Bioinspired Green Technologies For The Environmental Protection

Environmental pollution has gradually become a bottleneck in the development of theworld.Environmental pollution will cause direct damage and impact on therelationship between man and nature,human living environment,human life and health,which causes harmful,latent and long-term consequences.The specific manifestation of environmental pollution problems mainly includes water,air,noise,soil and radioactive pollution.The problems of air,water and soil pollution are closely related to people’s daily life,which have been paid more and more attention in recent years.The major source of air pollution is due to the fact that modern industrial societies burn too much coal,oil and natural gas,and these fuels burn and emit large amounts of carbon dioxide gas into the atmosphere.The main reason for water and soil pollution is due to industrial waste water which contains heavy metal ions.Therefore,from the perspective of environmental protection and development,the effective carbon dioxide removal and immobilization technology and heavy metal ion detection technology have always been hot issues of scientific research.This thesis focuses on carbon dioxide immobilization and utilization and high sensitivity biosensor detection of mercury ions technology,and the specific work is divided into the following three aspects:1.Porous polymers bearing functional quaternary ammonium salts as efficient solid catalysts for the fixation of C02 into cyclic carbonatesA series of porous polymers bearing functional quaternary ammonium salts were solvothermally synthesized through the free radical copolymerization of divinylbenzene(DVB)and functionalized quaternary ammonium salts.The obtained polymers feature highly cross-linked matrices,large surface areas,and abundant halogen anions.These polymers were evaluated as heterogeneous catalysts for the synthesis of cyclic carbonates from epoxides and CO2 in the absence of cocatalysts and solvents.The results revealed that the synergistic effect between the functional hydroxyl groupsand the halide anions Br-afforded excellent catalytic activity to cyclic carbonates.In addition,the catalyst can be easily recoveredand steadily reused at least five cycleswithout significant loss in activity.2.Triphenylphosphine-based functional porous polymer as an efficient heterogeneous catalyst for the synthesis of cyclic carbonates from C02A novel triphenylphosphine-based porous polymer(TPDB)with a high BET surface area was synthesized through Friedel-Crafts alkylation of triphenylphosphine andα-dibromo-p-xylene.Then,the functional hydroxyl groups were successfully grafted onto the polymer framework by post modification of TPDB with 3-bromo-l-propanol(BP)and triethanolamine(TEA).The resulting sample TPDB-BP-TEA was characterized by various techniques such as FT-IR,TG,SEM,EDS mapping,ICP-MS,and N2 adsorption-desorption.This new polymer was tested as the catalyst in the solvent free cycloaddition reaction of CO2 with epoxides,which exhibited excellent performance,with high yield,selectivity,and stable recyclability for several catalytic cycles.The comparison experiment results demonstrate that the bromide ions and hydroxyl groups,as well as high surface area are key factors in improving the catalytic activity of this new catalyst.3.Engineered Highly Sensitive Whole-Cell MercuryBiosensors Based onPositive Feedback Loop fromQuorum-Sensing SystemMercury contamination represents a global threat.A simple,sensitive,and rapid means of detectingtrace mercury are urgently needed.Herein,we have developed a series of mercury biosensorsby combining quorumsensing-based positive feedback systems with a mercury-specific operon merR.Our results have demonstrated that sensitivity and fluorescence intensity of the engineered E.coli cells were greatly improved thanks to the positive feedback system.In addition,by fitting the fluorescence signals to the classic Hill equation,we discovered that the responses of the engineered E.coli cells were close to ultrasensitive curves.Our work highlights quorum-sensing systems as a powerful tool in biosensor designs.4.Whole Cell Based Hydrogen Sensor in Model Microorganism:Structural Construction and Functional ExaminationBased on the previous study about the whole-cell bio-detection and bio-sensor,together inspired by Ralstonia eutropha’s metabolic pattern,this project aims at using synthetic biological technology(i.e.BglBrick)to integrate a novel selective hydrogen bio-sensor into Escherichia coli.This integration succeeded in selective and sensitive detection of hydrogen molecules from the mixture of natural air(minimal detectable concentration lower than 0.05 atm and fluorescent responding time shorter than 1h).Further discussing,this study would broaden the patterns of whole cell detectors’constructions and functions,realizing a more convenient monitoring system in the field of hydrogen energy.