Preparation of Newly Polymer-Coated Microbial Pellets and Their Adsorption and Degradation Properties for Oil-Containing Wastewater.

Water is the lifeblood of everything on earth, nourishing and nurturing all forms of life, while also contributing to the development of civilization. However, with the rapid development of economic construction, especially the accelerated process of modern industrialization, the pollution of oily sewage is becoming increasingly serious, affecting the ecological balance and human health. The efficient elimination of pollutants in sewage is, therefore, particularly urgent. In this paper, a core-shell microbial reactor (MPFA@CNF-SA-AM) was fabricated by using nanocellulose and sodium alginate (SA) particles embedded with microorganisms as the core and lipophilic and hydrophobic fly ash as the outer shell layer. Compared with that of free microorganisms and cellulose and SA aerogel pellets loading with microorganisms (CNF-SA-AM), which has a degradation efficiency of 60.69 and 82.89%, respectively, the MPFA@CNF-SA-AM possesses a highest degradation efficiency of 90.60% within 240 h. So that this self-floating microbial reactor has selective adsorption properties to achieve oil-water separation in oily wastewater and high effective degradation of organic pollutants with low cost. The adsorption curves of MPFA@CNF-SA-AM for diesel and n-hexadecane were studied. The results showed that the adsorption follows the Freundlich model and is a multimolecular layer of physical adsorption. In addition, the degradation mechanism of diesel oil was studied by gas chromatography-mass spectrometry. The results showed that diesel oil was selectively adsorbed to the interior of MPFA@CNF-SA-AM, and it was degraded by enzymes in microorganisms into n-hexadecanol, n-hexadecaldehyde, and n-hexadecanoic acid in turn, and finally converted to water and carbon dioxide. Compared with existing oily wastewater treatment methods, this green and pollution-free dual-functional core-shell microbial reactor has the characteristics of easy preparation, high efficiency, flexibility, and large-scale degradation. It provides a new, effective green choice for oily wastewater purification and on-site oil spill accidents.

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 Fe3O4/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 Fe3O4 for selective absorption of oil and maganetic recycling. The core-shell-structured bioreactor Fe3O4/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 Fe3O4/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 Fe3O4/MHNTs-CNF@aerogel possessed a strong tolerance ability under different pH and salinity conditions. The Fe3O4/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.

MXene-doped kapok fiber aerogels with oleophobicity for efficient interfacial solar steam generation.

Although the evaporation efficiency of photothermal materials (PMs) in pure water and brine solutions has been extensively studied, there few research on the performance in complex oily wastewater. Herein, a new monolithic solar steam generator derived from kapok fiber-based MXene composite aerogel (named as KFs-MXene) was fabricated by dipping the aerogels (KFs) which composed of kapok fiber and sodium alginate (SA) as substrates in the suspension of MXene. Benefitting from the outstanding light absorption (about 97%), better thermal insulation (thermal conductivity, 0.05039 W m-1 K-1), abundant porosity (95.60%) and rapid water transportation. KFs-MXene show good interfacial solar steam generation (ISSG) performance, resulting in a high water evaporation rate of 1.47 kg m-2h-1 with an outstanding evaporation efficiency of 90.4% under 1 kW m-2 irradiation. To improve the antifouling performance of KFs-MXene, chemically hydrophilic and oleophobic modification was applied, making the KFs-MXene can also be widely used in oily wastewater. Under 1 kW m-2 illumination, the evaporation rate and energy conversion efficiency of KFs-MXene with hydrophilic and oleophobic modification (O-KFs-MXene) in 1 wt% oily water can reach to 1.40 kg m-2h-1 and 82.87%, and the evaporation efficiency and rate of O-KFs-MXene remain stable in the continuous 6 h solar driven interface evaporation process.