Preparation and characterization of a superabsorbent slow‐release fertilizer with sodium alginate and biochar

Abstract

A novel hydrogel was synthesized through the graft copolymerization of acrylic acid (AA) and acrylamide (AM) onto sodium alginate with ammonium persulfate as the initiator, methylene bisacrylamide as the crosslinking agent, and calcium chloride as the precipitating agent. Rapeseed meal biochar made at 300 °C was also used. A series of graft copolymers with various molar ratio of AA to AM was prepared. The structures of the hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The free absorbency and rate of release were investigated. The grafting efficiency increased as the concentration of AM increased. There was a considerable percentage of nitrogen in the graft copolymers, and the release rate of nitrogen from fertilizer in soil and water decreased with increasing concentration of AM. The water retention of soil without hydrogel remained at 63 and 53.4% on the 10th and 20th days, but with the hydrogels, it was above 70% even on the last day. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45966.

Lignin improves release behavior of slow‐release fertilizers with high content of urea

“…In view of the economic and environmental factors, abundant natural materials including lignin and montmorillonite (Mt) have been considered to be ideal carriers for slow‐release urea fertilizers. Lignin is a natural organic polymer that is abundantly available as a byproduct of the production of wood pulp . Moreover, lignin is a renewable, biodegradable, eco‐friendly, and amorphous biopolymer for soluble fertilizer .…”

Superabsorbent Hydrogels Based to Polyacrylamide/Cashew Tree Gum for the Controlled Release of Water and Plant Nutrients

“…In the equilibrium condition, the phosphorus concentration found was 2.5 mg L −1 . BaKi et al (2018) observed a similar behavior for SHAs based on polyacrylamide grafted with sodium alginate and biochar [ 73 ]. The slow release of fertilizer is important to ensure better nutrient absorption and minimize nutrient loss [ 74 ].…”

Preparation and Characterization of Superabsorbent Polymers Based on Sawdust

“…This indicates that the sawdust contains cellulose, hemicellulose, and lignin. In the infrared spectrum of the SW-AA-AM polymer, the peaks at 3443 and 1677 cm −1 were caused by the stretching vibration of –NH in acrylamide and the stretching vibration of the amide group (–CONH 2 ), respectively [39,43]. The new peak at 1409 cm −1 was assigned to the stretching vibration of C–N in acrylamide.…”