A simple physicochemical method for detection of organic contaminations in water

The paper presents a simple physicochemical method (SPMD) elaborated for detection of organic contaminations in water. The SPMD method is based on measurements of lowering the rising bubble velocity by surface active contaminants present in water. A simple set-up consisting of a long glass tube with the capillary in bottom, air container and stop-watch was elaborated. It was showed that precision of the SPMD method was satisfactory when the time of the bubble rise over distance of 140 cm was measured at least 20 times to calculate the average bubble velocity. Measurements of influence of concentration of model non-ionic surfactant (n-pentanol) and two commercial detergents ("Ludwik" and "Vizir") on velocity of the rising bubbles were carried out using the laboratory (CCD camera, stroboscopic illumination and Motic Images Plus 2.0 digital recording system) and the SPMD method set-up. It was showed that the bubble velocity can be lowered by over 50% by the surface active substances (SAS) present in water and the rapid decrease of the bubble velocity occurred at lowest concentrations of the SAS studied. Thus, the bubble velocity is very sensitive to presence of surface active pollutants in water and this is one of the main advantages of the SPMD method elaborated. Sensitivity and reliability of the SPMD method was positively tested on five environmental water samples collected from different rivers in Poland and Baltic Sea. (C) 2007 Elsevier B.V. All rights reserved.