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Water equilibrium

M I Garrudo-Guirado, A Blanco-Flores, H P Toledo-Jaldin, V Sánchez-Mendieta, A R Vilchis-Néstor
Water pollution caused by heavy metals and organic compounds is an environmental problem with negative impact, making the restoration of water quality a priority. In this paper, the adsorption of xylenol orange dye (XO) on vitreous tuff mineral (VT) was studied. It was established that the adsorption capacity of VT was 45.17 mg/g. The removal was carried out by interactions between active sites on the surface of the material and the functional groups of the dye. The solid waste obtained from this process (VTXO) was reused as adsorbent material for Cu removal in the form of the complex Cu-NH3 because this process was done in an ammoniacal medium...
December 5, 2017: Journal of Environmental Management
Shuqin Jin, Bettina Bluemling, Arthur P J Mol
Pesticide packages that are discarded on agricultural land can contaminate water bodies and pose a threat to the environment and human health. Little is known about how developing countries deal with this kind of land pollution. While in developed countries, packages are collected by professional organizations, the smallholder context in developing countries makes the collection of this waste much more difficult. This paper introduces and analyses a successful Pesticide Package Collection Scheme in one of the poorest regions in China, i...
December 5, 2017: Science of the Total Environment
Liying Jiang, Qichao Ye, Jianmeng Chen, Zhong Chen, Youli Gu
In this study, bentonite-Fe3O4-MnO2 composite was synthesized by combining bentonite with Fe3O4 and MnO2 through co-precipitation. Vibrating-sample magnetometry, scanning electron microscopy with energy-dispersive X-ray spectrometry, transmission electron microscopy, Brunauer-Emmett-Teller measurements, and X-ray powder diffraction techniques were used to characterize the composite. The composite consists of Fe3O4 nanoparticles orderly assembled on the surface of bentonite and an outer layer of MnO2 sheets...
November 22, 2017: Journal of Colloid and Interface Science
Olushola S Ayanda, Simphiwe M Nelana, Leslie F Petrik, Eliazer B Naidoo
The application of nano-TiO2 as adsorbent combined with ultrasound for the degradation of N-acetyl-para-aminophenol (AAP) from aqueous solution was investigated. The nano-TiO2 was characterized by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Experimental results revealed that the adsorption of AAP by nano-TiO2 fitted the pseudo-second-order kinetic model, the equilibrium could be explained by the Freundlich isotherm and the treatment process is exothermic...
October 2017: Journal of Water and Health
Fang Pan, Zongyi Li, Thomas Leyshon, Dominic Rouse, Ruiheng Li, Charles Smith, Mario Campana, John Robert Peter Webster, Steven M Bishop, Rojaramani Narwal, Christopher F van der Walle, Jim Warwicker, Jian Ren Lu
Spectroscopic ellipsometry (SE) and neutron reflection (NR) data for the adsorption of a monoclonal antibody (mAb, termed COE-3, pI 8.44) at the bare SiO2/water interface are here compared to simulations based on DLVO theory. COE-3 adsorption was characterized by an initial rapid increase in the surface adsorbed amount (Γ) followed by a plateau. Only the initial rate of increase in Γ was strongly correlated to the bulk concentration (0.002-0.2 mg/ml), with Γ at plateau being about 2.2 mg/m2 (pH 5.5). Simulations captured COE-3 adsorption at equilibrium most accurately: the point at which the outgoing flux of molecules within the adsorbed plane matched the adsorption flux...
December 7, 2017: ACS Applied Materials & Interfaces
Guanyun Zhang, Wenyun Li, Caiyun Liu, Jiong Jia, Chen-Ho Tung, Yifeng Wang
A novel family of water-soluble, polyoxocationic titanium-oxide host-guest clusters are reported herein. They exhibit an unprecedented hexagonal prismatic core structure for hosting univalent cationic guests like K+, Rb+, Cs+ and H3O+. Guest exchange has been studied using 133Cs NMR, showing the flexible pore of a host permits passage of a comparatively larger cation and giving an equilibrium constant of ca. 13 for displacing Rb+ by Cs+. Attractive ion-dipole interaction, depending on host-guest size complementarity, plays a dominant role for the preferential encapsulation of larger alkali-metal cationic guests...
