Investigation of the Antifouling Mechanism of Electroless Nickel–Phosphorus Coating against Sand and Bitumen

Abstract

Antifouling coatings have attracted much attention in applications of industrial equipment and systems. The accumulation of foulants on downhole equipment used in the steam-assisted gravity drainage process for oil sand extraction reduces the recovery efficiency of bitumen and causes failures of the equipment. Applying suitable coatings is expected to endow antifouling property to the related substrate surface. Understanding the interaction mechanism between foulants and antifouling coating is critical for the evaluation and prediction of antifouling performance. In this work, antifouling coating consisting of Ni and P was prepared on the L80 carbon steel substrate, which is a commonly used material in downhole equipment. The surface properties (e.g., morphology and surface energy) of the Ni–P coating and pristine L80 substrates were characterized. The intermolecular and surface forces between typical foulants (e.g., silica and bitumen-coated silica) and Ni–P coated and uncoated L80 substrates were directly measured using the atomic force microscope colloidal probe technique to investigate the fouling mechanisms and predict the fouling behaviors of the foulants at the nanoscale. It was found that the Ni–P coating possessed lower surface energy, weaker attractive van der Waals interaction, and smaller adhesion to both silica and bitumen as compared to the uncoated L80 substrate. Bulk soaking experiments were also conducted accordingly which further demonstrated the antifouling performance of Ni–P coating against silica and bitumen, agreeing well with the surface force measurements. This work has improved the fundamental understanding of fouling behaviors of silica and bitumen and the antifouling mechanism of Ni–P coating at the nanoscale, with potential applications in many related processes in chemical and petroleum industries. The methodologies employed in this work can be readily extended for investigating fouling and antifouling mechanisms of different materials in various engineering fields.

Effect of substrate’s surface roughness on corrosion and wear rate of Ni-GO nanocomposite coating

“…Furthermore, it was observed that the intensity of the XRD peaks decreases as the surface roughness of the substrate decreases. This suggests that the coating is more evenly deposited on a rougher substrate surface compared to a smoother one This suggests that the crystalline structure of the coating is influenced by the roughness of the substrate [15]. The XRD analysis also revealed an overlap between the peaks corresponding to graphene and nickel in the coating.…”

Understanding the Interaction Mechanism between Elemental Selenium and Ferric Hydroxide in Wastewater Treatment

“…The Derjaguin–Landau–Verwey–Overbeek (DLVO) model for colloidal forces ( F dlvo ), which includes van der Waals forces ( F vdw ) and electrical double-layer forces ( F edl ), was used to describe the surface forces acting between the Se 0 probe and Fe­(OH) 3 surface. A constant charge DLVO model was applied for the theoretical calculation in the case of a sphere approaching to an infinite flat substrate. ,,, The equations are described as follows where A is the Hamaker constant for the Se 0 probe interacting with Fe­(OH) 3 across water, R is the Se 0 probe radius, D is the separation distance between the Se 0 probe and flat Fe­(OH) 3 surface, ε is the relative permittivity, ε 0 is the vacuum permittivity, σ T is the probe surface charge density, σ S is the substrate surface charge density, κ is the Debye length, k B is the Boltzmann constant, T is the temperature, C 0 is the bulk concentration of ions, N A is Avogadro’s number, and e is the elementary charge. The surface potential Ψ is correlated to the surface charge density by the Grahame equation (eq ).…”

“…A constant charge DLVO model was applied for the theoretical calculation in the case of a sphere approaching to an infinite flat substrate. 35,36,44,45 The equations are described as follows…”

“…The effects of water composition and pH on the removal efficiency of Se 0 particles were studied. The surface properties of Fe­(OH) 3 and Se 0 particles were characterized, and their intermolecular interactions were quantitatively measured using atomic force microscopy (AFM), which has been successfully employed for probing surface interactions in a variety of colloidal systems. − …”