Crayfish shell-based micro-mesoporous activated carbon: Insight into preparation and gaseous benzene adsorption mechanism

The preparation of hierarchically porous carbon via a low-cost way for gaseous benzene adsorption remains a challenge that needs to be addressed urgently. In this study, crayfish shell from kitchen garbage was employed as the precursor for synthesis of activated carbon (AC) via chemical activation strategy, which could be potential in synthesis because of the cost-effective precursor and simple way. Orthogonal design test and various characterization techniques were adopted to explore the optimal preparation conditions of AC. As a result, AC7 with the large specific surface area (2669.40 m2/g) and well-developed pore volume (1.42 cm3/g) has been synthesized successfully. Compared with other adsorbents, AC7 exhibited more excellent adsorption performance for gaseous benzene (684.6 mg/g) in the dynamic adsorption experiments. The influences of preparation factors by the range analysis method and environmental conditions via the single factor method on the adsorption performance of AC7 for gaseous benzene were investigated and analyzed, comprehensively. Based on the isotherm and thermodynamic models, the adsorption experiment data were fitted, analyzed and evaluated to figure out the adsorption mechanism. The results showed that the adsorption process was exothermic, and mainly physical. The partition coefficient and breakthrough volume were also applied to evaluate the benzene adsorption performance objectively. In addition, the reusability tests were carried out. In the eleventh cycle, the adsorption capacities under different initial concentrations were higher than 96.92% of the initial adsorption capacities, showing that AC7 possessed the good reusability. These results showed that AC7 would be an attractive and potential adsorbent for the gaseous benzene adsorption.