Marianna A. Busch

Laborator studies on magnetic water treatment and their relationship to a possible mechanism for scale reduction

Laboratory studies indicate that magnetohydrodynamic effects may be responsible for claims that magnetic treatment devices are sometimes effective for scale control in water-using systems. In addition to enhancing corrosion of metals in the vicinity of the device, or within the device itself, application of the field 90° to the flow of a conducting fluid can alter the hydrodynamics of fluid flow. Depending on experimental conditions, this may increase or decrease turbulence in the fluid, promoting aggregation or deaggregation of both ferromagnetic and diamagnetic colloids. Important factors in promoting magnetohydrodynamic forces on fluid flow include conductivity of the solution, linear flow velocity of the fluid, and the flux density (magnetic induction) of the transverse field. Finally, magnetic treatment devices that are physically designed to create additional turbulence by constricting or otherwise altering fluid flow may further enhance the anti-scaling effect by purely mechanical means.

Determination of the enantiomeric composition of some molecules of pharmaceutical interest by chemometric analysis of the UV spectra of guest–host complexes formed with modified cyclodextrins

Multivariate regression modeling techniques (PLS-1 regression modeling) were applied to ordinary UV spectral absorption data obtained on solutions containing inclusion complexes formed between homochiral modified cyclodextrins (methyl-beta-cyclodextrin, alpha-, beta-, and gamma-carboxymethyl cyclodextrins and alpha-, beta-, and gamma-hydroxypropyl cyclodextrins) and four guest molecules of pharmaceutical interest (ephedrine, norephedrine, norepinephrine-l-bitartrate, and tryptophan methyl ester). The PLS-1 regression models were developed by correlating the known enantiomeric composition of laboratory prepared samples with ordinary UV absorption spectral data. The regression models were subsequently validated with laboratory-prepared test sets. The rms percent relative error in the predicted mol fraction of (1S, 2R)-(+)-ephedrine, (1S, 2R)-(+)-norephedrine, (R)-(-)-norepinephrine-l-bitartrate, and d-tryptophan methyl ester obtained with the independently prepared test sets was heavily dependent on the host molecule used.

Studies of a Water Treatment Device That Uses Magnetic Fields

Abstract It is experimentally shown that voltages and currents are produced when conducting solutions are made to flow through a water treatment device that uses magnetic fields. The magnitude of this voltage is found to vary with the solution flow rate in accordance with well-known laws of physics governing the motion of charged particles under the influence of a magnetic field. Current vs flow rate plots and surface pH measurements yield results that are in accord with the presence of enhanced corrosion of the metal housing of the device. It is postulated that the current generated magnetohydrodynamically produces a precipitation initiator that favors the precipitation of scaling salts in the bulk of the solution rather than on the walls of the plumbing.

Determination of the enantiomeric composition of phenylalanine samples by chemometric analysis of the fluorescence spectra of cyclodextrin guest–host complexes

A novel strategy for determining the enantiomeric composition of phenylalanine samples that combines ordinary fluorescence spectroscopy, guest-host cyclodextrin chemistry, and multivariate regression modeling is investigated. Partial-least-squares regression (PLS-1) models were developed from fluorescence spectral data obtained with a series of samples containing cyclodextrin guest-host complexes of phenylalanine with different known enantiomeric compositions. The regression models were subsequently validated by determining the enantiomeric composition of a set of independently prepared phenylalanine samples. The ability of the models to correctly predict the enantiomeric compositions of future samples was evaluated in terms of the root-mean-square percent relative error (RMS%RE). The RMS%RE in the mol fraction of D-phenylalanine ranged from 1.3% to 3.0% when beta-cyclodextrin was used as the host molecule for different guest-host concentrations. The RMS%RE in the mol fraction of D-phenylalanine obtained in a similar validation study conducted with gamma-cyclodextrin ranged between 1.8% and 4.0% for different guest-host concentrations. Compared with previous studies done in absorption, fluorescence data were found to be more sensitive and the spectral differences observed as a function of enantiomeric composition were more uniformly spaced, making regression modeling more reliable. As a result, good regression models could be made at lower concentrations than were possible previously when absorption measurements were used.

Effect of a weak magnetic field on hematite sol in stationary and flowing systems

The effect of a weak magnetic field on the aggregation state and electrophoretic mobility of hematite sol was studied in flowing (dynamic) systems as a function of time and electrolyte concentration (0–60 mmol/dm3 KCl) and compared with the effect of the field in stationary (static) systems and flow in the absence of the field. During the entire treatment period, the pH remained almost constant (4.06–4.24). Conductance varied with KCl concentration, but except for minor fluctuations appeared to be unaffected by any form of treatment. While aggregation of hematite was observed during dynamic magnetic treatment (change in turbidity, scattered light intensity, and photon correlation spectroscopy), little effect on aggregation state was observed for the static systems or for the flowing systems in the absence of the field. Mobility also increased during the first 30 min of static and dynamic magnetic treatment. After longer treatment periods (90–120 min), the mobility decreased, but in almost all cases remained larger than in the case of untreated systems. Changes in both mobility and particle aggregation state also showed a significant dependence on electrolyte concentration. These effects are discussed in terms of a magnetohydrodynamic interaction between the magnetic field and the charged colloidal particles, which results only when the particles are made to pass rapidly through the field.

