Advances
in industrial ecology, desalination, and resource recovery
have established that industrial wastewater, seawater, and brines
are important and largely untapped sources of critical metals and
elements. A Grand Challenge in metal recovery from
industrial wastewater is to design and synthesize high capacity, recyclable
and robust chelating ligands with tunable metal ion selectivity that
can be efficiently processed into low-energy separation materials
and modules. In our efforts to develop high capacity chelating membranes
for metal recovery from impaired water, we report a one-pot method
for the preparation of a new family of mixed matrix polyvinylidene
fluoride (PVDF) membranes with in situ synthesized poly(amidoamine)
[PAMAM] particles. The key feature of our new membrane preparation
method is the in situ synthesis of PAMAM dendrimer-like particles
in the dope solutions prior to membrane casting using low-generation
dendrimers (G0 and G1-NH2) with terminal primary amine
groups as precursors and epichlorohydrin (ECH) as cross-linker. By
using a combined thermally induced phase separation (TIPS) and nonsolvent
induced phase separation (NIPS) casting process, we successfully prepared
a new family of asymmetric PVDF ultrafiltration membranes with (i)
neutral and hydrophilic surface layers of average pore diameters of
22–45 nm, (ii) high loadings (∼48 wt %) of dendrimer-like
PAMAM particles with average diameters of ∼1.3–2.4 μm,
and (iii) matrices with sponge-like microstructures characteristics
of membranes with strong mechanical integrity. Preliminary experiments
show that these new mixed matrix PVDF membranes can serve as high
capacity sorbents for Cu(II) recovery from aqueous solutions by ultrafiltration.