Particle Deposition and Aggregation: Measurement, Modelling and Simulation describes how particle deposition and aggregation can be measured, modeled, and simulated in a systematic manner. It brings together the necessary disciplines of colloid and surface chemistry, hydrodynamics, experimental methods, and computational methods to present a unified approach to this problem. The book is divided into four parts. Part I presents the theoretical principles governing deposition and aggregation phenomena, including a discussion of the forces that exist between particles and the hydrodynamic factors that control the movement of the particles and suspending fluid. Part II introduces methods for modeling the processes, first at a simple level (e.g. single particle-surface, single particle-single particle interactions in model flow conditions) and then describes the simulation protocols and computation tools which may be employed to describe more complex (multiple-particle interaction) systems. Part III summarizes the experimental methods of quantifying aggregating and depositing systems and concludes with a comparison of experimental results with those predicted using simple theoretical predictions. Part IV is largely based on illustrative examples to demonstrate the application of simulation and modeling methods to particle filtration, aggregation, and transport processes. This book should be useful to graduates working in process and environmental engineering research or industrial development at a postgraduate level, and to scientists who wish to extend their knowledge into more realistic process conditions in which the fluid hydrodynamics and other complicating factors must be accommodated.

Particle aggregation with simultaneous surface growth was modeled using a dynamic Monte Carlo method. The Monte Carlo algorithm begins in the particle inception zone and constructs aggregates via ensemble-averaged collisions between spheres and deposition of gaseous species on the sphere surfaces. Simulations were conducted using four scenarios. The first, referred to as scenario 0, is used as a benchmark and simulates aggregation in the absence of surface growth. Scenario 1 forces all balls to grow at a uniform rate while scenario 2 only permits them to grow once they have collided and stuck to each other. The last one is a test scenario constructed to confirm conclusions drawn from scenarios 0-2. The transition between the coalescent and the fully-developed fractal aggregation regimes is investigated using shape descriptors to quantify particle geometry. They are used to define the transition between the coalescent and fractal growth regimes. The simulations demonstrate that the morphology of aggregating particles is intimately related to both the surface deposition and particle nucleation rates.

Kinetics of Aggregation and Gelation

Engineered nanomaterials (ENMs) are used in numerous applications due to their unique advantages. Gold nanomaterials (AuNMs) are one such functional ENM, which are utilized as model nanoparticles due to their controlled properties. AuNMs can be synthesized with highly uniform size and shape, where increase in the anisotropy gives rise to novel properties; e.g., unique Plasmon resonance, shape dependent physico-chemical properties, and quantum confinement, etc. These advantages have popularized the use of AuNMs in a wide range of applications in sensing, drug delivery, and photodynamic therapies. Increased use of these ENMs calls for systematic evaluation of the AuNMs to assess the effect of their size and shape on fate and transport in aquatic environment. The natural environment, due to the presence of natural colloids and potential presence of secondary ENMs, presents additional system complexities in studying ENM fate and transport. This dissertation was designed to address two major data gaps: i.e., roles of i) anisotropy and ii) presence of secondary particles on aggregation and deposition of AuNMs. Poly-acrylic acid (PAA) coated uniform-sized gold nanospheres (AuNS) and nanorods (AuNR) are utilized as model nanoparticles. The first part of this research investigated the effect of shape of AuNMs on their aggregation and deposition in singular particulate system under relevant ionic strengths. The second part of this dissertation focused on investigation of the effects of a secondary nanoparticle, i.e., pluronic acid modified single-walled carbon nanotubes (PA-SWNTs), on aggregation and filtration of AuNSs under a wide range of ionic strength. Effects of shape of AuNMs on their aggregation kinetics were investigated by employing time resolved dynamic light scattering (TRDLS) in a wide range of mono- and di-valent electrolyte conditions. Aggregation histories were obtained for the AuNSs and AuNRs in presence of a wide range of NaCl and CaCl2 conditions. The critical coagulation concentrations (CCCs), computed from the stability plots of the AuNMs, were used to compare the aggregation propensity of the PAA coated AuNSs with the AuNRs. The deposition kinetics was monitored using the quartz crystal microbalance with dissipation (QCM-D) technique for a range of NaCl concentrations. Deposition rates determined were used to understand the effects of shape of the AuNMs on their deposition kinetics. Experimental findings suggest that the shape of nanomaterials can influence interfacial properties and result in unique aggregation and deposition behavior under typical aquatic conditions Effects of AuNS size on their aggregation behavior was investigated using citrate stabilized 30 nm and 60 nm sized National Institute of Standards and Technology (NIST) standard particles in biological media. Continuous size evolution of AuNS aggregates was monitored over a 24 h period employing DLS and static light scattering (SLS). Electrokinetic measurements, UV-vis spectroscopy, and electron microscopy were performed for material characterization. The findings from this study indicate that initial differences in AuNS sizes diminish over time as the particles aggregate under the influence of elevated ionic strength in the media. The results from this study will likely influence characterization and experimental design considerations for in vitro nanotoxicity studies. The effects of the presence of a secondary particle, PA-SWNTs, on hetero-aggregation behavior of PAA coated AuNS were systematically studied over a wide range of mono- and divalent electrolyte conditions. PA modification of SWNTs made them stable in the entire range of electrolyte concentration where SWNT-SWNT aggregation has been eliminated via steric interaction. Hetero-aggregation mechanisms of AuNS were deciphered utilizing electron microscopy and electrokinetics. Experimental results suggest that the AuNS aggregates faster in hetero-dispersion in presence of PA-SWNT than in homo-disperstion at elevated ionic strength. However, hetero-rates are slower in case of low ionic strength cases. Techniques developed in this study can be can be adopted elsewhere to assess hetero-aggregation of a wider set of ENMs, hence achieving reliability in nanoparticle environmental exposure and risk. Co-transport of AuNS in presence of PA-SWNTs through saturated porous media was also assessed using bench-scale column experiments under a wide range of aquatic conditions (1-100 mM NaCl). Homogenous AuNS suspensions were utilized as control to compare their breakthrough properties with those of the AuNS hetero-dispersions (in presence of PA-SWNTs). This study also assessed the role of pre-coating of the collectors (with PA-SWNTs) on AuNS' mobility to understand the order of introduction of the secondary particles. The study results demonstrate that the presence of secondary particles and the order in which these are introduced to the experimental system strongly influence AuNS mobility. Thus ENM can be highly mobile or can get strongly filtered out, depending on the secondary PA-SWNT and background environmental conditions. This research not only evaluates the role of material attributes in their fate and transport but also extends to assess the role of environmental complexities on the same. The research findings enhance our current understanding of environmental interaction of the ENMs and call for further studies, incorporating additional complexities (i.e., material and system), to assess the fate, transport, and effects of the ENMs in the natural environment.

