Removal and recovery of dye from paper machine efffluents

Abstract

For production of various kinds of coloured paper, dyes are employed. The un-adsorbed dyes go with the effluents to the water bodies. The dyes used are usually not biodegradable and therefore they must be removed by any means to make the process environment friendly. Adsorption of dye on a suitable adsorbent is thus a plausible alternative of abating colour (dye) pollution from paper machine effluents. Experimental studies have been carried out using Methyl violet and Victoria blue dyes as adsorbents, on adsorbents like wood meal, bagasse pith, saw dust and crushed paper for both batch as well as continuous packed column. Parametric effects of particle size, agitation, initial dye concentration, time, and temperature on the rate of dye removal have been investigated in batch as well as continuous adsorption column. Results indicate that a rapid initial uptake of dye takes place attributing to surface mass transfer and the rate of dye removal is found to be reduced greatly at the later stage as intra particle diffusion becomes the rate-controlling step. The surface mass transfer coefficients, Ks correlated in terms of dimensionless Sh/Sc0.33 term, against the particle variables and the intra particle rate parameter K as a function of agitation, initial dye concentration and particle size are simulated. (98.0-99.5 % of the dye adsorption has been possible within one hour. Regeneration of adsorbent and desorption of adsorbate have been tried. Experiments show promising results. © 2018 American Institute of Chemical Engineers ( AIChE ). All rights reserved.