Interaction of Cadmium with Phosphate on Goethite

Effect of phosphate on the adsorption of Cu and Cd on natural hematite

“…2). The results are inconsistent with the previous works (Venema et al, 1997;Collins et al, 1999;Wang and Xing, 2002;Wang and Xing, 2004), in which enhanced Cd adsorption on goethite by phosphate pretreatment or in the presence of phosphate were observed. The authors explained the reason as the phosphate adsorption increasing surface negative charges and consequently decreasing the electrostatic potential near the solid surface (Diaz-Barrentos et al, 1990;Collins et al, 1999;Wang and Xing, 2004).…”

“…Diaz-Barrentos et al (1990) found that phosphate increased the Zn adsorption on lepidocrocite and explained it as the results of the decrease in electrostatic potential near the solid surface by phosphate. By using the CD-MUSIC surface complex model, Venema et al (1997) investigated Cd adsorption on goethite in the presence of phosphate and revealed that phosphate enhanced the Cd loading. Collins et al (1999) employed extended X-ray absorption fine structure spectroscopy (EXAFS) to investigate Cd adsorption in the Cd-phosphate-goethite tannery system, there was no evidence for the formation of Cd-phosphate complex.…”

Surface modification of goethite by phosphate for enhancement of Cu and Cd adsorption

“…Among the changes of surface properties, the decrease of surface charge was the most significant. Therefore, it would be responsible most for the higher adsorption capacity of the phosphate-modified goethite, which was also in agreement with the previous studies [8][9][10][11]. Furthermore, enhanced adsorption of Cu and Cd could be also well explained by the rising amount of total adsorption sites possibly caused by phosphate surface precipitation on goethite, which leading to the generation of new adsorption sites.…”

“…Phosphorus, which has a high affinity to iron hydroxide surfaces, was reported to enhance Cd adsorption on iron hydroxide [8][9][10][11]. Phosphate has also been used as an in situ chemical immobilizer [12].…”

Optimization of kinetic data for two‐stage batch adsorption of Pb(II) ions onto tripolyphosphate‐modified kaolinite clay

“…20,21,22 It is therefore possible to suggest that Pb(II) ion adsorption takes place at the negatively charged O-P-O sites. The presence of up to three negative charged sites per molecule of pentasodium tripolyphosphate adsorbed onto the kaolinite clay may have contributed to raising the adsorption capacity of the TPP-modified adsorbent.…”