In this study the removal methylene blue (MB) and methyl orange (MO) from aqueous solutions was investigated usin a covalent organic polymer (COP). The absorbent properties were investigated using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction analysis (XRD), scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDX) and BET method. Different affecting factors such as pH, initial concentrations of dyes, amount of adsorbent, temperature, contact time were optimized. The effect of electrolyte were investigated. Also, the simultaneous elimination of methylene blue and methyl orange was investigated. Finally, the possibility of recovery of the absorbent was investigated. The optimum results for methylene blue were obtained using 0.01 g of adsorbent, pH=7, temperature 25 ° C and contact time of 5 minutes. These results were calculated for methyl orange dye using 0.01 g of adsorbent, pH=4, temperature 25 ° C, and contact time of 5 minutes. According to obtained data, the Freundlich isotherm and Langmuir adsorption isotherm were matched for methylene blue and methyl orange, respectively. Maximum adsorption capacites were found to be 48.1 and 43.9 mg/g for methylene blue and methyl orange, respectively. The kinetics of adsorption of methylene blue and methyl orange dyes were evaluated. The data obtained for both dyes were matched with the second-order kinetic model. The simultaneous removal of two dyes using the successful p-phenylenediamine-COP adsorbent, with a removal efficiency of over 99% for both dyes. After three times recovery of the absorbent using HCl solution 0.5M the adsorbent keep 99% of initial capacity. The PDA-COP adsorbent was successfully applied for removal of methylene blue and methyl orange from industrial waste.
