Methylene blue adsorption by activated carbon, nickel alginate/activated carbon aerogel, and nickel alginate/graphene oxide aerogel: a comparison study

Abstract

Three adsorbents, trichosanthes kirilowii maxim shell activated carbon (TKAC), nickel alginate/activated carbon (NA/AC) aerogel and nickel alginate/graphene oxide (NA/GO) aerogel were prepared in the present study. The three-dimensional network structure of the NA/AC aerogel and NA/GO aerogel was found to effectively control the dispersion state of TKAC and GO. The adsorption behavior was systematically investigated in terms of adsorption temperature and time, initial adsorbate pH and concentration, as well as the dose of adsorbents. The methylene blue (MB) adsorption process of TKAC was in accordance with the Langmuir isotherm model and followed a pseudo-second order mechanism. The adsorbing capacity of TKAC was 505.050 mg/g at 303 K while the BET surface area was 349.400 m2/g. Thermodynamic analysis demonstrated the spontaneous and endothermic properties of the entire adsorption process. The MB adsorption of the NA/AC aerogel satisfied the Langmuir isotherm and Freundlich isotherm models. Moreover, the MB adsorption on the NA/AC aerogel followed a pseudo-second order mechanism. The adsorbing capacity of the NA/AC aerogel was observed to be 465.120 mg/g at 303 K while the BET surface area was 100.690 m2/g. Thermodynamic investigation demonstrated a spontaneous and exothermic nature of the overall adsorption process. The MB adsorption of the NA/GO aerogel aligned with the Langmuir isotherm model and followed pseudo-second order mechanism. The adsorbing capacity of NA/GO aerogel was found to be 537.630 mg/g at 303 K, while the BET surface area was 5.050 m2/g. Furthermore, thermodynamic studies exhibited spontaneous and exothermic properties of the entire adsorption process.

Keywords

• Activated carbon
• Nickel alginate/activated carbon aerogel
• Nickel alginate/graphene oxide aerogel
• Adsorption
• Methylene blue