PH shifting effect on anionic dye removal by surfactant-modified sugar beet pulp: Modeling of column studies

Abstract

pH shifting effect on the adsorption of anionic RBB dye was tested by using untreated and CTAB-treated SBP as adsorbent in both batch and continuous systems. Characterization of the sorbents revealed the effects of surface modification. Enhanced binding sites and more porous surface structure resulted in improved adsorption capability. Flow rate and initial RBB concentration effects were tested in packed bed column. Optimum pH value of the adsorption, which was determined as 2.0 in the batch studies with untreated SBP, shifted to 8.0 with 20 g/L CTAB treated SBP. Experimental data in column studies showed the decreasing capacity with increasing flow rate and enhanced performance with increasing inlet RBB concentration for both sorbents. Maximum capacities of the columns were found as 36.9 and 2.6 mg/g with dried SBP at pH 2.0 and 8.0, respectively, at a maximum inlet RBB concentration of 500 mg/L and a minimum flow rate of 0.8 mL/min. The highest capacity value at pH 8.0 was found as 140.0 mg/g under the same operating conditions, which reveals positive effect of the treatment on adsorptive performance. Langmuir isotherm was found to be most convenient model for the all equilibrium cases in the column. Moreover, Thomas model accurately predicted the breakthrough curves of each system. This is the first study reporting the modeling data of an anionic dye adsorption in a packed bed column by using modified SBP.