Poly(trimesoyl chloride-melamine) grafted on palygorskite for simultaneous ultra-trace removal of methylene blue and toxic metals

Poly(trimesoyl chloride-melamine) was grafted on palygorskite via in situ interfacial polymerization. The poly(trimesoyl chloride-melamine)-grafted palygorskite (PTMP) composite was characterized by Fourier transform infrared spectroscopy (FTIR), Energy Dispersive X-Ray Spectroscopy (EDX), N₂-physisorption, and scanning electron microscope (SEM). The performance of PTMP as an adsorbent was evaluated for the removal of methylene blue dye (MB) in batch and column systems. The effects of initial dye concentration, contact time, temperature and initial pH on the efficiency of MB removal were investigated. A high adsorption efficiency (≈100%) was shown by PTMP removal within 8 min with high Langmuir monolayer capacity of 64.5 mg/g at 25 °C. The mechanisms of adsorption were evaluated by isotherm and kinetic models. The activation energy E_a and different thermodynamic parameters, for example, ΔG^o, ΔS^o, and ΔH^o were calculated. The prepared composite demonstrated to be an efficient adsorbent for simultaneous removal of dye and toxic metals such as As(III), Cr(III), Mo(II), Co(III), Ni(II), and Hg(II). The dye removal was evaluated by a packed bed column system and showed an excellent adsorption performance with 90 min breakthrough at 160 ppm of initial dye concentration.