Highly effective and reusable Ni-Al oxide/Zn_0.4Co_0.6Fe₂O₄ superparamagnetic aerogel for oil-water separation

Oily wastewater from the oil industry and oil spill accidents has become a serious environmental problem and has attracted worldwide attention. The present study reports on the successful preparation of a novel magnetic Ni-Al oxide/Zn_0.4Co_0.6F₂O₄ mesoporous aerogel (MNA) as a highly selective adsorbent for oil removal from water. Oleic acid (OA) and Triton X-100 (TX) were used as hydrophobic agents for MNA surface modification. It was found that the attached amount of OA on the mesoporous MNA aerogel is 3.5 times larger than that of TX, giving an advantage to MNA-OA in oil separation. The MNA-OA displayed superhydrophobicity (contact angle ∼150°) and superparamagnetism properties that allowed the adsorbent to be used selectively for oil removal. The MNA-OA was found to have a high oil removal efficiency of ∼97% with an adsorption capacity of ∼2 g/g. Furthermore, the produced magnetic adsorbent has high stability due to the strong chemical binding of OA, which is demonstrated by its good reusability performance. Throughout five separate runs, the MNA-OA was shown to be a very efficient and reusable adsorbent for oily wastewater.