Adsorption mechanism of expanded graphite for oil and dyes

Expanded graphite （r-;G） shows higher adsorption capacity for oils than for dyes. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of dyes and oil on EG were firstly studied. And then stepwise adsorption for oils was carried out with EG which has been saturated firstly by dyes, the difference between adsorbance of oil on EG was checked with deviation analysis. Scanning electronic microscopy （SEM） analysis was used to show structure difference of EG adsorbed different adsorbates. These used adsorbates were SD300 oil, basic fuchsine, Auramine lake yellow O and acid brilliant red 3B. The adsorption isotherm of dyes on EG is type 11 or type 1, and their equilibrium adsorbances are less than 1.0 g/g. While, adsorbance for SD300 oil can reach 104.5 g/g. Deviation analysis for stepwise adsorbances of oil shows no statistical significance. EG saturated firstly by dyes, still has an average adsorption capacity of 35 g/g for SD300 oil, and it does not change with the initial dyes concentration. SEM photos illustrate the adsorption of oil on EG is mainly filling, In the adsorption of dyes, there is severe breakage of the V-type pore and shrinkage of the particle. Kinetic difference is analyzed also.

Magnetic core-shell microparticles for oil removing with thermal driving regeneration property

Here, we report the construction of magnetic core-shell microparticles for oil removal with thermal driving regeneration property. Water-in-oil-in water (W/O/W) emulsions from microfluidics are used as templates to prepare core-shell microparticles with magnetic holed poly (ethoxylated trimethylolpropane triacrylate) (PETPTA) shells each containing a thermal-sensitive poly (N-Isopropylacrylamide) (PNIPAM) core. The microparticles could adsorb oil from water due to the special structure and be collected with a magnetic field. Then, the oil-filled microparticles would be regenerated by thermal stimulus, in which the inner PNIPAM microgels work as thermal-sensitive pistons to force out the adsorbed oil. At the same time, the adsorbed oil would be recycled by distillation. Furthermore, the adsorption capacity of the microparticles for oil keeps very stable after 1st cycle. The adsorption and regeneration performances of the microparticles are greatly affected by the size of the holes on the outer PETPTA shells, which could be precisely controlled by regulating the interfacial forces in W/O/W emulsion templates. The optimized core-shell microparticles show excellent oil adsorption and thermal driving regeneration performances nearly without secondary pollution, and would be a reliable green adsorption material for kinds of oil.

Fabrication of super-elastic graphene aerogels by ambient pressure drying and application to adsorption of oils

Three-dimensional graphene-based aerogels have promising applications in oil adsorption and environmental restoration.However,current research of graphene-based aerogels is often hindered by high preparation cost,poor mechanical properties and low recycling efficiency.Here,superelastic graphene aerogel(SGA)was prepared through one-step freezing and twice hydrothermal reduction followed by drying under ambient pressure.The simple atmospheric drying provides a possibility for large-scale preparation of high performance graphene-based aerogels.The prepared SGA not only has the ability of highly repeatable compression rebound,but also exhibits excellent oil adsorption performance.And the overall performance of SGA is better than most of graphenebased aerogels prepared by freeze drying.After the SGA was cyclically compressed with 70%strain for 300 times,it can return to the original shape and height substantially.SGA retained about 90%of the initial adsorption capacity after 50 cycles of adsorption and compression regeneration for cyclohexane.

Three-dimensional graphitic carbon sphere foams as sorbents for cleaning oil spills

Frequent offshore oil spill accidents, industrial oily sewage, and the indiscriminate disposal of urban oily sewage have caused seri- ous impacts on the human living environment and health. The traditional oil-water separation methods not only cause easily environmental secondary pollution but also a waste of limited resources. Therefore, in this work, three-dimensional (3D) graphitic carbon sphere (GCS) foams (collectively referred hereafter as 3D foams) with a 3D porous structure, pore size distribution of 25-200 μm, and high porosity of 62vol% were prepared for oil adsorption via gel casting using GCS as the starting materials. The results indicate that the water contact angle (WCA) of the as-prepared 3D foams is 130°. The contents of GCS greatly influenced the hydrophobicity, WCA, and microstructure of the as-prepared samples. The adsorption capacities of the as-prepared 3D foams for paraffin oil, vegetable oil, and vacuum pump oil were approximately 12-15 g/g, which were 10 times that of GCS powder. The as-prepared foams are desirable characteristics of a good sorbent and could be widely used in oil spill accidents.

Microstructure Characterization and Oil Absorption Performance of Superhydrophobic Cotton Cellulose Aerogel

Superhydrophobic cotton cellulose (CC) aerogel was prepared from budget cotton with huge output.CC aerogels were synthesized by using commercial cotton extract as a precursor through the nano-self-assembly process,CO2 supercritical drying process,and vapor deposition.Typical,uniform hydrophobic CC aerogel structure can be confirmed by several characterization techniques.Maximum specific surface areas before and after modification are 213.80 m^(2)·g^(-1) and 184.33 m^(2)·g^(-1)with average pore sizes at 14.01 nm and 32.56 nm.The water contact angle is up to 153°,showing its superhydrophobic property.The maximum adsorption efficiency can be up to 16.0 g·g^(-1),which exhibits excellent cycling property after 5 adsorption tests.The oil absorption mechanism of the superhydrophobic CC aerogels is investigated in detail as well.This superhydrophobic CC aerogel has excellent adsorption performance and simple,rapid,effective oil contamination treatment which has promising applications in the field of oil adsorption and water remediation in oil adsorption.

Superhydrophobic and superlipophilic biochar produced from microalga torrefaction and modification for upgrading fuel properties

Torrefaction operation is an essential pathway for solid biofuel upgrading,and good hydrophobicity of torrefied biochar is conducive to its storage.Herein,a two-stage treatment of torrefaction followed by modification by hexadecyltrimethoxysilane was adopted to improve the moisture resistance performance of biochar.This two-stage treatment process led to a longer torrefied microalgal biochar preservation time(60-200%improved)and great superhydrophobicity and superlipophilicity.Therefore,the modified microalgal biochar could significantly adsorb leaking oil for environmental remediation and further improve the calorific value of the biochar.The obtained results indicated that the oil adsorption capacity of modified microalgal biochar was correlated to torrefaction temperature and oil species.Specifically,the oil adsorption capacity was enhanced up to 70-80%from the modification process when comparing to raw microalga.Increasing the torrefaction temperature enhanced the adsorption quantity of the modified microalgal biochar.By adsorbing the oil,the calorific value of oilchar,namely,biochar with adsorbed oil,could be higher than 40 MJ kg^(−1).Furthermore,the pyrolysis and combustion characteristics suggested that biochar stability gradually rose as the torrefaction temperature increased.By comprehensively analyzing and comparing the fuel performance of the modified microalgal biochar with previous literature,the obtained modified microalgal biochar possessed better fuel properties and environmental sustainability.