Study On Fabrication Of Allochemical Modified Composite Materials And Their Algae-inhibition Efficiency

In recent years,lake eutrophication has become more and more serious,and algae blooms have broken out frequently,severely damaging the ecological environment,so it is urgent to take some measures.As a new type of algae control technology,plant allelopathic substances have attracted much attention in recent years.However,throwing allelopathy substances directly into the water body is not easy to control and will have a nagative impact,which greatly limits its use.In this study,according to the stages before and after the occurrence of algal blooms combined with the distribution characteristics of algal cells in the water body,heavy composite material was designed and fabricated for the inhibition of algal cell growth at the bottom of the water body to prevent the occurrence of blooms.Suspension composite materials,and lightweight composite materials that inhibit the growth of the blooming algae in the surface water body are magnetically trapped and removed,respectively,for various reaction conditions and parameters such as reaction temperature,reaction time,and fabrication speed during the fabrication of the modified composite material.After adjustment and optimization,in light of the algae suppression effect combined with the characterization data,the composite functional material with the best algae suppression effect will be selected.The above results will provide a new idea for the ecological control of water bloom in the future,and provide theoretical basis and data support for the application of allelochemicals modified composite materials in the control of water bloom.Diatomite was used as the heavy material,and lactic acid,nonanoic acid and palmitic acid were the allelochemicals to be selected.The modified heavy composite allelopathic material was fabricated by the blending and dipping method.SEM characterization showd that there are obvious mesoporous holes in the heavy materials of the original diatomite the composite material pores,however,were closed,indicating that the allelochemicals had entered the diatomaceous earth separately.The results of algae inhibition experiments showed that lactic acid as a modifier was suitable for allelopathic,while nonanoic acid and palmitic acid were not.The optimum fabrication conditions for obtaining lactic acid/diatomite material by orthogonal test method are temperature 70?,rotation speed of 180 r/min and running time5 h.The optimal lactic acid/diatomaceous earth material has an EC₅₀ value of 8.49 mg/L for the 300 m L initial algal density of 5×10⁵cells/m L Microcystis aeruginosa,and the CTC value of lactic acid/diatomite composite is calculated to be 299.8>200,indicating significant synergistic effect.It was found that with the increase of the initial algal density of Microcystis aeruginosa,the algae inhibiting effect of lactic acid/diatomite material gradually weakened.Biochar was selected as suspension material and allelopathic algal inhibitor of modified suspension compound was prepared by blending and impregnating method.As SEM characterization showed that mesopores obviously existed in the original biochar material,while the pores in the synthetic material lactic acid/biochar were closed,which indicated indicating that the lactic allelopathic substance had entered the biochar.The results of algae inhibition experiments showed that the degree of biochar crushing had an effect on the algae inhibition effect of the lactic acid/biochar composite material,and the inhibition effect of lactic acid/biochar/lactic acid/biochar composite was better than that of lactic acid/biochar.The optimum fabrication conditions for obtaining lactic acid/biochar materials by orthogonal method are temperature 50?,rotation speed of 180 r/min and running time 8 h.The EC₅₀ value of the half inhibitory concentration of lactic acid/biochar on the growth of 300 m L Microcystis aeruginosa with an initial algal density of 5×10⁵cells/m L was 11.20 mg/L and the CTC value of the lactic acid/diatomite composite fabricated under the optimal conditions is 252.2>200,which indicates significant synergistic effect.The expanded perlite was taken as a lightweight material,which was magnetized by hydrothermal method,and then allelopathic algal inhibitor of magnetized compound modified lightweight was made by blending impregnation method.By SEM characterization it is clear that mesopores in the magnetically expanded perlite,while the pores in the synthetic material lactic acid/magnetically expanded perlite were closed,which meant that the lactic acid allelochemical had entered into the magnetically expanded perlite.The results of algae suppression experiments showed that the particle size had an effect on the algae suppression effect of the lactic acid/magnetic expanded perlite composite material,and regarding to this effect,lactic acid/magnetic expanded perlite(3 mm)material is superior to the lactic acid/magnetic expanded perlite(0.5 mm)material.By orthogonal test,the optimum fabrication conditions for obtaining lactic acid/magnetic expanded perlite material the running time was 8 h,the are temperature of 50?and rotation speed of 180 r/min.Lactic acid/magnetic expanded perlite material had an half of the inhibition concentration EC₅₀of lactic acid/magnetic expanded perlite material on the growth of 300 m L Microcystis aeruginosa with an initial algal density of 5×10⁵cells/m L was 10.41 mg/L and the co-toxicity coefficient CTC value of lactic acid/magnetic expanded perlite composite fabricated under the optimal conditions is223.2>200,indicating significant synergizing effect.