Infrared Spectroscopy of Organoclays Synthesized with the Surfactant Octadecyltrimethylammonium Bormide

Infrared spectroscopy using a smart endurance single bounce diamond ATR cell has been used to study the changes in the spectra of the surfactant octadecyltrimethylammonium bromide upon intercalation into a sodium montmorillonite. The wavenumbers of bands attributed to CH stretching and bending vibrations in general decrease as the concentration of the surfactant measured in terms of the cation exchange capacity (CEC) up to 1.0 CEC. After this point the bands increase approaching a value the same as that of the surfactant. Significant changes occur in the HCH deformation modes of the methyl groups of the surfactant. These changes are attributed to the methyl groups locking into the siloxane surface of the montmorillonite. Such a concept is supported by changes in the SiO stretching bands of the montmorillonite siloxane surfac

TEM, XRD, and Thermal Stability of Adsorbed Paranitrophenol on DDOAB Organoclay

Water purification is of extreme importance to modern society. Organoclays through adsorption of recalcitrant organics provides one mechanism for the removal of these molecules. The organoclay was synthesised through ion exchange with dimethyldioctadecylammonium bromide labeled as DDOAB of formula (CH3(CH2)17)2NBr(CH3)2. Paranitrophenol was adsorbed on the organoclay at a range of concentrations according to the cation exchange capacity (CEC) of the host montmorillonite. The paranitrophenol in solution was analysed by a UV-260 spectrophotometer at 317nm, with detection limits being 0.05mg/L. The expansion of the montmorillonite was studied by a combination of X-ray diffraction and transmission electron microscopy. Upon adsorption of the paranitrophenol the basal spacing decreased. The thermal stability of the organoclay was determined by a combination of thermogravimetry and infrared emission spectroscopy. The surfactant molecule DDOAB combusts at 166, 244 and 304 degrees Celsius and upon intercalation into Na-montmorillonite is retained up to 389 degrees Celsius thus showing the organoclay is stable to significantly high temperatures well above the combustion/decomposition temperature of the organoclay

PREDICTION PROGRAMMING OF THE WATER QUALITY AND ITS APPLICATION

This paper predicts the total phosphorus concentration in the water in the West Lake using a model of the convection and dispersion equation. The theory of the model is presented and predictions are made using a FORTRAN 77 program in a Dell 486 micro-computer. The results of numerical simulations are also discussed. The results presented in the paper have a practicable significance in controlling the environment of the water quality.Article信州大学理学部附属諏訪臨湖実験所報告 11: 99-108(1999)departmental bulletin pape

A Type of Delay Feedback Control of Chaotic Dynamics in a Chaotic Neural Network

A chaotic neural network consisting of chaotic neurons exhibits such rich dynamical behaviors as nonperiodic associative memory. But it is difficult to distinguish the stored patterns from others, since the chaotic neural network shows chaotic wandering around the stored patterns. In order to apply the nonperiodic associative memory to information search or pattern identification, it is necessary to control chaotic dynamics. In this paper, we propose a delay feedback control method for the chaotic neural network. Computer simulation shows that, by means of the control method, the chaotic dynamics in the chaotic neural network are changed. The output sequence of the controlled network wanders around one stored pattern and its reverse pattern

NUMERICAL SIMULATION AND EXPERIMENTAL ANALYSIS OF SPRAY FIELD OF IMPINGEMENT NOZZLE

ABSTRACT The shape of a spray droplet from a flat-fan nozzle in the plant protection sector is similar to a ‘U shape’, the middle particle size being small but the diameter of both sides being too large. So, flat-fan nozzles have the defects of wide droplet size and poor uniformity of droplet size. This paper simulates and tests the impingement nozzle, based on the coupling effect of the jet and impinging stream, so as to improve the droplet size uniformity and droplet spectrum. After jet impingement, it was found that the droplet size of the spray fan surface of the impingement nozzle showed the characteristics of large, uniform and smaller sides. This was beneficial in solving the uneven distribution of droplet size distribution in the field operation of the sprayer. The droplet distribution of the impingement nozzle is more concentrated, forming a narrow droplet spectrum. The experimental results are in good agreement with the results of numerical simulations and theoretical analysis. The impingement nozzle solves the shortcomings of wider fan droplets and smaller particle size uniformity, and provides feasible technical support for developing intelligent precision spray equipment

