Synthesis of a slow‐release and superabsorbent nitrogen fertilizer and its properties

Abstract

A slow‐release and superabsorbent nitrogen fertilizer (SSNF) was synthesized by aqueous solution copolymerization of acrylic acid and maleic anhydride using N,N′‐methylene bisacrylamide as a crosslinker, ammonium persulfate and sodium sulfite as an initiator in the presence of urea. The effects on water absorbency such as amount of crosslinker, initiator, urea and maleic acid, degree of neutralization, etc. were investigated. To improve slow release and water retention properties, the product was surface‐crosslinked with trihydroxymethyl propane glycidol ether (6360). The nitrogen content of the SSNF synthesized under optimal conditions was 28.5%, and the water absorbencies were about 900 (g/g) in distilled water and 180 (g/g) in tap water. The nitrogen slow release behavior of the SSNF in water and water retention capacity of the soil with SSNF were also investigated. The results showed that the surface‐crosslinked product not only had good slow release property but also excellent soil moisture preservation capacity, which could effectively improve the utilization of fertilizer and water resources simultaneously. The results of the present work indicated that the SSNF could be found an application in agriculture and horticulture, especially in drought‐prone areas where the availability of water is insufficient. Copyright © 2006 John Wiley & Sons, Ltd.

Hydrogel/clinoptilolite nanocomposite-coated fertilizer: swelling, water-retention and slow-release fertilizer properties

“…SRFs are designed to gradually release nutrients to plants at a rate to coincide with the nutrient requirement of a plant, while simultaneously reducing nutrient loss potential [4,5]. Other advantages of SRFs compared with common fertilizers are lowering application frequency, minimizing potential negative effects associated with over dosage [6]. These types of fertilizers can be made by coating the common granular fertilizers with a membrane that serves as a diffusion barrier [7].…”

Superabsorbent Polymer Properties and Concentration Effects on Water Retention under Drying Conditions

“…Mixing SAPs with soils has been found to (i) decrease soil bulk density (similar to organic matter function) and penetration resistance, (ii) increase soil aggregation, porosity, aeration and water retention capacity (Huttermann et al, 1999;Akhter et al, 2004;Busscher et al, 2009;Bai et al, 2010;Han et al, 2010), (iii) decrease soil saturated hydraulic conductivity and drainage (Abedi- Koupai et al, 2008;Andry et al, 2009;Bhardwaj et al, 2007), and (iv) serve as a source of slow release of nutri-ents, and reduce plant sensitivity to soil salinity (Liu et al, 2006;Teodorescu et al, 2009;Dorraji et al, 2010;Qu and Varennes, 2009). The application of SAP increased soil water content at field capacity and at permanent wilting point, which may lead to a considerable increase in available water content in soils of different texture used under various crops' management (Karimi et al, 2009;Agaba et al, 2010;Shahid et al, 2012;Banedjschafie and Durner, 2015;Montesano et al, 2015).…”

Application of Superabsorbent Polymers for Improving the Ecological Chemistry of Degraded or Polluted Lands

“…For the design of this special type of soil conditioner, a variety of different polymers have been developed and tested, which included guar [16], starch, polyacrylate and poly(ethylene glycol) [17], alginate-poly(sodium acrylate-coacrylamide) [18], alginate-g-poly(sodium acrylate)/kaolin [19], carboxymethylchitosan-g-poly(acrylic acid) copolymer [20], acrylic acid and maleic anhydride-copolymerizate [21], polyvinylalcohol-phosphate [22], acrylic acid-polyvinyl alcohol copolymer [23], polyacrylamide [24 -27], acrylamide/Nvinylpyrrolidone/3(2-hydroxyethyl carbamoyl) acrylic acid [28], poly(acrylamide-co-methyl methacrylate) [29], polyacrylamide/sodium alginate [30], polyacrylic acid [31], sodium polyacrylate, prepared by solution polymerization with N,N-methylene-bisacrylamide (bisAM) as a cross-linking agent, surface cross-linked by ethylene glycol diglycidyl ether (EGDE) [32], poly(sodium acrylate) cross-linked with modified poly(ethylene glycol) [33], sulfonated polystyrene [34], hydrolysed acrylonitrile sulfonated polystyrene [35], poly(ethylene oxide) [36], n-vinyl-2-pyrrolidone and partially neutralized acrylic acid [37], poly(tartaramide)s, poly(ester-amide)s containing oxyethylene segments [38], poly(aspartic acid) and its derivatives [39,40] poly(acrylic acid)/attapulgite/sodium humate [41].…”