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Blockage of pipelines due to accretion of salt particles is detrimental in desalination and water-harvesting industries as they compromise productivity, while increasing maintenance costs. We present a micro-/nanoscale approach to study fundamentals of scale formation, deposition, and adhesion to engineered surfaces with a wide range of surface energies fabricated using the initiated chemical vapor deposition method. Silicon wafers and steel substrates are coated with poly(1H,1H,2H,2H-perfluorodecylacrylate) or pPFDA, poly(tetravinyl-tetramethylcyclotetrasilohexane) or pV4D4, poly(divinylbenzene) or pDVB, poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasilohexane) or pV3D3, and cross-linked copolymers of poly(2-hydroxyethylmethacrylate) and poly(ethylene glycol) diacrylate or p(PHEMA-co-EGDA). Particles of salt (CaSO 4 •2H 2 O) are formed and shaped with a focused ion beam and adhered to a tipless cantilever beam using a micromanipulator setup to study their adhesion strength with a molecular force probe (MFP). Adhesion forces were measured on the substrates in wet and dry conditions to evaluate the effects of interfacial fluid layers and capillary bridges on net adhesion strength. The adhesion between salt particles and the pPFDA coatings decreased by 5.1 ± 1.15 nN in wet states, indicating the influence of capillary bridging between the particle and the liquid layer. In addition, scale nucleation and growth on various surfaces is examined using a quartz crystal microbalance (QCM), where supersaturated solution of CaSO 4 •2H 2 O is passed over bare and polymer-coated quartz substrates while mass gain is measured in real time. The salt accretion decreased by 2 folds on pPFDA-coated substrates when compared to that on p(HEMA-co-EGDA) coatings. Both MFP and QCM studies are essential in studying the impact of surface energy and roughness on the extent of scale formation and adhesion strength. This study can pave way for the design of scale-resistant surfaces with potential applications in water treatment, energy harvesting, and purification industries.

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This paper presents an optimization study of catalytic hydrotreating reactors processing heavy residuum feedstock. The focus is on conversion, throughput and catalyst life. The core of the proposed optimization model is a cost function representing the essential economical parameters of hydrotreating processes and accounts for additional costs imposed by deeper desulfurization in addition to the monetary benefit of lower sulfur products. Operational variables are estimated using a mathematical model, which accounts for catalyst deactivation. Simulation results are presented to illustrate the effect of various operating variables on the process performance. An industrial scale atmospheric residue desulfurization process has been selected as a typical hydrotreating unit to demonstrate the capabilities of the optimization model. Optimization results were found quite reliable and consistent with actual industrial practices.