Removal of Congo Red dye from aqueous solution using Amberlite IRA-400 in batch and fixed bed reactors

Abstract

Removal of Congo Red (CR) azo dye by adsorption process using Amberlite IRA-400 resin was evaluated in both batch and fixed bed system. From the batch adsorption results, maximum loading efficiency (99.99%) of CR dye was obtained at the conditions pH 4.5, temp. 303K, contact time 180min., Amberlite IRA-400 dose 0.5g. The isotherm study ascertained on favorability of adsorption process as the value of separation factor (K-L=0.88) and Freundlich constant (1/n=0.96<1.0) obtained from Langmuir and Freundlich equations are rational, though, overall adsorption process showed best fit with Langmuir (R-2=0.99) than Freundlich model (R-2=0.97). The kinetic data studied at three different CR dye concentration (50, 75, 100mg) and results were fitted with both pseudo-first-order and second-order model equations. The values of R-2 obtained are of 0.95 and 0.99 for former and later one, respectively, ensuring on best fitting of pseudo-second-order kinetics and also suggesting about the chemisorptions type of adsorption. The bed depth service model was applied for competitive analysis of the CR dye adsorption in column variables indicating mass transfer from aqueous solution to Amberlite IRA-400 phase. Fourier transform infrared analysis of CR-loaded resin Amberlite IRA-400 showed a band shifted from 1057 to 1130cm(-1) confirming CR adsorption with Amberlite IRA-400. Scanning electron microscope analysis of resin before and after adsorption was well evident from the phase patterns. Selective separation of CR dye from waste effluent of a textile industry bearing CR dye along with other trace heavy metal was achieved.