Removal of reactive dyes from aqueous solutions by kefir biomass

In the present study the potential use of living and non-living kefir grains on removal of dyes from aqueous solutions were investigated. Remazol Ultra Red RGB and Remazol Navy RGB were selected as target dyes for the study and batch experiments were carried out under different process conditions such as initial pH (2-8), temperature (18-39°C) and initial dye concentration (50 - 400 mg/L). 93% and 56.4% dye removal for Remazol Ultra Red and 96.3% and 79.4% dye removal for Remazol Navy were obtained with living and non-living kefir grains respectively, at pH 2, 25°C for 100 mg/L initial dye concentration by using 2.4 g/L kefir grain, in 180 minutes. The living kefir grains exhibited higher dye removal potential than the non-living grains at all examined conditions. The maximum adsorption capacities by living and inactivated kefir grains were obtained as 134.59 and 56.92 mg/g. As a result of the modelling studies performed the kinetics of biosorption by living and non-living kefir grains were best described with pseudo-first-order model. On the other hand the biosorption equilibrium was well described by Temkin and Langmuir models respectively for living and non-living kefir grains.