Plugging performance and mechanism of an OBDF oil-absorbing resin (MMA-SMA-St) plugging agent

To treat the issue of increased resource wastage due to the higher plugging tendencies of oil-based drilling fluids (OBDF) relative to water-based drilling fluids, this study synthesized a ternary composite oil-absorbing resin and optimized its synthesis parameters. The influence of temperature variations on the resin's oil absorption capacity was assessed. Techniques such as infrared spectroscopy, scanning electron microscopy, TGA-DSC measurements, crosslinking degree analysis, contact angle analysis, X-ray photoelectron spectrometry analysis and examination of the resin's plugging mechanism were employed to investigate its molecular structure, oil absorption properties, and plugging efficiency. Additionally, the impact of various synthesis conditions on the oil absorption expansion rate of the oil-absorbing resin was examined. The findings indicate that the resin developed in this research maintains robust oil absorption capabilities at 160 °C, exhibiting an oil absorption expansion rate of 12.5 g g-1. At this temperature, the composite resin particles effectively sealed leaks of widths 0.25, 0.5, and 0.75 μm. Comparative analysis revealed that adding 3% of these resin particles to OBDF significantly enhanced the sealing of fractures. Remarkably, at 160 °C, OBDF amended with resin particles managed to completely seal fractures measuring 0.25 μm. The novelty of this study is attributed to the utilization of styrene for enhancing the resin's rigidity, coupled with the application of octadecyl methacrylate, which contains long-chain alkyl groups, to optimize the oil absorption and expansion characteristics of the oil-absorbing resin.

Fluorine-Free Superhydrophobic Covalent-Organic-Polymer Nanosheet Coating for Selective Dye and Emulsion Separation

Covalent organic polymer nanosheets (COPNs) endowed with porous networks and large surface areas in their structures offer great advantages over other materials in addressing environmental problems. In this study, fluorine-free superhydrophobic COPNs were designed and applied to selective dye absorption. Notably, COPNs selectively adsorb dyes with a high hydrophobic index (HI) and reject low HI dyes with maximum adsorption capacities of 361 and 263 mg/g for crystal violet and methylene blue, respectively. The adsorption isotherm model showed that the COPNs follow the Langmuir adsorption isotherm model and pseudo-second-order kinetics. Next, we explored the superhydrophobicity of the COPNs by in situ fabrication with melamine sponge (COPNs-MS), which incorporates the superhydrophobicity of COPNs [water contact angle (WCA) of >150°] with the structure and flexibility of the MS skeleton. The COPNs-MS shows various oil-adsorbing properties with good adsorption capacity (from 60 to 120 g/g) and also effectively separates various surfactant-stabilized emulsions with a separation efficiency of over 99%. The as-fabricated COPNs-MS retains its superhydrophobicity in various solvents and hazardous conditions (WCA ≥ 150°) and exhibits good flame retardancy and excellent compression properties with excellent antifouling property due to the superhydrophobic COPN coating. Furthermore, COPNs-MS also demonstrates excellent recyclability because the strong COPN coating in the MS skeleton retains its hydrophobicity. Therefore, our fluorine-free superhydrophobic COPNs are not only capable of selective dye adsorption but also exhibit very good oil adsorption and surfactant-stabilized emulsion separation performance.

Synthesis and characterization of porous fibers/polyurethane foam composites for selective removal of oils and organic solvents from water

In the field of oil/water separation, functional oil-absorbing materials with both controllable porous structures and swelling properties are highly desirable.