THE STREAMING CURRENT DETECTOR - A QUANTITATIVE MODEL

The streaming current detector (SCD) is an instrument used for continu ous characterization of colloidal surface charge. It measures the alte rnating current generated by mobile countering when charged material m omentarily adheres to cylinder and piston walls while the piston recip rocates, The utility of the SCD for coagulant control is generally acc epted, as evidenced by the estimated one thousand units in service in North America, However, one drawback to this device has been the lack of an exact quantitative model explaining its functioning, This paper provides such a description, relating the generated current to the zet a potential of the characterized material as a function of instrument parameters and solution chemistry, The model, programed in Mathematica , agrees closely with an earlier analytical solution under many condit ions, Its inclusion of an inertial term, however, allows behavior of t he SCD to be simulated under a more general range of conditions. (C) 1 996 Academic Press, Inc.