Abstract

The effect of K and Ca homoionization in chloride, phthalate-chloride, phosphate-chloride, and phthalate-phosphate-chloride adsorption on the <2 mu m size fraction of the Osorno B unfertilized soil sample is studied. Results show that chloride adsorption on Ca2+ homoionized sample is higher than on K+ homoionized sample. Phthalate adsorption an Osorno-K+ is higher than on Osorno-Ca2+ when phthalate is equilibrated in presence of chloride, due to the high affinity of Ca2+ homoionized surface for chloride. These results showed the importance of electrostatic factors as one of the mechanisms involved in phthalate adsorption. Minimal differences due to homoionization were observed in phosphate adsorbed in competence with chloride, showing that phosphate adsorption mechanisms are highly selective. In phosphate-phthalate-chloride competence, no effect of phthalate on phosphate adsorption was observed, but phthalate adsorption is drastically reduced from 46 to 17 cmolkg(-1) due to phosphate.