Background Cellulose fibers extracted from printed paper wastes are utilized to synthesize spherical cellulose microspheres via water-in-oil microemulsion and precipitation methods. Span 80 was used as a surfactant and acetic acid as a precipitating agent in the microemulsion and precipitation process to obtain cellulose microspheres. The effects of synthesis conditions such as cellulose concentrations and drying techniques were observed to have profound effects on the surface morphology, particle sizes, and surface area of cellulose microspheres produced. Results Spherical cellulose microspheres with particle sizes ranging from 5.2 to 9.3 µm were synthesized. Increasing cellulose concentrations led to larger particle sizes. Among various kinds of drying techniques, freeze-drying is the most preferable method in obtaining better yields and yet, larger cellulose microspheres. The potential applications of the synthesized cellulose microspheres as controlled-release carriers for fertilizer in various soil types were evaluated. The larger size of cellulose microspheres have a smaller specific surface area, but with higher loading capacities and slower urea release. Conclusions Our studies showed that the loading capacity and release profiles of urea could be tailored by modulating the mean particle sizes of the cellulose microspheres. Hence, cellulose microspheres have the potential to be utilized as fertilizer-controlled release carriers.

Background: Cellulose fibers extracted from printed paper wastes are utilized to synthesize spherical cellulose microspheres via water-in-oil microemulsion and precipitation methods. Span 80 was used as a surfactant and acetic acid as a precipitating agent in the microemulsion and precipitation process to obtain cellulose microspheres. The effects of synthesis conditions such as cellulose concentrations and drying techniques were observed to have profound effects on the surface morphology, particle sizes, and surface area of cellulose microspheres produced. Results: Spherical cellulose microspheres with particle sizes ranging from 5.2 to 9.3 µm were synthesized. Increasing cellulose concentrations led to larger particle sizes. Among various kinds of drying techniques, freeze-drying is the most preferable method for obtaining better yields of cellulose microspheres. The potential applications of the synthesized cellulose microspheres as controlled-release carriers for fertilizer in various soil types were evaluated. The larger particle sizes of cellulose microspheres have a smaller specific surface area, but with higher loading capacities and slower urea release. Conclusions: Our studies showed that the loading capacity and release profiles of urea could be tailored by modulating the mean particle sizes of the cellulose microspheres. Hence, cellulose microspheres demonstrated great potential to be utilized as sustainable controlled-release carriers for fertilizer.