| Pickering emulsions are emulsions stabilized by colloidal-sized solid particles,which have the advantages of small stabilizer dosage and high thermodynamic stability,and are widely used in food science,drug delivery,reaction catalysis,electromagnetic electrodes,tissue engineering and wastewater treatment,etc.A variety of materials such as emulsion gels,aerogels,nanoparticles and microcapsules can be prepared using emulsions as templates.Among them,Pickering emulsions stabilized with bio-based particles have received a lot of attention from researchers because of their low tissue toxicity and high degradability.The research of this thesis for bio-based stabilizer Pickering emulsion and its template application includes two main works:the one was to prepare high internal phase Pickering emulsion with polysaccharide complex formed by sodium octenyl succinate and chitosan as stabilizer,and to prepare macroporous aerogel with emulsion as template for adsorption of various mixed dyes for wastewater treatment purpose.The second one was to use wheat hydrolyzed protein as stabilizer and emulsion as template to prepare oil-in-water emulsion by adding glutaraldehyde to crosslink the oil-water interface to obtain microcapsules,which could be used for controlled release of oil-soluble components under acidic conditions.The results of the paper help to promote the development of designability and enrichment studies for template applications of Pickering emulsions.The paper consists of the following main parts.Chapter Ⅰ:The basic concept of Pickering emulsions,the stabilization principle,an overview of the types of stabilizers for Pickering emulsions,the types of liquid phases,the types of materials prepared by the emulsion template method,and the applications of Pickering emulsions in various fields of production and life are introduced.By summarizing the shortcomings of previous studies,the main research objectives,research content and significance of this thesis are introduced.Chapter Ⅱ:The macroporous aerogel material was constructed using the emulsion template method.Polysaccharide complex originating from sodium octenylsuccinate starch and chitosan served as stabilizer,and water and hexane acted as external and internal phase,respectively.Acrylic acid was introduced into external phase to initiate UV polymerization,and the emulsion template was removed through freeze drying,thereby producing aerogel material with macroporous structures.The SEM photographs showed the pore size of aerogel material was similar to that of emulsion droplets,verifying the template role of emulsion in polymerization process.In addition,aerogels possessed good mechanical properties,and thus could withstand pressure of MPa level and exhibit favorable stability when floating in the water for a long time.Methyl violet,malachite green,methylene blue and basic orange were selected as model dyes to explore the removal mechanism.The adsorption process was conformed to be the pseudo-second-order kinetic model and the Freundlich adsorption isotherm,namely,the dye adsorption of the aerogel was the multilayer adsorption on the uneven surface,and the mechanism of the adsorption was related to the π-π interaction.Chapter Ⅲ:Microencapsulated materials were constructed using the emulsion-template method.A water-in-oil Pickering emulsion was prepared using natural wheat hydrolyzed protein as stabilizer,water as external phase and glycerol octanedioate as internal phase.When glutaraldehyde,a cross-linking agent,was added,the side chains and residual amino groups of wheat hydrolyzed protein reacted with the aldehyde groups at both ends of the glutaraldehyde molecule to form microcapsules by cross-linking the interfacial phase.Since Schiffbase was a dynamic covalent bond with pH responsiveness and could be broken under acidic conditions,the microcapsules were pH responsive and could undergo structural rupture under acidic conditions to achieve the purpose of controlled release of oil-soluble components. |
PDF Full Text Request