Study On Kinetics And Products Of Palygorskite Dissolution In Alkaline Solutions And Implications For Geochemistry

Palygorskite is a kind of clay catenate silicated mineral, which is nano-claviform.The products and process of palygorskite when it reacts on acidit and alkalescent condition can be studied easily. We can gestimate the mechanism of silicated mineral by studying properties of palygorskite when it solutes in acidic and alkalescent environment.The kinetics of dissolution of deposited palygorskite and hydrothermal palygorskite in alkaline solution was studied with elements analyzed by spectrophotometry.The results indicate that the kinetics of hydrolysis of palygorskite should be described with the cylinder model in control. The relationship between leaching rate (x) and reaction time (t) can be represented as (1-x)+x1nx=kt. The apparent activation energies of hydrolysis reaction of Al³⁺ and Si⁴⁺ are 18.16 and 18.53 kJ/mol for deposited palygorskite, for hydrothermal palygorskite are 31.2 and 32.95 kJ/mol, respectively.With the XRD and TEM investigation for the products of palygorskite It indicates that deposited palygorskite is more alkali resistant compared to hydrothermal palygorskite. According to the process of palygorskite during solution in alkalescent environment and the result of study in kinetic area, we can guestimate that there are obvious phenomenons of different solution during the process, which is to say, the velocity of tetrahedral silicon stripping is greater than the octahedral cation stripping.