Organic Suspensions Research Articles

Bactericidal Effectiveness of O3, O3/H2O2 and O3/TiO2 on Clostridium perfringens

The purpose of this research is to evaluate the bactericidal capacity of different Advanced Oxidation Treatments (AOTs) based on ozone: ozone, ozone/hydrogen peroxide and ozone/titanium dioxide on a wild strain of Clostridium perfringens, a fecal bacterial indicator in drinking water. The dose of ozone consumed ranges from 0.6 mg L−1 min−1 to 5.13 mg L−1 min−1 depending on the process and on the sample. In the treatments combined with O3, H2O2 dose utilized is 0.04 mM and TiO2 dose, 1 g L−1. In order to evaluate the influence of natural organic matter and suspension solids over the disinfection rate, treatments are performed with two types of water – natural water from Ebro River (Zaragoza, Spain) and NaCl solution 0.9%. To achieve 4 log units of inactivation, 3.6 mg O3 L−1 is necessary in O3 treatment, 4.25 mg O3 L−1 in O3/TiO2 system and 2.7 mg O3 L−1 in O3/H2O2 after processing the natural water. In NaCl solution, to get the same inactivation, 0.42 mg O3 L−1 is necessary in O3 treatment, 1.15 mg O3 L−1 in O3/TiO2 system and 0.06 mg O3 L−1 in O3/H2O2 process. Even though the three treatments studied have a high bactericidal activity due to the number of surviving bacteria decreases to non-detectable levels, O3/H2O2 is the most effective system for eliminating C. perfringens cells in a lower contact time, followed by O3 and finally O3/TiO2 system.

Electrophoretic deposition of La 0.6Sr 0.4Co 0.8Fe 0.2O 3− δ cathodes on Ce 0.9Gd 0.1O 1.95 substrates for intermediate temperature solid oxide fuel cell (IT-SOFC)

Porous thick films of La 0.6Sr 0.4Co 0.8Fe 0.2O 3− δ (LSCF) on Ce 0.9Gd 0.1O 1.95 (CGO) substrates were prepared by the electrophoretic deposition (EPD) method. Organic suspensions of different compositions containing LSCF ceramic particles were investigated with the aim to determine the optimal composition of the suspension and EPD conditions. Stainless steel substrates were used in order to determine the optimal parameters for the EPD process. The best results were achieved with solutions containing acetylacetone, iodine and starch. The EPD conditions leading to uniform LSCF films were: applied voltage 20 V and deposition time 120 s, with the electrodes separated 1.5 cm. EPD was also demonstrated to be a simple and useful method for making porous LSCF cathodes on CGO substrates. It was shown that the microstructure of the films can be controlled by changing the applied voltage, deposition time and concentration of additives in suspension.

Rheological behaviour of BaZrO 3 suspensions in non-aqueous media

The colloidal behaviour of concentrated non-aqueous suspensions of barium zirconate is investigated. Optimum dispersing conditions are investigated for organic suspensions prepared with different solvent systems: methylethylketone (MEK)/ethanol, trichloroethylene (TCE)/ethanol, a methylisobutylketone (MIBK)/methylethylketone/cyclohexanone (CHN) and pure ethanol. Stabilisation of the suspensions is achieved by using two different dispersants: ester phosphate (EPH) and Hypermer KD-6. Rheological studies have been made in order to determine the optimum of each dispersant concentration as a function of the solvent systems. The best stabilisation of 30 vol.% suspensions is obtained by using EtOH with 3 wt.% KD-6 and TCE/EtOH with 1 wt.% EPH. Zeta potential studies show that the use of dispersants increases the positive surface potential on the particles. The zeta potential values increasing from +10 mV in the absence of EPH to +42 mV with 1.0 wt.% EPH and to +33 mV with KD-6. These results suggest that electrostatic repulsion plays an important role on the stability of these organic suspensions. Stabilised suspensions were slip cast in plaster molds and green densities higher than 55% of the theoretical density was obtained.

