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Desorption and regeneration of dye colours from low-cost materials
War. Res. Vol. 21, No. 3, pp. 375-377, 1987 Printed in Great Britain. All rights reserved
0043-1354/87 $3.00+0.00 Copyright © 1987 Pergamon Journals Ltd
RESEARCH NOTE DESORPTION A N D REGENERATION OF DYE COLOURS FROM LOW-COST MATERIALS G. McKAY, ~* G. RAMPRASAD2 and PRATAPA MOWLI 2 tDepartment of Chemical Engineering, The Queen's University of Belfast, Belfast BT9 5DL, Northern Ireland and 2Department of Civil Engineering, S.V. University College of Engineering, Tirupati, India
(Received May 1986) Abstract--Experimental methods and results are reported in this paper on the desorption and regeneration of eight dye colours individually from six low-cost sorbent materials. Desorption and regeneration values give an idea about the type of interaction between the sorbate and the sorbent, and the possibility of regeneration of the sorbent. Bentonite clay, amongst the six low-cost materials studied in the present investigation, could sorb all the dyes used in investigation with the exception of the acid dyes. No regeneration of clay is possible in the sorption of dyes, since strong chemical bonding occurs between it and the sorbed dyes. Rice husk, bark, cotton waste and hair could sorb only the red and blue basic dyes and a combination of ion-exchange and chemical bonding occurs in the sorption process.
Key word~----dyes, sorption/desorption, sorbents
classification No. 50240), (2) Sandolan Rhodine an acid red dye----C.I. No. 18050), (3) Congo Red (a direct red dye---C.I. No. 21120), (4) Foron Brill Red (a disperse red dye----C.I. No. 11110), (5) Methylene Blue (a basic blue dye----C.I. No. 52015), (6) Sandolan Blue (an acid blue---C.I. No. 63010), (7) Solar Blue (a direct blue----C.I. No. 22625), (8) Foron Blue (a disperse blue----C.I. No. 64500). The six low-cost materials chosen for studying the sorption phenomenon were teak wood bark, rice husk, cotton waste, coal, hair and bentonite clay. Bark, rice husk and coal were powdered into a particle size of 300-425/~m. Cotton waste and hair were cut manually into lengths of approx. 500/tm. All these five materials were washed first with tap water and then with distilled water to remove fines. Powdered bentonite clay of particle size < 150/~m was used without crushing. Preliminary kinetic studies on all the dye-sorbent material systems indicated the equilibrium time to be 4 h. Thus batch desorption and regeneration experiment were conducted using 200 ml of 100 mg din- 3dye solution and 2 g of sorbent material. The contents were shaken vigorously in a Griffin wrist action shaker for 4h, after which the shaker was stopped and the contents of the reaction bottles were analysed for dye colour concentration. The sorbent material in the reaction bottle was separated by filtering through Whatman No. 1 filter paper. When all the dye solution dropped out, the sorbent material on the filter paper was air dried for 24 h. The dried sorbent material was separated into two halves of I g each. 1 g of dried sorbent material was put into a reaction bottle containing 100ml of 0.05 M H2SO4, and the other half of the dried sorbent material was placed into another reaction bottle containing 100ml distilled water. Both the reaction bottles were then shaken for 4 h and the dye colour concentration was measured separately from the contents of both the reaction bottles. The dye
INTRODUCTION A great variety of alternative low-cost materials like fly ash, soil, w o o d chippings, tyre cuttings, coconut shell powder, hair, coal etc, are being tried in place of activated carbon for the sorption o f different pollutants like pesticides, detergents, heavy metals, dyes etc. (Chu et al., 1978; Emig, 1973; H u a n g and Liao, 1970; Aga, 1983; M c K a y and Poots, 1980; Michelson et al., 1975). The chemical and physical characteristics of sorbent materials as well as those of sorbates vary widely and it is difficult to recommend specific low-cost materials to sorb specific pollutants. There is a necessity to do experimental work with different materials to sorb different pollutants to understand the variations in the sorption phenomena. This paper presents the results of the experimental work done on the desorption and regeneration of eight different dye colours from six low-cost materials. These experiments are expected to indicate the type of bonding between the sorbate and the sorbent materials. They also give an idea whether the sorbent materials can be regenerated or not after exhaustion. EXPERIMENTAL
The eight dyes chosen for this study (Society of Dyers and Colourists, 1971) were" (1) Safranine (a basic red dye--C.I. *To whom all correspondence should be addressed. 375
376
Research Note
~
-
,,¢
~
colour concentration of the contents of the bottle in which distilled water was used gave the desorption value and the dye colour concentration of the contents of the bottle in which 0.I M H 2SO4 was used gave the regeneration value. All the dye colour concentrations were measured on a Photochem Colorimeter at appropriate wavelengths.
