LABORATORY EXPERIMENT OF IRON NANOPARTICLE TRANSPORT IN A ROCK FRACTURE WITH ONLINE CONCENTRATION DETECTION PROBES

Principles, design and pilot use of a new probe for zero-valent iron nanoparticles (nZVI) concentration measurement in a micro-borehole are described in the paper. Effect of nZVI on coil inductance is known and used for such measurement before; the presented improvements relate to smaller dimensions, configuration, and electric circuit data accuracy, so that the probe can detect nZVI in small volume of suspension in a narrow fracture. Multichannel apparatus was made for a grid of boreholes. Test experiments were made with nZVI particles breakthrough in an artificial fracture in a granite block. The concentration is measured both by the new probe inside the block and by chemical analyses of samples at the outlet. The spontaneous particle immobilization did not allow saturation with constant concentration necessary for calibration, but within the constraints of input and output concentration and a fully submerged probe test, the quantitative sensitivity of the probe corresponds to theoretical expectations. Probe temperature dependence was also resolved.