Thermally assisted mechanical dewatering (TAMD) of suspensions of fine particles: Analysis of the influence of the operating conditions using the response surface methodology

Thermally assisted mechanical dewatering (TAMD) is a new process for energy-efficient liquid/solids separation which enhances conventional-device efficiency. The main idea of this process is to supply a flow of heat in mechanical dewatering processes to favour the reduction of the liquid content. This is not a new idea but the proposed combination, especially the chosen operating conditions (temperature <100 °C and pressure <3000 kPa) constitutes an original approach and a significant energy saving since the liquid is kept in liquid state. Response surface methodology was used to evaluate the effects of the processing parameters of TAMD on the final dry solids content, which is a fundamental dewatering parameter and an excellent indicator of the extent of TAMD. In this study, a two-factor central composite rotatable design was used to establish the optimum conditions for the TAMD of suspensions of fine particles. Significant regression models, describing changes on final dry solids content with respect to independent variables, were established with regression coefficients (usually called determination coefficients), R 2, greater than 80%. Experiments were carried out on a laboratory filtration/compression cell, firstly on different compressible materials: synthetic mineral suspensions such as talc and synthetic organic suspensions such as cellulose, and then on industrial materials, such as bentonite sludge provided by Soletanche Bachy Company. Experiment showed that the extent of TAMD for a given material is particularly dependent on their physical and chemical properties but also on processing parameters.

The Practical Application of Fractal Dimension in Water Treatment Practice–the Impact of Polymer Dosing

The application of floc fractal dimension has been investigated in this work to determine if this parameter can have operational significance in water treatment. Natural organic matter suspensions were coagulated with aluminium sulphate and varying concentrations of a non‐ionic polymer. The fractal dimensions of the flocs formed were measured using light scattering and settling combined with image analysis. By using the correct methodology, optimum floc properties could be determined using the floc fractal dimension combined with the floc size and strength data.

Attenuated Total Reflection Infrared Studies of Oleate and Trioctylphosphine Oxide Ligand Adsorption and Exchange Reactions on CdS Quantum Dot Films

Ligand exchange reactions at the surface of oleate- and trioctylphosphine oxide (TOPO)-capped CdS quantum dots have been studied with attenuated total reflection infrared (ATR-IR) spectroscopy, using thin films deposited from organic solvent suspensions. The oleate and trioctylphosphine capping ligands were found to form highly ordered and densely packed monolayers on the CdS surface. Adsorbed oleate is coordinated to CdS in a chelating bidentate manner through the carboxylate functional group, while adsorbed trioctylphosphine oxide is coordinated though the P=O functional group and appears to have numerous adsorption environments on the CdS surface. Exposure of such films to aqueous solution was found to cause partial delamination of the films from the ATR prism interface which was reversible upon redrying. Ligand exchange reactions on the oleate- and trioctylphosphine-capped CdS films were studied in situ at room temperature by allowing the films to be exposed to dilute aqueous solutions of thiol-containing ligands. Oleate and trioctylphosphine oxide are both strongly adsorbed to the CdS surface, and ligand exchange with monothiol-containing ligands has been found to be highly dependent upon experimental conditions, in particular pH, where exchange is only observed at solution pH where the exchanging ligand is uncharged. This is attributed to the inability of a charged ligand to penetrate the hydrophobic polymethylene layer on the CdS surface.

Preparation of the Materials, Sampled in Combined Foci of Plague and Arbovirus Infections, for Immunologic Assaying. Communication 2

The results of the second phase of the experiments are presented in the paper, where β-propiolactone was used to decontaminate materials from Yersinia pestis. Both slurries and suspensions of the internal organs were decontaminated of Y. pestis 231 with 0.1 % concentrations of the preparation after 18 to 24 hours' exposition in the refrigerator, as well as at 37 °C for as long as 6 hours or more. Optimal schedules for immunologic examination are offered to prepare the samples taken in the combined foci of plague and arboviral infections.

The viscosity of organic liquid suspensions of trimethyldococylammonium-montmorillonite complexes

