Supported liquid membrane technique applicability for removal of chromium from tannery wastes

The concentration of Cr and other ions have been determined in the effluent liquors of the tanneries around Multan city in Pakistan. The Cr ions concentration varies from 2500 ppm to 8000 ppm and sodium ions from 2100 ppm to 38,000 ppm. Cu has been found in the range of 40 ppm, Ca from 900–1000 ppm, Mg up to 170 ppm, Fe up to 65 and Zn below 2 ppm level. In the present work it has been shown that the Cr ions present in the tannery wastes can be removed by SLM technique with prior treatment by H2O2 and NaOH. The flux for 4800 ppm waste samples is in the order of 40 × 10−5 mol m−2s−1 with permeability of 5 × 10−11m2s−1. The membrane area required to treat tannery waste coming out at the rate of 100 gallons per day has been calculated to be only 12.6 m2. The optimum conditions of treatment are 0.87 mol dm−3 trin-octylamine in the membrane and pH 1. If the tannery waste is at 32°C (Multan temperature in summer), the flux is expected to be higher as shown in the present study and the process will be even more efficient. Application of the other systems of Cr removal have also been discussed in brief.