Study On Reaction Kinetics And Adsorption Behaviors Of Chlorella Pch-19 On The Surface Of The Modified Membrane

Microalgae is considered to be a potential renewable biomass energy because of its advantages,for example high growth rate,high photosynthetic efficiency,high oil content and non-occupation of cultivated land.Industrialization of biodiesel achieved by application of microalgae is the current research hotspot.Currently,the traditional suspension culture mode of microalgae has some drawbacks,including low biomass yield,high cultivation cost and large energy consumption.It is reported that the immobilized culture of microalgae could effectively overcome the disadvantages of suspension culture because of its relatively convenient operation.To improve the biomass of microalgae and reduce the cost of harvesting,kinetic and adsorption characteristics of microalgae are investigated,which may provide some scientific basis and theoretical support for the large-scale culture of microalgae.Mechanism of effect modified membrane materials on Chlorella Pch-19 adsorption characteristic was studied.Firstly,tetraethyl orthosilicate?TEOS?and methyl triethyl silane?MTES?employed as hybrid silicon source were utilized to synthesize nano-silica for modifying surface of PTFE,a selective permeable membrane served as substrate material.And then,a gas-liquid separation membrane bioreactor was designed and fabricated.Additionally,effects of surface characteristics of modified membrane materials on Chlorella Pch-19 adsorption growth characteristics was investigated using as-fabricated bioreactor.The results suggest that ratios of TEOS to MTES played a significant role on hydrophilic-hydrophobic properties of PTFE membrane.Chlorella Pch-19 grow on membrane materials with property of relatively lower hydrophobicity preferentially.Nevertheless,amount of Chlorella Pch-19 adsorption on modified PTFE membrane is relatively low at higher hydrophobicity?contact angle of 130°?.The maximum biomass yield?53.84 g/m2?,biomass production rate?5.98 g/m2/d?and oil yield?2.14 g/m2/d?were obtained on the modified PTFE membrane?contact angle of 105.5 °?with ratio of TEOS to MTES of 6: 6.The effects of CO₂ concentration,light intensity and gas flow on the adsorption characteristics of Chlorella Pch-19 cultures on optimized PTFE membrane in the gas-liquid separation membrane photobioreactor were studied.The results indicate that too low or too high concentration of CO₂ could limit the growth of Chlorella Pch-19,the increase of light intensity promote the adsorption growth of Chlorella Pch-19,the effect of gas flow on the adsorption growth of Chlorella Pch-19 on the membrane material was small,but the three is no obvious effects of them on the lipid content in the algal cells.The optimum conditions for the adsorption and growth of Chlorella Pch-19 were: CO₂ concentration of 5%?v/v?,light intensity of 6mW/cm2,gas flow rate of 20 mL/min.Investigation of effects of CO₂ concentration,light intensity and gas flow on biochemical reactions kinetics characteristic were performed due to their significant impacts on the growth of Chlorella Pch-19 to construct its dssential kinetics mathematical model.Empirical relationship of maximum specific growth rate under different culture conditions was obtained.And subsequently kinetics model of Chlorella Pch-19 growth,substrate consumption and lipid synthesis were also established.The effect laws of CO₂ concentration,light intensity and gas flow rate on kinetics characteristics of growth,substrate consumption and lipids synthesis of Chlorella Pch-19 culture obtained by experiment were in good agreement with ones expected by as-obtained model.