Periodic Reporting for period 3 - DESCALE (De-railing scaling: From fundamentals of crystallization fouling on nano-materials to rational design of scale-phobic surfaces)
Período documentado: 2023-02-01 hasta 2024-07-31
Crystallization fouling, a process where limescale forms on surfaces, is pervasive in nature and technology, negatively impacting the energy conversion and water treatment industries. Despite significant work, rationally designed materials that are intrinsically resistant to crystallization fouling without the use of active methods like antiscalant additives (which can persist long after their disposal and the toxicological impact of which in effluent is questioned) remain elusive. This is because antiscalant surfaces are constructed today without sufficient reliance on an intricate but necessary science-base, of how interweaved interfacial thermofluidics, nucleation thermodynamics, and surface nanoengineering control the onset of nucleation and adhesion of frequently encountered scaling salts like calcium carbonate and calcium sulfate. Such scaling salts are common components of fouling deposits in industrial heat exchangers and membranes, which significantly inhibit heat transfer and flow performance. Therefore, guided by interfacial thermofluidic and thermodynamics theories, and employing advanced experimental methods in the areas of surface nanoengineering and diagnostics, this project will develop an integrated knowledge-base for how engineered surfaces can beneficially interact with interfacial transport phenomena in order to significantly advance antiscalant surfaces. We aim to pinpoint mechanisms for inhibiting scale nucleation and reducing adhesion in order to design and engineer antiscalant materials based on the collaborative action of their composition and topography. The effects of surface texture curvature, surface composition, and substrate compliance on scale nucleation and adhesion have intertwined and sometimes competing impacts, which we aim at elucidating to realize high performance scale-phobic surfaces. Connected to this are cutting edge materials fabrication techniques and considerations to the development of surfaces for future applications. This project ran from 1 Feb 2020 until 31 Jan 2024.
We recruited and trained the research team, including two doctoral students, acquired the necessary equipment, and developed our methodologies for investigation the fundamentals of crystallization fouling. We were able to design and realize nanoengineered surfaces which are promising regarding crystallization inhibition (under peer-review). We were also able to design, fabricate, and test promising low adhesion surfaces with inherent scalephobicity properties (published in Science Advances). Using a fouling experimental unit, which mimics a water-cooled heat exchanger, we have also identified promising nanotextured metallic surfaces for repelling the formation of calcium carbonate and calcium sulfate (under peer-review).
Guided by nucleation theory, we have identified specific surface nanotexture and composition, which acts to delay the onset of crystallization fouling of calcium carbonate or limescale, an important foulant. We have created a knowledge-base on the relationship between surface nanotexture and super-saturation and the onset of nucleation of calcium carbonate. We have also studied the effect of coating composition, compliance, and textured on calcium carbonate crystallite adhesion and have identified a class of surfaces where flowing water is able to passively remove such deposits when they are microscopic before they become problematic for water and energy applications. We have therefore demonstrated surfaces with intrinsic scalephobic properties.