Ion Interfacial Reaction And Its Effect On Mineral And Mineral-Bacterial Mixed Colloidal Aggregation

Soil minerals,organic and microbial colloidal particles have a large amount of charge on their surface that can form a strong electric field on their surface.Different ions adsorbed on the surface of the colloid are affected by a strong electric field near the interface,which will produce different effects,resulting in ion-specific effects.The microscopic mechanism of ion reaction at the solid/liquid interface of soil colloid profoundly affects the interaction between various colloidal particles in soil,which affects nutrient cycling,heavy metal pollution,pathogen migration,soil erosion,and soil agglomeration in soil/water environment.Macroscopic phenomena such as formation and stability and soil water infiltration and material migration.In this study,montmorillonite minerals,Escherichia coli and Bacillus subtilis were selected as research objects to study the adsorption kinetics of different ions on the surface of montmorillonite,aswellas"montmorillonite-montmorillonite"and"montmorillonite-bacteria".The cohesive kinetics of interactions reveals the mechanism of ion-specific effects in the ion interface reaction,revealing the mechanismofion-specificeffectsintheinteractionof montmorillonite-montmorillonite and montmorillonite-bacteria.Some new scientific discoveries have been made.?1?In the adsorption experiment of ions on the surface of clay minerals,the interface adsorption of Li⁺and Cs⁺ions with non-nuclear electrons and H⁺,extranuclear electrons with different ionic radii,was studied with montmorillonite as experimental material.Can,to clarify the role of electrostatic forces,coordination bonds,non-classical polarization,dispersive forces and ion pairs in the"cation-montmorillonite"interface reaction.The results show that:1)Cs⁺with the largest electron number of ionic radius and H⁺interface with the smallest ionic radius and no extranuclear electrons are very close,but their interface adsorption energy with Li⁺is very different;2)Li⁺adsorption can be used classically electrostatic adsorption,but both H⁺and Cs⁺have non-electrostatic adsorption,and their non-electrostatic adsorption energy increases with the decrease of electrolyte concentration.3)When the electrolyte concentration is as high as 0.1 mmol L^-1,the adsorption amount of Cs⁺will be Exceeding the amount of cation exchange.Further theoretical analysis found that the non-electrostatic adsorption of H⁺can be explained by the coordination adsorption between“H⁺-O”,and the coordination bond strength is electric field dependent;the non-electrostatic adsorption of Cs⁺can be used for non-classical polarization of Cs⁺The role is explained,it is also electric field dependent;Cs⁺and accompanying anion NO₃^-at high electrolyte concentration are adsorbed on the surface of montmorillonite by Cs⁺-NO₃^-ion pair due to the action of dispersive force.?2?The aggregation kinetics study between"montmorillonite-montmorillonite"showed that there were ion-specific effects in the aggregation of montmorillonite,K⁺-montmorillonite colloid and H⁺-montmorillonite colloid.For the alkali metal cations Li⁺and Cs⁺,the critical coagulation concentration values?CCC?in the montmorillonite coagulation process are 121.1 and 45.8 mmol L^-1,respectively.The critical coagulation concentration values in the K⁺-montmorillonite coagulation process were 88.9 and 23.7 mmol L^-1,respectively.The critical coagulation concentration values?CCC?values in the colloidal aggregation of H⁺-montmorillonite were 11.6 and 4.4 mmol L^-1,respectively.In the colloidal aggregation,the ion-specific effect sequence of the critical coagulation concentration value is Li⁺>Cs⁺.The ion-specific effects of the overall average coagulation rate are more pronounced at lower cation concentrations.The results also showed that the order of CCC values in the coagulation of three kinds of montmorillonite colloids was as follows:montmorillonite>K⁺-montmorillonite mineral colloid>H⁺-montmorillonite mineral colloid.the CCC value of Cs⁺is 3.75 times that of Li⁺In the K⁺-montmorillonite colloidal agglomeration,and in the H-montmorillonite colloid,the CCC value of Cs⁺is2.64 times that of Li⁺.The overall average aggregation rate of H⁺-montmorillonite colloid induced by Li⁺and Cs⁺is greater than that of K⁺-montmorillonite colloid.This difference in K⁺and H⁺-montmorillonite colloids is due to the steric hindrance,covalent interaction,and polarization of the two ions.The CCC value of Li⁺in the colloidal coagulation process of montmorillonite minerals at different pH shows that H⁺covalently bonds with the exposed O on the surface and is closely distributed on the mineral surface.?3?In the study of the"bacteria-bacteria"aggregation,it was found that the monovalent cations Li⁺,Cs⁺and the divalent cation Ca²⁺could not aggregate the colloids of Escherichia coli and Bacillus subtilis in the suspension.In the"bacterial-mineral"interaction study,it was found that for B.subtilis-K⁺montmorillonite mixed system,B.subtilis-H⁺montmorillonite mixed system,E.coli-K⁺montmorillonite mixed system or E.coli-H⁺montmorillonite mixed system,the CCC values in the coagulation process all follows the sequences:Li⁺>Cs⁺>Ca²⁺.For the CCC values of Li⁺,Cs⁺and Ca²⁺,in the mixed system of B.subtilis-K⁺montmorillonite mixed system are 122.015,51.728 and 3.848 mmol L^-1,respectively.In B.subtilis-H⁺montmorillonite.They were 17.329,5.505,3.5256mmol L^-1,respectively.As well as in the mixed system of E.coli-K⁺montmorillonite are 70.85,40.282,1.032 mmol L^-1,respectively.For the mixed system of E.coli and H⁺-montmorillonite minerals.They were 9.481,6.319,and 0.567 mmol L^-1,respectively.At the same electrolyte concentration of given"bacterial-mineral"mixed system,the overall average aggregation rate appears as a sequence of Ca²⁺>Cs⁺>Li⁺.For the overall average aggregation rate of the"K⁺-montmorillonite-bacteria"and"H⁺-montmorillonite-bacteria"mixed colloids,the latter is greater than the former.The total average aggregation rate of the"B.subtilis-K⁺/H⁺-montmorillonite"is higher than that of the"E.coli and K⁺/H⁺-montmorillonite"mixed system.Bacterial-K⁺-montmorillonite and"bacteria-H⁺-montmorillonite"show similar results with"K⁺-montmorillonite"and"H⁺-montmorillonite",respectively,which is that the behavior of colloidal aggregation is determined by the adsorption of ions at the mineral interface.The difference in the aggregation of"B.subtilis-mineral"and"E.coli-mineral"is mainly due to the difference in the adsorption of ions on the surface of bacteria.Based on the above research results,we can draw the following conclusions:?1?H⁺,Li⁺,K⁺,Cs⁺,and Ca²⁺all exhibit strong ion-specific effects in both ion interface adsorption and“bacterial-montmorillonite”interactions..?2?For the same-valent ion,the intensity order of the ion-specific effect is H⁺?Cs⁺>K⁺>Li⁺.?3?The type of force and the strength of the adsorption at the ion interface are the root causes of the ion-specific effect.Li⁺has almost only electrostatic action on the surface of montmorillonite.The adsorption of K⁺/Cs⁺/Ca²⁺on the surface of montmorillonite contraled by static,polarization,polarization-induced covalent action and dispersive force.H⁺adsorption is the superposition of electrostatic interaction and covalent action.?4?The ion-specific effect in the ion interface adsorption is the origin of the ion-specific effect in the"bacterial-montmorillonite"interaction.