous Solutions by Adsorption on Coal Char. The effects
of pH, temperature and concentration of hexavalent Chromium were
investigated. Under ambient temperature and pH condition removal efficiency
to the extent of 70 %. The rate process follows first order kinetics.
Rao et al (2003) have conducted experiments on removal of Cr(VI)
and Ni(II) using low – cost adsorbents. In this study, the efficiency of low-
cost materials, namely bagasee and fly ash were assessed. These low cost
adsorbents are used for the removal of Chromium and Nickel (II) from aqua
solution. The effects of pH, contact time, initial concentration of adsorbate
and particle size on the uptake of Chromium and Nickel (II) have been
studied in the experiments. The order of selectivity is PAC > bagasee > fly
ash for Cr (VI) removal and PAC > fly ash > bagasee for Ni (II) removal at
optimum conditions.
Senthilkumar et al (2001) conducted experiments on pollution
studies on Sugar mill effluent – Physico Chemical characteristics and Toxic
metals. The concentration of toxic metals Viz, Cd, Cu, Fe, Hg, Mg, Mn, Pb
and Zn were determined by inductively coupled plasma Atomic Emission
Spectrometry. Author concluded that Fe, Hg, Mg, Mn and Pb content
35
exceeded the permissible limits and Cd, Cu and Zn are within the permissible
limits while Ni is found in traces only.
Singh et al (2001) studied the removal of Chromium (VI), Iron (III)
and mercury (II) from aqueous solutions using activated carbon obtained from
used Tea leaves. Break through and exhaustive capacities, removal and
recovery of Cr (VI), Hg (II) and Fe (III) and effect of diverse ions have been
studied. The experimental results showed that Cr (VI), Fe (III) and Hg (II)
were strongly adsorbed by the adsorbent; Zi (II), Mn (II) and Cu (II) were
adsorbed partially.
Saravanane et al (2002) have conducted experiments for the
removal of heavy metals from wastewater using the chemically modified low
– cost adsorbents. Saw dust and rice husk have the potential of adsorbing
heavy metals, namely Cu(II), Mn(II),Fe(II) ,Cd(II), Pb(II) , Zn(II), Ni(II) and
Cr(VI) either in their natural form or in their chemically activated form, from
synthetic aqueous solution. The extent of removal depends on metal
concentration and pH. Saw dust in its natural form is found to be superior to
rice husk, with respect to the removal efficiency of the above metals from
aqueous solutions, under experimental conditions. The optimum pH for Cd
removal using the rise husk and saw dust is 4 – 6. The efficiency of the Cd
removal for the saw dust and rise husk is 64.81% and 58.62%. For the
chemically activated Carbon with combination of low cost adsorbent the
removal efficiency is increased to 95%.
Verma et al (2000) investigated the removal of Nickel (II) from
Electro Plating Industry Effluent by Agrowaste Carbons, prepared by using
wheat stem and spent Babul bark as the raw materials and data was compared
with a commercially available activated carbon. Almost 100 % removal of Ni
(II) was observed at a pH value of 4.0.The Nickel removal increased with
36
carbon dose, adsorption period, pH and decrease with increase in Nickel
concentration.
Rashed (2001) studied the suitable conditions for using Peach and
Apricot stones, (produced from food industries as solid waste), as adsorbents
for the removal of Lead ions from aqueous solution. Chemical stability of
adsorbents, pH, adsorbent dose, contact time and equilibrium concentration
were studied. The results revealed that adsorption efficiency of Lead ions was
more in the case of Peach stone than Apricot stone.
Rajkumar et al (2001) studied the feasibility of using red mud for
removing trivalent Chromium from wastewater. Experiments were carried out
by batch study at room temperature (27oC) to study the effects of pH, initial
chromium concentration, adsorbent dose and agitation time on the removal of
chromium. The maximum adsorption efficiency of 99.9% was recorded when
1.5 g of red mud was used in test solution containing 150 mg Cr3+ / 100 mL.
The idle pH and agitation time were 6 and 10 h respectively.
Lua et al (2001) investigated adsorption of Sulfur Dioxide on
Activated Carbon from oil – Palm waste. Experimental results showed that
the adsorption temperature and SO2 concentration significantly determined
the amount of SO2 adsorbed and the equilibrium time. Author concluded that
Sample particle size had minimum effect on equilibrium time.
Altin et al (1999) have studied the effect of pH, flow rate and
concentration on the sorption of Pb and Cd on montmorillonite. Continuous
column adsorption of Lead (II) and Cadmium (II) was studied using pH
adjustment and calcium-saturated montmorillonite in a short stainless steel
column. At intermediate pH (4-6), ionic size played the major role in
adsorption and ion exchange. At low flow rates, sorption of both Lead (II) and
Cadmium (II) increased due to the long retention time in the column. It was
37
found that, when both Lead (II) and Cadmium (II) ions were present in the
feed, adsorption remained the same while that of Cadmium (II) decreased
compared with single ion experiments.
