Calcium Carbonate Crystal And Morphology Control Based On Reverse Microemulsion System

As an important chemical raw material,calcium carbonate is widely used in industrial production.The morphology,particle size and crystal form of calcium carbonate particles are important performance indicators.In this work,micro-nano-calcium carbonate was prepared by reverse microemulsion system,and the morphology,crystallization,and size of calcium carbonate were regulated by gas-liquid multiphase reaction.The effects of composition,ratio,and reaction conditions of reverse microemulsion on the crystal form and morphology of calcium carbonate particles were studied.The first chapter mainly introduced the properties,applications,classification,morphology and preparation methods of calcium carbonate.The second chapter adopts the reverse microemulsion method,Using polyoxyethylene octyl phenol ether-10(OP-10)as the surfactant,alcohols with different chain lengths as the co-surfactant,the mixed solution of calcium chloride and ammonia as the aqueous phase,and cyclohexane as the oil phase,calcium carbonates with different morphologies were prepared.The effect of several alcohols with different chain lengths as co-surfactants on the morphology of calcium carbonate was studied.It is found that when the cosurfactant is a short-chain alcohol,the prepared calcium carbonate is spherical,and when the cosurfactant is a long-chain alcohol,a discus calcium carbonate is prepared and its formation mechanism is studied.The third chapter adopts the reverse microemulsion method,Using cetyltrimethylammonium bromide(CTAB)and n-butanol as surfactant and co-surfactant,respectively,cyclohexane as the oil phase,and a mixed solution of calcium chloride and ammonia as the water phase,chrysanthemum-shaped micro-nano calcium carbonate was prepared.The effects of stirring rate and microemulsion composition on the crystal form and morphology of calcium carbonate were studied,and the formation mechanism of chrysanthemum-shaped micro-nano calcium carbonate was explored.Chapter four used polyoxyethylene octyl phenol ether-10(OP-10)as the surfactant,n-heptanol as the co-surfactant,the mixed solution of calcium chloride and ammonia as the water phase,and cyclohexane as the oil phase to prepared reverse microemulsions.Coral-like micro-nano calcium carbonate was prepared by gas-liquid heterogeneous reaction.Since the surface of coral-like calcium carbonate has a special micro-nano composite structure similar to the surface of a lotus leaf,it is made into a coating and compared with ordinary micron-level cubic calcium carbonate,the contact angle was measured,and the values were found to be 76.6°and 51.9°,respectively.After further modification of the surface,the contact angles are 136.0° and 127.1°,respectively.It shows that calcium carbonate with micro-nano composite structure has good hydrophobicity,and the formation mechanism of coral-like micro-calcium carbonate is explored.In summary,in this paper,the reverse microemulsion method was used to prepare calcium carbonate with different morphologies,and the formation mechanism was studied.The prepared discus-shaped calcium carbonate is expected to be used in lubricating oil and paper industry;chrysanthemum-shaped and coral-like micro-nano calcium carbonate are expected to be used in the preparation of superhydrophobic materials.These studies provide a reference for the preparation of a new type of ultrafine calcium carbonate with special morphology,and also provide new ideas and new methods for the in-depth development and application of calcium carbonate.