IJCPE Vol.11 No.1 (March 2010) 
 

55 

 

 
Iraqi Journal of Chemical and Petroleum Engineering 

 Vol.11 No.1 (March 2010) 55-57 
ISSN: 1997-4884 

Removal of dyes from polluted water by adsorption on maize cob   

Ibtihage Faisal 

Chemical Engineering Department - College of Engineering - University of Baghdad – Iraq 

Abstract 

This research aimed to examine the effect of concentration of dyes stuff, contact time, temperature and ratio of 

adsorbent weight in (gm) to volume of solution in (ml) on the percentage removal. Two dyes were used; direct blue 6 

and direct yellow and the adsorbent was the maize cob. Batch experiments were performed by contacting different 

weights of adsorbent with 50 ml of solution of desired concentration with continuous stirring at various temperatures. 

The percentage of removal was calculated and the maximum percentage of removal was 80%. And as the concentration 

of solution, contact time, temperature and the ratio of adsorbent to volume of solution increase the percentage of 

removal increase. 

 

Introduction 

Dyes are a large group of chemicals used in chemical 

industries especially in textile industry. Dyes in use are so 

different compound and their environmental behavior is 

largely unknown (Albanis, 2000). Most of them are 

considered non –toxic, although some of them are not 

totally innocuous because they made of known 

carcinogens such as benzidine(Klimiuk, 1999) . Removal 

of dyes is difficult and poorly efficient upon the use of 

conventional physic-chemical and biological methods. 

Usually, dyes containing sewage are treated by means of 

absorption, ozonization, membrane processes, 

coagulation with flocculation and biological processes 

(Urszula, 2007). 

The process of adsorption is one of the most efficient 

methods for dye removal from sewage especially when 

the adsorbent is cheap and easily available (Mahir, 1991). 

One of the effective techniques for removal of color from 

waste water is sorption by activated carbon. However, 

owing to expensive price of it, the use of activated carbon 

for removal of color is limited (James 1991). 

Using agricultural by-products as adsorbents for the 

removal of pollutants such as dyes from waste solutions 

has been on the increase. This is because these 

agricultural by-products are naturally occurring; hence 

they are available at little or no cost. They also have 

advantages over the conventional adsorbent such as 

activated carbon particularly because of their low cost 

and high availability. There is also no need for 

complicated regeneration. One of these by-products is the 

maize cob (Hema 2007).  

Experimental Work 

1. The maize cob obtained was washed with water cut 
into small pieces, air dried, and crushed.  

2. The sample of maize cob was washed again with 
distilled water to remove any contaminant that could 

affect the color measurement.  

3. Stock of solution of dyes (1000 ppm) were prepared 
by dissolving  1gm of each dye in a   liter of distilled 

water and subsequently diluted with distilled water to 

the required concentration 500 ppm , 250 ppm, 125 

ppm , 75 ppm , and 50 ppm .  

4. Step 3 was repeated for two dyes used for wool 
dying. The first was direct blue 6 and the second was 

direct yellow. The absorbency of each dye with the 

different concentration was measured using spectro 

University of Baghdad 

College of Engineering 
Iraqi Journal of Chemical 

and Petroleum Engineering 

 



Removal of dyes from polluted water by adsorption on maize cob   

 

56 
IJCPE Vol.11 No.1 (March 2010) 

 

SC spectrophotometer using wave length suitable for 

each dye as shown in table 1. 

 

Table 1:- structure and the wave length at extinction 

measurement of the dyes examined. 
structure Wave length, ג 

nm 

Dyes 

 430 Direct yellow 

C32H24N6O14S4 .Na4 900 Direct blue 6 

There is approximately a linear relationship between the 

concentration of each dye and the absorbency so the 

concentration of each sample after treating with maize 

cob could be known by measuring the absorbency. 

  

5. A 50 ml of each dye solution of known initial 
concentration was in contact with a required dose of 

maize cob. The sample was placed in a shaker and 

the absorbency after that was measured again.  

6. The percentage removal was calculated by:- 
 

Percentage removal =         (1) 

 

Where  

Ci = initial concentration ppm 

Cf = final concentration ppm 

Results and Discussion 

Effect of contact time  

The efficiency of adsorption of a dye from a solution was 

analyzed based on the changes in its concentration in the 

solution and the percentage of removal was calculated 

using equation (1). 

