A membrane electroflotation process for recovery of recyclable chromium(III) from tannery spent liquor effluent

A two-compartment membrane electroflotation reactor has been demonstrated for recovery of recyclable chromium(III) from tannery spent liquor effluent. Dimensionally stable RuO2/TiO2-Ti and Ti were used as anode and cathode, respectively. The spent liquor effluent was used as catholyte and 0.01 N H2SO4 used as anolyte which was separated by Nafion 117 membrane. About 98% of chromium(III) was recovered and the removal efficiency correlated with the presence of organics in the effluent. The advantage of two-compartment membrane electroflotation process is capable of removing chromium(III) without oxidising it into chromium(VI) in chloride containing tannery spent liquor effluent. The mechanism of chromium(III) removal has been discussed. The recovered Cr(OH)3 was successfully demonstrated for tanning of cowhide.