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

Oil spills, waste disposal, synthetic organic compounds (SOCs), volatile organic compounds (VOCs), and other organic pollutants significantly contaminate the food chain and water supply. Over the years, there has been an increase in interest in the science and engineering of water purification, especially oil–water separation. Three main strategies have been developed: (1) the filtration method using specific wettability that only permits oil or water to pass through; (2) the absorption strategy using porous sponges, fibers, and aerogels that can selectively absorb oil or water; and (3) filtration or separation technology that is switchable and controllable in functionality. Among the conventional methods, sorption using organogels is considered an efficient and promising approach because of its fast and effective absorption ability and reusability. Herein we report an amino acid-based thermoresponsive organogel for oil–water separation. The efficiency of the organogel prepared for oil and solvent extraction was determined via absorption and desorption kinetic studies. The swelling behavior of organogel was investigated in various solvents (2.25 ≤ ε ≤ 46.7), showing a maximum average absorption of ∼1100% for nonpolar solvents and 850% for polar solvents. The organogel followed pseudo-second-order absorption kinetics, exhibited excellent reusability, and could withstand at least 40 absorption/desorption cycles, retaining almost 95% efficiency. Considering the favorable structural morphology, excellent porosity, and highly oleophilic characteristics, the prepared organogel membranes showed >96% oil/water emulsion separation efficiency with a separation flux of 2.4 × 102 L·m–2·h–1, with flux recovery of 87.5% after the 10th separation cycle. The organogel membrane employed here for oil/solvent water separation has sufficient hydrophobicity, fast and high uptake ability, good resilience, durability over different aqueous media, and reusability, making it a suitable candidate for oil/water extraction.