Rapid and efficient removal of acetochlor from environmental water using Cr-MIL-101 sorbent modified with 3, 5-Bis(trifluoromethyl)phenyl isocyanate.

The excessive use of acetochlor (ACT), a commonly used herbicide with latent endocrine disrupting functions, causes surface water pollution. The efficient removal of ACT from contaminated water supplies is of paramount importance. In the current work, 3,5-Bis(trifluoromethyl)phenyl isocyanate (BTP) was successfully anchored onto Cr-MIL-101 walls via covalent incorporation to afford Cr-MIL-101-BTP as a novel adsorbent for the high-efficiency removal of ACT in aqueous solutions. The kinetic adsorption process, adsorption isotherms, adsorbent regeneration, and key parameters, such as adsorbent dosage, pH value, and ionic strength, for the adsorption of ACT were studied. Results showed that a pseudo-second-order rate equation effectively describes the adsorption kinetics. The Langmuir model exhibited a better fit to adsorption isotherm than the Freundlich model. Given the π-π stacking and hydrogen bond interaction, the adsorption capacity in Cr-MIL-101-BTP approached a maximum of 312.5 mg/g for ACT, which was considerably higher than the adsorption capacities of many other reported adsorbents. The excellent adsorption characteristics of Cr-MIL-101-BTP toward ACT were preserved in a wide pH range and high concentration of background electrolytes. In addition, the result showed that partition coefficient (PC) of Cr-MIL-101-BTP was 356.14 mg/g/μM at 5 mg/L of ACT concentration, which was found as the outperformer in all tested subjects. The ACT adsorption capacity of Cr-MIL-101-BTP at the breakthrough point was greatly influenced by initial concentration, and could be described by the Thomas model. Regeneration experiments indicated that the Cr-MIL-101-BTP was recycled at least six times without significant loss of adsorption capacity. Moreover, Cr-MIL-101-BTP did not show cytotoxic activity against the tested HepG2 cell lines and did not pose serious risks to Daphnia carinata survival (48 h LC = 446.6 μg/mL). These results prefigured the promising potential of Cr-MIL-101-BTP as a novel adsorbent for the efficient removal of ACT from aqueous solutions.