AbstractAn organophilic bentonite was prepared by means of a reaction of natural Na-montmorillonite with trimethyldococylammonium which has an especially long n-alkyl chain. The addition of trimethyldococylammonium to montmorillonite was in the range 0.25–3.0 times the cation exchange capacity (CEC) of the clay (i.e. 0.23–2.82 mmol/g clay). The particle morphology in organic liquid suspensions of organoclay complexes was studied by measuring the viscosity based on Eyring’s rate process and Robinson’s relative sediment volume. In toluene, montmorillonite with 1.17 mmol/g clay trimethyldococylammonium (1.25 times the CEC) had the largest specific gel volume, relative sediment volume, and K-factor. The results of the stoichiometry for trimethyldococylammonium-montmorillonite show that practically all of the quaternary ammonium was adsorbed to montmorillonite. Maximum half widths of 001 reflections from X-ray diffraction patterns were obtained in the range 0.74–1.17 mmol/g clay, indicating a disordered arrangement of the organic cation molecules intercalated between the layers. Appreciable shifts to lower-frequency regions in the Fourier transform infrared absorption spectra as a result of CH2-stretching vibrations were observed with increasing amounts of the organic cation. When increasing the amount of organic cation added to the clay from 0.94 to 1.41 mmol/g clay, a large shift occurred to the lower-frequency side, approaching the frequency of the organic cation alone. This indicates that the interaction between adjacent hydrocarbon chains becomes progressively stronger, due to van der Waals attraction, with increases in the amount of organic cation. Interactions of the alkyl chains in trimethyldococylammonium-montmorillonite complexes with irregularly distributed and randomly arranged alkyl chains between the silicate layers were weak, and, as a result, solvation with external organic liquids occurred and gel formation developed through macroscopic swelling of the organoclay.

Treatment of Genital Prolapse by Laparoscopic Lateral Suspension Using Mesh: A Series of 73 Patients

Study Objective To evaluate the efficacy of laparoscopic lateral suspension using mesh in patients with pelvic organ prolapse (POP). Design A prospective cohort study (Canadian Task Force classification II-2). Setting A tertiary referral center for operative laparoscopy. Patients In all, 73 patients with POP were assessed in the preoperative and postoperative stages. The assessment included a description of their functional symptoms and the degree of their POP condition, established according to the Baden-Walker prolapse classification system. The patients were followed in the postoperative stage for a median of 19 (range 12–41) months. Interventions Laparoscopic lateral suspension of pelvic organs using mesh carried out from January 2004 through September 2006. Measurements and Main Results Satisfactory anatomic results were obtained in 64 (87.7%) patients. Neither major complications, nor postoperative pelvic infection were reported. None of the operations required laparotomy. Conclusion Laparoscopic lateral suspension using mesh effectively treats POP with low morbidity.

Dispersion of Titania Powder in an Electronic Ink for Electrophoretic Display

The colloidal stability of titania powder in electronic ink, which contains an organic solvent of octane and a dispersant of phosphate ester, has been investigated. The concentration of phosphate ester required to stabilize the nonaqueous titania suspension agrees with that needed for monolayer adsorption. Theoretical calculations of potential energies show that the colloidal stability of organic titania suspension is caused by the steric repulsion mechanism. The results of optical properties including reflectivity and response time show that the resulting nonpolar titania suspension meets the requirements of an electronic ink for electrophoretic display.

Dispersion of Oleate‐Modified CuO Nanoparticles in a Nonpolar Solvent

Two nanosized cupric oxide powders, which are synthesized by a vapor‐phase reaction and aqueous precipitation, are surface modified with oleic acid to form cupric oleate on the surface. This enhances the dispersibility of cupric oxide powders in a nonpolar solvent of octane. The cupric oxide powder prepared by aqueous precipitation exhibits much better dispersion in octane than that synthesized by vapor‐phase reaction. This is attributed to the presence of larger amounts of hydroxyl group on the particle surface, forming more cupric oleate and thus enhancing the colloidal stability of the resulting organic suspension.

Maghemite Nanocrystal Impregnation by Hydrophobic Surface Modification of Mesoporous Silica

Here, we report the design of a hybrid inorganic/organic mesoporous material through simultaneous pore engineering and hydrophobic surface modification of the intramesochannels to improve the uptake of superparamagnetic maghemite nanocrystals via impregnation techniques. The mesoporous material of the SBA-15 type was functionalized in situ with thiol organo-siloxane groups. Restricting the addition of the thiol organo-siloxane to 2 mol % yielded an inorganic/organic hybrid material characterized by large pores and a well-ordered hexagonal p6mm mesophase. The hydrophobic surface modification promoted the incorporation of 7.5 nm maghemite (gamma-Fe2O3) nanocrystals, prepared through temperature-controlled decomposition of iron pentacarbonyl in organic solvents. The hydrophobic, oleic acid capped superparamagnetic maghemite nanocrystals were incorporated into the porous network via wet impregnation from organic suspensions. Combining diffraction, microscopy, and adsorption data confirmed the uptake of the nanocrystals within the intramesochannels of the silica host. Magnetization dependencies on magnetic field at different temperatures show a constriction in the loop around the origin, which indicates immobilization of maghemite nanocrystals inside the thiol-functionalized silica host.

