molecular weight (Mw) ∼ 35 kDa)
and ECH (M.W = 92.52 g/mol, >98%) were purchased from Sigma-Aldrich.
Poly(vinylpyrrolidone) (PVP) (Mw 10 kDa),
sulfuric acid (H2SO4, M.W = 98.079 g/mol, =95–98%),
SDS (C12H25NaO4S, M.W = 288.38 g/mol,
∼90%), H2O2 (M.W = 34.01 g/mol, =35%),
and KMnO4 (M.W = 158.034 g/mol) was obtained from Merck,
Germany, whereas N-methyl-2-pyrrolidone (NMP), alcohol
(C2H5OH, M.W = 46.07 g/mol, =99.08%), and phthalic
acid (C8H6O4, M.W = 166.14 g/mol,
=99%) were purchased from RCI Labscan and BDH, England, respectively.
HCl (M.W = 36.46 g/mol, =36.5–38%) and NaNO3 (M.W
= 84.99 g/mol) were purchased from J.T. Baker and Panreac, respectively.
NaOH, hyperbranched polyethylenimine (HPEI), and all other chemicals
were analytically graded and used as received.