"5-
RESULTS
"5 .~
i
e,t
'r"
~-
o=
..° = - . i
a~
N'=°'-- I
¢,4~
AND DISCUSSION
While the desorption values give an idea about the quantity of physical bonding in the sorption process, the regeneration values give an idea about the degree of ion-exchange taking place on the sorbent materials. Table 1 presents desorption and regeneration values of the six low-cost materials for the eight dyes, along with their sorption values. Bentonite sorbed almost all the dyes, more than 80%, with the exception of the acid dyes. But both its desorption and regeneration values for all the dyes are less, indicating perhaps, that there is strong chemical bonding between the dyes and the bentonite clay surface. Formation of strong hydrogen bonding, as suggested by Huang and Liao (1970) between clay and pesticides, may be taking place between the dyes and bentonite clay. Emig (1973) has also suggested that hydrogen bonding plays a significant role in the sorption of heavy metals by clays. Good sorption is shown by rice husk and bark for the basic dyes Safranine and Methylene Blue. Considerable regeneration values are shown by rice husk, bark, cotton waste and hair in the regeneration of the basic dyes, implying that ion-exchange exists between them. Desorption values in most cases under investigation are low, implying that physical bonding between the dyes and sorbent materials only occurs to a small extent and that chemical bonding is largely responsible for the sorption process. As could be observed from Table 1, some materials have shown desorption and regeneration values, though no sorption took place on them. For example, rice husk, bark, hair and coal have shown desorption and regeneration values for Sandolan Rhodine and Congo Red though there was no sorption. This could be because of the fact that, either some unsorbed dye solution was caught up in the solid and this when placed in the desorption and regeneration systems gave some colour measurement, or a second possibility is that some unwashed colour of organic matter has leached out of the sorbent to a slight extent.
CONCLUSION
Strong chemical bonding occurs in the sorption of dyes by bentonite clay, and thus no regeneration of clay is possible. Rice husk, bark, cotton waste and hair could sorb only the basic dyes and a combination of ion-exchange and chemical bonding occurs in their sorption.
Research Note REFERENCES
Aga J. (1983) Colour removal from aqueous solutions using adsorption techniques. Ph.D. thesis, The Queen's University of Belfast. Chu T. Y. J., Stainer G. R. and McEntyre C. L. (1978) Removal of complex copper-ammonia ions from aqueous wastes with fly ash. J, War. Pollut. Control Fed. 50, 2157-2174. Emig D. K. (1973) Removal of heavy metals from acid bath plating wastes by soil. Ph.D. thesis, Perdue University. Huang J. C. and Liao C. S. (1970) Adsorption of pesticides
377
by clay minerals. J. sanit. Engng Div. Am. Soc. cir. Engrs 96, 1057-1078. McKay G. and Poots V. J. P. (1980) Kinetics and diffusion processes in colour removal from effluents using wood as an adsorbent. J. chem. Technol. Biotechnol. 30, 279-292. Michelson D. L., Gideon J. A., Grifflth G. P., Pace J. E. and Kutat H. L. (1975) Removal of soluble mercury from water by complexing techniques. U.S.D.I. Office of Water Research and Technology, Bulletin No. 74, Virginia Polytechnique Institute, Blacksburg, Va. Society of Dyers and Colourists (1971) Colour Index. P.O. Box 224, Perkin House, 82 Grattan Road, Bradford, Yorkshire, U.K.
