Acronym: POLYSAND
Quartz sand/polyelectrolyte composite microparticles with high
loading/release of some inorganic/organic compounds from polluted waters
A 1.1. Sieving the quartz sand microparticles and selective collection of fractions.
Figure 1. Collecting the sand fractions (F<70, F70, F100, F200, F355 and F>425) after sieving at 90 Hz.
Figure 2. SEM micrographs (A) and XPS spectrum (B) of a natural sand fraction (F100).
A 2.1. Precipitation deposition of polycations and polyanions onto different sand fractions.
Figure 3. Behaviour of sand/PEI-GA composites before (left) and after extraction of PAA in strong basic media (right) as function of sand size (F70, F100, F200, F355) and cross-linking degree (A = 1:10; B = 1:5; and C = 1:1).
A 2.2. Stabilization of polyelectrolyte architecture onto sand surface by chemical cross-linking with GA.
Figure 4. Volume of sediments measured as function of cross-linking degree for each modified sand fraction.
A 2.3. Morphological characterization of sand/polyelectrolyte composites by SEM
Figure 5. SEM micrographs of sand F100 before (A) and after (B) deposition of PEI-GA organic layer onto solid surface.
A 2.4. Quantification of organic deposited amount onto sand surface using X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG) and IR spectroscopy.
Figure 6. XPS wide spectra of modified sand microparticles F70/PEI-GA (A), F100/PEI-GA (B) and F200/PEI-GA (C).
A 2.9. Extraction in basic media of polyanion chains from cross-linked polycation architecture deposited onto sand microparticles.
Figure 7. Extraction of PAA chains from strong (A) and weak (B) cross-linked F100/PEI-GA, F200/PEI-GA and F355/PEI-GA composites.
A 2.10. Extraction in acidic media of non-crosslinked polycation chains.
Figure 8. Extraction of polycation chains in acidic media after chemical crosslinking with GA.
A 2.11. Electrokinetic measurements of modified sand microparticles with polyelectrolytes.
Figure 9. Zeta potential as function of pH for unmodified (F70) and modified sand composites (F70/PEI-GA) cross-linked with GA at three molar ratios.
A 2.12. Testing the stability of sand composites in different aqueous solutions.
Figure 10. Sand/polyelectrolyte composites obtained by chemical (A) and thermal (B) cross-linking tested in aqueous environment with different pH values.