Influence of natural organic matter and pH on phosphate removal by and filterable lanthanum release from lanthanum-modified bentonite

Lanthanum modified bentonite (LMB) has been applied to eutrophic lakes to reduce phosphorus (P) concentrations in the water column and mitigate P release from sediments. Previous experiments suggest that natural organic matter (NOM) can interfere with phosphate (PO 4 )-binding to LMB and exacerbate lanthanum (La)-release from bentonite. This evidence served as motivation for this study to systematically determine the effects of NOM, solution pH, and bentonite as a La carrier on P removal. We conducted both geochemical modeling and controlled-laboratory batch kinetic experiments to understand the pH-dependent impacts of humic and fulvic acids on PO 4 -binding to LMB and La release from LMB. The role of bentonite was studied by comparing PO 4 removal obtained by LMB and…