| Microalgae harvesting is a necessary step in the utilization of microalgae biomass,but the high energy consumption in the harvesting process has limited the use of microalgae biomass to a large extent.At the same time,the self-corrosion of aluminum anodes reduces the utilization of aluminum to a great extent during the discharge of aluminum air batteries.In this paper,the coupling process of aluminum-air battery flocculating Dunaliella Salina and aluminum anode corrosion was studied to explore the harvesting efficiency of Dunaliella Salina by aluminum air battery and the harvest principles as well as the mechanism that Dunaliella Salina could inhibit the self-corrosion of aluminum anodes.Moreover,the mesoporous alumina was prepared by using the product of the flocculation and recovery process as a precursor.The main findings are as follows:(1)During the process of harvesting Dunaliella Salina in an aluminum air battery,D.Salina was used as the electrolyte.The positively charged by-product aluminum hydroxide hydrate produced by the discharge of aluminum air battery was an effective flocculant which could combine with algal cells to form larger floes to achieve settlement recovery.When the discharge current intensity was 100 mA,the algae concentration was 0.8 g/L,and the NaCl concentration was 2 M,the harvesting efficiency could reach 97%within 20 min and the production capacity could reach 0.11 kWh/kg.At the same time,the combination of microalgae and aluminum hydroxide hydrate produced by the discharge could effectively reduce the effect of the accumulated aluminum hydroxide hydrate on the performance of the aluminum air battery.(2)By testing the polarization curves and impedance of aluminum flakes in D.Salina with different algae concentrations(0-0.8 g/L),it was found that with the increase of algae concentration,the corrosion current icorr showed a tendency to decrease,which proved that D.Salina could effectively relieve the self-corrosion of aluminum flakes.The FTIR analysis was performed on the surface of aluminum flakes soaked in D.Salina for different periods of time.The results showed that a protective film was formed on the aluminum anode,mainly due to the complexationof Al3+ with the proteins in the algae and the absorption of polysaccharides on aluminum anodes.At a discharge density of 2.5 mA/cm2,the discharge time in D.Salina was nearly 50 h longer than that in 2 M NaCl solution.In D.Salina,the discharge capacity was 223 mAh/cm2,which was 27.8%higher than that of 2 M NaCl solution.(3)The flocculent product of the process that aluminum air battery harvesting D.Salina was used to prepare alumina.The experimental results showed that the prepared ?-Al2O3 has a good mesoporous structure,showing a film-like tremella structure.And the surface area up to 333 m2/g,pore volume up to 0.782 cm3/g.The effects of algal cells and hydrothermal treatment on the morphology and specific surface area of alumina were investigated.It was found that both algal cells and hydrothermal treatment were beneficial to the formation of thin-film white fungus morphology and could increase the specific surface area of alumina.Compared with the alumina prepared by traditional electrocoagulation products,it was found that the prepared alumina also appeared tremella,but the sheet was thicker and had a specific surface area of only 201 m2/g.In the presence of algae,the mesoporous ?-Al2O3 prepared can interact with Dunaliella biomass. |
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