December 7, 2017: Journal of the American Chemical Society
Tamás Vajda, András Perczel
The crucial role of water in amyloid-β(Aβ) fibril proteins is evaluated in several ways including the water's thermodynamic and kinetic solvation effects. As regards the water's character, its hindered-rotation barriers are also considered. The following protein molecules considered here are: the Aβ40 (PDB ID: 2LMN), Aβ42 (PDB ID: 5KK3 and 2NAO) and the double-layered Aβ17-42 fibril. We discuss: (i) extracellular Aβ40 and Aβ42 fibril monomers exhibit an ambivalent propensity to transform into a helical form toward the N-term region and a β-strand-like form near the C-terminal; (ii) interfacial water molecules play a crucial role in protein-protein interactions, as molecular dynamics simulations have shown a significant impact on the protein-protein binding; (iii) it is shown that the spontaneous dimerization process of the Aβ42 fibril protein in water occurs via a two-step nucleation-accommodation mechanism; (iv) MD simulations of the double-layered Aβ17-42 fibril model show that the C↔C interface appears more energetically favorable than the N↔N interface due to large hydrophobic contacts; (v) the water's role in the HET-s prion and in the Aβ fibrillar aggregates; (vi) it was found that the monomer-oligomer equilibrium spontaneously dissociates into stable monomeric species when they are incubated up to 3 μm for a longer time (>1 week) in a physiological buffer...
December 20, 2017: Biomolecular Concepts
Ranran Tian, Mengbo Luo, Jingyuan Li
When nanoparticles enter blood or other biological fluids, they tend to contact with a variety of proteins which may hamper their application and even bring adverse impacts. Such nonspecific protein binding is usually weak and proteins reach dynamic equilibrium between adsorption and desorption. Studies on the spontaneous desorption of weakly bound proteins should not only be helpful to enrich our understanding about such nonspecific interactions but also shed light on the strategy to avoid nonspecific binding of proteins...
December 6, 2017: Physical Chemistry Chemical Physics: PCCP
Elías Vera-Sigüenza, Marcelo A Catalán, Gaspar Peña-Münzenmayer, James E Melvin, James Sneyd
We develop a mathematical model of a salivary gland acinar cell with the objective of investigating the role of two [Formula: see text] exchangers from the solute carrier family 4 (Slc4), Ae2 (Slc4a2) and Ae4 (Slc4a9), in fluid secretion. Water transport in this type of cell is predominantly driven by [Formula: see text] movement. Here, a basolateral [Formula: see text] adenosine triphosphatase pump (NaK-ATPase) and a [Formula: see text]-[Formula: see text]-[Formula: see text] cotransporter (Nkcc1) are primarily responsible for concentrating the intracellular space with [Formula: see text] well above its equilibrium potential...
December 5, 2017: Bulletin of Mathematical Biology
Keith M Carroll, Colin Rawlings, Yadong Zhang, Armin W Knoll, Seth R Marder, Heiko Wolf, Urs Duerig
Diffusion relates the flux of particles to the local gradient of the particle density in a deterministic way. The question arises what happens when the particle density is so low that the local gradient becomes an ill-defined concept. The dilemma was resolved early last century by analyzing the average motion of particles subject to random forces whose magnitude is such that the particles are always in thermal equilibrium with their environment. The diffusion dynamics are now described in terms of a probability density of finding a particle at some position and time and a probabilistic flux density which is proportional to the gradient of the probability density...
December 5, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Ya-Qi Zhang, Marta Markiewicz, Juliane Filser, Stefan Stolte
The study aims to establish a preliminary environmental assessment of a quinaldine-based LOHC system composed of hydrogen-lean, partially hydrogenated and fully hydrogenated forms. We examined their toxicity toward the soil bacteria Arthrobacter globiformis and the Collembola Folsomia candida in two exposure scenarios, with and without soil, to address differences in the bioavailability of the compounds. In both scenarios, no or only slight toxicity toward soil bacteria was observed at the highest test concentration (EC50 > 3397 µmol L-1 and > 4892 μmol kg-1 dry weight soil)...
December 5, 2017: Environmental Science & Technology
Mehdi Fazlzadeh, Mohammad Ansarizadeh, Mostafa Leili
Among various water and wastewater treatment methods, adsorption techniques are widely used to remove certain classes of pollutants due to its unique features. Thus, the aim of this data article is to synthesize zero valent iron nanoparticles (NZVI) from Nettle leaf extract by green synthesis method as an environmentally friendly technique, and to evaluate it's efficiency in the removal of furfural from aqueous solutions. The data of possible adsorption mechanism and isotherm of furfural on the synthesized adsorbent are depicted in this data article...
