Adsorption mechanism of low-carbon alcohols and acids on carbon nanotubes in Fischer-Tropsch synthesis wastewater

Adsorption is a promising strategy to remove harmful substances from Fischer-Tropsch synthesis (FTS) wastewater, and clarifying the adsorption mechanism is an important issue. In this paper, carbon nanotubes (CNTs) with different pore size were used for the adsorption of low-carbon alcohols (methanol, ethanol, propanol, butanol, pentanol) and acids (acetic acid, propanoic acid, butyric acid). After the micropores being occupied by chloroform, the percentage of micropores decrease is found to exhibit a positive correlation with adsorption capacity, indicating that the micropores dominanate the adsorption properties of alcohols and acids. Based on density functional theory (DFT) calculation results, the adsorption energy of pentanol is the largest and that of methanol is the smallest, in consistent with the experimental results. The similar polarity of pentanol with CNTs improves the adsorption property. Furthermore, with similar polarity, the kinetic diameter of adsorbate being close to the pore size is beneficial for improving adsorption behavior of CNTs. [Display omitted] •Adsorption mechanisms of alcohols and acids in FTS wastewater by CNTs were studied.•Chloroform pre-adsorption validates the crucial role of micropore in adsorption.•Similar polarity and kinetic diameter of adsorbent to the pore of CNTs improve adsorption ability.•Adsorption energy calculated by DFT is consistent with experimental results.