Calcium Chelation of Lignin from Pulping Spent Liquor for Water-Resistant Slow-Release Urea Fertilizer Systems

Mika Henrikki Sipponen*, Orlando J. Rojas, Ville Pihlajaniemi, Kalle Lintinen, Monika Österberg

*Tämän työn vastaava kirjoittaja

Tutkimustuotos: LehtiartikkeliArticleScientificvertaisarvioitu

26 Sitaatiot (Scopus)
231 Lataukset (Pure)


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 slow release 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).

JulkaisuACS Sustainable Chemistry and Engineering
DOI - pysyväislinkit
TilaJulkaistu - tammikuuta 2017
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

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