1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

The article focuses on adsorption of heavy metal ions on soils and soils constituents such as clay minerals, metal (hydr)oxides, and soil organic matter. Empirical and mechanistic model approaches for heavy metal adsorption and parameter determination in such models have been reviewed. Sorption mechanisms in soils, the influence of surface functional groups and surface complexation as well as parameters influencing adsorption are discussed. The individual adsorption behavior of Cd, Cr, Pb, Cu, Mn, Zn and Co on soils and soil constituents is reviewed.

Adsorption of heavy metal ions on soils and soils constituents

http://files.aprendiendoquimica7.webnode.com.co/200000006-1247d13423/Limousin,%20G%20et%20al.%20Sorption%20Isotherms%20A%20review%20on%20Physical%20Bases,%20modeling%20and%20measurement.pdf

Sorption isotherms: A review on physical bases, modeling and measurement

Advances in nanoscale science and engineering suggest that many of the current problems involving water quality could be resolved or greatly ameliorated using nanosorbents, nanocatalysts, bioactive nanoparticles, nanostructured catalytic membranes and nanoparticle enhanced filtration among other products and processes resulting from the development of nanotechnology. Innovations in the development of novel technologies to desalinate water are among the most exciting and promising. Additionally, nanotechnology-derived products that reduce the concentrations of toxic compounds to sub-ppb levels can assist in the attainment of water quality standards and health advisories. This article gives an overview of the use of nanomaterials in water purification. We highlight recent advances on the development of novel nanoscale materials and processes for treatment of surface water, groundwater and industrial wastewater contaminated by toxic metal ions, radionuclides, organic and inorganic solutes, bacteria and viruses. In addition, we discuss some challenges associated with the development of cost effective and environmentally acceptable functional nanomaterials for water purification.

/pdf/nanomaterials-and-water-purification-opportunities-and-2o4nfvmn9e.pdf

Nanomaterials and Water Purification: Opportunities and Challenges

Mathematical models have become indispensable tools for studying vadose zone flow and transport processes. We reviewed the history of development, the main processes involved, and selected applications of HYDRUS and related models and software packages developed collaboratively by several groups in the United States, the Czech Republic, Israel, Belgium, and the Netherlands. Our main focus was on modeling tools developed jointly by the U.S. Salinity Laboratory of the USDA, Agricultural Research Service, and the University of California, Riverside. This collaboration during the past three decades has resulted in the development of a large number of numerical [e.g., SWMS_2D, HYDRUS-1D, HYDRUS-2D, HYDRUS (2D/3D), and HP1] as well as analytical (e.g., CXTFIT and STANMOD) computer tools for analyzing water flow and solute transport processes in soils and groundwater. The research also produced additional programs and databases (e.g., RETC, Rosetta, and UNSODA) for quantifying unsaturated soil hydraulic properties. All of the modeling tools, with the exception of HYDRUS-2D and HYDRUS (2D/3D), are in the public domain and can be downloaded freely from several websites.

Development and Applications of the HYDRUS and STANMOD Software Packages and Related Codes

This paper describes an investigation of the uptake of Cu(II) by poly(amidoamine) (PAMAM) dendrimers with an ethylenediamine (EDA) core in aqueous solutions. We use bench scale measurements of proton and metal ion binding to assess the effects of (i) metal ion−dendrimer loading, (ii) dendrimer generation/terminal group chemistry, and (iii) solution pH on the extent of binding of Cu(II) in aqueous solutions of EDA core PAMAM dendrimers with primary amine, succinamic acid, glycidol, and acetamide terminal groups. We employ extended X-ray absorption fine structure (EXAFS) spectroscopy to probe the structures of Cu(II) complexes with Gx-NH_2 EDA core PAMAM dendrimers in aqueous solutions at pH 7.0. The overall results of the proton and metal ion binding measurements suggest that the uptake of Cu(II) by EDA core PAMAM dendrimers involves both the dendrimer tertiary amine and terminal groups. However, the extents of protonation of these groups control the ability of the dendrimers to bind Cu(II). Analysis of the EXAFS spectra suggests that Cu(II) forms octahedral complexes involving the tertiary amine groups of Gx-NH_2 EDA core PAMAM dendrimers at pH 7.0. The central Cu(II) metal ion of each of these complexes appears to be coordinated to 2−4 dendrimer tertiary amine groups located in the equatorial plane and 2 axial water molecules. Finally, we combine the results of our experiments with literature data to formulate and evaluate a phenomenological model of Cu(II) uptake by Gx-NH_2 PAMAM dendrimers in aqueous solutions. At low metal ion−dendrimer loadings, the model provides a good fit of the measured extent of binding of Cu(II) in aqueous solutions of G4-NH_2 and G5-NH_2 PAMAM dendrimers at pH 7.0.

