CHROMIUM(III) REMOVAL BY POLY(ETHYLENEIMINE) GRANULAR SORBENTS MADE BY A NEW PROCESS OF TEMPLATED GEL FILLING

By the new process of templated gel-filling (TGF), a gel-type granular sorbent has been prepared using poly(ethyleneimine) as the chelating resin, Cr3+ as the template ion and glutaraldehyde as the crosslinking agent. The templating is found to increase the Cr(III) selectivity of the base resin PEI, in binary mixtures of Cr(III) with Cu(II), Ni(II) and Fe(III). The new TGF sorbent has, however, significant Cr(III) se lectivity only relative to Ni(II), being much superior to the commerci al resin Chelex-100 in this respect. The Cr(III) sorption on both thes e sorbents is enhanced significantly by NaCl and Na2SO4, the effect be ing more marked on the TGF sorbent which shows greater than 100% incre ase in Cr(III) sorption capacity in 0.5 M NaCl and 0.25 M Na2SO4 solut ion containing Cr(III) in low concentrations. The sorbent is thus suit able for removing low level chromium from strong salt solutions and ha s fast kinetics with a tilt of 1.5 min in 2 mM Cr(III) solution.