1. Equilibrium Isotherms of Basic Dyes on Sugar Cane Dust
Tsung-Pao Lina, Kuo-Tung Nia, Yuh-Shan Hob# and Wen-Ta Chiua*
aTaipei Medical University – Wan Fang Hospital,
bSchool of Public Health, Taipei Medical University
Introduction
Sugar cane dust is a complex material basically containing lignin and cellulose as major constituents. [1] Cellulose can be a sorbent for removing dyes from solution. [2] A strong anion-exchange resin has been prepared from sugar cane bagasse, a lignocellulosic byproduct of sugarcane processing, which effectively and inexpensively decolorizes dyehouse wastewater in an environmentally benign manner. [3] Sugar cane bagasse has been studied for removing acid dyes such as Acid Red 114 and Acid Blue 25, basic dyes such as Basic Red 22, Basic Blue 69, Malachite Green, Methylene Blue, Crystal Violet and of Rhodamine B, direct dyes and reactive dyes.
Materials and Methods
50 ml of dye solution with properly ranged concentrations and 0.25 g accurately weighed sugar cane dust sample were placed in a 125 ml conical flask. A series of such conical flasks was then shaken at a constant speed of 100 rpm in a 25ºC water bath for 24 h. Then the sugar cane dust was separated by centrifugation and the solution was analyzed for the remaining dye concentration by using spectrophotometer.
Table 1. Isotherms and Their Linear Forms
Results and Discussion
The isotherms and their respective linear forms were shown in Table 1 where the linear form of Langmuir-1 was more common. The coefficient of determinations, Chi-square, and isotherm constants were shown in Table 2. Fig. 1 to 4 show experimental data and linear isotherm equations. Comparison of the isotherms are shown in Fig. 5 and 6.
Table 1. Comparison of linear regression coefficient of determination, r2, and Chi-square test statistic 2.
Fig. 5. Comparison of different isotherms for sorption of basic dyes on sugar cane dust.
Fig. 1. Langmuir isotherms of basic dyes sorbed on sugar cane dust.
Fig. 2. Langmuir-1 isotherms of basic dyes sorbed on sugar cane dust.
Fig. 6. Linear Freundlich and Langmuir isotherms for Basic Violet 10, Basic Violet 1 and Basic Green 4 on sugar cane dust.
Fig. 3. Freundlich isotherms of basic dyes sorbed on sugar cane dust.
Fig. 4. Redlich-Peterson isotherms of dyes sorbed on sugar cane dust.
References
[1] Abd-El-Thalouth I, Kamel MM, Haggag K, El-Zawahry M. Am. Dyest. Rep. 1993;82: 36.
[2] Youssef BM. Am. Dyest. Rep. 1993;82:36.
[3] Laszlo JA. Text. Chem. Color. 1996;28:13.
Conclusion
The results revealed the potential of sugar cane dust, a waste material, could be a low-cost sorbent for removing basic dyes. The Langmuir monolayer saturation sorption capacities for the three basic dyes are 50.4, 20.6 and 13.9 mg/g sugar cane dust for Basic Violet 1, Basic Green 4 and Basic Violet 10, respectively. The best-fit isotherm was Redlich-Peterson isotherm. Non-linear Chi-square method provided better optimum determination for the three sets of experimental data.