| Ferric oxide was used as the solid adsorbent to study the coprecipitation and adsorption of copper from solution as a function of oxide age. It was hypothesized that as an oxide aged its surface area decreased, and hence the amount of adsorbate uptake from solution was decreased. Further, coprecipitation should yield the greatest uptake because the adsorbate is present at the onset of oxide precipitation.; The removal of copper as a function of oxide age and pH at constant total copper concentration (3 {dollar}times{dollar} 10{dollar}sp{lcub}-5{rcub}{dollar} M) was determined. It was found that both coprecipitation and adsorption by the 15 minute aged oxide yielded the same percent copper removals. Less copper was adsorbed by the oxide aged 4 hours. Copper isotherm results at pH 5.3, however, showed that there was a significant difference in adsorption density as a function of oxide age.; Three regions of removal were determined. At densities below 0.01 mole Cu{dollar}sp{lcub}+2{rcub}{dollar} sorbed/mole Fe, coprecipitation, freshly precipitated and aged ferric oxides yielded the same removal. At densities below 0.04 mole/mole, coprecipitation and freshly precipitated ferric oxide caused the same removals. Less removal was achieved by the oxide aged 4 hours. Finally, at densities greater than 0.04 mole/mole, the removal by coprecipitation was greater than either adsorption process. It was thus theorized that at densities below 0.04 mole/mole, the mechanism controlling removal by coprecipitation was adsorption. However, at higher densities, other removal mechanisms, such as occlusion or entrapment, produced additional copper uptake.; Differences between adsorption experiments were found to be caused by a differences in surface area. Nearly 30% greater area was found by sodium negative adsorption experiments with freshly precipitated ferric oxide. Other mechanisms such as complexation, competition, and diffusion were found to be negligible between solid ages. Industrially it was concluded that coprecipitation at higher densities will enable treatment processes to meet micropollutant discharge levels. |
