The Electrostatic Field Effect from Surface Charges on Ion Diffusion/Adsorption in Soil

摘要: Soil is a system exhibiting strong electrostatic field in aqueous solution, even though it electrically neutral macroscopically. Therefore, the gradient of electric potential will be main driving forces for ions transportation, adsorption/desorption soil. In this chapter, we firstly discuss theoretical descriptions mass diffusion with multi-potential fields. Based on macroscopic thermodynamic analysis, generalized linear theory describing non-linear external fields and non-ideal systems, such as soil, can established, included: flux equation diffusion; an apparent conservation non-steady state diffusion. This section critical ion diffusion/adsorption study because coupling multiple soil have been unified to single force: concentration gradient, which changes complex problem linear. second section, effect from surface charges particles exchange equilibrium. show that, adsorption cations treated process driven by particle surface. Therefore are essentially same process, one. concept, new equilibrium distribution equations obtained, those clearly how charges, strength, ionic volume interaction solution influence exchange. last adsorption/diffusion kinetics. exerts significant By considering surface, exact kinetic cation developed. The when both force weak coexist experiment, initial stage described zero-order then shifts first-order kinetics adsorption. mathematically precise, they were derived actual physical mechanism Thus, fundamentally different classic equations. All parameters definite significance. using equations, some important dynamic estimated experimental data.