Unusual eight-membered rings with linear symmetric methyl groups from yttrium and lutetium methyl complexes

Abstract New examples of symmetric linear bridge bonding of methyl groups between two metal ions is demonstrated in the complexes [M(Cp*)2μ-Me2M′Me2]2 (1) (M = yttrium or lutetium; M′ = aluminum or gallium; Cp* = pentamethylcyclopentadienyl) which are formed by reversible dimerisation of M(Cp*)2μ-Me2M′Me2. X-ray crystallography shows the metal atoms in Y(Cp*)2μ-Me2AlMe2 to be arranged in a flat square array with alternating Y and A1 atoms at the vertices, and methyl groups along the sides. The linear YCAl bonds so formed subtend a bond angle of 176°(1). Equilibrium constants between +40 °C and −40 °C for dimerisation to 1 of Y(Cp*)2μ-Me2AlMe2, Y(Cp*)2μ-Me2GaMe2 and Lu(Cp*)2μ-Me2AlMe2 in toluene were obtained, giving the thermodynamic parameters ΔHeq = −10.4, −5.6 and −8.1(±0.2) kcal mol-1 and ΔSeq = −29.9, −18.0 and −27.4(±3) e.u. respectively. From NMR data, particularly comparison of coupling constants (Jch values = 118–124 Hz for linear bridge methyl groups in these systems), the products from reaction of M(Cp*)2μ-MeM(Cp*)2Me (M = yttrium or lutetium) and [Y(C5H5)2Me]2 are also linearly methyl-bridged tetra-metal complexes [M(Cp*)2MeY(C5H5)2Me-]2.

Fourier Transform Flame Infrared Emission Spectroscopy

The thermal fragmentation of organic compounds in a hydrogen/air flame is studied via Fourier transform flame infrared emission (FT-FIRE) spectroscopy. In this preliminary survey of more than 75 organic compounds, it is shown that compound and element-specific infrared emission bands are produced when organic compounds containing C, H, Cl, F, S, and Si are combusted in the flame. Correlations of these infrared emission bands with possible combustion products are presented.

Residual variations in the zeta potential of TiO2 (Anatase) suspension as a result of exposure to radiofrequency electric fields

Abstract Suspensions of TiO 2 (anatase) powder in both deionized water and dilute NaCl solutions were exposed to a radiofrequency (RF) electric field with a peak-to-peak, no-load amplitude of 34 V and a frequency of 44 MHz. Examination of the suspension after various exposure times revealed that significant changes in zeta potential, pH, and solution conductivity occurred as a result of treatment by the RF field. Under the conditions employed in this study, the maximum decrease in zeta potential for the TiO 2 suspensions occurred after approximately 30 min of exposure time. Oscillatory variations in the zeta potential were also observed to persist for periods of at least 90 min after the radiofrequency field had been removed. The changes in zeta potential observed during these studies are discussed in terms of interfacial polarization and residual, field-induced changes in the TiO 2 particles.

An Element-Specific, Dual-Channel, Flame Infrared Emission, Gas Chromatography Detector for Chlorinated and Fluorinated Hydrocarbons

A flame infrared emission (FIRE) gas chromatography (GC) detector for organofluorine and organochlorine compounds has been developed and evaluated. The element-specific GC-FIRE detector makes use of a beamsplitter to divide the source radiation into two optical paths. The divided radiation passes through appropriate notch filters to isolate the background and analyte emission, which are each monitored by separate lead selenide detectors that form part of a Wheatstone bridge network. The output from the Wheatstone bridge is fed into the differential mode (A-B) input of a lock-in amplifier (LIA). In the chlorine mode of operation, a 3.7-μm optical notch filter is used in the analytical channel to isolate a portion of the HCl emission that results when organochlorine compounds are combusted in the hydrogen/air flame. In the fluorine mode of operation, a 2.35-μm optical notch filter in combination with a 2.55-μm short-pass filter is used to isolate a portion of the HF emission that results when organofluorine compounds are combusted. With the use of the dual-channel system, selectivity ratios of at least 760 (F) and 100 (Cl) were obtained, respresenting improvements by factors of about 104 (F) and 30 (Cl) in comparison with results from the single-channel mode of operation. With the use of Freon-113® (C2Cl3F3) as a representative analyte, detection limits in both the chlorine- and fluorine-selective modes were 200 ng s−1, representing improvements by factors of about 9.5 (F) and 4.5 (Cl), in comparison with results from the single-channel mode of operation.

A Miniature Electrical Furnace as an Excitation Source for Low-Temperature, Gas-Phase, Infrared Emission Spectroscopy

The analytical utility of low-temperature, gas-phase infrared emission spectroscopy is studied with the use of a specially designed miniature electrical furnace. This furnace, designed to minimize blackbody radiation from the source itself, was capable of operating between 100 and 1000°C and producing infrared emission from parent analyte molecules, as opposed to their terminal combustion products, such as CO2 and H2O. The low-temperature, infrared emission spectra of nitrous oxide (225°C) and methyl benzoate (250 and 700°C) are reported, and the feasibility of determining ethanol in gasohol is evaluated with the use of the alcohol C-O stretching vibration (observed at 1070 cm−1 in emission). The detection limit for ethanol in gasohol at 202°C was found to be 0.124% v/v, and the relative standard deviation of eight single-scan determinations of ethanol in a 10% v/v gasohol blend was found to be 4.01%. Some of the advantages and limitations associated with analytical, low-temperature, gas-phase, infrared emission spectroscopy are discussed and compared with results obtained with a hydrogen/air flame as the excitation source.