Design and preparation of carbendazim-loaded alumina nanoparticles as a controlled-release biocide for wood protection

- Ball-milling was efficient to reduce alumina size and promote biocide loading in it.
- Carbendazim could be slowly release from alumina supports.
- High alumina to biocide ratio helps to decrease the biocide release rate.
- Surfactant was important to impregnate the nanobiocide into pinewood.
- Carbendazim load of 0.4 kg m−3 was sufficient to protect wood against decay fungi.

Biocide delivery systems are intelligent strategies towards improving the efficiency of biocides over time. Here, we have developed a biocide system by loading alumina nanoparticles with carbendazim through surfactant-assisted ball milling. The obtained biocides were further validated by their impregnation into pinewood, followed by in vitro fungi tests. Fourier-transformed infrared spectroscopy stated physical adsorption of carbendazim on alumina, while the thermogravimetric analysis revealed its adsorption in a pseudo-molecular level. The carbendazim loading efficiency was improved after surfactant addition, which was also fundamental to effectively impregnate the pinewood. The biocide release profiles could be described using the parabolic-diffusion and Korsmeyer-Peppas kinetic models, which fitted the experimental data with determination coefficients over 0.9. After 600 h, the biocide systems have released 42-76% of carbendazim, where systems with higher biocide content released faster. The pinewood solid samples were completely impregnated with the prepared biocides; however, it tended to concentrate on the wood surface. A biocide retention of only 0.4 kg m−3 of sufficient to increase in 10 times the decay resistance of the pinewood, indicating very promising results.