International Journal of Scientific & Engineering Research, Volume 4, Issue 8, August-2013 1790
ISSN 2229-5518
Some studies on removal of phenol from waste
water using low cost adsorbent
Shri. M.W. Barve Dr.P.V.Vijayababu
7-8. The suitability of the Freundlich and Langmuir adsorption models to the equilibrium data was investigated for phenol-rice husk system. Results showed that the equilibrium data for all the phenol- rice husk system fitted the Freundlich model best within the concentration range studied. However Langmuir model is fitted well for the phenol-activated carbon system for the concentration range 100-1000 ppm. A comparative study showed that rice husk is very effective and low cost adsorbent for phenol removal. The studies showed that the rice husk could be used as a polishing/pretreatment for removal of phenol from water and wastewater in combination with Amberlite-XAD4 and Activated Carbon .
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water, phenols form chlorophenol, which has a medicinal
taste, which is quite pronounced and objectionable. Phenols
There is growing concern about wide-spread
contamination of surface and ground water by
various organic compounds due to the rapid
development of chemical and petrochemical
industries over the past several decades. So, many
industrial wastes contain organics, which are difficult,
or impossible to remove by conventional biological treatment processes. In the past several decades, extensive research has been conducted to develop innovative and promising adsorbent material for dealing with the treatment problem of contaminated industrial effluents. Phenols and phenolic wastes from chemical and petrochemical industries at low concentration i.e. 100-1000 ppm. are the major threat to the environment and aquatic life as a whole. The ultimate goal of this endeavor is to identify an effective and low cost adsorbent for Removal of Phenol from waste water at low concentration range where other conventional methods are ineffective.
Phenols as a class of organics are similar in structure the more common herbicides and insecticides in that
they are resistant to Biodegradation. Phenol is soluble in water. The odor threshold for phenol is 0.04 ppm (U.S.EPA). Their presence in water supplies is noticed as bad taste and odor. In the presence of chlorine in drinking
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*Address for email correspondence:mandarbarve@yahoo.com
are considered as priority pollutants since they are harmful to organisms at low concentrations and many of them have been classified as hazardous pollutants because of their potential harm to human health.Stringent US Environmental Protection Agency (EPA) regulation call for lowering phenol content in the wastewater less than 1mg/l.
There are many methods such as oxidation, precipitation, ion exchange, solvent extraction and adsorption for removing phenols and its derivatives from aqueous solution. Adsorption is a well-established and powerful technique for treating domestic and industrial effluents. However, in water treatment the most widely used method is adsorption onto the surface of activated carbon. Activated carbons remove many of the impurities occurring in water and wastewater. In spite of these characteristics, because of the high cost and variable performance of carbon regeneration, single use materials are desirable. (2) This has led many workers to search for more economical, practical and efficient techniques. Bottom ash, brick-kiln ash, fly ash, peat, soil, wood, saw dust, bagasse and carbonized bark are some new adsorbent used for organic pollutants.(3) In the search for new and low cost agricultural wastes material as an adsorbent, Rice husk is an agricultural waste produced as by-product of the rice milling industry to be about more than 500 million tonnes, 70% of which is generated in developing countries. The utilization of this source of biomass would solve both a disposal problem and also access to cheaper material for adsorption in water pollutants control system. Since, the main components of rice husk are carbon and silica (15-22 % SiO2 in hydrated amorphous
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form like silica gel), it has the potential to be used as an adsorbent. The aim of this study is to explore the possibility of use of rice husk for removing phenol from aqueous solution (Bisphenol-A manufacturing plant waste water) in combination with Amberlite-XAD4 and Activated Carbon. The influences of various factors such as initial pH and initial pollutant concentrations, flow rate on the sorption capacity were also studied.
The Freundlich and Langmuir models were used to analyze the adsorption equilibrium.
The problem associated with Bisphenol-A manufacturing plant waste water is its low Phenol concentration along with traces of Acetone which affect the performance of E.T.P. plant and bacterial life. (1)
C) Objectives:-
The objectives of the present work are:
1) To see the effect of flow rate, concentration of phenol and the presence of other component on adsorption for phenol-Amberlite-XAD4 system. (column study)
2) To find out sorption capacity of rice husk (agricultural waste product) as a low cost adsorbent for phenol-rice husk system and phenol-Activated Carbon system( batch study)
Formula:------------------C6 H 5 OH Molecular weight:-------94.11
Specific gravity:--------- 1.071
Melting point:----------- 420C
Boiling point:-------------181.40C
Solubility:---------------- 8.2 gm/100 gm of water at 150C
Specific gravity:---------- 1.025
Form:-----------------------Granular
Colour:---------------------Brown
Microstructure:----------Non-functional,
crosslinked.
