Synthesis and Mechanism of Adsorption Capacity of Modified Montmorillonite with Amino Acids for 4-Acetaminophenol Removal from Wastewaters

4-Acetaminophenol (PCT) is a kind of micropollutant in nature, and its existence has caused serious harm to the biological environment. In this work, sodium montmorillonite (Na-Mt) was modified with amino acids, l-histidine hydrochloride (His), l-arginine hydrochloride (Arg), and l-methionine (Met), to investigate the adsorption of PCT in the wastewater. The adsorption capacities of the modified adsorbents for PCT under the same conditions were Arg-Mt-1.0 (8.45 mg/g) > His-Mt-1.0 (8.23 mg/g) > Met-Mt-1.0 (7.18 mg/g) > Na-Mt (4.84 mg/g). The investigation showed that Na-Mt and Met-Mt-1.0 conformed to the Temkin model in the temperature range of 15 to 55 °C. The adsorption of His-Mt-1.0 to PCT was consistent with the D-R model within the studied temperature range. The adsorption of Arg-Mt-1.0 on PCT at 15 and 35 °C was consistent with the Freundlich model, and the adsorption of PCT at 55 °C was consistent with the Langmuir model, indicating that when the temperature was high, the adsorption sites tended to be the same. The adsorption of PCT by the modified adsorbents was exothermic, and all the adsorption processes were in accordance with pseudo-second-order kinetic characteristics. Amino acid's modified montmorillonite can improve the adsorption capacity for PCT because the interlayer spacing was increased.