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Water equilibrium

Aarthi Pandiarajan, Ramakrishnan Kamaraj, Sudharshan Vasudevan, Subramanyan Vasudevan
This study presents the orange peel activated carbon (OPAC), derived from biowaste precursor (orange peel) by single step pyrolysis method and its application for the adsorption of chlorophenoxyacetic acid herbicides from the water. The OPAC exhibited the surface area of 592.471 m2  g-1 , pore volume and pore diameter of 0.242 cc g-1 and 1.301 nm respectively. The adsorption kinetics and thermodynamic equilibrium modelling for all chlorophenoxyacetic acid herbicides were investigated. The various parametric effects such as pH and temperature were evaluated...
April 12, 2018: Bioresource Technology
Chukwunonso P Okoli, Augustine E Ofomaja
The realization that the observed kinetic coefficient (kobs ) varies with time in most real-time adsorption system, as against the constant value conceived in the most widely-applied adsorption kinetic models, have attracted much attention in recent time. Understanding the factors that control the extent/degree of time dependency (otherwise known as fractal-like kinetics), is therefore central in taking manipulative advantage of this phenomenon in critical adsorption applications. This study therefore deployed non-fractal-like and fractal-like kinetic approach to study the adsorption of tetracycline on monodispersed starch-stabilized magnetite nanocomposite (MSM)...
April 17, 2018: Journal of Environmental Management
Xin Li, Xiaoguo Ma, Renfeng Huang, Xiaowen Xie, Lihui Guo, Menyuan Zhang
Atrazine contamination of water is of considerable concern because of the potential hazard to human health. In this study, a magnetic molecularly imprinted polymer for atrazine was prepared by the surface imprinting technique using Fe3 O4 as the core, mesoporous silica as the carrier, atrazine as the template and itaconic acid as the functional monomer. The magnetic molecularly imprinted polymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and vibration sample magnetometry...
April 20, 2018: Journal of Separation Science
Aouda Khalfa, Senia Mellouk, Kheira Marouf-Khelifa, Amine Khelifa
Dolomite was treated at 800 °C (D800), characterized, and used in the adsorptive removal of catechol (1,2-dihydroxybenzene) from aqueous solutions. The performances of the D800 sample, named dolomitic solid, were compared with those of the raw material. A bibliographic review shows that the data on the adsorption of phenolic compounds by dolomites are non-existent. Kinetic data, equilibrium isotherms, thermodynamic parameters, and pH influence were reported. Special attention was paid to the spectroscopic study, before and after adsorption...
April 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Nasir Emami, Reza Sobhani, Diego Rosso
A model was developed for a water resources recovery facility (WRRF) activated sludge process (ASP) in Modified Ludzack-Ettinger (MLE) configuration. Amplification of air requirements and its associated energy consumptions were observed as a result of concurrent circadian variations in ASP influent flow and carbonaceous/nitrogenous constituent concentrations. The indirect carbon emissions associated with the ASP aeration were further amplified due to the simultaneous variations in carbon emissions intensity (kgCO2,eq (kWh)-1 ) and electricity consumption (kWh)...
April 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Kenji Caprice, Marion Pupier, Anneli Kruve, Christoph A Schalley, Fabien B L Cougnon
We report the efficient condensation of imine-based macrocycles from dialdehyde A and aliphatic diamines B n in pure water. Within the libraries, we identified a family of homologous amphiphilic [2]catenanes, whose self-assembly is primarily driven by the hydrophobic effect. The length and odd-even character of the diamine alkyl linker dictate both the yield and the conformation of the [2]catenanes, whose particular thermodynamic stability further shifts the overall equilibrium in favour of imine condensation...
February 7, 2018: Chemical Science
Yin Li, Arun Meas, Shengdao Shan, Ruiqin Yang, Xikun Gai, Hongpeng Wang, Nyamkhand Tsend
A series of bamboo hydrochars were prepared through acid-assisted and two-stage hydrothermal carbonization, characterized and evaluated for the adsorption of Congo red and 2-naphthol in aqueous solutions. The hydrochars have rough surfaces with BET surface areas of 6.77-57.74 m2 /g and oxygen-rich functional groups. The additives in feed water revealed critical influences on the physical-chemical and adsorption properties of the hydrochars. The hydrochars can adsorb the two organics effectively, the highest adsorption capacities for Congo red and 2-naphthol are 90...
