The Interfacial Interaction And Mechanisms Of The Micro-Nano Mineral Dust/Common Bacteria Complex

The material in the natural environment is not single and independent,showing a certain similarity with the physical-chemical-biological interaction.In recent years,the environmental problems are looming large in our country,which the contaminants present complexity,mixed,regional,and homology.The suspended particles of pollutants from the atmosphere is made up of minerals,heavy metal ions,organic pollutants and microorganism,resulting the corresponding prevention measures are becoming more and more complex and difficult.The soil pollution formed by minerals-microbes-humus and adhesion other pollutants,have the characteristics of concealment,complexity,and difficult to control.Therefore,understanding its formation mechanism and the interfacial interaction mechanism can help predict the removal way and the conversion process of the compound pollution.It can provide theoretical guidance for the prevention and control of atmospheric pollution,soil pollution.This study selected three kinds of micro minerals?quartz,calcite,montmorillonite?,two kinds of nano minerals?nano silicon dioxide,nano calcium carbonate?,3 strains of common bacteria?Escherichia coli,Staphylococcus aureus,Bacillus pumillus?,under the solution system successful preparation 15 kinds of mineral/bacteria complex.Taking the micro-nano mineral/bacteria complex as the research object,combineding with the scanning electron microscope?SEM?,laser confocal microscope?CLSM?,particle size analyzer,zeta potential analyzer,ultramicro heat meter?C80?,Fourier infrared spectrometer?FTIR?,nuclear magnetic resonance spectrometer?AVANCE ? HD?technology,study the complex mineral/bacteria forming characteristics,forming process,the interfacial thermodynamics,interfacial molecular interaction mechanism,and its active effect on A549 cells,revealing the interfacial interaction mechanism anf effect behavior of the mineral/bacteria complex.The main achievements and conclusions are as follows:?1?The features of mineral/bacteria complex:the mesoscopic appearance characteristics of the mineral/bacteria complex is showing that the bacterial adhesion in the surface of larger particles mineral or nano mineral flocculation group,and a single mineral nanoparticle adsorbed on the surfaceof bacteria.The particle size was characterized by nano-mineral>micron minerals,Bacillus pumillus>Escherichia coli>Staphylococcus aureus.The surface electrical characteristics of the mineral/bacteria complex is showing that the pH value of its isoelectric point larger than the mineral isoelectric pH value.The micro calcite/bacteria complex surface electrical is between minerals and bacteria,Nano-CaCO₃/bacteria complex surface electrical approach mineral particles.The surface electrical of the micro-nano silica/bacteria complex is approaching the surface electrical of the bacteria.The montmorillonite/bacteria complex present a negative charge,there is no isoelectric point.The matching trend of the complex is characterized by the Bacillus pumillus>Escherichia coli>Staphylococcus aureus,montmorillonite>calcite,>quartz.?2?The formation process and influencing factors of the mineral/bacterial complex:The best preparation complex condition in the solution system is that the compound time is 4.0 h,and the dry weight ratio of the mineral and bacteria is 1:1.The pH value,Ca²⁺and the activity of the bacteria can affect the formation of the complex,which the pH value is the main factor.Bacteria which adhesing the surface of the mineral/bacteria complex can promote ion dissolution of the mineral.Nano-CaCO₃/bacteria complex lattice diffraction results show that the changes of the mineral crystal lattice of complex is weak.The mineral surface adhesion with organic material such as C,N,P,confirming that the mineral/bacteria complex including contact adhesion and indirect contact adhesion,for example mineral/EPS complex.The bacterial activity was stable during the forming process.Specific forming process of the mineral/bacteria complex is that,bacteria gathering at the area of the mineral surface edge?bacteria adhereing at the area of the mineral surface edge?several bacteria adsorded on the surface of the mineral?mineral surface completely wrapped by a certain number of bacteria.?3?The mineral/bacteria complex interface thermodynamics and interface molecular interaction:The forming process of mineral/bacteria complex is exothermic reaction.The heat effect is showing that spherical bacteria>rod-shaped bacteria,nano mineral>micro mineral,clay mineral>high calcium mineral dust.The calcite/bacteria complex have the largest heat release.The thermal sequence of micron mineral/bacteria complex is the montmorillonite>calcite>quartz.The heat release process of nano-CaCO₃/bacteria complex is long than nano-SiO₂/bacteria complex.The FTIR spectra of the mineral/bacterial complex are mainly based on the infrared characteristics of the minerals,carrying with some infrared characteristics of the bacteria.The results of the bacterial membrane protein secondary structure of the mineral/bacteria complex show that the electrostatic attraction is the major effect of micro-nano calcite/bacteria complex.In the Nano-SiO₂/bacteria complex,the hydrogen bond force becaom strong.Besides physical adsorption,hydrogen bonding force is another dominant interaction in the montmorillonite/bacteria complex.The?-sheets/?-helix value increase in the mineral/Staphylococcus aureus complex,indicating that the secondary structure of the surface protein molecule was more stable and the hydrogen bond effect was strong.?4?The interfacial organic matter interaction and behavior effect of the mineral/bacteria complex:It is the first time using superconducting nuclear magnetic resonance?NMR?to clarify the mechanism of the interfacial organic matter interaction of the mineral/bacteria complex.Hydrocarbon such as polysaccharide exist in the solution phase,gel phase and solid phase of the mineral/bacteria complex.Fatty substances exist in the gel phase and solid phase.Aromatic substance exists only in solution phase,while the lignin is located in the solid phase,and can through the inner surface of the mineral/bacteria complex.Taking the dust full as a comparison,the mineral/bacteria complex prepared in the lab shows the higher peak and high resolution,this is mainly because the strong biological chemistry process of the complex.The mineral/bacteria complex thermal behavior in the pure water is exothermic.The heating effect of the micro mineral/bacteria complex is better than nano the mineral/bacteria complex.The mineral/Bacillus pumillus complex thermal behavior in the pure water in order is quartz>calcite>montmorillonite>nano-CaCO₃>nano-SiO₂.The mineral/bacteria complex could slow the cytotoxic effect caused by mineral,but still show some fatality rate:nano-SiO₂>montmorillonite>quartz>calcite>nano-CaCO₃.The mineral/Bacillus pumillus complex can change the secondary structure stability of amide?band in the A549 cell membrane protein,in order showing montmorillonite>calcite.