Transport Processes in Chemically Reacting Flow Systems discusses the role, in chemically reacting flow systems, of transport processes—particularly the transport of momentum, energy, and (chemical species) mass in fluids (gases and liquids). The principles developed and often illustrated here for combustion systems are important not only for the rational design and development of engineering equipment (e.g., chemical reactors, heat exchangers, mass exchangers) but also for scientific research involving coupled transport processes and chemical reaction in flow systems. The book begins with an introduction to transport processes in chemically reactive systems. Separate chapters cover momentum, energy, and mass transport. These chapters develop, state, and exploit useful quantitative ""analogies"" between these transport phenomena, including interrelationships that remain valid even in the presence of homogeneous or heterogeneous chemical reactions. A separate chapter covers the use of transport theory in the systematization and generalization of experimental data on chemically reacting systems. The principles and methods discussed are then applied to the preliminary design of a heat exchanger for extracting power from the products of combustion in a stationary (fossil-fuel-fired) power plant. The book has been written in such a way as to be accessible to students and practicing scientists whose background has until now been confined to physical chemistry, classical physics, and/or applied mathematics.

This book covers the rich phenomenology exhibited by fine powders when they are fluidized by a gas flow. Fine powder cohesiveness leads to poor flowability, clumping, difficulty in fluidizing, irregular avalanching behavior, etc. Despite all the inconveniences, fine powder processes pervade the chemical, pharmaceutical, agricultural and mining industries among others. The author in this book analyzes the mechanism by which interparticle adhesive forces are reduced by means of surface additives. Different techniques have been developed in the last years to assist fluidization by helping the gas flow to mobilize and break cohesive aggregates, which help to homogenize fluidization. As reviewed in this book, the use of these techniques may have a relevant impact on novel processes based on fluidized beds of fine powder and with relevant applications on leading edge technologies such as Atomic Layer Deposition on nanoparticles and CO2 capture by gas-fluidized beds of adsorbent powders. The study of fluidized beds has a marked interdisciplinary character. This book is thus intended for academic and industrial researchers in applied physics, mechanical, chemical, and environmental engineering, who are interested in the special characteristics of fine powders.

Based on the authors more than 35 years of experience, Particles in Water: Properties and Processes examines particles and their behavior in water systems. The book offers clear and accessible methods for characterizing a range of particles both individually and as aggregates. The author delineates the principles for understanding particle

Specific ion effects are important in numerous fields of science and technology. This book summarizes the main ideas that came up over the years. It presents the efforts of theoreticians and supports it by the experimental results stemming from various techniques.

Nanomaterials - structures with characteristic dimensions between 1 and 100 nm -exhibit a variety of unique and tunable chemical and physical properties that have made engineered nanoparticles central components in an array of emerging technologies. The use of nanotechnology is increasing; however its potential adverse effects on human health are n