Absolute rate of turbulent coagulation from turbidity measurement

Turbidity method has been applied to assess colloid stability. While the method is simple and easy, it is not straightforward in evaluating absolute coagulation rates of colloidal particles. That is, the method requires the evaluation of the extinction cross section of doublets. Recently, the turbidity measurement has been successfully utilized to evaluate the absolute Brownian coagulation rate constant with the T-matrix method, which calculates the extinction cross section of doublets at arbitral size range. The present work was performed to extend the applicability of the method to turbulent coagulation. To this end, we measured the turbidity change of coagulating latex suspensions in a turbulent flow. The measurement was performed as a function of particle size. From the turbidity vs. time relationship, we evaluated turbulent coagulation rate constant using the T-matrix method. Obtained values of the constants agreed well with theoretical ones, demonstrating the usefulness of turbidity method for turbulent coagulation.