“…Polyethyleneimine (PEI) is quite effective in removing metal ions such as Hg 2+ , Cd 2+ [8], Cu 2+ [9], Zn 2+ [10], Co 2+ [11][12][13], Cr 3+ , Cr 4+ [14] and Ni [15]. Polyallylamine has been also reported to bind metal ions like Cu 2+ , Co 2 and Ni 2+ [16,17].…”