Controlled-release urea encapsulated by ethyl cellulose/butyl acrylate/vinyl acetate hybrid latex

Controlled release fertilizer delivery system derived from rice straw cellulose nanofibres: a circular economy based solution for sustainable development

Recently, the development of sustainable and environmentally friendly biomaterials has gained the attention of researchers as potential alternatives to petroleum-based materials. Biomaterials are a promising candidate to mitigate sustainability issues due to their renewability, biodegradability, and cost-effectiveness. Thus, the purpose of this study is to explore a cost-effective biomaterial-based delivery system for delivering fertilizers to plants. To achieve this, rice straw (agro-waste) was selected as a raw material for the extraction of cellulose. The cellulose was extracted through alkali treatment (12% NaOH), followed by TEMPO-based oxidation. The cellulose nanofibers were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, and transmission electron microscopy. In scanning electron microscopy, a loosening of the fibrillar structure in cellulose nanofibers (CNFs) was observed with a diameter of 17 ± 4 nm. The CNFs were loaded with nitrogen-based fertilizer (ammonium chloride) in 1:1, 1:2, and 2:1 (w/w) proportions. The loading was estimated through surface charge variation; in the case of the 1:1 sample, maximum reductions in surface charge were seen from -42.0 mV to -12.8 mV due to the binding of positive ammonium ions. In the release kinetics study, a controlled release pattern was observed at 1:1, which showed a 58% cumulative release of ammonium ions within 8 days. Thus, the study paves the way for value-added uses of rice straw as an alternative to the current environmentally harmful practices.

Esterification modified starch by phosphates and urea via alcohol solvothermal route for its potential utilization for urea slow-releasing

The natural starch (NS) is modified by an esterification process which is accomplished by reacting the NS and phosphate together with urea via a facile alcohol solvothermal method. After modification, a series of obvious variations can be easily confirmed for the resulted starch phosphate carbamides (denoted as SPC) compared with that of NS, such as the introduction of new groups of CO, PO, P-O-C and P-O-H together with new elements of N and P in starch molecular structure unit confirmed in FT-IR and XPS analyses and the decreased crystallinity along with formed surface defect demonstrated in XRD and SEM measurements. Furthermore, the formed SPC has a higher viscosity of 480 mPa.s^-1 and lower gelatinization temperature of under 10 °C than that of the NS. More importantly, when the SPC is utilized as outer coating material together with ethylcellulose (EC) as inner coating material for preparing double-layer slow-release urea (denoted as EC/SPC based SRU), the EC/SPC based SRU has a desirable slow-release behavior with release percentages of 40.9% for 12 h in water and merely 59.6% for 20 day together with even exceeding 30 days in soil. Conclusively, this work provides a facile preparation approach for the SPC and its creative application for the preparation of SRU.

Cellulose based materials for controlled release formulations of agrochemicals: A review of modifications and applications

Controlled release formulations (CRFs) of agrochemicals have been attracted considerable attention due to their friendliness to environment. The commercial supporting materials for CRFs of agrochemicals are non-degradable, leading to secondary pollution issue. Cellulose, as the most abundant natural materials in the world, is regarded as one of the most ideal substitutes for non-degradable supporting materials thanks to its good biocompatibility and biodegradability. As raw cellulose materials suffer several problems, such as poor mechanical strength, fast release rate, etc., chemical modifications are commonly performed to improve their properties. In this review, modification methods of cellulose materials for CRFs of agrochemicals were introduced. The relationships between release rate and cellulose based materials were discussed in detail. The applications of cellulose materials for CRFs of agrochemicals were also expounded.