Facile synthesis of lignin/polyethyleneimine foams incorporating zeolitic imidazole framework-8 to efficiently remove tetracycline from aqueous solution

Lignin, as a by-product produced in the biological refining and papermaking processes, is often discarded or burned, resulting in environmental pollution and resource waste. Herein, a novel environmental-friendly ternary hybrid foams adsorbent (SLS/PEI/ZIF-8) was designed for effectively removal TC from aqueous solution. The adsorption properties of the adsorbent were systematically studied. The results show that the adsorption process for TC were fitted well by the pseudo-second-order kinetics model and the Langmuir isotherm model, respectively. The maximum Langmuir monolayer adsorption capacity of SLS/PEI/ZIF-8 for TC was calculated as 1098 mg/g at 30 °C, which was superior to most reported adsorbents. Thermodynamic analysis indicated the adsorption process for TC was spontaneous and endothermic. Moreover, the electrostatic interactions, hydrogen bonding interactions and π–π interactions were proposed as the possible adsorption mechanism. The adsorbent still maintained superior adsorption capacity for TC in ions solution, HA solution and actual water samples, and had good reusability. Therefore, it is a promising adsorbent for the removal of TC from wastewater.