Reed et al (2000) made investigations on the removal of As(III),
As(V), Hg(II) and Pb(II) by virgin and Fe(III) impregnated Activated Carbons
(FeAC). Observations made indicate that iron oxide impregnation increased
the pH of the carbon from 7.5 to about 8.2 - 8.7, but had no change in the
surface area or pore volume. Results indicated that metal removal was a
function of pH with removal increasing with pH for Hg(II) and Pb(II) and
decreasing with pH for As(V). As(III) removal was not a strong function of
pH below 5. It was concluded that As(III) and As(V) removal were about one
and two orders of magnitude higher, respectively, for the FeAC compared
with the non-impregnated carbon, while for Hg(II) and Pb(II) removal, it was
only slightly higher.
Jayasankar et al (1999) found that tamarind nut, a waste product
from agricultural sector, when processed under suitable conditions to achieve
the required porosity, bulkiness and adsorption capacity, could be used to
remove Lead (II) ions effectively. The results are compared with
commercially available granular activated carbon. The authors discussed the
advantages of using this type of locally available activated carbon from
indigenous sources for removal of Lead (II) ions.
Cormick and Cannon (1999) studied that Enhanced Copper
removal from Activated Sludge using Bio Ferric / Selectors. Effluent copper
concentrations from a pilot – scale conventional activated – sludge system
(control) was compared with those from a conventional pilot treatment
process that also integrated bio ferric / selector units.
38
Swamy et al (1997) have investigated the possibility of utilizing the
bagasse fly ash and activated carbon for the removal of resorcinol from
aqueous solution. They have concluded that equilibrium data of various
systems at 30 0.5oC and pH 6.5 fit will to the Freundlich equation and the
removal of resorcinol increases with pH of the solution and is maximum at
pH 6.5. The column studies carried out indicate that the absorbed amount of
resorcinol decreased with increasing flow rate and decreasing bed height.
Balasubramaniam and Ahmed (1997) studied the adsorption
technique for the removal of Pb (II) ions from aqueous solutions using lignite
as adsorbent. Authors conducted the batch adsorption tests and found that the
optimum conditions of pH as 3.58, equilibrium contact time as 270 min.,
temperature of effluent as 29.1oC, and initial Pb (II) concentration of
500 mg/L for the maximum removal of Pb (II).
Teik et al (1997) carried out the batch adsorption study to find out
the capability of marine clay to immobilize Zn, Pb, Cd, Cu and Cr under
acidic, neutral and alkaline conditions. The sorption capacity of the heavy
metals in acidic conditions follow the sequence of Cd>Zn>Cu>Pb>Cr.
Raji et al (1997) investigated the use of chemically modified saw
dust in the removal of Lead (II) ions from aqueous media. The sorption of
Lead (II) on polymerized saw dust has been found to be dependent on contact
time, concentration, temperature, particle size and pH. Maximum removal of
Lead (II) ions was 98.6% with sorbent concentration of 10 mg/L and
adsorbent dosage of 2.0 g/L with pH 6.0 at 60ºC. The equilibrium data fit well
with the Langmuir and Freundlich isotherms.
Periasamy and Namasivayam (1994) studied the removal and
recovery of Cadmium (II) from wastewater by a Low-Cost adsorbent, peanut
hull. It was reported that carbon derived from peanut hull, a waste agricultural
39
by-product, removed Cd(II) efficiently from aqueous solution. The
investigation also details a comparative study of peanut hull carbon and
commercial activated for the removal of Cd(II) from aqueous solution.
Prasad et al (1995) investigated the sorption of Arsenic on partially
activated crushed coconut shell under sorption kinetics. The removal
efficiency was found to be 72% when 1 mg/L of Arsenic (III) was taken with
5 g/L of sorbent of pH 6.2 and sorbent size 548 µm. The equilibrium sorption
data fitted to both Langmuir isotherm and Freundlich isotherm. The
adsorption found to increase when the pH is below 7 and decreases as the pH
increases.
Gajghate and Saxena (1991) have studied the removal of Lead (II)
from aqueous solution using Commercial Carbon. Different grades of
activated carbon were used and claimed that adsorption does not increase
with decrease in size alone.
Vaishya and Agarwal (1993) conducted the batch adsorption
studies for the removal of Arsenic (III) from contaminated ground water using
Ganga sand at Arsenic concentrations ranging from 0.1 to 1.6 mg/L at
different adsorption doses of 5-40 g/L .The equilibrium data followed the
Langmuir Isotherm. The maximum removal occurred between pH range of 7
and 9.
2.3 NEED FOR THE PRESENT STUDY
From the above observations it is found that the conventional
approaches are much costly for the removal of metal ions and salts from
effluent. This strongly necessitates the alternative treatment to remove such
contaminants. Hence in the present work an alternative method using agro-
based waste materials is proposed for the removal of metal ions and salts.
40
2.4 SUMMARY
In this chapter a literature review relating to the treatment of
aqueous solutions using agro - based waste materials is presented. Further the
need for the present study is set out.