Synthesis and mechanism analysis of a non-toxic amine-based clay mineral surface hydration intercalation inhibitor

The surface hydration of clay minerals remains a serious challenge for drilling projects. Herein, we synthesized a non-toxic amine-based clay mineral surface hydration intercalation inhibitor (ODBB) whose structure was characterized using Fourier transform infrared spectroscopy, mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The inhibitory ability of ODBB was evaluated through isothermal adsorption, X-ray diffraction, thermogravimetric analysis, linear expansion, rolling recovery, and sedimentation stability. The biological toxicity of ODBB was tested with a bioluminescent bacteriological method. The inhibition mechanism was analysed using elemental analysis, atomic absorption spectroscopy, wettability Measurement, zeta potential analysis, capacity of exchangeable cation, scanning electron microscopy, and molecular dynamics simulation. The addition of more than 0.5 wt% ODBB resulted in a reduction in the base spacing of Na-MMT/ODBB from 2.10 to 1.31 nm, while the derivative thermogravimetric curve showed a single peak at 50–200 °C. These results showed that the surface hydration of Na-MMT was completely inhibited. Meanwhile, an EC50 value of 93,000 indicated that ODBB was non-toxic. ODBB intercalated into the crystal layer space of Na-MMT, replaced interlayer cations (Na+), adsorbed on the surface (d001) of Na-MMT by electrostatic interactions, and formed hydrogen bonds with the oxygen atoms on the surface (d001). Furthermore, ODBB tightened the crystalline layer and reduced the base spacing through hydrogen bonding and electrostatic forces.