[Performance of Novel Macromolecule Flocculant in the Treatment of Wastewater Containing Cr (VI) Ions].

A novel macromolecule flocculant, polyethyleneimine-sodium xanthogenate (PEX), was applied in the treatment of wastewater containing Cr(VI) ions. The trapping performance of PEX for Cr(VI) ions was studied, and effects of selective important factors, such as initial Cr(VI) concentration, pH value, coexisting inorganic substance and turbidity etc., on the removal of chromium by PEX were investigated. The experimental results indicated that PEX could efficiently remove different concentrations of chromium in strong acidic media. The maximum removal rate of Cr(VI) and total Cr reached 99.1% and 96.6% at pH 2.0, respectively. The existence of influencing substance (e. g. NaCl, NaF, Na2SO4, CaCl2 and turbidity) would inhibit the removal of Cr(VI) ions, and promote the removal of total Cr to some extent. Fourier transform infrared spectroscopy (FTIR) analysis showed that the behaviors in the removal of Cr(VI) ions included reduction and chelation. Cr(VI) ions were reduced to Cr(III) ions by dithiocarboxylic acid groups on the PEX molecule, and then chelating reactions existed between Cr(III) ions and dithiocarboxylic acid groups and amino groups of PEX.