The rice husks used were obtained from Lonere, Raigad district, India. The typical reported composition analysis of rice husk is shown in Table (1). The rice husk
Composition | Percentage (%) |
Cellulose | 32.24 |
Hemicellulose | 21.34 |
Lignin | 21.44 |
Extraetives | 1.82 |
Water | 8.11 |
Mineral ash | 15.05 |
was crushed and sieved with a 30-mesh siever. Then, the husks were thoroughly washed by distilled water to remove all dirt and were dried at 1000C till constant weight. The dried husks were stored in desiccator until used.
The test solutions were prepared by diluting of stock solution of phenol to the desired concentrations. A stock solution was obtained by dissolving 1.0g of phenol, (obtained from Merck), in cooled distilled water and diluted to 1000 ml. Intermediate phenol solution was
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obtained by dissolving 100 ml of stock solution of phenol in distilled water and diluted to 1000 ml and finally, standard phenol solution prepared by dissolving 100 ml intermediate phenol solution in distilled water and diluted to 1000 ml. The range in concentrations of phenol prepared from standard solution varied between 100 ppm to 20000ppm. Before mixing the adsorbent, the pH of each test solution was adjusted to the required value with diluted and concentrated H2 SO4 and NaOH solution, respectively. All pH measurements were carried out with a standard pH meter.
The concentration of residual phenol in the sorption medium was determined by direct Spectrophotometer method. At the end, after the preparation of samples according to the standard methods, the residual phenol concentrations were measured using spectrophotometer equipment (spectrophotometer Thermo-Merck Model). The absorbance of phenol was read at 270 nm.
As shown in Fig.(1.0) experimental set-up consists of a 1.0 inch diameter Borosile Glass tube( Burette) of approximately 1.0-m height. For convenience and easy operability it is supported at the center in two parts (using burette stand). At the bottom of the bed strainer is used in the form of glass wool. To avoid air voids as well to keep bottom flow rate constant a liquid head of approximately
1.0 inch is maintained. At the bottom control valve is used.
1) At the top feed tank is kept. The peristaltic pump is used to achieve constant flow rate. Small diameter tubing is used to transport phenol from feed tank to the column. First column was checked for any leaks.
2) Column was filled with water, and then slurry in
water was poured up to a 1.0 meter height of column.
3) Solution of appropriate phenol concentration was made.
4) Flow rate was maintained by adjusting the knob of
the peristaltic pump.
5) The sample was collected after every 10.0 minutes
and checked for phenol concentration by
ultraviolet spectrophotometer, which was already
calibrated.
6) When less difference in outlet concentration was
observed resin was regenerated by acetone.
Sorption studies were conducted in a routine manner by the batch technique. Each phenol solution was placed in 250 ml beakers and a known amount of rice husk(1 to 7g), was added to each beaker. The flasks were agitated on a shaker at a 100 rpm constant shaking rate for 2hr to ensure equilibrium was reached. The supernatant fluid analyzed for the remaining phenol. The studies were performed at a constant temperature of 30ºC to be representative of environmentally relevant condition. Finally the suitability of the Freundlich and Langmuir adsorption model to the equilibrium data were investigated for phenol - sorbent system. All the experiments were carried out in duplicates and the average value were used for further calculations.
Sorption studies were conducted in a routine manner by the batch technique. Each phenol solution was placed in 250 ml beakers and a known amount of Activated Carbon(0.02 to 0.12 g), was added to each beaker. The flasks were agitated on a shaker at a 100 rpm constant shaking rate for
10 min. to ensure equilibrium was reached. The
supernatant fluid analyzed for the remaining phenol. The studies were performed at a constant temperature of 30ºC to be representative of environmentally relevant condition. Effect of phenol concentration on rate of adsorption was also studied for fixed adsorbent concentration of 100mg. and shaking time Finally the suitability of the Freundlich and Langmuir adsorption model to the equilibrium data were investigated for phenol – activated carbon system. All the experiments were carried out in duplicates and the average value were used for further calculations.