http://www.wag.caltech.edu/publications/sup/pdf/553.pdf

Dendritic Chelating Agents. 1. Cu(II) Binding to Ethylene Diamine Core Poly(amidoamine) Dendrimers in Aqueous Solutions

Distinguishing between interlayer and external sorption sites of clay minerals using X-ray absorption spectroscopy

Sorption of metals and metalloids from reverse osmosis concentrate on drinking water treatment solids

The rates of cadmium and selenite uptake by porous aluminas were studied using three porous transition aluminas. The three adsorbents differed in size and pore structure, CP-5 and CP-100 being the smallest and largest particles, respectively, both exhibiting some microporosity, and C-33 being intermediate-size, mesoporous particles. The rate data were interpreted with a diffusion model, assuming solute diffusion in a sphere from limited volume. The diffusion model was in fair agreement with the rate data, suggesting that cadmium and selenite uptake is controlled by intraparticle mass transfer. Solute uptake by the smaller particles (CP-5) was considerably faster than uptake by the larger particles (CP-100). The measured apparent diffusivities for both adsorbates and all adsorbents were orders of magnitude lower than bulk aqueous diffusivities, in accordance with expectations for highly retarded sorption. The measured effective diffusivities were substantially lower than aqueous molecular diffusivities, suggesting the presence of strong hindrance effects in these microporous adsorbents.

Modeling the rate of cadmium and selenite adsorption on micro- and mesoporous transition aluminas.

To enhance our understanding of trace element partitioning at oxide-water interfaces, we studied the local coordination environment of cadmium(II) and selenite complexes sorbed on aluminum oxides, in situ, using X-ray absorption spectroscopy (XAS). The adsorbents included porous, high surface area transition aluminas (ALCOA CP-5 and C-33) and the minerals corundum (α-Al 2 O 3 ) and gibbsite (γ-A1(OH) 3 ). Cadmium sorption densities ranged from 1.2 to 12.0 μmol/m 2 and selenite sorption densities ranged from 1.2 to 4.6 μmol/m 2 . X-ray absorption fine structure (XAFS) analysis of the selenite spectra indicates that Se is coordinated to three O atoms at 1.69 A, regardless of substrate, and that the complexes are mononuclear. XAFS analysis of low sorption density cadmium complexes suggests that cadmium is coordinated to six oxygens at 2.33 A and that the complexes are mononuclear. Analysis of a high total cadmium concentration sample (10 -3 M) gave O first neighbors at 2.35 A and Cd second neighbors at 3.84 A, suggesting the formation of a disordered cadmium hydroxide or cadmium hydroxocarbonate precipitate. Absence of Al second neighbors in the selenite and the low sorption density cadmium samples is probably caused by the low backscattering amplitude of A1 and thermal and static disorder effects. These results, in combination with sorption isotherm data, suggest that, under the conditions studied, cadmium and selenite diffuse into the pores of the transition aluminas and sorb as mononuclear complexes. These results have significant implications for the fate of trace elements in subsurface environments and the remediation of waters and groundwaters.

Charalambos Papelis

Papers

Dendritic Chelating Agents. 1. Cu(II) Binding to Ethylene Diamine Core Poly(amidoamine) Dendrimers in Aqueous Solutions

Distinguishing between interlayer and external sorption sites of clay minerals using X-ray absorption spectroscopy

Sorption of metals and metalloids from reverse osmosis concentrate on drinking water treatment solids

Modeling the rate of cadmium and selenite adsorption on micro- and mesoporous transition aluminas.

X-ray absorption spectroscopic studies of cadmium and selenite adsorption on aluminum oxides