____________________________________________________________________________________________ *Corresponding author: Email: hnisa25@atauni.edu.tr; Annual Research & Review in Biology 4(17): 2730-2754, 2014 SCIENCEDOMAIN international www.sciencedomain.org Azo Dye Removal from Aqueous Solutions Using Laccase-modified Red Mud: Adsorption Kinetics and Isotherm Studies H. Nadaroglu 1* , E. Kalkan 2 and N. Celebi 1 1 Ataturk University, Erzurum Vocational Training School, 25240 Erzurum, Turkey. 2 Ataturk University, Oltu Earth Sciences Faculty, Geological Engineering Department, 25400 Oltu-Erzurum, Turkey. Authors’ contributions This work was carried out in collaboration between all authors. Author HN designed the study, performed the statistical analysis, wrote the protocol and wrote the first draft of the manuscript. Author NC managed the analyses of the study. Author EK managed the literature searches. All authors read and approved the final manuscript. Received 14 th March 2014 Accepted 7 th April 2014 Published 6 th May 2014 ABSTRACT Removal of acid red 37 from aqueous solutions has been studied using red mud waste material after its modification with laccase from Russulaceae (Lactarius volemus). Laccase was purified by using saturated precipitate (NH 4 ) 2 SO 4 , diethylaminoethyl celulose (DEAE- cellulose) and immobilized on red mud. The removal of acid red 37 by the laccase- modified red mud has been demonstrated in order to explore its potential use as low-cost adsorbent. The adsorption kinetics of acid red 37 dye on the laccase-modified red mud with respect to pH, contact time, temperature and adsorbent dose were investigated. The optimum results were obtained at pH 4, contact time of 60 min and temperature of 30ºC. The Freundlich equation was found to have the highest value of R 2 compared with the Langmuir model. Thermodynamic parameters including the Gibbs free energy, enthalpy and entropy changes indicated that the adsorption of acid red 37 onto laccase-modified red mud was feasible, spontaneous and endothermic. Keywords: Laccase-modified red mud; acid red 37; dye removal; adsorption isotherm; wastewater. Original Research Article