Adsorption Performance of Modified Nkalagu Bentonite in Dye Removal: Kinetics, Equilibrium, Thermodynamics and Structural Properties of the Modified Samples

Use of Modified Bentonite in Dye Removal

Abstract

The adsorption performance of modified Nkalagu bentonite in removing Congo red (CR) from solution was investigated. The raw bentonite was modified by three different physicochemical methods: thermal activation (TA), acid activation (AA), and combined acid and thermal activation (ATA). The Congo red adsorption increased with increase in contact time, initial dye concentration, adsorbent dosage, temperature, and pH change. The results of the kinetics analysis of the adsorption data revealed that adsorption follows pseudo second-order kinetics. Analysis of the equilibrium data showed that Langmuir isotherm provided a better fit to the data. Evaluation of the thermodynamic parameters revealed that adsorption process is spontaneous and endothermic. The results from this study suggest that a combination of thermal and acid activation is an effective modification method to improve adsorption capacity of bentonite and makes the bentonite as low-cost adsorbent for removal of water pollutants.