A Study On The Thermodynamic Behaviors And CO₂ Biofixation Of Microalgae Via An Isothermal Microcalorimetric Method

Microalgae biological system has potential application in fixing CO₂ from various industrial activity.During autotrophic growth of microalgae culture,it needs inorganic carbon sources,usually CO₂,light along with other nutrients supply to support photosynthesis of microalgae and their metabolic activity.Therefore,a LED-illumination isothermal microcalorimetric method is designed to investigate the thermodynamic behaviors of marine and fresh water algae to better understand their role in CO₂ fixation.The microalgae strains Chlorococuum sp.GIEC-038,Scenedesmus obliquus GIEC-172,Chlorella vulgaris GIEC-179 and Skeletonema costatum were studied in this research.An isothermal microcalorimetric method were optimized to investigate and compare the carbon sequestration capacity of microalgae with 0,7.48,14.96,29.92,74.8g/L dissolved carbon source concentration.The LED-illumination was mounted within the commercial calorimeter 4.5 ml ampoule caps inside of stainless still at 90° angle and the output light was directed to the sample cells and reference cells.Out of four strain,we have selected two species of microalgae,which give us better response against of their thermal activity.One is C.vulgaris GIEC-179?fresh water algae?,the other one is S.costatum?marine water algae?.Microalgae thermodynamic behaviors were recorded as a function of power-time curves,and their indices,the total heat evolution?QT?,maximum power output?Pmax?,Generation time?TG?,Growth rate constant?k?,Inhibition Ratio?I?and heat generated by per algae cell?JQ/N?were calculated.For the C.vulgaris GIEC-179,the value for highest?74.80 g/L?and the control sample?0.00 g/L?of QT,Pmax and JQ/N;20.85 and 2.32 joule;252.17 and 57.67?W;7.91-06 and 8.80-07 joule/cell respectively.Meanwhile,to S.costatum,the value for highest C sources?74.80 g/L?and the control sample?0.00 g/L?of QT,Pmax and JQ/N;20.23 and 5.74 joule;307.43 and 108.25?W;3.20-05 and 9.08-06 joule/cell respectively.According to the values of QT,Pmax,JQ/N,a general order of promotion concentration was found to be 74.8g/L >29.92g/L >14.96g/L >7.48g/L>0g/L for both marine and fresh water algae species of microalgae.In respect of this,it is found that the marine water algae were showing better response compare to fresh water algae.Both of algae shows highest peak Pmax,QT and J/Q/N at 74.8g/L CO₂ concentration.From the relationship of different thermodynamic parameters?QT,TG,Pmax,JQ/N?analysis that total heat output,total power evolution and a single cell heat generation are directly related with the cell biomass and CO₂ concentration which are consistent with our typical analysis?pH changes,Optical analysis,Cell counting?.The results indicated that higher the CO₂ concentration higher the algal biomass and higher the CO₂ fixation rate.Therefore,it was directly transformed with their biomass concentration.So that,it could be a potential novel approach to better understanding the suitable algae to solve the current global warming challenge.