Experiments for removal of phenol were carried out by using Amberlite-XAD4 resin as an adsorbent in column. The influent concentration of phenol and feed rate was varied and at particular concentration of phenol and effluent concentration was noted down. The same was repeated for different concentration of phenol varying from
100 ppm to 1000 ppm for different feed rate at constant
time interval. The feed rate has been changed from 30
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ml/min to 80 ml/min. the presence of polar compound like
Acetone at different concentration was also studied. From
the analysis of the experimental data following points were observed.
To study the effect of flow rate on percent adsorption, the percent adsorption of phenol vs. operation time was plotted in figure 2 and 3, It has been observed from the graph that the 90% removal of phenol can be obtained for 30 ml/min to 50 ml/min, whereas same can be obtained for 80 ml/min for 10 minutes duration. This result is obvious and supported by the theory, of course some irregularity has been found for 65 ml/min, which may be due to some experimental error. In general as flow rate increases percent adsorption decreases.
At different flow rates of feed the percent adsorption of phenol was plotted against operation time for different influent concentration. These are shown in figure 4 and
5.The figures showe that at low feed concentration i.e. 100 ppm, 90 percent adsorption was obtained for longer time due to presence of sufficient active sites. For 1000 ppm phenol concentration the percent adsorption obtained was higher as compared to that at low concentration of course for small time span. In general as concentration of phenol in influent stream increases percent adsorption also increases.
To observe the effect of Acetone on percent adsorption of phenol the experimental data obtained was plotted in figure 6. The figure indicate the high influence on increase in percent adsorption. This is happened due to swelling of resin bed. Basically swelling increases the adsorption area
of resin, which results in more adsorption of phenol.
120
100
60
40
20
0
0 50 100 150
Time ( Min)
30 ml/min
50 ml/min
65 ml/min
80 ml/min
120
100
80
60
40
20
% Adsorption Influent Conc.(100ppm)
% Adsorption Influent Conc.(200ppm)
% Adsorption Influent Conc.(500ppm)
Fig 2 Graph of % Adsorption VS Time
0
0 50 100 150
Time(Min)
% Adsorption Influent Conc.(1000ppm)
Fig 4 % Adsorption Vs Time
for 30 ml/min
120
100
80
60
40
20
0
0 50 100 150
Time ( Min)
30 ml/min
50 ml/min
65 ml/min
80 ml/min
100
80
60
40
20
0
% Ads orpti on
Infl ue nt
C on c.(100ppm )
% Ads orpti on
Infl ue nt
C on c.(200ppm )
% Ads orpti on
Infl ue nt
C on c.(1000ppm )
Fig 3 Graph of % Adsorption VS Time for 1000 ppm concentration
0 50 100 150
Tim e (Min )
Fig 5 % Ads orption Vs tim e for 80m l /m i n
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120
120
100
80
60
40
20
0
0 50 100 150
Tim e (Min )
% Ads orpti on 2%
phe nol
% Ads orpti on
(2%
ph e n ol +500ppm
Ace ton e )
% Ads orpti on
(2%
ph e n ol +1000ppm
Ace ton e )
100
80
60
40
20
0
0 2 4 6 8
Rice Husk (grms.)
Fig 7 Effect of rice husk on adsorption
(Phenol-Rice Husk System)
1000ppm
500ppm
400ppm
300ppm
200 ppm
Fi g 6 Graph of % Ads orpti on Vs Ti m e
For Batch study
Phenol-Rise Husk system
The adsorption of phenol in aqueous solution on rice husk was examined by optimizing various physicochemical parameters such as pH, contact time, and the amount of adsorbent and adsorbate.
The amount of adsorbent on the efficiency of adsorption was also studied. Fig 7shows the removal of phenol by rice husk at the solution pH of 7. Adsorbent dosage was varied from 1g to 7g for rice husk. The results show that for removal of 500 µg/l of phenol in 100 ml of solution, a minimum dosage of 7 grams. of rice husk is requied for
The adsorption data for the uptake of phenol versus contact time at 500µg/l initial concentration with 7g rice husk was carried out in pH value of 7. The results Fig 8 show that equilibrium time required for the adsorption of phenol on rice husk was 2hr. These results also indicate that the sorption process can be considered very fast because of the largest amount of phenol attached to the sorbent within the first 120min of adsorption.
