| The coupling of microalgal biomass production and wastewater treatment technology can help to solve problems such as energy shortage and environmental pollution.Microalgae mainly grows through photoautotrophic,but no matter it is a natural light source or an artificial light source,it currently has its own problems of being unable to use part of the light(500-600 nm)and low biomass yield.Spectral conversion materials are considered to be an effective method to improve microalgal biomass yield and wastewater treatment efficiency.Among them,carbon quantum dots(CDs)are a new type of fluorescent nanomaterials,which have the advantages of high quantum yield and good biocompatibility.However,there have been few studies and applications that matched the fluorescence emission spectrum of CDs with the photosynthesis spectrum of microalgae.In this study,we plan to prepare fluorescent emission CDs that meet the photosynthesis spectrum of microalgae,and discuss their effects on microalgae cultivation and simulated wastewater treatment,and analyze the mechanism of CDs on microalgal biomass production and wastewater resource utilization.First,CDs were successfully prepared by solvothermal method using formamide and citric acid as precursors,with an average diameter of 2.57 nm,which has the characteristics of graphite-like carbon core and abundant functional groups such as surface amine groups and hydroxyl groups.Spectral analysis shows that CDs can absorb light with a wavelength of 500-600 nm and convert it into red light(580-700 nm)that can be used by microalgae through fluorescence emission.Using CDs for LED light conversion during microalgae cultivation,the microalgal biomass increased by 15.6% after 12 days,and the productivity of intracellular pigments,carbohydrates,proteins and lipids also increased by 23.9%,29.0%,22.8% and 14.3%.The characterization results show that CDs obtain more red light through light conversion and bind to the extracellular polymer to adsorb on the cell surface,continuously providing optimized light for microalgae.Appropriate light energy input improves the photosynthetic activity of microalgae cells and upregulates the gene expression of the light-harvesting complex,enhancing the photosynthesis and biological growth of microalgae.Secondly,the application of CDs to the enhanced microalgae treatment to simulate antibiotic wastewater treatment was studied,and the impact of CDs on the microalgae wastewater utilization was explored.The degradation rate of amoxicillin under the action of 1 mg / L CDs reached 99.3% on the 13 th day,which was 15.5% higher than that of the control group.With the extension of the cultivation time,the removal rate of total nitrogen and phosphate also increased by 14.6% and 9.9% compared with the control group.At the same time,the production of biomass resources such as microalgal biomass,pigments,proteins and lipids has also been correspondingly improved.PS? activity test results show that the red light generated by the fluorescence effect of CDs can restore and improve the PSII reactivity of cells,stimulate photosynthesis and growth of microalgae,thereby accelerating the degradation of AMO and the absorption of N and P,and improving the efficiency of microalgae wastewater recycling.It can be seen that this study establishes a green,economical and simple strategy to improve the production of microalgal biomass resources and waste water utilization,laying a theoretical foundation for the application of CDs in the coupling technology of microalgal biomass resources and wastewater treatment processes. |
PDF Full Text Request