A Study On The Synthesis Of Aluminum Adjuvant In Continuous Stirred Tank Reactor Based On PID Control

As a kind of substance that can assist vaccine to enhances immunogenicity,adjuvant has become an essential component of modern vaccine.Among the aluminum salt adjuvants approved for human vaccines,aluminum hydroxide(AlOOH)adjuvant has attracted much attention due to its excellent safety and low synthesis cost.With the increasing demand for vaccines in human society,the mass production process of adjuvants has also become a hot spot in the field of vaccine research and development.At present,the process of synthesizing AlOOH adjuvant by calcination,hydrothermal and other methods is relatively mature,but the discontinuous production process,high temperature and high-pressure synthesis conditions limit the further enlargement of this process.Although the emerging Total Mixed Flow Reactor(CSTR)method for the synthesis of AlOOH adjuvant has low energy consumption and can be continuously reacted,the production process requires manual control of the pH value of the system,which is not conducive to industrial production.Based on the above reasons,this study adopts the incomplete differential proportionalintegral-derivative(PID)algorithm,and the automatic control program of pH value of the reaction system is written by the programming software Visual Basic 6.0.Communication capabilities with devices such as pH sensors.Finally,the continuous production of CSTR adjuvant with controllable pH value,temperature and peristaltic pump flow rate was realized through the visual remote operating system.The 5 L and 20 L AlOOH adjuvant preparation pilot experiments were carried out using the PID automatic control CSTR.After the PID parameters were adjusted,the pH automatic control system could stabilize the pH value of the reaction system within 120 seconds.Within the range,and the whole process fluctuation does not exceed ±0.05,the control effect is significantly better than the commercial industrial-grade pH automatic controller.The TEM and hydraulic particle size characterization results of the synthesized AlOOH adjuvant showed that compared with the commercial AlOOH adjuvant,the particle size distribution of the AlOOH nano-adjuvant synthesized by the 5 L and 20 L selfcontrolled reaction systems was more uniform,and the morphology was the same.Rod-shaped nanoparticles of 80-120 nm;XRD pattern shows that the synthesized product is pure γ-AlOOH without impurities;UV spectrophotometry proves that the stability of the synthesized AlOOH nano-adjuvant in solution is also significantly better than that of similar products.In conclusion,this study successfully established a fully automatic synthesis process of AlOOH nano-adjuvant in CSTR based on PID control.