Rapid and solvent-free synthesis of pH-responsive graft-copolymers based on wheat starch and their properties as potential ammonium sorbents

Geo-Agriculture: Reviewing Opportunities through Which the Geosphere Can Help Address Emerging Crop Production Challenges

“…Although generally effective, manufactured soil amendments entail production costs. Moreover, in some cases, they pose detrimental environmental impacts at the field application stage, especially non-degradable polymers that could be precursors to microplastic pollution [88] and metal frameworks, which can contain high levels of mobile toxic trace metals [89].…”

Functional starch-based hydrogels: renewable material solutions for wastewater and agriculture industries

“…The characteristic bands of acrylamide are also present at ~3290, 1668, ~15680, and ~1448 cm −1 , corresponding to the N-H stretching, C=O stretching, N-H bending, and -C-N stretching vibrations of the amide group, respectively. The stretching vibrations of O-H and O=S=O of the AMPS sulfonic groups also appear at ~1032 cm −1 and 1205 cm −1 , respectively (Siyamak et al, 2020c). The appearance of these characteristic peaks, in addition to the stretching vibration peaks of aliphatic -CH of the polymeric chain at ~2849 and 2924 cm −1 , which replaced the starch C-H absorption bands (~2750 cm −1 ), as well as the absence of C=C characteristic peak in the 1610-1640 cm −1 region due to complete polymerisation of the constituent monomers, indicate the success of the graft copolymerisation reaction during extrusion.…”

“…The extrusion conditions were selected from (Siyamak et al, 2020b;Siyamak et al, 2020c) and as described in chapter 4.1. to ensure efficient copolymerisation. The screw configuration of 6 forwardconveying screw elements (6×F), 4 mixing-elements orientated at 90º (4×90º), 6 reverse kneadingelements oriented at 60º (6×60ºR), (3×F), (3×60ºF), (3×F), (3×90º), (3×60ºR), (3×F), (3×90º), (1×R), (4×F), (4×90º), (3×60ºR) (4×F), (3×90º), (1×R), (4×F), at a screw speed of 85 rpm, with the barrel temperature set points from feeding section to die being 90/100/100/110/110/110/100/100/90/80°C.…”

“…This is mainly due to the complications associated with their large-scale production, including costly and complex production methods with poor reproducibility, wherein large quantities of toxic chemical reagents and substantial amounts of solvent are required both during the synthesis and at the end of the process during product isolation (Dragan, 2014;Farag et al, 2018;Mandal & Ray, 2015). To address these technical limitations, we developed a processing method based on reactive extrusion (REx) and demonstrated this method's viability for grafting starch with AAm using a laboratory-scale co-rotating twin-screw extruder (Siyamak et al, 2020b;Siyamak et al, 2020c). Though extrusion processing is one of the most versatile and energy-efficient technologies available for the rapid and solvent-free manufacture of starch-based commodities (Carr, 1994;Fanta et al, 2012a;Moad, 2011), the number of studies that explore the preparation of starch-based sorbents using REx is limited (Tomaszewska-Ciosk et al, 2014).…”

“…This is mainly due to their costly and complex production methods, wherein large quantities of toxic chemical reagents and substantial amounts of solvent are required both during the synthesis and at the end of the process during product isolation (Adeleye et al, 2016a;Blann et al, 2009;Riding et al, 2015). To address these technical limitations, we developed a processing method based on reactive extrusion (REx) and evaluated its viability for the production of starch hydrogels using a laboratory-scale co-rotating twinscrew extruder (Siyamak et al, 2020b;Siyamak et al, 2020c). Rex technology combines the advantages of using an extruder as a continuous flow reactor with the process of chemical reaction for producing high-value starch-based products, with the possibility of a rapid, solvent-free, and scalable process (Fanta et al, 2012a).…”