Sulfur-Modified Coated Slow-Release Fertilizer Based on Castor Oil: Synthesis and a Controlled-Release Model

Abstract

There has been advancement in the preparation of coated slow-release fertilizer, but problems remain, such as a complex production process, high production costs, and uncontrollable nutrient release. Herein, a new interpenetrating polymer network (IPN) for coating urea was prepared with inexpensive castor oil via a one-pot method. Considering the low strength of oil-based materials, sulfur was used as a reinforcing material to synthesize the interpenetrating network. After prepolymerization, the material strength increased by a maximum of 455.9% and the antiswelling ability increased by 46.10%; however, the thermal stability decreased. The results show that the nutrient release longevity of coatings with only 5.0 wt % polymer could reach 210 days, which is probably the widest applicability range reported so far. Furthermore, a nutrient release model was established to provide guidance for the preparation of slow-release fertilizers suitable for the growth of different plants. Pot experiments show that different slow-release fertilizers have different promoting effects on plant growth, and selecting a suitable slow-release fertilizer according to the needs can maximize the nutrient utilization efficiency. This work offers a simple and effective method to prepare slow-release fertilizers and can guide their development.

Physicochemical Characterisation and the Prospects of Biofuel Production from Rubberwood Sawdust and Sewage Sludge

“…The HHV of RWS (21.01 MJ/kg) was higher than that of SS (13.98 MJ/kg), RWS50:SS50 (17.01 MJ/kg), and RWS75:SS25 (19.01 MJ/kg). The HHV of RWS, SS, RWS50:SS50, and RWS75:SS25 was higher than the HHV of other studies, such as that of the trunk (17.85 MJ/kg), branches (190.3 MJ/kg), and bark (20 MJ/kg), but lower than for phyllodes (21 MJ/kg) [39]. In comparison to petroleum feedstock fuels (Figure 3), such as natural gas (50.84 MJ/kg), gasoline (46.94 MJ/kg), diesel (45.60 MJ/kg), and kerosene (45.99 MJ/kg), the HHV of RWS, SS, RWS50:SS50, and RWS75:SS25 was lower than that of petroleum feedstocks [43].…”

“…The moisture content of RWS (5.38 wt.%) and SS (6.60 wt.%) was lower than th moisture content of corn straw (7.55 wt.%), whereas the VM and FC content of RWS (77.4 wt.% and 17.50 wt.%, respectively) were slightly lower than that of the corn-straw feed stock [38]. However, the VM content of RWS (77.47 wt.%) was higher than that of phy lodes (69.03 wt.%) and trunks (67.66 wt.%) [39]. Therefore, the results of our study demon strated better percentages of organic compounds and could produce a suitable amount o liquid yield.…”

“…SS is considered a useful nutrient, and in the form of a fertiliser in a biochar yield, it can aid plant growth [40]. C and H are both principal components for producing bioenergy, especially biofuel or liquid yield with a lower O content [39]. Moreover, in biomass, a higher C and H content and a lower O content is immensely favourable for biofuel or liquid products because C and H can be converted into aromatic compounds that produce fuel or liquid [28].…”

The Prospering of Macromolecular Materials Based on Plant Oils within the Blooming Field of Polymers from Renewable Resources

“…The use of castor oil as a polyol in combination with the previously mentioned sulfur crosslinking strategy was employed to produce high strength vulcanized polyurethane interpenetrating polymer networks. Thus, castor oil was vulcanized with sulfur and subsequently polymerized with polymeric diphenylmethane diisocyanate, forming a coating for the slow release of a urea-based fertilizer [ 66 ]. Various synthetic tools can be employed for the production of polyols from other unsaturated vegetable oils.…”

Mechanochemistry as an emerging tool for the preparation of sustained release urea cocrystals as a nitrogen source

“…3 In recent years, slow release fertilizers have been developed to control the release rate of plant nutrients into the soil medium, which minimizes the loss of fertilizer nutrients. 4–8 On the other hand, the emerging nanotechnology field has contributed to the production of slow release nanofertilizers incorporating nanoscale nutrient particles and nanomaterials to hold plant nutrients, which is even more effective than conventional polymer-coated slow release fertilizers. 9–12 In general, nano-fertilizers are prepared by encapsulating plant nutrients such as urea inside nanoporous matrices or as a nanoparticle or nanoemulsions.…”