Preparation And Application Of Attached Materials For Microalgae Cultivation

Energy is the basic driving force for social development and economic growth,which plays an important role in economic development.Non-renewable energy sources such as coal,natural gas,fossil fuels and so on are facing the problems of shortage and ecological environment.Therefore,it is particularly important to seek renewable energy to solve energy shortages and mitigate climate change and energy safety.Microalgae bio-energy has the environmental benefits of carbon sequestration,self-purification and effective use of land.It is an ideal energy source to replace non-renewable energy.At present,industrial microalgae cultivation adopts conventional aqua-suspend methods,mainly including open cultivation in runway pond and closed photobioreactor?PBR?,which consume more than 90%of the whole cultivation system.The microalgae grow slowly and are easily polluted by algae in open cultivation.What's more,the pond covers a large area.The PBR solves the shortages of open cultivation pond and can significantly improve the density of microalgae cultivation,but it has the shortcomings of high building and operation cost,hardly achieving the goal of low cost and large-scale cultivation of microalgae.The semi-dry attached cultivation for microalgae is a novel method based on biofilms.Its cultivation efficiency,nutrient consumption and water requirement are superior to those of the conventional aqua-suspend methods under the same environmental conditions.In order to solve the core problem of the semi-dry attached cultivation for microalgae,the synthesis of attached materials are taken as the goal of this study.The films prepared by different method are studied by means of Fourier infrared?FT-IR?,transmission electron microscopy?TEM?,atomic force microscopy?AFM?,Zeta potential and other techniques to the characterize the properties of the films and the performances of attached materials as the cultivation medium.The main contents and conclusions are as follows:?1?A new cationic acrylate emulsion is prepared using butyl acrylate?BA?/methyl methacrylate?MMA?/ammonium acrylate?AM?/methacryloyloxyethyl trimethyl ammonium chloride?DMC?as comonomers,which is suitable for preparing the attached material for cultivation of negatively charged microalgae,such as oil algae and freshwater spirulina.Although the corn starch gel is degradable,it is worse than the cationic acrylate emulsion as an attached material due to its solubility.?2?The semi continuous pre-emulsion polymerization process is optimal for the synthesis of cationic acrylate emulsions with BA as soft monomer,MMA as hard monomer,AM as cross-linking functional monomer,and DMC as monomer of cationic monomer.Under the condition of 400r/min stirring rate and 75?,when the mass of BA:MMA=30:70,initiator 1wt%,emulsifier 4.5wt%,water 70wt%,the comprehensive properties of emulsion and films are best after 4 hours reaction.The latex particle diameter is 150-200nm,with core-shell structure.?3?The microalgae biomass on cationic acrylate membrane increased with increasing the cultivation time.The growth rate increases until the microalgae completely cover the surface of films on the 9^th day when the biomass of microalgae reaches 1.364mg/cm².?4?The microalgae are more likely to attach and grow on the surface of film materials with large surface roughness and positive charge density.The biomass is correlated with surface roughness and surface charge density of film materials.