100
80
96% removal of phenol. The results also clearly indicate that the removal efficiency increases up to the optimum dosage beyond which the removal efficiency is negligible.
60
40
20
0
0 100 200
Tim e (Min )
% Ads orpti on
Fi g 8 Effe ct of con tact ti m e on Ads orpti on
( Phe nol -Ri ce Hus k Sys te m )
The adsorption of phenol from aqueous solution is dependent on the pH of the solution, which affects the surface charge of the adsorbent, degree of ionization and speciation of the adsorbate species. The adsorption of
phenol by rice husk was studied at various pH values. The
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results are displayed in Fig 9. As was expected, the adsorbed amount decreases with increasing the pH value.
This can be attributed to the dependence of phenol
ionization on the pH value. Obviously,
ions io n
time 10 min., Vol. of solution 10 ml
fraction of phenolate ion) increases as the pH value increased. Accordingly, phenol, which is a weak acid (pKa=10), will be adsorbed to a lesser extent at higher pH values due to the repulsive force prevailing at higher pH values. Also, in the higher pH range phenol forms salts, which readily ionize leaving negative charge on the phenolic group. At the same time the presence of OH(−)ions on the adsorbent prevents the uptake of phenolate ions . pH also affects the surface properties of the sorbent, i.e., surface charge of the cells used as sorbent. At very low pH values, the surface of the sorbent would also be surrounded by the hydronium ions, which enhance the phenol interaction with binding site of the sorbent by greater attractive forces,
hence its uptake on polar adsorbent is reduced.
120
100
80
60
40
20
0
0 5 10 15
pH
Fig 9 Effect of pH on adsorption
(Phenol-Rice Husk System)
200ppm
300ppm
400ppm
500ppm
1000ppm
Effect of Initial pH:
The adsorption of phenol from aqueous solution is dependent on the pH of the solution, which affects the surface charge of the adsorbent, degree of ionization and speciation of the adsorbate species. The adsorption of phenol by rice husk was studied at various pH values. The results are displayed in Fig 9. As was expected, the adsorbed amount decreases with increasing the pH
value. This can be attributed to the dependence of phenol
-5.82
-5.84
-5.86
-5.88
-5.9
-5.92
-5.94
-5.96
4.6 4.8 5 5.2 5.4 5.6
y = 0.1894x - 6.8625
R2 = 0.936
ionization on the pH value. Obviously, ϕ ions (ion fraction of phenolate ion) increases as the pH value increased. Accordingly, phenol, which is a weak acid (pKa=10), will be adsorbed to a lesser extent at higher pH values due to the repulsive force prevailing at higher pH values. Also, in the higher pH range phenol forms salts, which readily ionize leaving negative charge on the phenolic group. At the same time the presence of
(−)
-5.98
lnCe
Fig 10 Linearized Freundlich adsorption isotherm
(Phenol-Rice Husk System)
Phenol-Activated Carbon System
OH ions on the adsorbent prevents the uptake of
phenolate ions . pH also affects the surface properties of the sorbent, i.e., surface charge of the cells used as sorbent. At very low pH values, the surface of the sorbent would also be surrounded by the hydronium
ions, which enhance the phenol interaction with binding
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site of the sorbent by greater attractive forces, hence its uptake on polar adsorbent is reduced.
120
100
80
60
40
20
0
0 5 10 15
pH
Fig 9 Effect of pH on adsorption
(Phenol-Rice Husk System)
200ppm
300ppm
400ppm
500ppm
1000ppm
-5.82
-5.84
-5.86
-5.88
-5.9
-5.92
-5.94
-5.96
-5.98
4.6 4.8 5 5.2 5.4 5.6
y = 0.1894x - 6.8625
R2 = 0.936
lnCe
Fig 10 Linearized Freundlich adsorption isotherm
(Phenol-Rice Husk System)
Phenol-Activated Carbon System
Influence of weight of active carbon on phenol adsorption Test conditions: - Phenol conc. 200-1000 ppm, Shaking time 10 min., Vol. of solution 10 ml
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The effect of phenol concentration on its own adsorption on active carbon was studied under optimum conditions of a shaking time of 10 minutes and 0.1 g of active carbon. The concentration of phenol was varied from 100 ppm to 1000 ppm. The results shows that the value of percentage adsorption up to 0.3g/l of phenol concentration remained
>92%. After that the value of percentage adsorption
decreases as the concentration of phenol increases, indicating that less favorable sites became involved in the
process with increasing concentration.
