title: Mechanism of protodesorption-exchange of heavy metal cations for protons in a heterophase system of H2O-H2SO4-MSO4-cellulose sorbent.
abstract: The influence of pH on the distribution of metal cations [Cd(II), Cu(II), Fe(II), Ni(II), Zn(II)] in a four-component heterophase system (H2O-H2SO4-MSO4-cellulose sorbent) was studied. Protodesorption of metal cations was studied with indicator and constant quantities of [MSO4] salts and constant solvent-sorbent ratio. Linear dependence lgКDМ2+=f(рН) with tgα=1/2 of the КDМ2+ metal ions distribution coefficients from the acidity of the aqueous phase is observed in logarithmic coordinates. Depression of the exponent corresponding to proton involvement in protodesorption from 2 (theory) to 0.5 (experiment) indicates that anions of the aqueous phase are involved in the process of exchange of metal cation for proton on the anionic centers of the sorbent, which corresponds to participation of the salt and acid components of the system in molecular non-dissociated form in an equivalent proportion H2SO4/MSO4=1/1. Different behavior of the salt and acid components in ion exchange of cations for cations and cations for protons is due to the differences in the constraint coefficients of their molecular and ionic forms which must be taken into consideration in equations describing thermodynamics of the interphase exchange.
authors: Ivanovo State University of Chemistry and Technology, Sheremetev avenue, 7, Ivanovo, Russia.
authors: V A
authors: VA
authors: Kozlov
authors: Ivanovo State University of Chemistry and Technology, Sheremetev avenue, 7, Ivanovo, Russia. Electronic address: tatianaenik@mail.ru.
authors: T E
authors: TE
authors: Nikiforova
authors: Ivanovo State University of Chemistry and Technology, Sheremetev avenue, 7, Ivanovo, Russia.
authors: V A
authors: VA
authors: Loginova
authors: Ivanovo State University of Chemistry and Technology, Sheremetev avenue, 7, Ivanovo, Russia.
authors: O I
authors: OI
authors: Koifman
mesh_terms: D002412:Cations; D002482:Cellulose / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011522:Protons; D013464:Sulfuric Acids / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D002412:Cations; D019216:Metals, Heavy; D011522:Protons; D013464:Sulfuric Acids; D014867:Water; D002482:Cellulose; C033158:sulfuric acid
keywords: Cellulose sorbents; Protodesorption; Sorption of heavy metal ions