March 31, 2018: Bioresource Technology
J Benedikt, M Mokhtar Hefny, A Shaw, B R Buckley, F Iza, S Schäkermann, J E Bandow
Non-equilibrium radio-frequency driven atmospheric-pressure plasma in He/0.6%O2 gas mixture has been used to study the reaction mechanism of plasma-generated oxygen atoms in aqueous solutions. The effluent from the plasma source operated with standard and 18O-labeled O2 gas was used to treat water in the presence of phenol as a chemical probe. Comparing the mass spectrometry and gas chromatography-mass spectrometry data of the solutions treated with plasma under normal and labeled oxygen provides clear evidence that O(aq) originating from the gas phase enters the liquid and reacts directly with phenol, without any intermediate reactions...
April 19, 2018: Physical Chemistry Chemical Physics: PCCP
Fenhong Song, Long Ma, Jing Fan, Qicheng Chen, Guangping Lei, Ben Q Li
Molecular dynamics simulations were applied to study the wetting properties of nanoscale droplets on a polar silica solid substrate subjected to constant and alternative electric fields with various field frequencies. Results show that the external applied electric fields have significant effects on the wetting of the nanoscale droplet on a polar solid substrate. The droplet spreads asymmetrically under the effect of the external applied field, and this asymmetry culminates to the maximum when the electric field equals to 0...
April 19, 2018: Physical Chemistry Chemical Physics: PCCP
Yi-Lin Lu, Shengjie Dong, Wei Zhou, Shuhua Dai, Baozeng Zhou, Hui Zhao, Ping Wu
Utilizing density functional theory, we investigate the structural stabilities, electronic structures, and optical properties of monolayer violet phosphorene, i.e., Hittorfene, under an external vertical electric field and upon in-layer biaxial strain control. We find that compared with monolayer black phosphorene, monolayer violet phosphorene has a significantly larger direct band gap of 2.50 eV, and it is sensitive to an external vertical electric field, under which it undergoes an intriguing direct-indirect and insulator-metal transition...
April 19, 2018: Physical Chemistry Chemical Physics: PCCP
Lei Lyu, Lu-Qi Huang, Tao Huang, Wei Xiang, Jing-Dong Yuan, Chuan-Hua Zhang
Background: Gambogic acid (GA) is the main active ingredient of resin gamboges and possesses anti-cancer activity toward various human cancer cells. However, clinical application of GA has been limited by its poor aqueous solubility and dose-limiting toxicities. Cell-penetrating peptides (CPPs) are widely used to deliver anti-cancer drugs into cancer cells and to enhance the water solubility of drugs. Purpose: The object of this study was to synthesize peptide-drug conjugates in which the cell-penetrating peptide TAT (trans-activator of transcription) was conjugated to GA and evaluated the anti-cancer activity of this GA-CPP conjugate (GA-TAT) in EJ bladder cancer cells...
2018: Drug Design, Development and Therapy
Yuri S Djikaev, Eli Ruckenstein
We study some thermodynamic aspects of the activation of aqueous organic aerosols into cloud droplets considering the aerosols to consist of liquid solution of water and hydrophilic and hydrophobic organic compounds, taking into account the presence of reactive species in the air. The hydrophobic (surfactant) organic molecules on the surface of such an aerosol can be processed by chemical reactions with some atmospheric species; this affects the hygroscopicity of the aerosol and hence its ability to become a cloud droplet either via nucleation or via Köhler activation...
April 18, 2018: Journal of Physical Chemistry. A
Wei-Qi Xie, Kong-Xian Yu, Yi-Xian Gong
The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples...
April 17, 2018: Journal of Separation Science
Franziska Ortner, Chantal Ruppli, Marco Mazzotti
A thermodynamically consistent description of binary adsorption in reversed phase chromatography is presented, accounting for thermodynamic nonidealities in the liquid and the adsorbed phase. The investigated system involves the adsorbent Zorbax 300SB-C18, as well as phenetole (PNT) and 4-tert-butylphenol (TBP) as solutes and methanol and water as inert components forming the eluent. The description is based on adsorption isotherms which are a function of the liquid phase activities, in order to account for non-idealities in the liquid phase...
