Development of an inductive concentration measurement sensor of nano sized zero valent iron

The injection of colloidal nano sized zero valent iron (nZVI) into a contaminated aquifer is a promising new in-situ groundwater remediation technique. An inductive sensor is presented to directly detect and measure the concentration of nZVI in the subsurface. The method is based on the inductive measurement of magnetic material properties of nZVI within an alternating magnetic field. The change of magnetic flux density generated by one coil is determined by measuring an induced voltage in a second coil. Numerical simulations with the finite element software COMSOL Multiphysics were performed to optimize the sensor design. Furthermore, these components were used to analyze the possible measuring range, taking into account the accuracy of the measuring device to be used. Since the susceptibility of nZVI in the aquifer is very small, it is necessary to use a background measurement to improve the sensitivity of the measurement system. Finally, the measuring concept was experimentally verified.