Polycysteine and other polyamino acid functionalized microfiltration membranes for heavy metal capture

Polycysteine and other polyamino acid functionalized microfiltration membra ne sorbents work exceptionally well for the removal and recovery of toxic h eavy metals from aqueous streams. These are high capacity sorbents (0.3-3.7 mg/cm(2)) with excellent accessibility and selectivity for heavy metals, s uch as Hg(ll), Pb(ll), and Cd(II) over nontoxic components such as calcium. Polycysteine functionalized membranes work particularly well for metals su ch as Hg(ll) and Cd(li), even in high total dissolved solids containing str eams. Parameters such as permeate flow rate,feed metal concentration, and c ounterion (for Hg(Il)) have also been found to influence sorbent behavior. For multicomponent systems, polyglutamic acid functionalized membranes have been found to selectively sorb Pb(II) versus COO. Selective sorption of Cr (III) has also been observed with actual waste streams containing several h eavy metals, hardness, and high sodium (2000 mg/L). The high capacity, site accessibility, and ease of regeneration of these membrane-based sorbents m ake them ideal for environmental separations when volume reduction or selec tive recovery is required.