Based on the measurements of conductivity and surface tension and our previously reported results of isothermal titration calorimetry (ITC), the surface activity and micellization parameters, such as the critical micellar concentration (CMC), the degree of counterion dissociation (β), and thermodynamic functions of micellization, for six quaternary ammonium surfactants, dodecyl-(2-hydroxyethyl)-dimethylazanium bromide, tetradecyl-(2-hydroxyethyl)-dimethylazanium bromide, hexadecyl-(2-hydroxyethyl)-dimethylazanium bromide, dodecyl-di(2hydroxyethyl)-methylazanium bromide, tetradecyl-di(2-hydroxyethyl)methylazanium bromide, and hexadecyl-di(2-hydroxyethyl)-methylazanium bromide in aqueous solutions have been investigated. The values of CMC determined from three different methods are compared, and they show reasonable agreement. From the CMC values obtained from the conductivity measurements in this work and the previously reported values of calorimetric enthalpy of micellization, the Gibbs free energy (ΔG mic ) and entropy (ΔS mic ) of micellization are calculated through the mass-action model. The influences on the micellization parameters of the temperature, the length of alkane chain, and the number of hydroxyethyl substituents on the surfactant headgroup are discussed.

Summary Nickel oxide nanoparticles were synthesized by microemulsion method and characterized by powder X‐ray diffraction, dynamic light scattering, and scanning electron microscopy. Thermal analyses were performed to identify the influence of nickel oxide nanoparticles on the in situ combustion of Liaohe heavy oil. Low‐temperature oxidation and coking process were investigated by analysing the effluent gases and the fractions of saturates, aromatics, resins, and asphaltenes. Combustion tube tests were also conducted to evaluate the catalytic performance of nickel oxide nanoparticles. Compared with the runs without catalysts, the effective activation energies were reduced by 4.22%, 20.57%, and 35.75% in terms of low‐temperature oxidation, pyrolysis, and high‐temperature oxidation, respectively. The reduction in O2 fraction and the increase in CO2 and O2 uptake were also confirmed. The overall trend presented the increase of saturates and aromatics fraction and the decline of resins and asphaltenes fraction while temperature was increased during low‐temperature oxidation. Adding nickel oxide nanoparticles led to the reduction in the fuel deposit during pyrolysis. Compared with the base combustion tube runs, combustion time in catalytic experiment was shortened by 12.1%, combustion front movement was accelerated by 9.1%, oil recovery was enhanced by 4.0%, and oil viscosity was reduced by 61.2%.

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The discharge of oily wastewater and oil spills at sea are the current difficulties in water pollution control. This problem often leads to terrible disasters. Therefore, the effective realization of oil-water separation is a very challenging problem. Superhydrophobic sponge is a promising oil-absorbing material. In this article, we reported a superhydrophobic sponge with nano-Fe3O4 for oil-water separation. The addition of nano-Fe3O4 allows the sponge to be recycled under the action of magnetic force. The sponge has the advantages of low cost, simple preparation and efficient oil-water separation. This kind of sponge is very worthy of promotion for the treatment of oily wastewater and marine oil spill accidents.

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CeO2 was synthesized by the co-precipitation method on the Cu mesh substrate and modified the surface of CeO2@Cu mesh by stearic acid (SA). The superhydrophobic behavior was ascribed to the combination of hierarchical micro–nanostructure of CeO2 and the hydrophobic alkyl groups from SA. The SA-CeO2@Cu mesh had antiacid and base stability and excellent durability as well as high separation efficiency. The separation efficiency can be up to 98.0% after separating 30 times.