Kinetics of Particulate Organic Matter Removal as a Response to Bioflocculation in Aerobic Biofilm Reactors

Recent research has identified that the major fraction of chemical oxygen demand in domestic wastewaters is in particulate form. The research presented herein develops the kinetics of particle removal as a response to bioflocculation at the surface of aerobic biofilms. This study focuses on the removal of particles that are maintained in aqueous suspension after 30 minutes of gravity settling. It is helpful to consider the particulate organics removal process in biofilms as the sum of four steps, namely (1) external transport of the particles to the biofilm surface, (2) bioflocculation, (3) organic particulate hydrolysis, and (4) diffusion and reaction of the solubilized organics by the bacterial cells comprising the biofilm. Organic (native corn starch) and inorganic particle (Min-U-Sil 10 [U.S. Silica Company, Berkeley Springs, West Virginia]) suspensions, with micronutrients, were continuously fed to a rotating disc biofilm reactor to verify a first-order kinetic expression that has been used to describe bioflocculation and to demonstrate that bioflocculation is the primary particle removal mechanism. Extracellular polymeric substances were extracted and quantified to describe the role they play in the bioflocculation process.

ZrO2-Ni Functional Gradient Bonding Interlayer

A functional gradient (FG) layer based on Ni-ZrO2 (3mol% Y2O3) was obtained by spraying diluted organic suspensions with an airbrush. The different layers were sequentially sprayed onto Y-TZP and Ni substrates, in 25 vol.% compositional steps. Afterwards, two ZrO2 bulk pieces as well as ZrO2 and Ni adherents were successfully joined using this type of FG structure as an interlayer. The microstructure and the possible reactions between the ZrO2 and Ni phases were analyzed. The porosity of each layer was evaluated by micro-hardness measurements.

Organic nanoparticles suspensions preparation by underwater excimer laser ablation of polycarbonate

Ablation with excimer laser pulses on polycarbonate (PC) film has been performed in ultrapure water. It is demonstrated that it is a new efficient method for organic nanoparticles (ONP) suspensions synthesis. Proof of the formation of ONP is given by analysis of the water phase with AFM and UV–vis spectroscopy. The obtained transmission measurements are approached with the aid of Mie theory to estimate composition of suspensions. Results indicate that the polycarbonate film is partly ablated into nanometric particles with size ranging from 8 up to 180 nm. This is also supported by force atomic microscopy. Confocal Raman microspectroscopy was done directly on water suspensions. Thanks to the optical trapping phenomenon of the nanoparticles, their vibrational Raman spectrum was more easily obtained. Original polycarbonate is lost although some polymeric structures are detected along with graphitic carbon.

Electrophoretic deposition of zirconia‐Bioglass® composite coatings for biomedical implants

Composite bilayer coatings on Ti6Al4V substrates were prepared by electrophoretic deposition, a simple and fast low temperature coating technique. Biocompatible yttrium-stabilized zirconia (YSZ) in the form of nanoparticles and bioactive Bioglass (45S5) in the form of microparticles were chosen as coating materials. The first layer consisted of 5 microm of YSZ, deposited with the intention to avoid any metal tissue contact. The second layer consisted of 15-microm thick 45S5-YSZ composite, supposed to react with the surrounding bone tissue and to enhance implant fixation. The adsorption of YSZ nanoparticles on 45S5 microparticles in organic suspension was found to invert the surface charge of the 45S5 particles from negative to positive. This enabled cathodic electrophoretic deposition of 45S5, avoiding uncontrolled anodization (oxidation) of the substrate. The coatings were sintered at 900 degrees C for 2 h under argon flow. The characterization was performed using SEM, EDX, and nanoindentation (cross section). Potential applications in the orthopedics field are discussed.