0043-1354/87 $3.00+0.00 Copyright © 1987 Pergamon Journals Ltd
RESEARCH NOTE DESORPTION A N D REGENERATION OF DYE COLOURS FROM LOW-COST MATERIALS G. McKAY, ~* G. RAMPRASAD2 and PRATAPA MOWLI 2 tDepartment of Chemical Engineering, The Queen's University of Belfast, Belfast BT9 5DL, Northern Ireland and 2Department of Civil Engineering, S.V. University College of Engineering, Tirupati, India
(Received May 1986) Abstract--Experimental methods and results are reported in this paper on the desorption and regeneration of eight dye colours individually from six low-cost sorbent materials. Desorption and regeneration values give an idea about the type of interaction between the sorbate and the sorbent, and the possibility of regeneration of the sorbent. Bentonite clay, amongst the six low-cost materials studied in the present investigation, could sorb all the dyes used in investigation with the exception of the acid dyes. No regeneration of clay is possible in the sorption of dyes, since strong chemical bonding occurs between it and the sorbed dyes. Rice husk, bark, cotton waste and hair could sorb only the red and blue basic dyes and a combination of ion-exchange and chemical bonding occurs in the sorption process.
Key word~----dyes, sorption/desorption, sorbents
classification No. 50240), (2) Sandolan Rhodine an acid red dye----C.I. No. 18050), (3) Congo Red (a direct red dye---C.I. No. 21120), (4) Foron Brill Red (a disperse red dye----C.I. No. 11110), (5) Methylene Blue (a basic blue dye----C.I. No. 52015), (6) Sandolan Blue (an acid blue---C.I. No. 63010), (7) Solar Blue (a direct blue----C.I. No. 22625), (8) Foron Blue (a disperse blue----C.I. No. 64500). The six low-cost materials chosen for studying the sorption phenomenon were teak wood bark, rice husk, cotton waste, coal, hair and bentonite clay. Bark, rice husk and coal were powdered into a particle size of 300-425/~m. Cotton waste and hair were cut manually into lengths of approx. 500/tm. All these five materials were washed first with tap water and then with distilled water to remove fines. Powdered bentonite clay of particle size < 150/~m was used without crushing. Preliminary kinetic studies on all the dye-sorbent material systems indicated the equilibrium time to be 4 h. Thus batch desorption and regeneration experiment were conducted using 200 ml of 100 mg din- 3dye solution and 2 g of sorbent material. The contents were shaken vigorously in a Griffin wrist action shaker for 4h, after which the shaker was stopped and the contents of the reaction bottles were analysed for dye colour concentration. The sorbent material in the reaction bottle was separated by filtering through Whatman No. 1 filter paper. When all the dye solution dropped out, the sorbent material on the filter paper was air dried for 24 h. The dried sorbent material was separated into two halves of I g each. 1 g of dried sorbent material was put into a reaction bottle containing 100ml of 0.05 M H2SO4, and the other half of the dried sorbent material was placed into another reaction bottle containing 100ml distilled water. Both the reaction bottles were then shaken for 4 h and the dye colour concentration was measured separately from the contents of both the reaction bottles. The dye
INTRODUCTION A great variety of alternative low-cost materials like fly ash, soil, w o o d chippings, tyre cuttings, coconut shell powder, hair, coal etc, are being tried in place of activated carbon for the sorption o f different pollutants like pesticides, detergents, heavy metals, dyes etc. (Chu et al., 1978; Emig, 1973; H u a n g and Liao, 1970; Aga, 1983; M c K a y and Poots, 1980; Michelson et al., 1975). The chemical and physical characteristics of sorbent materials as well as those of sorbates vary widely and it is difficult to recommend specific low-cost materials to sorb specific pollutants. There is a necessity to do experimental work with different materials to sorb different pollutants to understand the variations in the sorption phenomena. This paper presents the results of the experimental work done on the desorption and regeneration of eight different dye colours from six low-cost materials. These experiments are expected to indicate the type of bonding between the sorbate and the sorbent materials. They also give an idea whether the sorbent materials can be regenerated or not after exhaustion. EXPERIMENTAL
The eight dyes chosen for this study (Society of Dyers and Colourists, 1971) were" (1) Safranine (a basic red dye--C.I. *To whom all correspondence should be addressed. 375
376
Research Note
~
-
,,¢
~
colour concentration of the contents of the bottle in which distilled water was used gave the desorption value and the dye colour concentration of the contents of the bottle in which 0.I M H 2SO4 was used gave the regeneration value. All the dye colour concentrations were measured on a Photochem Colorimeter at appropriate wavelengths.
