Reusable Amino Acid/<i>N</i>‑Isopropylacrylamide-Based\nOrganogels for Efficient Oil and Solvent Removal from Water

Oil spills, waste disposal, synthetic organic compounds\n(SOCs),\nvolatile organic compounds (VOCs), and other organic pollutants significantly\ncontaminate the food chain and water supply. Over the years, there\nhas been an increase in interest in the science and engineering of\nwater purification, especially oil–water separation. Three\nmain strategies have been developed: (1) the filtration method using\nspecific wettability that only permits oil or water to pass through;\n(2) the absorption strategy using porous sponges, fibers, and aerogels\nthat can selectively absorb oil or water; and (3) filtration or separation\ntechnology that is switchable and controllable in functionality. Among\nthe conventional methods, sorption using organogels is considered\nan efficient and promising approach because of its fast and effective\nabsorption ability and reusability. Herein we report an amino acid-based\nthermoresponsive organogel for oil–water separation. The efficiency\nof the organogel prepared for oil and solvent extraction was determined\nvia absorption and desorption kinetic studies. The swelling behavior\nof organogel was investigated in various solvents (2.25 ≤ ε\n≤ 46.7), showing a maximum average absorption of ∼1100%\nfor nonpolar solvents and 850% for polar solvents. The organogel followed\npseudo-second-order absorption kinetics, exhibited excellent reusability,\nand could withstand at least 40 absorption/desorption cycles, retaining\nalmost 95% efficiency. Considering the favorable structural morphology,\nexcellent porosity, and highly oleophilic characteristics, the prepared\norganogel membranes showed >96% oil/water emulsion separation efficiency\nwith a separation flux of 2.4 × 10<sup>2</sup> L·m<sup>–2</sup>·h<sup>–1</sup>, with flux recovery of 87.5% after the\n10th separation cycle. The organogel membrane employed here for oil/solvent\nwater separation has sufficient hydrophobicity, fast and high uptake\nability, good resilience, durability over different aqueous media,\nand reusability, making it a suitable candidate for oil/water extraction.