This study focused on the removal of copper (II) and lead (II) ions in single component systems using pyrolytic tyre char. The copper (II) and lead (II) ion removal ability of pyrolytic tyre char had been demonstrated in both equilibrium isotherm sorption studies and fixed-bed sorption column studies....[ Read more ]

This study focused on the removal of copper (II) and lead (II) ions in single component systems using pyrolytic tyre char. The copper (II) and lead (II) ion removal ability of pyrolytic tyre char had been demonstrated in both equilibrium isotherm sorption studies and fixed-bed sorption column studies.

Four isotherm equations, namely, Langmuir, Freundlich, Redlich-Peterson and Sips, were used to correlate the equilibrium relationship between these two ions and the pyrolytic tyre char. It was found that the Sips equation gave the most accurate correlation for both ions. The monolayer sorption capacity of copper (II) ion and lead (II) ion of pyrolytic tyre char (at pH 4) was found to be 0.70mmol/g and 0.74mmol/g respectively.

Fixed-bed sorption column studies were performed to investigate the dynamic heavy metal ions sorption onto pyrolytic tyre char. Bed Depth Service Time (BDST) model was used to examine the performance of the columns and the effect of different operating variables. The BDST model provided good correlation between the service times and the bed depths of the columns with reasonable accuracy.

The pyrolytic tyre char was modified using different chemical reagents, attempting to minimise the zinc leachate problem. It was found that 10wt% nitric acid reduced the zinc content in pyrolytric tyre char more effectively than other chemical reagents, but also decreased the copper removal capacity and lead removal capacity by 90% and 75% respectively. It was found that the metal removal capacity of that modified tyre char was restored by impregnation with saturated calcium hydroxide solution. In addition, ion exchange process and precipitation were proposed to be the major heavy metal ions removal mechanisms.

In conclusion, although pyrolytic tyre char demonstrated heavy metals removal ability, it cannot be applied in practical use unless the zinc leachate problem is completely solved. However, a low-cost two-step modification method was demonstrated to resolve the zinc leachate problem without sacrificing the heavy metals removal capacity. It believed that the application of modified pyrolytic tyre char as a heavy metal ion sorbent will be feasible.