| An aqueous nanodispersion(i.e.,nanosuspensions,nanoemulsions or nanobubbles)is a system with nano-scale aggregated substances(i.e.,particles,droplets or bubbles)dispersed in a liquid phase.The nanodispersion usually has a good suspendability,uniformity,light transmittance and lower viscosity,making it very promising in scientific researches,daily life,and industrial applications.However,the current production of nanodispersions usually requires a high energy consumption,low energy efficiency,high cost,large and heavy mechanical equipments,and tedious methods,which hinders a wide and massive application of nanodispersions.The flash nanoformation(FNF)technology aims to overcome these issues and can be used to simply,quickly,continuously and massively generate nanodispersions in an energy-saving,high energy-efficient,and economical way,and efficiently.By using its small-sized confined impinging jets(CIJ)micromixers presenting a low pressure drop,the FNF technology is expected to be capable to overcome the current situation of large and heavy devices for preparing nanodispersions,and break through the bottleneck on difficulties in further miniaturization of microchemical devices due to a high pressure drop.Based on the basic preparation methods of the FNF technology,this paper designed and built miniaturized devices for producing nanodispersions with the confined impinging jets with loop(CIJ-L)micromixer.It would be successfully applied in three scenarios:a production of nanobubbles,a gas-liquid copolymerization,and an in-situ preparation and immediate application of nanopesticides.In addition,this work would accumulate valuable practical experience for the miniaturization of microchemical engineering devices from the process design,unit selection and assembly after integrating all unit components to achieve the miniaturization of the FNF devices with a low pressure drop.The specific works of this paper are as follows:1)In Chapter 2,based on the gas-liquid CIJ-L micromixing,three set of nanobubble miniaturized generator(NBMG)with mode of ambient(A),pressured(P)and isobaric filling(IF)were designed and built a miniaturized device capable of a mobile and distributed production of nanobubbles with a low energy consumption and a high energy efficiency.The corresponding continuous process was developed.This chapter took the CO2 absorption as an example and developed three nanogenerators with different pressure modes for a production of CO2 nanobubbles.Among them,the modes of P-NBMG and IF-NBMG can obtain nanobubbles with an average particle size of about 400 nm,which were capable to be stable for at least 1 month and 6 months,respectively.In addition,pressurization was benefical to an increase of the gas content(the gas content for A-NBMG was 2.14 g/L,and the supersaturation 1.27;the average gas content for P-NBMG and IF-NBMG was about 3.6 g/L,and the average supersaturation 2.1)Compared with P-NBMG,IF-NBMG was more suitable for a subpacking,transfer,and long-term storage in seal of nanobubbles.Furthermore,by adding ethanol to the dispersion,the gas content of CO2 of nanobubble can be increased upto 7.23 g/L.The work used Aspen Plus to simulate the solubility of CO2 in aqueous medium at 0-50℃,a pressure of 1-10 atm,and an ethanol percentage of 0-100 vol%,which provided a theoretical basis for a prediction of a supersaturation of nanobubbles.2)In Chapter 3,based on the gas-liquid CIJ-L micromixing,the P-NBMG built in Chapter 2 was modified for synthesizing the polymeric surfactant of isobutylene-alt-maleic anhydride(ISOBAM)as an example.A miniaturized device with the CIJ-L gas-liquid micromixer and a homemade reactor was built and the corresponding continuous process was designed.The miniaturized device had a low energy consumption and was capable of a mobile and distributed production of the copolymer.The reaction temperature,monomer concentration,initiator type and concentration,and the results were optimized by using this device.To obtain the highest yield,the optimized conditions were of 75℃ and AIBN concentration 5.0 wt%(initiator over two monomers),bringing out the product having a intrinsic viscosity(corresponding to molecular weight)of 0.92 L/g.When the reaction temperature was 65℃ and AIBN concentration 1.0 wt%,the intrinsic viscosity of the product was 1.85 L/g.It was worth noting that when the total feeding concentration of the monomers did not exceed 15 wt%,the solid products in the dispersion medium was less likely to block the pipeline,and would not affect a normal operation of the micromixer and the device.In addition,two rapid detection methods suitable for an industrial production,i.e.,sedimentation height measurement and turbidity measurement,were developed in this work to evaluate the performance of the ISOBAM dispersing slurry of Al2O3 particles.The results showed that ISOBAM by CIJ-L had better overall dispersibility than the one by tank stirring as well as the prevailing commercial product of I-104 from Kuraray.To facilitate the quality control of the dispersant,this study found that ISOBAM prepared by CIJ-L with an intrinsic viscosity of 1.94-2.93 L/g could achieve good and consistent performances dispersing the Al2O3 surry.3)In Chapter 4,based on the CIJ-L liquid-liquid micromixing method,the work successfully designed and built a drone-mountable nanogenerator,which had a weight as low as 3.5 kg,a small volume of 5.9 L,a power supply by lithium battery,and a capability of a mobile and distributed application.The corresponding continuous process was developed.A preparation of an azoxystrobin nanosuspension fungicide was adopted as an example in this chapter,and the concentration of azoxystrobin(40 mg/mL DMSO solution),the concentration of TW80 surfactant(10 mg/mL DMSO solution),the mixing ratio of organic solution to the aqueous phase(1:1,water circulation,200 folds of the dilution),and the mixing Reynolds number(no less than 1900)were optimized by using the nanogenerator.An azoxystrobin nanosuspension with an average particle size of about 500 nm and stable for at least an hour before an application was successfully generated.The work further used the plant protection drone to carry the nanogenerator,and successfully realized an on-site preparation and immediate application of the azoxystrobin nanosuspension in a paddy field,anticipating to circumvent the unstability of a nanopesticide during storage and a nonuniversal formulation,and broaden the application scenarios of nanopesticide. |
PDF Full Text Request