Batch  adsorption studies  dyes were carried out by 

agitating in a shaker with rpm 75 min
-1

 50 gm of maize 

cob particles in 50 ml dyes solution with concentration 

250 ppm at different periods of time (3 hr,4 hr, 6 hr ,8 hr, 

one day ).After adsorption ,  a liquot was separated by 

using a mesh with opening 125 µm to prevent any dust 
from maize cob to go with the liquot  and the dye 

concentration was determined again .  

As shown in figure (1), as the contact time increases the 

percentage removal increases and for one day 80% of the 

dye was adsorbed. 

 

 

 

 

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20 25 30

Contact time  (hr)

%
  

R
e

m
o

v
a

l

Series1

Series2

  direct yellow

direct blue 6concentration 250ppm

Temperature 30º C

 

Fig(1) Effect of contact time on the percentage removal. 

 

Effect of concentration 

 

The effect of concentration on the percentage removal 

was studied using 50 gm of maize cob with50 of dyes 

solution with different concentration for four hours at 30 

˚c and the results shown in figure (2). As the 

concentration increases the percentage removal increases 

for both types of dyes. 

0

10

20

30

40

50

60

0 100 200 300 400 500 600

Concentration (ppm)

%
 R

e
m

o
v
a
l

Yellow

Blue 6

 
Fig(2) Effect of concentration on the percentage removal. 

 

Effect of temperature  
Increasing temperature has shown a less effect on the 

percentage of removal but also as the temperature 

increases the percentage of removal increases too as 

shown in figure (3). This was done by using magnetic 

stirrer with heater to reach different temperatures 25˚c , 

30˚c, 35˚c and 40˚c during stirring 50 gm of maize cob 

with solutions with 250 ppm concentration . 

 

 

 



Ibtihage Faisal 

 

IJCPE Vol.11 No.1 (March 2010) 57 

0

10

20

30

40

50

0 10 20 30 40 50
Te mpe rature  ºC

%
 R

e
m

o
v

a
l

Series1

Series2

concentration 250ppm

Time 4 hrs

direct blue 6

direct yellow

 

Fig(3) Effect of temperature on the percentage removal. 

 

Effect of ratio of adsorbent weight to volume of 

solution  

0.25, 0.5, 1, 1.25, 1.5 ratio of weight of adsorbent in gm 

to volume of solution with 250 ppm concentration in ml 

was used and the contact time was four hours at 30˚c. The 

result was better to increase the ratio to have high 

percentage removal. This is shown in figure (4). 

0

10

20

30

40

50

60

0 0.5 1 1.5 2

Ratio  o f adso rbent/  Vo lume o f so lutio n

%
 R

e
m

o
v

a
l

Series1

Series2direct blue 6

direct yellow

 
Fig(4) Effect of increasing ratio of weight of adsorbent(g) 

to volume of solution in (ml) on the percentage removal. 

Conclusions 

The following conclusions were detected from the 

present investigations: 

1. The removal of dye by adsorption on to agricultural 
by-product has been found to be useful means for 

controlling water pollution. 

2. Increases the ratio of adsorbent weight to the volume 
of solution show increasing in the percentage of 

removal. 

3. Temperature shows a less effect on the percentage of 
removal. 

References 

1- Albanis , T.A ; Hela , D.G ; Sakellarides , T.M. 

Removal of Dyes from aqueous solution by adsorption on 

mixtures of fly ash and soil in batch and column 

techniques . Global nest ; the Int, J. vol 2 , No 3 , pp 237-

244 , 2000 

2- Hema. M; Arivoli . S. Comparative study on the 

adsorption kinetics and thermodynamics of dyes on to 

acid activated low cost carbon. International journal of 

physical sciences Vol.2 (1), pp.010-017, January, 2007  

3- James G , Martin ; William . Cobey . Waste reduction, 

Hand book for using a waste reduction approach to meet 

aquatic toxicity limits, 1991 

4- Klimiuk , E; Filipkowska , U ; Korzeniowska , A . 

Effects of ph and coagulant Dosage on Effectiveness of 

coagulation of reactive Dyes from model waste water by 

polyaluminium chloride (PAC). Polish. Jornal of 

environmental studies vol .8, No.2 (1999), 73-79  

5- Mahir Alkan ; Mehmet Dogan . Removal of acid 

yellow 49 from aqueous solution by adsorption . 

Fresenius environmental Bulletin . Volume 13-No 11 a. 

2004  

6- Urszula Filipkowska. Adsorption and desorption 

efficiency of black 8 and black 5 on to chitin and chitosan 

. polish chitin society , Monograph XII, 2007