[Sorption of o-Phthalate onto Calcite in Open-System]

The batch sorption methods were deployed to study the sorpti of p-phthalate on calcite in open-system. Results show that: (1) The o-phthalate sorption reached the equilibrium within 3 hours. Both pseudo first-order and pseudo second-order models described the kinetic characteristics well; (2) The o-phthalate sorption rate decreased with pH (7. 7-9.7). This phenomenon was due to the competition effect of HCO3- and CO(3)2-, and the electrostatic effect on the surface; (3) The o-phthalate sorption rate also decreased with the increase in ionic strength. This was due to the rise in concentration of HCO3- and CO(3)2- induced by salt effect; (4) Compared with m-phthalate and p-phthalate, o-phthalate sorption rate was much higher due to the proximity of its two carboxyl groups which easily formed a chelate ring of surface complex. By studying the factors that influence o-phthalate sorption onto calcite, the sorption mechanism can be well understood. This mechanism can be applied in the removal of o-phthalate from the environment.