Chitosan–bleaching earth clay composite as an efficient adsorbent for carbon dioxide adsorption: Process optimization

Abstract

In this study, chitosan–bleaching earth clay composite (Chi–BE) was prepared in three different ratios (1:0.4, 1:0.6 and 1:0.8) by the alkali gelation method for carbon dioxide (CO2) adsorption in a fixed-bed adsorption system. Chi–BE (1:0.6) with best adsorption capacity was selected through fractional factorial design and characterised through Brunauer–Emmett–Teller, scanning electron microscope and Fourier transform infrared analyses. The CO2 adsorption study was carried out via a central composite design and optimised it using desirability function. Results showed significantly positive roles of temperature, adsorbent loading and CO2 concentration on CO2 adsorption by Chi–BE within the range and individual levels. However, only adsorbent loading and CO2 concentration presented a mutual effect on CO2 adsorption. The optimised factor levels of 38.13 °C for temperature, 0.72 g for adsorbent loading and 25% CO2 concentration were obtained, which resulted in the CO2 adsorption capacity of 344.98 mg/g. The regeneration study revealed that the spent Chi–BE was recycled 10 times. This study suggests that Chi–BE is an effective and stable CO2 adsorbent under moderate environment.