The study of the potential capability of sugar beet pulp on the removal efficiency of two cationic dyes

This study utilizes sugar beet pulp as a low-cost absorbent to remove two different cationic dyes, methylene blue and safranin, in aqueous solutions. The effects of operational parameters on the efficiency of dye removal including pH, adsorbent mass, initial dye concentration and contact time have been investigated. All sets of experiments were carried out in batch mode. For both dyes, the maximum absorption was reached at pH 10 while point zero charge was known to be at pH 6. Boehm method showed that the amount of the acidic and basic groups have been 0.4075 mmol g⁻¹ and 0.0089 mmol g⁻¹, respectively. Freundlich and Langmuir models were used to analyse the obtained experimental data. In comparison, Langmuir model was understood to be a better fit for the experimental data than Freundlich model. Pseudo first-order and pseudo second-order models were used to determine the adsorption kinetics and it was observed that pseudo second-order model was the most suited model for both dyes. The equilibrium state for both dyes was reached after 210 min of the absorption experiment with more than 93% removal of dyes. The absorption capacities were found to be 211 mg/g and 147 mg/g for methylene blue and safranin, respectively.