"5-
RESULTS
"5 .~
i
e,t
'r"
~-
o=
..° = - . i
a~
N'=°'-- I
¢,4~
AND DISCUSSION
While the desorption values give an idea about the quantity of physical bonding in the sorption process, the regeneration values give an idea about the degree of ion-exchange taking place on the sorbent materials. Table 1 presents desorption and regeneration values of the six low-cost materials for the eight dyes, along with their sorption values. Bentonite sorbed almost all the dyes, more than 80%, with the exception of the acid dyes. But both its desorption and regeneration values for all the dyes are less, indicating perhaps, that there is strong chemical bonding between the dyes and the bentonite clay surface. Formation of strong hydrogen bonding, as suggested by Huang and Liao (1970) between clay and pesticides, may be taking place between the dyes and bentonite clay. Emig (1973) has also suggested that hydrogen bonding plays a significant role in the sorption of heavy metals by clays. Good sorption is shown by rice husk and bark for the basic dyes Safranine and Methylene Blue. Considerable regeneration values are shown by rice husk, bark, cotton waste and hair in the regeneration of the basic dyes, implying that ion-exchange exists between them. Desorption values in most cases under investigation are low, implying that physical bonding between the dyes and sorbent materials only occurs to a small extent and that chemical bonding is largely responsible for the sorption process. As could be observed from Table 1, some materials have shown desorption and regeneration values, though no sorption took place on them. For example, rice husk, bark, hair and coal have shown desorption and regeneration values for Sandolan Rhodine and Congo Red though there was no sorption. This could be because of the fact that, either some unsorbed dye solution was caught up in the solid and this when placed in the desorption and regeneration systems gave some colour measurement, or a second possibility is that some unwashed colour of organic matter has leached out of the sorbent to a slight extent.
CONCLUSION
Strong chemical bonding occurs in the sorption of dyes by bentonite clay, and thus no regeneration of clay is possible. Rice husk, bark, cotton waste and hair could sorb only the basic dyes and a combination of ion-exchange and chemical bonding occurs in their sorption.
Research Note REFERENCES
Aga J. (1983) Colour removal from aqueous solutions using adsorption techniques. Ph.D. thesis, The Queen's University of Belfast. Chu T. Y. J., Stainer G. R. and McEntyre C. L. (1978) Removal of complex copper-ammonia ions from aqueous wastes with fly ash. J, War. Pollut. Control Fed. 50, 2157-2174. Emig D. K. (1973) Removal of heavy metals from acid bath plating wastes by soil. Ph.D. thesis, Perdue University. Huang J. C. and Liao C. S. (1970) Adsorption of pesticides
377
by clay minerals. J. sanit. Engng Div. Am. Soc. cir. Engrs 96, 1057-1078. McKay G. and Poots V. J. P. (1980) Kinetics and diffusion processes in colour removal from effluents using wood as an adsorbent. J. chem. Technol. Biotechnol. 30, 279-292. Michelson D. L., Gideon J. A., Grifflth G. P., Pace J. E. and Kutat H. L. (1975) Removal of soluble mercury from water by complexing techniques. U.S.D.I. Office of Water Research and Technology, Bulletin No. 74, Virginia Polytechnique Institute, Blacksburg, Va. Society of Dyers and Colourists (1971) Colour Index. P.O. Box 224, Perkin House, 82 Grattan Road, Bradford, Yorkshire, U.K.