The influence of lake water alkalinity and humic substances on particle dispersion and lanthanum desorption from a lanthanum modified bentonite.
Water Res
; 125: 191-200, 2017 11 15.
Article
in En
| MEDLINE
| ID: mdl-28858690
A 12 days laboratory study on potential desorption of Lanthanum (La) from a commercial La modified clay (Phoslock) was conducted using lake water from 17 Danish lakes with alkalinities between 0.02 and 3.7 meq L-1 and varying concentrations of DOC and humic acids (HA's). A similar study was conducted in artificial lake water with alkalinities from 0 to 2.5 meq L-1in order to exclude interference from dissolved HA's. To test if La in solution (FLa) was associated with fine particles, the water samples were filtered sequentially through three filter sizes (1.2 µm, 0.45 µm and 0.2 µm), and finally, ultracentrifugation was used in an attempt to separate colloidal La from dissolved La. The study showed that higher FLa (up to 2.5 mg L-1 or 14% of the total La in the Phoslock) concentrations were found in soft water lakes compared to hard water lakes, probably due to dispersion of the clay at low alkalinities. In addition, this study showed that HA's seem to increase the FLa concentrations in soft water lakes, most likely through complexation of La retained in the Phoslock matrix. In summary, we conclude that elevated La concentrations in lake water after a Phoslock treatment should only be expected in soft water lakes rich in DOC and HA's.
Key words
Full text:
1
Collection:
01-internacional
Health context:
12_ODS3_hazardous_contamination
Database:
MEDLINE
Main subject:
Bentonite
/
Lakes
/
Lanthanum
Type of study:
Diagnostic_studies
Country/Region as subject:
Europa
Language:
En
Journal:
Water Res
Year:
2017
Document type:
Article