Potential low-cost carbon-based adsorbent from gold mine tailings for anionic dye removal

In this study, a mesoporous carbon (CMK-3) was successfully synthesized using mesoporous silica (SBA-15) prepared from gold mine tailings (sample C_GMT) for removal of anionic dye from aqueous solution. For comparison, CMK-3 was prepared by the same method from pure silica (sample C_T), and the other CMK-3 sample was prepared by a one-pot route mixing with Pluronic P123 (sample C_P). The effect of the carbonization time on the synthesis of all CMK-3 samples was investigated, and the samples were characterized by X-ray diffraction and N₂ adsorption-desorption. The sample with the highest surface area was chosen as an adsorbent, for each CMK-3 obtained from different methods. Batch adsorption experiments were studied to determine the influence of pH, contact time, and initial dye concentration. The adsorption kinetics obeyed the pseudo-second-order model. All carbon-based adsorbents were observed to be quite effective for the removal of dye with adsorption percentage in the order of C_P > C_T > C_GMT. The maximum adsorption capacities were 188.99 and 204.57 mg·g^-1 for C_T and C_GMT, respectively. The comparative results of all carbon-based adsorbents show that C_GMT can be applied as a low-cost alternative to C_T for dye removal.