Preparation of a Magnetic Core–Shell Bioreactor for Oil/Water Separation and Biodegradation

With the frequent occurrence of offshore oil spills, the effective separation and treatment of oily wastewater are essential to the environment. In this work, the core–shell bioreactor (abbreviated as Fe 3 O 4 /MHNTs-CNF@aerogel) was prepared with a core composed of camphor leaf cellulose-based aerogels for loading microorganisms and a shell derived from hydrophobic silane-modified halloysite doping with Fe 3 O 4 for selective absorption of oil and maganetic recycling. The core–shell-structured bioreactor Fe 3 O 4 /MHNTs-CNF@aerogel has excellent self-floating properties and can float on water for up to 100 days. The whole core–shell structure not only has excellent oil/water separation performance but also has good microbial degradation performance. By applying it in water containing 5% diesel for the biodegradation test, the biodegradation efficiency of Fe 3 O 4 /MHNTs-CNF@aerogel for diesel can reach 82.4% in 10 days. The efficiency was 20% higher than for free microorganisms, and it still had excellent degradation ability after three degradation cycles, with a degradation rate of over 75%. In addition, the result obtained from the study on environmental tolerance shows that Fe 3 O 4 /MHNTs-CNF@aerogel possessed a strong tolerance ability under different pH and salinity conditions. The Fe 3 O 4 /MHNTs-CNF@aerogel also has superior mechanical properties; i.e., nearly no deformation occurs at 30 kPa. Compared with those conventional oil/water separation materials which can only absorb or separate the oils for water with limited capacity and taking the risk of secondary contamination, our core–shell-structured bioreactor is capable of not only selectively absorbing oil from water through its hydrophobic shell but also degrading it into a nontoxic substance by its microorganism-loaded core, thus showing great potential for practical application in oily wastewater treatment.