Column experiments are carried out by using glass or Plexiglas adjustable heigth columns.
These are fed by peristaltic pumps. Tests are conducted so that packed columns are saturated for the whole run-time of the experiments. Porous media are normally sands, which are treated so that they’ll get rid of the organic matter and the oxides adsorbed on the grain surface, a goal that is prior to our experiments. Results from column tests are then used to create and validate transport numerical models developed by the group.
We are currently working to build a large size column for the elution of highly concentrated suspensions of zerovalent iron nanoparticles.
The spectrophotometer is employed to analyze dispersions and solutions eluting from the columns, and used for the sedimentation experiments of colloidal suspensions.
The instrument is accessoried with a rotating carousel for the simultaneus analysis of the cells in “slow time scan”, i.e. measuring cyclically the absorbance of each cell. Flow-through cells can be used as well.
The system allows us to analyze the absorbance of different suspensions flowing from different channels: it is possible to acquire continuous measurements of the column outlet and to obtain together datas from the bypassed column inlet and the reference blank.
The instrument can be employed simultaneously with a “fraction collector” to sample the column outlet.
Acoustic and Electro-acoustic Spectrometer
The spectrometer is able to analyze the dimensional distribution of highly concentrated colloidal dispersions with a size range that goes from 0.005 up to 1000 microns. In addition, the instrument can be used to measure the electrophoretic mobility of the nanoparticles in aqueous suspensions. Other than a great characterization instrument, the spectrometer can be used as a part of a recirculating system with:
– a column, to obtain inline measurements of the size distribution of particles eluting from the column itself;
– a rotor/stator mill or a ultrasonicator, to break nanoparticles flocs.
Our laboratory has an Anton Paar Physica MCR 301, this device has tension control and separated systems for the determination of fluid viscosity, such as:
– flat plates PP50;
– cone and plate CP50;
– concentrical cylinders.
The rheometer has a Peltier system and an external thermostatic bath that can be used to control the fluid temperature; with an external device, which applies a magnetic field in a confined measure cross-section, it is possible to make magneto-rheological measurements on fluids with magnetic-dependent properties.
The group team also employs many other instruments which are Politecnico University property or run through the collaboration of various departments and research centers. We can count on a good variety of machines, such as AFM/MFM (atomic force microscopes/magnetic force microscopes), magnetometers, Turbiscan, XRD (X-ray diffraction), BET analyzers, TEM (transmission electron microscopes), SEM (scanning electron microscopes), Spettroscopi Raman, ICP (inductively coupled plasma), DLS (dynamic light scattering).
The group is currently working to collect all the possible instruments needed in order to perform force measurements between particles or between particles and collectors in liquid, using AFM.