A self-assembling guar gum hydrogel for efficient oil/water separation in harsh environments

Abstract “Green” and cost-effective materials for oil/water separation are in high demand to address worldwide water pollution issues. Herein we report a guar gum (GG)-based self-assembling hydrogel for oil/water separation. A cotton fabric was first coated with GG solution, followed by immersion in a sodium periodate (NaIO4) solution. The GG gelation was induced by regioselective oxidation with NaIO4. The in-situ formed aldehydes react with hydroxyl groups in the GG polymer chains, leading to the formation of acetals that crosslink the GG chains. The resultant GG hydrogel-coated cotton fabric was demonstrated to be capable of selectively separating different oily wastewaters, with separation efficiency of 98.11%, 97.53% and 99.47% for silicone oil, canola oil and cyclohexane, respectively. Due to the excellent antifouling properties and reasonable strength of the GG hydrogel, as well as its good affinity with cotton fabric, the as-prepared filtering material possesses high separation efficiency after 10 times of reuse. Moreover, it maintains good oil/water separation capability in alkaline and salty environment.