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Herein, an excellent cathode of ZnO-CeO2/CF was fabricated successfully via one-step electro-deposition method for the degradation of ciprofloxacin (CIP) in sewage by electro-Fenton (EF) technology. The detailed characterizations of ZnO-CeO2/CF material were conducted by SEM, XRD, XPS, CV and EIS. Effects of deposition time, initial pH and voltage value on degradation performance of ZnO-CeO2/CF were investigated systematically. The results showed nearly 100% degradation efficiency was easily obtained at 2 h owing to the large specific surface area of cathode, the good oxygen storage ability and Fenton-like performance of ZnO-CeO2. It was worth to mention that the favorable capability still existed in cathode body after 10 consecutive runs. Moreover, electron paramagnetic resonance (EPR) test and sacrificial agent experiments revealed that the increase of active substance accelerated the degradation efficiency of CIP during the process of valence state transition of Ce3+/Ce4+ or Fe2+/Fe3+.

Adaptability in improving hydrophobically associating polyacrylamide (HAPAM) flooding by reducing hydrophobicity (to decrease retention) while increasing molecular weight (to ensure viscosity), was researched by the comparative study of an accordingly modified HAPAM (M-HAPAM), a conventional HAPAM (C-HAPAM) and a classical hydrolyzed polyacrylamide (HPAM). Attention is paid to their thickening ability, injectivity and propagation, retention, and finally oil-displacing performance. Results show that hydrophobicity reduction helps retention decrement and propagation enhancement of M-HAPAM, making it outperform C-HAPAM with regard to injectivity, propagation, and oil recovery: however, HPAM works best at permeabilities of ∼1 μm2 ∼ 3 μm2, and M-HAPAM needs more hydrophobicity reduction.

Wormlike micelles (WLMs) have been successfully constructed from many different C22-tailed surfactants. Here, we creatively introduced a bulky piperazine group onto a C22-tailed zwitterionic surfactant, N-erucamidopropyl-N,N-piperazine-N-methyl ammonium propanesulfonate (EDPS), and investigated the micellar structure and properties of the EDPS WLMs via molecular dynamics simulation, cryo-TEM and rheological techniques. It was found that 25 mM EDPS increased the zero-shear viscosity to as high as ∼106 mPa s. Furthermore, abnormal rheological behaviors, such as an inflection in the shear thinning region of steady rheology and an abrupt decrease of the shear stress at a critical shear rate, were observed, which was attributed to the unique ladder shape micellar structure. The EDPS WLMs were superior to other C22-tailed surfactants in many aspects, such as a low overlapping concentration, higher viscosity, stable viscosity over the whole pH range, and great temperature and salt (NaCl, CaCl2 and MgCl2) tolerance.

It is generally accepted that polymer flooding gets less effective as the heterogeneity of a reservoir increases. However, very little experimental information or evidence has been collated to indicate which levels of heterogeneity correspond to reservoirs that can (and cannot) be efficiently developed using polymer flooding. Therefore, to experimentally determine a heterogeneity limit for the application of polymer flooding to reservoirs, a series of flow tests and oil displacements were conducted using parallel sand packs and visual models possessing different heterogeneities. For low-concentration polymer flooding (1.0 g/l), the limit determined corresponds to permeability contrasts (PCs) of 10.8 and 10.2, according to the parallel and visual tests, respectively. A significant increase in oil recovery can be achieved by polymer injection within these limits. Increasing the polymer concentration to 2.0 g/l increased these limiting PCs to 52.8 and 50.0, respectively. Additionally, within or beyond these limits, the combined use of polymer and gel may be the best.