Studies on equilibrium and kinetics of ACRY red 4G removal from aqueous solutions using low cost adsorbents

Applications of low cost adsorbents have been investigated as a replacement for the current expensive methods of reducing COD and colours from dyes/intermediate industrial wastewaters. Presently, PAC (powdered activated charcoal) is widely used in the industries. However, it is costly. Hence, other options have been explored which are low in cost. Effective adsorbents have been developed from bagasse fly ash, thermal fly ash, rice husk, jute thread and sawdust and successfully employed for the removal of dye, ACRY red 4G from aqueous solutions. Factors influencing the adsorption process, e.g., pH, contact time, adsorbent doses and adsorbent particle size are investigated. The experimental data fits well to the second-order kinetic model, which indicates that the chemical sorption is the rate-limiting step. A continuous method for removal of ACRY red 4G from industrial wastewater without prior treatment using all solid adsorbents such as bagasse fly ash, thermal fly ash, rice husk, jute thread and sawdust has also been proposed. An important. aspect of the proposed method is that the removal is performed at a pH range in which the dye ACRY red 4G undergo an adsorption process, making the method useful for wastewater treatment.