B2O3-SiO2-Na2O Controlled-release Material: Synthetic Parameters Optimization and Release Mechanisms Exploration

Aiming at optimization of synthetic process, reduction of raw materials loss and control of production cost, the single factor method was used to study the effects of different heating rate, holding time, melting temperature, and initial temperature on the B 2 O 3 volatilization and bubble formation during the preparation of borate controlledrelease material (BCRM). The physicochemical properties of BCRM before and after controlled-release were characterized by X-ray diffraction analysis, infrared spectroscopy and X-ray photoelectron spectroscopy, and the release mechanism of BCRM was analyzed by Korsmeyer-Peppas model. The results show that the amount of B 2 O 3 volatilization can be reduced to 1.08%, no bubble forms in the transparent BCRM, and controlled-release performance is acceptable under optimum conditions of initial temperature 1050 , holding time 2 h and melting temperature 1050 . Controlled-release mechanism of BCRM, affected by temperature, is Super Case II transport at 30 and 35 while it is non-Fickian diffusion at 40 . However, the cumulative release rate of boron is greater than 95% at different temperatures.