Selective Adsorption of Textile Dyes using Pre-treated Graphite Waste and Graphite/Fe₃O₄ Composites

In the present study, we describe the application pre-treated graphite waste (PTG) and graphite waste/Fe₃O₄ composites as adsorbents to remove different textile dyes from water. Selective adsorption of methylene blue (MB), methyl orange (MO), methyl violet (MV), and rhodamine B (RB) textile dyes on PTG and graphite waste/Fe₃O₄ composites were studied. The removal of dyes in water was assessed to evaluate the selectivity of PTG and graphite waste/Fe₃O₄ composites. The graphite/Fe₃O₄ (1:0.5), graphite/Fe₃O₄ (1:1), and graphite/Fe₃O₄ (1:2) composites based PTG is abbreviated GF1, GF2, and GF3, respectively, were prepared with different weights of Fe₃O₄ magnetic nanoparticles with ratio of 1:0.5, 1:1, and 1:2 (w/w%). The adsorption experiment was carried out in batch reactor with adsorbent dosage of 0.1 g and dye concentration of 10 mg/L. The results showed that the optimum adsorption capability of the PTG was 96.3, 89.2, 100, and 75.3 for MB, MO, MV, and RB, respectively. Under comparable experimental condition, the GF2 (2M HCl) showed the optimum removal of dyes of 81.6% (MB), 40.9% (MO), 76.0% (MV) and 20.9% (RB). The adsorption capacity of the dyes is governed by electrostatic interaction between the dyes and the functional groups on the adsorbent. The PTG and the GF2 (2M HCl) composite are promising candidates as low-cost adsorbents for removal of pollutive dyes from waste water.