Quick-curing of ordinary superphosphate: determination of optimum operating conditions on a laboratory scale and initial pilot plant work

The present paper describes a simple, selective and sensitive kinetic method for the determination of trace amounts of Sb(III) in the presence of Sb(V) based on its inhibition effect on the redox reaction between bromate and Victoria blue 4R (V.B. 4-R) in hydrochloric acid media. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of V.B. 4-R at 596.3 nm. Optimum operating conditions regarding reagent concentrations were established. The optimized conditions yielded a theoretical detection limit of 1.30·10‒8 g cm–3 Sb(III) based on the 3S0 criterion. The method allows the determination of Sb(III) in the range of 5·10‒8 ‒ 1.1·10‒6 g cm–3. The effects of certain foreign ions the reaction rate were determined for an assessment of the selectivity of the method. The kinetic parameters of the reaction were reported, and the rate equations were suggested. The results were validated statistically and through recovery studies. The proposed method has been successfully applied to the determination of Sb(III) in various model and real samples.

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Portable pilot plant for evaluating marine biofouling growth and control in heat exchangers-condensers

Water Science & Technology ◽

10.2166/wst.2003.0291 ◽

2003 ◽

Vol 47 (5) ◽

pp. 99-104 ◽

Cited By ~ 9

Author(s):

J.F. Casanueva ◽

J. Sánchez ◽

J.L. García-Morales ◽

T. Casanueva-Robles ◽

J.A. López ◽

...

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Pilot Plant ◽

Economic Cost ◽

Automatic Monitoring ◽

Operating Conditions ◽

Optimum Operating ◽

Indirect Measure ◽

Transfer Equations ◽

And Control

Biofouling frequently involves a serious impediment to achieving optimum operating conditions in heat exchangers-condensers. The economic cost and energy losses associated with this phenomenon are significant and the environmental impact of biocides must satisfy stringent regulations. A portable pilot plant has been designed in order to carry out in-situ experimental study as biofilm is formed under thermal and hydrodynamically controlled conditions. The pilot plant has an automatic monitoring, control and data acquisition system, which automatically processes data from indirect measure of fouling in terms of increased fluid frictional and heat transfer resistances. A particular method is used and proposed for direct measuring and biofilm characterization. Once we know the actual film thickness, we can calculate the effective thermal conductivity of the layer by using the appropriate heat transfer equations.

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Quantitative analysis of ibuprofen in pharmaceuticals and human control serum using kinetic spectrophotometry

Journal of the Serbian Chemical Society ◽

10.2298/jsc0809879m ◽

2008 ◽

Vol 73 (8-9) ◽

pp. 879-890 ◽

Cited By ~ 5

Author(s):

Snezana Mitic ◽

Gordana Miletic ◽

Aleksandra Pavlovic ◽

Biljana Arsic ◽

Valentina Zivanovic

Keyword(s):

Rapid Determination ◽

Pharmaceutical Formulations ◽

Operating Conditions ◽

Optimum Operating ◽

Kinetic Spectrophotometry ◽

Human Control ◽

Control Serum ◽

Tangent Method ◽

Kinetic Spectrophotometric

The aim of this work was to develop a new kinetic spectrophotometric method for the determination of ibuprofen in pharmaceutical formulations. Ibuprofen was determined in an acidic ethanolic medium by monitoring the rate of appearance of 1-nitroso-2-naphthol, resulting from the displacement by ibuprofen of Co(III) from the tris(1-nitroso-2-naptholato)cobalt(III) complex. The optimum operating conditions regarding reagent concentrations and temperature were established. The tangent method was adopted for constructing the calibration curve, which was found to be linear over the concentration range 0.21-1.44 and 1.44-2.06 ?g ml-1. The optimized conditions yielded a theoretical detection limit of 0.03 ?g ml-1 based on the 3.3 S0 criterion. The interference effects of the usual excipients of powdery drugs, foreign ions and amino acids on the reaction rate were studied in order to assess the selectivity of the method. The developed procedure was successfully applied for the rapid determination of ibuprofen in commercial pharmaceutical formulations and human control serum. The unique features of this procedure are that the determination can be performed at room temperature and the analysis time is short. The newly developed method is simple, inexpensive and efficient for use in the analysis of a large number of samples.

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