February 2018: Data in Brief
Asghar Dolatkhah, Lee D Wilson
The ability to achieve exquisite control over polymer building blocks within multi-compartment magnetite nanocomposites (NCs) to afford predictable and ordered packing hierarchical structures remains a significant challenge for the design of NCs. Thus, there is an urgent need to develop new types of nano dimensional assemblies that undergo responsive shape-shift, size-, phase- and morphological transitions, especially for processes that are triggered by biologically relevant stimuli such as ionic gradients to meet the demand for diverse applications...
December 4, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
S Zubair Hossain, Kevin G Mumford, Allison Rutter
Diluted bitumen (dilbit) spilled to rivers has the potential to sink and become trapped in coarse bed sediments. Hyporheic flow through the river bed can then lead to the dissolution of hydrocarbons from this trapped oil, and subsequent risks to water quality and aquatic life. It is important to understand the concentrations of dissolved hydrocarbons in water, relative to aqueous solubility, that may result from mass transfer under these conditions, particularly under conditions where coarse sediments lead to faster hyporheic flow that could promote rate-limited mass transfer conditions...
December 4, 2017: Environmental Science. Processes & Impacts
Lorenz M R Keil, Friederike M Möller, Michael Kieß, Patrick W Kudella, Christof B Mast
Proton gradients are essential for biological systems. They not only drive the synthesis of ATP, but initiate molecule degradation and recycling inside lysosomes. However, the high mobility and permeability of protons through membranes make pH gradients very hard to sustain in vitro. Here we report that heat flow across a water-filled chamber forms and sustains stable pH gradients. Charged molecules accumulate by convection and thermophoresis better than uncharged species. In a dissociation reaction, this imbalances the reaction equilibrium and creates a difference in pH...
December 1, 2017: Nature Communications
Stewart Sherrit, Aaron C Noell, Anita Fisher, Mike C Lee, Nobuyuki Takano, Xiaoqi Bao, Thomas C Kutzer, Frank Grunthaner
This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction...
November 2017: Review of Scientific Instruments
Rui Wang, Chao Yang, Kuanjun Fang, Yuqing Cai, Longyun Hao
In this research, a stable graphene oxide (GO) suspension was prepared by chemical reduction method from graphite powder. By TEM, the irregular GO sheets with single-atom-layered structure could be observed. The zeta potentials measurement indicated the surface charges of GO were strongly related to pH. BET analysis showed the GO had a specific surface area of 30.7 m2/g and pore volume of 0.10 cm3/g. When the GO was used to remove the residual cellulase in bio-polishing effluent, it was found the removal capacity reached its maximum value at the pH 4-5...
November 27, 2017: Journal of Environmental Management
Starla D Glover, Robin Tyburski, Li Liang, Cecilia Tommos, Leif Hammarström
Protein "hole" hopping typically involves spatially arranged redox-active tryptophan and/or tyrosine residues. Thermodynamic information is scarce for this type of process. The well-structured α3W model protein was studied by protein film square wave voltammetry and transient absorption spectroscopy to obtain a comprehensive thermodynamic and kinetic description of a buried tryptophan residue. A Pourbaix diagram, correlating thermodynamic potentials (E°') with pH, is reported for W32 in α3W and compared to equivalent data recently presented for Y32 in α3Y (Ravichandran, K...
November 30, 2017: Journal of the American Chemical Society
Tássia R T Santos, Murilo B Andrade, Marcela F Silva, Rosângela Bergamasco, Safia Hamoudi
In this study, the proposed adsorbent composed of graphene oxide (GO) functionalized by magnetic nanoparticles of iron oxide (α-γ-Fe2O3), was obtained by a simple ultrasonication process. This new material was used for the removal of glyphosate in water. Glyphosate is a large spectrum herbicide used extensively all over the world to control weeds. The presence of glyphosate in water bodies is linked with several toxic effects. Therefore, it is important to develop treatment processes to remove this notorious contaminant from water...
November 29, 2017: Environmental Technology
Fuyu Wang, Jinli Jiang, Jiashu Zhang, Qun Wang
The pituitary stalk (PS) is crucial to endocrine function and water-electrolyte equilibrium. Preservation of the PS during craniopharyngioma (CP) surgery is critical; however, in a pathological state, it is difficult to identify. The hypothalamo-hypophyseal tract (HHT) connects the hypothalamus and the posterior pituitary gland and projects through the PS. Thus, visualization of the HHT can help locate the PS. Preoperative visualization of the neural fasciculus has been widely achieved using diffusion tensor imaging (DTI) tractography...
November 28, 2017: Neurosurgical Review
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