Adsorption of methylene blue dye by pyrolytic tire char in fixed-bed column

The adsorption of methylene blue (MB) dye from aqueous solutions using acid-treated pyrolytic tire char in a fixed-bed adsorption column has been studied. The adsorbent was characterized by X-ray diffraction, specific surface area, Fourier transform infrared spectroscopy, elemental analysis, Boehm titration, pH(pzc) and scanning electron microscopy. The effects of dye concentration and feed flow rate have been studied. Breakthrough curves and characteristic parameters of the column have been determined and modeled according to Adams-Bohart, Yoon-Nelson and Thomas models. Error analysis (average relative error) and R-2 values for each model showed that MB adsorption was fitted better to Yoon-Nelson model followed by Thomas model. Desorption of MB for the reuse of the column can be performed with 0.1 M HNO3 solution while more than 64% of the initial adsorption capacity can be retained after three adsorption cycles. Considering the ample waste tire feedstock and the waste tire pyrolysis management needs, tire char can be a promising low-cost adsorbent for MB removal.