pH-Dependent kinetics of tuff dissolution

摘要: Despite the widespread use of commercial tuffs as growth substrates, their dissolution kinetics and time variation solution compositions have not hitherto been investigated. To fill this gap in our knowledge, rates ion release by two were measured a function pH batch steady-solution-flow suspensions. Reaction was characterized rapid H+/OH− consumption, Si, Al, Ca, Mg, P during first day. This followed period which H+ consumption linear functions for at least 720 h. On basis reaction stoichiometry equilibrium calculations, short-term studied related to cation exchange fine particles volcanic glass hydroxyapatite (HA). The rate laws long-term acid fractional-order with respect concentration ranges 3.4–6.5 3.6–9.6, black yellow tuffs, respectively. proton-consumption data ionic composition, attributed halloysite-like allophane tuff, HA both tuffs. Aluminum from tuff under conditions below 4 may create toxic environment plant roots.