The dependence of phenol adsorption on shaking time was examined in the initial study. The study was performed by shaking 10 ml phenol solution of 0.01 g/l (pH 3.4) with 0.1 g of active carbon for different intervals of time ranging from 2 to 120 minutes. It was observed that the adsorption process is instantaneous and attained equilibrium within five minutes. Therefore, a shaking time of 10 minutes was selected for all further studies. The quick establishment of equilibrium indicates the high adsorption capacity of the active carbon for phenol.
The linearized form of the Freundlich's equation was applied to the adsorption data and is shown in Figure 13,
here X is the amount of the phenol adsorbed per gram of the active carbon, C is the concentration of phenol (g/l) left in the solution, i.e. the final concentration, 1/n is the slope showing the variation of adsorption with concentration and A is the intercept, showing the adsorption capacity from solution of unit concentration. This demonstrates the non- validity of the equation over the whole range of
concentrations studied.
The Langmuir equation was applied to the data of Figure
13 in the linear form
(C/X) = 1/KX +C/Xm,
where C and X have already been defined. Xm is the measure of monolayer capacity and K is the constant related to the heat of adsorption. A straight line is obtained by plotting (C/X) versus C (Figure 14), indicating the conformity of the data to the Langmuir equation in the concentration range studied.
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6 A. Knop & L. A. Pilato, Phenolic Resins - Chemistry, Applications and Performance, Springer-Verlag, 1985, p.104.
7 K. H. Radeke, D. Loseh, K. Struve & E. Weiss, Comparing
• The capacity of the Amberlite – XAD4 resin increases with increase in phenol concentration and also in the presence of other polar component. Phenol can be recovered without any deterioration in its characteristics with a affordable time and cost for reuse. Amberlite – XAD4 resin can be used for waste water treatment of higher phenol concentrations and for recovery
• Rice husk can be used as low-cost, natural and abundant source of adsorbent for the removal of phenol. The adsorptive capacity of rice husk is limited to low concentration and low flow rate. Hence it can be used for a polishing/pretreatment for removal of phenol from water and wastewater. Disposal of rice husk (after use) is easy compare to any other solid waste disposal. After sun drying, Brick manufacturing industry can use Rice Husk or it can be incinerated in waste heat boiler.
• Activated carbon can be used as a effective adsorbent for the phenol adsorption at low concentration (100-1000 ppm) range. The cost of activated carbon is more than Rice husk but less compare to Amberlite-XAD4 resin for same treatment capacity.
REFERENCES
1. Kesar PetroProducts Ltd., “Process Manual of Bisphenol-A Plant” , pp.01-69
2. Mahajan S.P., “Pollution Control in Process Industries”, Tata
McGraw Hill Co., New Delhi 1996
3 S. Rengaraj , Seung-Hyeon Moon, R. Sivabalan, Banumathi Arabindoo, V. Murugesan., “Removal of Phenol from Aqueous Solution and Resin Manufacturing Industry Wastewater Using an Agricultural Waste: Rubber Seed Coat” , Journal of Hazardous Materials B89 (2002) pp. 185–
196
4 T.G. Chuah , A. Jumasiah , I. Azni , S. Katayon , S.Y. Thomas
Choong “Rice Husk as a Potentially Low-Cost Biosorbent for
Heavy Metal and Dye
Removal: An Overview”, Desalination ,75(2005), pp. 305-316
5 E. Costa, G. Calleja & L. Marjuan, Comparative adsorption
of phenol, p-nitrophenol and p-hydroxy benzoic acid on
activated carbon, Adsorp. Sci. Technol., 5 (3), 213-28, (1988).
adsorption of phenol from aqueous solution onto silica fangasite, activated carbon and polymeric resin, Zeolites, 13 (1), 69-70, (1993).
8 M. Kastelan-Malan, S. Cerjan-Stefanovic & M. Petrovic, Phenol adsorption on activated carbon by mean of thin layer chromatography, Chromatographic, 27 (7-8), 297-300, (1989).
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