Pore Structure of Surfactant Modified Montmorillonites

A series of organoclays with different surfactant arrangements were prepared by ion exchange. The resulting organoclays were investigated using a combination of characterization techniques, including XRD, FTIR, TG and N2 adsorption-desorption. In the present study, the pores within the organoclays were discussed on the basis of the microstructural parameters, including BET-N2 surface area, pore volume, pore size, surfactant loading and distribution. The results show that both BET-N2 surface area and pore volume decrease from low to high packing density of the surfactant as the average pore size increases. Two basic organoclay models were proposed for hexadecyltrimethylammonium bromide (HDTMAB) modified montmorillonites: 1) the surfactant mainly occupied the clay interlayer and 2) both the clay interlayer space and external surface were modified by surfactant. This study demonstrates that the pore structure of the resulting organoclays has a significant influence on the sorption efficiency and mechanism of p-nitrophenol onto the organoclays

Identification of multi-drug resistant genes in P. aeruginosa isolates from patients under mechanical ventilation and respiratory support in an intensive care unit

Purpose: To determine multi-drug resistant (MDR) and metallo β-lactamase (MBL)-resistant genes from Pseudomonas aeruginosa isolated from intensive care unit (ICU) patients under mechanical ventilation and respiratory support.Methods: P. aeruginosa was isolated from 387 purulent tracheobronchial secretions collected from ICU patients who were intubated and mechanically ventilated for at least 48 h. Antibiotic resistance was determined by minimum inhibitory concentration (MIC) assay while MDR genes, viz, blaTEM, blaOXA, blaVIM, blaCTX-M-15 were determined by polymerase chain reaction (PCR).Results: A total of 144 (37.2 %) P. aeruginosa were isolated from the purulent tracheobronchial secretions. A majority of the isolates (51.4 %) were resistant to gentamicin. Meropenem-gentamicin was the predominant (35.4 %) resistant combination. Out of the 144 isolates, 102 (70.8 %) were positive for blaTEM gene, 51 (35.4 %) for were positive for blaOXA gene, 22 (15.3 %) were positive for blaVIM gene, while 19 (13.2 %) were positive for blaCTX-M gene.Conclusion: The high prevalence of MDR P. aeruginosa indicates the need for continued monitoring of MDR P. aeruginosa especially in ICU patients who are under mechanical respiratory support.Keywords: Multi-drug resistance genes, Mechanical ventilator, Respiratory support, Pseudomonas aeruginos

A CIRCULATION DYNAMICS MODEL IN THE ECOSYSTEM FOR THE WEST LAKE, HANGZHOU

This paper focuses the researches on an eutrophication model after drainage of wastewater and drawing water from the Qiantang River to West Lake. The model describes the circulation of nutritive matters (such as phosphorus, nitrogen, and carbon) in the ecosystem of the Lake. The model was established according to observed values of water quality and relevant parameters in 1995. The results of model calibration and verification show that the model can reasonably respond to the changes of forcing functions for drawing quantity and temperature of water. The model has been used to forecast the water quality in different drawing quantities. The predictions given by the model are also believed to be useful to comprehensively harness the West Lake.Article信州大学理学部附属諏訪臨湖実験所報告 11: 87-98(1999)departmental bulletin pape

A Review of the Role of Natural Clay Minerals as Effective Adsorbents and an Alternative Source of Minerals

The minerals with unique properties such as natural clay minerals (NCMs) have promising approach in environmental and industrial sphere. In fact, under some specific conditions the NCMs could be used either as effective adsorbent material or alternative source of minerals. This chapter presents an outline of a general review of factors that affect the application ability of NCMs and a descriptive analysis of NH4+ and REE adsorption behavior and extraction of rare earth elements (REE) by an ion-exchange with NH4+ ions onto NCMs. Clays and NCMs both effectively remove various contaminants from aqueous solution and serve as alternative sources of minerals, as extensively discussed in this chapter. This review compiles thorough literature of current research and highlights the key findings of adsorption (NH4+ and REE) that use different NCMs as adsorbents or alternative sources of minerals (i.e., REE). The review confirmed that NCMs excellently remove different cations pollutants and have significant potential as alternative source of REE. However, modification and further development of NCMs applications for getting the best adsorption and the best extraction of REE onto NCMs, which would enhance pollution control and leaching system is still needed