April 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Poly Buragohain, Ankit Garg, Song Feng, Peng Lin, S Sreedeep
The concept of sponge city has become very popular with major thrust on design of waste containment systems such as biofilter and green roofs. Factors that may influence pollutant ions retention in these systems will be soil type and also their interactions. The study investigated single and competitive interaction of copper in two soils and its influence on the fate prediction. Freundlich and Langmuir nonlinear isotherms were selected to quantify the retention results. Series of numerical simulations were conducted to model 1 D advection-dispersion transport for the two soils and analyse the role of isotherms...
April 11, 2018: Science of the Total Environment
Wei Lin, Ruifen Jiang, Yong Shen, Yaxin Xiong, Sizi Hu, Jianqiao Xu, Gangfeng Ouyang
Pre-equilibrium passive sampling is a simple and promising technique for studying sampling kinetics, which is crucial to determine the distribution, transfer and fate of hydrophobic organic compounds (HOCs) in environmental water and organisms. Environmental water samples contain complex matrices that complicate the traditional calibration process for obtaining the accurate rate constants. This study proposed a QSAR model to predict the sampling rate constants of HOCs (polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides) in aqueous systems containing complex matrices...
April 13, 2018: Science of the Total Environment
Stephan N Steinmann, Rodrigo Ferreira de Morais, Andreas W Götz, Paul Fleurat-Lessard, Marcella Iannuzzi, Philippe Sautet, Carine Michel
Metal/water interfaces are key in many natural and industrial processes, such as corrosion, atmospheric or environmental chemistry. Even today, the only practical approach to simulate large interfaces between a metal and water is to perform force field simulations. In this work, we propose a novel force field, GAL17, to describe the interaction of water and a Pt(111) surface. GAL17 builds on three terms: (i) a standard Lennard-Jones potential for the bonding interaction between the surface and water; (ii) a Gaussian term to improve the surface corrugation and (iii) two terms describing the angular dependence of the interaction energy...
April 16, 2018: Journal of Chemical Theory and Computation
Bethany A Wellen Rudd, Andrew S Vidalis, Heather C Allen
Of the major cations in seawater (Na+, Mg2+, Ca2+, K+), Ca2+ is found to be the most enriched in fine sea spray aerosols (SSA). In this work, we investigate the binding of Ca2+ to the carboxylic acid headgroup of palmitic acid (PA), a marine-abundant fatty acid, and the impact such binding has on the stability of PA monolayers in both equilibrium and non-equilibrium systems. A range of Ca2+ conditions from 10 μM to 300 mM was utilized to represent the relative concentration of Ca2+ in high and low relative humidity aerosol environments...
April 16, 2018: Physical Chemistry Chemical Physics: PCCP
Nesrine Ouadah, Claudine Moire, Fabien Brothier, Jean-François Kuntz, Olivier Deschaume, Carmen Bartic, Hervé Cottet
Aluminum chlorohydrates (ACH) are used in numerous applications and commercial products on a global scale including water treatment, catalysis or antiperspirants. They are complex mixtures of water soluble aluminum polycations of different degrees of polymerization, that are difficult to separate and quantify due to their susceptibility to depolymerize in solution when placed out of equilibrium, which is inherent to any separation process. We recently achieved the first capillary electrophoresis separation and characterization of ACH oligomers using 4-morpholineethanesulfonic acid (MES) as background electrolyte counter-ion...
March 29, 2018: Journal of Chromatography. A
Tong Hou, Bernard Charlier, François Holtz, Ilya Veksler, Zhaochong Zhang, Rainer Thomas, Olivier Namur
The origin of iron oxide-apatite deposits is controversial. Silicate liquid immiscibility and separation of an iron-rich melt has been invoked, but Fe-Ca-P-rich and Si-poor melts similar in composition to the ore have never been observed in natural or synthetic magmatic systems. Here we report experiments on intermediate magmas that develop liquid immiscibility at 100 MPa, 1000-1040 °C, and oxygen fugacity conditions (fO2 ) of ∆FMQ = 0.5-3.3 (FMQ = fayalite-magnetite-quartz equilibrium). Some of the immiscible melts are highly enriched in iron and phosphorous ± calcium, and strongly depleted in silicon (<5 wt...
April 12, 2018: Nature Communications
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