Equilibrium, kinetic and thermodynamic studies on methylene blue adsorption by Trichosanthes kirilowii Maxim shell activated carbon

New kind of adsorbent was produced from Trichosanthes kirilowii Maxim shell. The KOH activation technology for preparation of Trichosanthes kirilowii Maxim shell activated carbon (TKMC_K) was optimized. Using methylene blue as the sample adsorbate, the adsorption behavior was systematically investigated in terms of the activation agent and temperature, the adsorption temperature and time, the initial adsorbate pH and concentration, as well as the dosage of adsorbent. Surface physical morphology of the TKMC_K prepared was observed by scanning electron microscopy (SEM), while the functional groups were determined with Fourier transform infrared (FTIR) spectra. Kinetic studies indicated that the adsorption process was more consistent with the pseudo-second-order kinetic. Both Langmuir and Freundlich isotherms were employed to fit the adsorption data at equilibrium, with the former giving a maximum adsorption capacity of 793.65 mg/g at 323 K. BET surface area of as-prepared TKMC_K was 657.78 m²/g.