Impact of pH, Dissolved Inorganic Carbon, and Polyphosphates for the Initial Stages of Water Corrosion of Copper Surfaces Investigated by AFM and NEXAFS

Abstract Nanoscale studies at the early stages of the exposure of copper surfaces after systematic treatments in synthesized water solutions can provide useful information about corrosion processes. The corrosion and passivation of copper surfaces as influenced by pH, dissolved inorganic carbon (DIC) and polyphosphate levels were investigated with nanoscale resolution, to gain insight about changes in surface morphology and the composition of adsorbates. Information regarding the surface morphology after chemical treatment was provided by atomic force microscopy (AFM) and the corresponding chemical composition of treated surfaces was obtained with near-edge X-ray absorption fine structure (NEXAFS). Changes in the surface topography of copper samples were readily detected within only 6 to 24 hours of exposure to water solutions. Topographic views of surface changes are presented to compare the growth of adsorbate layers that take place during the evolution of mineral deposits. Slight changes in the pH and concentrations of phosphates in the water samples have a substantial impact on the rate of growth and composition of surface deposits. These studies provide insight on the mechanisms and resulting chemical constituents that lead to surface passivation or corrosion of copper, simulating conditions that occur in water distribution systems

The Effect of Water Chemistry on the Properties of Iron Particles and Aqueous Iron Suspensions Derived From the Oxidation of iron(II)

278 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.The properties of iron particles and colloids are important in understanding the properties of iron corrosion scale and deposits, iron release mechanisms, the stability and mobility of iron particles in water, and the color and turbidity of aqueous iron suspensions. Their properties are also important in source water iron removal effectiveness, particle deposition rates, and the transport of adsorbed contaminants such as organic matter, e.g., organics, heavy metals, and microorganisms, through aqueous systems. Numerous research reports have been published on iron in the areas of iron chemistry, corrosion, mineralogy, and limnology. Despite an overwhelming abundance of available information, iron control and water discoloration in drinking water systems remain poorly understood. In addition, very little practical information on iron removal processes and the removal of contaminants such as arsenic during iron removal that considers the role of iron particle properties is available. The objective of this research was to study the properties of iron colloidal particles and aggregates synthesized from the oxidation of Fe(II) by oxygen and the properties of the resulting aqueous iron suspensions. Particle properties including size, morphology, mineralogy, adsorptive characteristics, and electrostatic charge were examined. Suspension color (apparent and true), turbidity, and particle stability were monitored. The impact of water quality including pH, dissolved inorganic carbon (DIC), silicate, orthophosphate, and several polyphosphate formulations on particle and suspension properties and water quality was evaluated. Finally the adsorptive properties of iron particles formed under different conditions toward phosphate and arsenic were considered. The experimental findings of this study will improve our understanding of iron release from distribution system materials, improve source water iron treatment processes, provide a scientific-basis for using "sequesterants" and corrosion inhibitors, improve the ability to reduce red water discoloration, and improve our ability to remove iron and arsenic from source waters.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

The Effect of Water Chemistry on the Properties of Iron Particles and Aqueous Iron Suspensions Derived From the Oxidation of iron(II)

278 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.The properties of iron particles and colloids are important in understanding the properties of iron corrosion scale and deposits, iron release mechanisms, the stability and mobility of iron particles in water, and the color and turbidity of aqueous iron suspensions. Their properties are also important in source water iron removal effectiveness, particle deposition rates, and the transport of adsorbed contaminants such as organic matter, e.g., organics, heavy metals, and microorganisms, through aqueous systems. Numerous research reports have been published on iron in the areas of iron chemistry, corrosion, mineralogy, and limnology. Despite an overwhelming abundance of available information, iron control and water discoloration in drinking water systems remain poorly understood. In addition, very little practical information on iron removal processes and the removal of contaminants such as arsenic during iron removal that considers the role of iron particle properties is available. The objective of this research was to study the properties of iron colloidal particles and aggregates synthesized from the oxidation of Fe(II) by oxygen and the properties of the resulting aqueous iron suspensions. Particle properties including size, morphology, mineralogy, adsorptive characteristics, and electrostatic charge were examined. Suspension color (apparent and true), turbidity, and particle stability were monitored. The impact of water quality including pH, dissolved inorganic carbon (DIC), silicate, orthophosphate, and several polyphosphate formulations on particle and suspension properties and water quality was evaluated. Finally the adsorptive properties of iron particles formed under different conditions toward phosphate and arsenic were considered. The experimental findings of this study will improve our understanding of iron release from distribution system materials, improve source water iron treatment processes, provide a scientific-basis for using "sequesterants" and corrosion inhibitors, improve the ability to reduce red water discoloration, and improve our ability to remove iron and arsenic from source waters.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Microwave-Assisted Combustion Synthesis of Nano Iron Oxide/Iron-Coated Activated Carbon, Anthracite, Cellulose Fiber, and Silica, with Arsenic Adsorption Studies

Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber, and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was completed within a few minutes. The method used no additional fuel and nitrate, which is present in the precursor itself, to drive the reaction. The obtained samples were then characterized with X-ray mapping, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), selected area diffraction pattern (SAED), transmission electron microscopy (TEM), X-ray diffraction (XRD), and inductively coupled plasma (ICP) spectroscopy. The size of the iron oxide/iron nanoparticle-coated activated carbon, anthracite, cellulose fiber, and silica samples were found to be in the nano range (50–400 nm). The iron oxide/iron nanoparticles mostly crystallized into cubic symmetry which was confirmed by SAED. The XRD pattern indicated that iron oxide/iron nano particles existed in four major phases. That is, γ-Fe2O3, α-Fe2O3, Fe3O4, and Fe. These iron-coated activated carbon, anthracite, cellulose fiber, and silica samples were tested for arsenic adsorption through batch experiments, revealing that few samples had significant arsenic adsorption

In Situ 2D Maps Of Ph Shifts Across Brass-Lead Galvanic Joints Using Microelectrodes

Galvanic corrosion in drinking water distribution systems, such as conditions following partial lead service line replacement, can be a significant source of lead in tap water. The objective of this work was to measure the pH directly near metal surfaces using a novel experimental tool in order to understand the water chemistry at a lead-containing galvanic couple in drinking water. Specifically, pH microprofiles in the proximity of corroding metal surfaces were measured using a microelectrode to construct detailed in situ 2D spatial maps of the pH across a galvanic couple at 100 μm above the metal\u27s surface under flowing and stagnation conditions. The opposite pH trend was directly observed across the galvanic couple under flow and stagnation conditions. Water stagnation resulted in a pH at the anode (leaded solder) of 1.5 pH units lower than the bulk water pH (9.0) and as much as 2.5 pH units lower than the cathode (brass). These conditions can enhance lead release at the anode, which reflects different anodic-cathodic relationships of coupled metals primarily controlled by water flow. Most importantly, this work has demonstrated the ability to make real pH measurement at the surface of corroding metals using a novel microelectrode approach

Nanoscale investigation of the impact of pH and orthophosphate on the corrosion of copper surfaces in water

Advanced surface characterization techniques were used to systematically investigate either the corrosion or passivation of copper after immersion in water as impacted by pH and orthophosphate water chemistries. Atomic force microscopy, depth profiling with time-of-flight secondary ion mass spectrometry, and X-ray diffraction were used to evaluate changes in surface chemistry of copper surfaces resulting from various chemical treatments. Nanoscale differences in surface morphology are clearly evident after 6 and 24 h immersion in water samples. Orthophosphate and pH dramatically influence the evolution and progression of changes during surface corrosion. For example, in the absence of orthophosphate the surface of copper exposed to water at pH 6 had formed relatively large cubic crystals on the surface up to 400 nm in height. In the presence of orthophosphate, the morphology and growth rate of corrosion byproduct changed dramatically, and the formation of identifiable crystals diminished. These investigations provide insight into the mechanisms of surface passivation and the evolution of nanoscale mineral deposits on surfaces at very early stages of the corrosion of copper surfaces in water. © 2010 American Chemical Society

In Situ Monitoring Of Pb\u3csup\u3e2+\u3c/sup\u3e Leaching From The Galvanic Joint Surface In A Prepared Chlorinated Drinking Water

A novel method using a micro-ion-selective electrode (micro-ISE) technique was developed for in situ lead monitoring at the water-metal interface of a brass-leaded solder galvanic joint in a prepared chlorinated drinking water environment. The developed lead micro-ISE (100 μm tip diameter) showed excellent performance toward soluble lead (Pb2+) with sensitivity of 22.2 ± 0.5 mV decade-1 and limit of detection (LOD) of 1.22 × 10-6 M (0.25 mg L-1). The response time was less than 10 s with a working pH range of 2.0-7.0. Using the lead micro-ISE, lead concentration microprofiles were measured from the bulk to the metal surface (within 50 μm) over time. Combined with two-dimensional (2D) pH mapping, this work clearly demonstrated that Pb2+ ions build-up across the lead anode surface was substantial, nonuniform, and dependent on local surface pH. A large pH gradient (ΔpH = 6.0) developed across the brass and leaded-tin solder joint coupon. Local pH decreases were observed above the leaded solder to a pH as low as 4.0, indicating it was anodic relative to the brass. The low pH above the leaded solder supported elevated lead levels where even small local pH differences of 0.6 units (ΔpH = 0.6) resulted in about four times higher surface lead concentrations (42.9 vs 11.6 mg L-1) and 5 times higher fluxes (18.5 × 10-6 vs 3.5 × 10-6 mg cm-2 s-1). Continuous surface lead leaching monitoring was also conducted for 16 h

Nanomaterials Synthesis, Applications, and Toxicity 2012

Nanotechnology presents new opportunities to create better materials and products. Nanomaterials find wide applications in catalysis, energy production, medicine, environmental remediation, automotive industry, and other sectors of our society. Nanomaterial-containing products are already available globally and include automotive parts, defense application, drug delivery devices, coatings, computers, clothing, cosmetics, sports equipment, and medical devices. This special issue includes emerging advances in the field, with a special emphasis given to nanomaterial synthesis and applications