Molecular dynamics study on structures and adsorption capacity of activated carbon prepared from corn straw and sewage sludge by molten salt method

Activated carbon was prepared from corn straw and sewage sludge by molten salt method, and its structures and adsorption capacity were studied. When the ratio of raw materials to ZnCl₂ was 1:1, the specific surface areas and carbon recovery ratios of straw- and sludge-based activated carbon were 875.981 m²/g and 302.293 mg_C/g_{activated carbon}, and 294.721 m²/g and 149.663 mg_C/g_{activated carbon}, respectively. In the adsorption experiment of methylene blue (MB), the adsorption capacities of straw- and sludge-based activated carbon were 186.653 and 79.968 mg_MB/g_{activated carbon}, respectively. The microstructure and adsorption capacity of the prepared activated carbon were simulated through molecular dynamics models. The straw and sludge-based activated carbon models and carbon atom numbers in the slit models were developed based on the carbon recovery ratio. E_int and Δξ of straw- and sludge-based activated carbon were − 446.666 kcal/mol and 0.002 eV, and − 209.138 kcal/mol and 0.005 eV, respectively. The simulation results indicated that the MB adsorption capacity of straw-based activated carbon was twice that of the sludge-based activated carbon. Compared with sludge-based activated carbon, straw-based activated carbon had a higher carbon recovery ratio, more adsorption active sites, and, therefore, stronger adsorption capacity.