Reactive Dyes Removal from Wastewaters by Adsorption on Eucalyptus Bark - Adsorption Equilibria

• Published in: Environmental technology 2000-05, Vol.21 (5), p.577-583
• Main Authors: Morais, L. C., Gonçalves, E. P., Vasconcelos, L. T., González Beça, C. G.
• Format: Article
• Language: English
• Subjects: adsorption equilibria; Applied sciences; Eucalyptus; eucalyptus bark adsorbent; Exact sciences and technology; Industrial wastewaters; Pollution; Reactive dyes removal; Wastewaters; Water treatment and pollution
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593332108618096

As research previously carried out with eucalyptus bark to remove reactive dyes in aqueous solution showed that it had interesting adsorption capacities [1, 2], it was decided to continue this investigation. Adsorption equilibria studies in order to optimize the experimental conditions were done. As it was already known that the highest adsorption capacities were observed at room temperature and that among all the other studied parameters that could influence the equilibrium (pH, temperature and both initial dye, sodium chloride and bark concentration) pH had a high significance level (1% in the Fisher test) [2] and was an easily adjustable variable in industrial practice, it was decided to carry out adsorption equilibria studies parametered by initial pH. Because the above mentioned studies [1, 2] had shown that there should be a maximum adsorption capacity near initial pH 2 for the chosen values of the selected parameters that influence adsorption equilibria besides initial pH, the last variable, initial pH (pH i ), was explored for pH 1.50-2.50. Confirmation that, under these circumstances, the maximum adsorption capacity occurred at initial pH 2.0 was demonstrated. Langmuir model fitted the isotherms individually very well. A trial to generalize this model to all the isotherms having Langmuir parameters expressed as a function of the initial hydrogen ion activity, a H i + , only succeeded forpH range, (1.50, 1.89) that is to say, just for one of the sides of the curve adsorption capacity = f ( a H i + ) As the parameters of Langmuir equation, Q and K L , vary in opposite senses with initial pH, it is thought that for the successful side of the curve, Q probably has predominant influence, while on the other side K L may have greater importance.