ABSTRACT
The degradation of triphenylphosphine oxide (TPPO) in water, a toxic compound typically found in effluents from the pharmaceutical industry, by means of ultrasonic irradiation at 20 kHz has been investigated with emphasis on the effect of various parameters on conversion and acute toxicity. Experiments were carried out at liquid volumes of 50 and 80 ml, electric power outputs of 125, 187.5 and 250 W, initial TPPO concentrations of 10, 100 and 350 mg/L and temperatures of 5, 20, 35, 50 and 70 degrees C. TPPO conversion was found to increase with increasing power output and decreasing initial concentration and temperature. Measurements of dissolved total carbon showed that liquid-phase degradation by-products were more stable to ultrasonic irradiation than TPPO. Addition of t-butanol as a radical scavenger at a concentration of 1000 mg/L nearly completely suppressed TPPO degradation. Conversely, addition of radical promoters (Fe(2+) ions or H(2)O(2)) had a positive effect on degradation. Acute toxicity to marine bacteria vibrio fischeri was measured before and after ultrasonic irradiation. At the conditions employed in this study, irradiated TPPO samples were always more toxic than TPPO itself with toxicity levels being a function of treatment conditions.
Subject(s)
Organophosphorus Compounds/chemistry , Ultrasonics , Water Pollutants, Chemical/toxicity , Water Purification/methods , Aliivibrio fischeri , Organophosphorus Compounds/toxicity , Toxicity Tests , Water MovementsABSTRACT
A universal temperature controlled membrane interface (TCMI) has been constructed for hollow-fibre membranes. The membrane temperature is controllable in the range -70 to 250 degrees C using an electric heater and a flow of cooled nitrogen or helium gas. Volatile and semi-volatile organic compounds may be detected either by continuous diffusion across the membrane or by in-membrane pre-concentration followed by thermal desorption into the detector. The TCMI interface is demonstrated in combination with mass spectrometry and GC-MS, for the determination of VOCs and SVOCs in aqueous and air samples and for the on-line monitoring of a bioreactor.
Subject(s)
Flow Injection Analysis/instrumentation , Gas Chromatography-Mass Spectrometry/methods , Membranes, Artificial , Organic Chemicals/analysis , Temperature , Flow Injection Analysis/methodsABSTRACT
This paper describes ideas together with preliminary experimental results for applying solvent nanofiltration to liquid phase organic synthesis reactions. Membranes for organic solvent nanofiltration have only recently (during the 1990s) become available and, to date, have been applied primarily to food processing (vegetable oil processing, in particular) and refinery processes. Applications to organic synthesis, even at a laboratory feasibility level, are few. However, these membranes have great potential to improve the environmental performance of many liquid phase synthesis reactions by reducing the need for complex solvent handling operations. Examples that are shown to be feasible are solvent exchanges, where it is desired to swap a high molecular weight molecule from one solvent to another between separate stages in a complex synthesis, and recycle and reuse of homogeneous catalysts. In solvent exchanges, nanofiltration is shown to provide a fast and effective means of swapping from a high boiling point solvent to a solvent with a lower boiling point-this is a difficult operation by means of distillation. Solvent nanofiltration is shown to be able to separate two distinct types of homogeneous catalysts, phase transfer catalysts and organometallic catalysts, from their respective reaction products. In both cases the application of organic solvent nanofiltration allows several reuses of the same catalyst. Catalyst stability is shown to be an essential requirement for this technique to be effective. Finally, we present a discussion of scale-up aspects including membrane flux and process economics.
Subject(s)
Biotechnology/methods , Membranes, Artificial , Water Purification/methods , Catalysis , Conservation of Natural Resources , Filtration , Membranes , Models, Chemical , Molecular Weight , Solvents , Ultrafiltration , Waste ManagementABSTRACT
Reversed-phase membrane inlet mass spectrometry incorporating a hollow-fiber Nafion membrane has been evaluated for the determination of low molecular weight alcohols in chloroform. The hydrophilic Nafion membrane preferentially transports methanol and ethanol, allowing percentage concentrations of the alcohols to be determined in a chloroform matrix. A linear response was observed for ethanol over the working range 0.5-2.5%, with a limit of detection of 0.1%. The application of reversed-phase membrane inlet mass spectrometry using a Nafion membrane to the monitoring of a chloroform recovery process has been investigated using a residual gas analyzer. Evolving methanol and ethanol concentrations were determined in real time and compared favorably with off-line determinations by gas chromatography.
ABSTRACT
La calidad de las vacunas depende en gran parte de la conservación ininterrumpida a bajas temperaturas durante el proceso de distribución y almacenamiento de las mismas. Metodología: el presente trabajo se llevó a cabo en los centros de salud de la zona IV de Salud del Ministerio de Salud publica de Misiones Rep. Argentina. Se trata de un estudio cuasi experimental longitudinal, con un solo grupo. Se estudiaron las variables independientes: capacitación del personal a cargo de la vacunación y la supervision capacitante continua de enfermeria, en relación al cumplimiento de la cadena de frío de las vacunas.
Subject(s)
Humans , Education, Nursing, Continuing , Nursing, Supervisory , Primary Health Care , Quality of Homeopathic Remedies , Drug Stability , VaccinesABSTRACT
La calidad de las vacunas depende en gran parte de la conservación ininterrumpida a bajas temperaturas durante el proceso de distribución y almacenamiento de las mismas. Metodología: el presente trabajo se llevó a cabo en los centros de salud de la zona IV de Salud del Ministerio de Salud publica de Misiones Rep. Argentina. Se trata de un estudio cuasi experimental longitudinal, con un solo grupo. Se estudiaron las variables independientes: capacitación del personal a cargo de la vacunación y la supervision capacitante continua de enfermeria, en relación al cumplimiento de la cadena de frío de las vacunas.AU