A study on electrophoretic deposition of Ni nanoparticles on pitted Ni alloy 600 with surface fractality

In the present work, the electrophoretic deposition of Ni nanoparticles used for self-repairing of pits in organic suspension was investigated on pitted fractal Ni alloy 600 with respect to surface fractality of the pits. For this purpose, Ni nanoparticles prepared by levitation–gas condensation were dispersed into an ethanol solution with the addition of a dispersant. Four kinds of pitted fractal specimens with different surface fractal dimensions d F , surf were prepared by applying various anodic potentials above pitting potential to alloy 600 in aqueous 0.1 M NaCl solution. From the scanning electron microscopy (SEM) images, it was observed that the pits repaired under applied electric field E of 100 V cm −1 comprised more agglomerates of Ni nanoparticles than those repaired under E of 20 V cm −1. This suggests that the higher the value of E is, the more agglomerates of Ni nanoparticles are deposited on the specimen due to more depletion of OH − in suspension near the specimen surface. Moreover, the specimen with higher d F , surf gave a higher value of electrophoretic current I p than one with lower d F , surf due to the increased electrochemical active area A ea of the specimen. From the above, it is concluded that the surface irregularities of the pit enhance the deposition of Ni nanoparticles on pitted fractal specimen during electrophoretic deposition.

Electrophoretic Deposition of Ni Nano-Particles for Self-Repairing of Heat Exchanger Tubes

The electrophoretic deposition process of Ni nano-particles in organic suspension was employed for self-repairing of heat exchanger tubes. For this purpose, Ni nano-particles prepared by levitation-gas condensation were dispersed into the solution of ethanol with the addition of dispersant. The pitted Ni alloy specimen was prepared by applying a potential of 0.9 V (vs. Ag/AgCl) in aqueous 0.1 M NaCl solution. For electrophoretic deposition of Ni nano-particles on the specimen, a constant electric field of 100 V cm-1 was applied to the specimen for 180 s in Nidispersed solution. It was found that as the electrophoretic deposition time increased, the size of the pit remarkably decreased due to the agglomeration of Ni nano-particles at the pit with a higher current value rather than the outer surfaces of the specimen with a lower current value. Moreover, the current density increased with electrophoretic deposition time and reached a constant value. From the above, it is concluded that as the electrophoretic deposition proceeds, the pit becomes smaller in size, and hence the nano-particles more extensively aggregate at the pit by lyosphere distortion.

Preparation of nanocapsules containing the two-phase core materials

In this study, copolymer nanocapsules containing the two-phase core materials were prepared by mini-emulsion polymerization using styrene (St) and methylmethacrylate (MMA) as comonomer, in which the ZnO nanoparticles organic suspension was prepared by solvothermal synthesis method. The obtained materials were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), UV-visible spectrophotometry and fluorescence spectrometer. The particle size of the prepared ZnO nanoparticles dispersed in the organic solvent was less than 20 nm. The resulting polymer nanocapsules have 100–200 nm in diameter and ∼ 10–20 nm in the wall thickness. The surface of the polymer nanocapsules is smooth and clear.

A Review of the Use of Chitosan for the Removal of Particulate and Dissolved Contaminants

Chitosan has unique properties among biopolymers, especially due to the presence of primary amino groups. Chitosan has been used for the chelation of metal ions in near‐neutral solution, the complexation of anions in acidic solution (cationic properties due to amine protonation), the coagulation of negatively charged contaminants under acidic conditions, and for precipitative flocculation at pH above the pKa of chitosan. The coagulation and flocculation properties can be used to treat particulate suspensions (organic or inorganic) and also to treat dissolved organic materials (including dyes and humic acid). This paper will give an overview of the principal results obtained in the treatment of various suspensions and solutions: (a) bentonite suspensions; (b) organic suspensions; (c) anionic dye solutions; and (d) humic acid solutions. Stoichiometry and charge restabilization were determined for the coagulation of humic acid, kaolin, and organic dyes with chitosan, indicating charge neutralization as the dominant mechanism for removal. Charge patch destabilization and bridging mechanisms were inferred in other cases, based on the effects of the apparent molecular weight of the chitosan preparations and effectiveness of sub‐stoichiometric doses of chitosan. For dye solutions, results showed that color can be removed either by sorption onto solid‐state chitosan or by coagulation‐flocculation using dissolved‐state chitosan; the reactivity of amine groups was significantly increased when dissolved chitosan was used. For humic materials, chitosan can be used as a primary coagulant or as a flocculant after coagulation with alum or other inexpensive coagulants. The influence of the degree of deacetylation and the molecular weight of chitosan on its performance as coagulant/flocculant is illustrated by several examples.