Abstract
Slow-release fertilizers represent a possible large-scale
application for plant polymers. Here we show a facile way
to stabilize urea in fertilizer systems by lignin.
Chelation of kraft black liquor with calcium acetate at
pH 13 precipitated lignin as a calcium complex
(Ca-lignin), which offered beneficial effects if compared
to those from lignin obtained by precipitation at low pH
(Acid-lignin). The reduced affinity of water to Ca-lignin
was exploited in the formulation of slowrelease
fertilizers comprising wheat straw sections impregnated
with Ca-lignin in molten urea. Compared to the case of
Acid-lignin, immersion in water was slowed down more
extensively by Ca-lignin. After 24 h incubation at low
moisture conditions, the highest proportion of urea
retained in the Ca-lignin/straw fertilizer system was
58%. The water resistance of Ca-lignin was explained by a
lower aqueous solubility that differed from the typical
pH-dependent solubility of Acid-lignin. Electron
microscopy, infrared spectroscopy, and accessible surface
areas suggested that Ca-lignin consisted of less densely
packed molecules organized as calcium-chelated chains.
Overall, the controlled water-solubility of lignin
precipitated by metal cations is greatly beneficial in
fertilizer systems and can open new opportunities in
material development (permeable films and others).
| Original language | English |
|---|---|
| Pages (from-to) | 1054-1061 |
| Journal | ACS Sustainable Chemistry & Engineering |
| Volume | 5 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2016 |
| MoE publication type | A1 Journal article-refereed |
Keywords
- sulfate lignin
- cationic
- complex
- wheat straw
- impregnation
- dissolution