Sorption of heavy metals on organozeolite - clinoptilolite modified with polyethylenimine from weak acid solution

Abstract

The method of dynamic output curves was used to study the sorption of heavy metals (HM) Cr, Ni,
Cu, Zn, Sr, Cd, Pb and macro-components H⁺, K⁺ and Ca²⁺ from surface water with pH 3.7 on modified
PEI–CLT in the joint presence of components and low concentrations (0.3-1.5 mg/l). Two parallel dynamic
experiments were carried out for each linear 0.038, 0.013 and 0.0064 cm /s.
ICP-MS method was used for the analysis of metal concentrations in solutions, ISP-AES with service
ICAP DUO Thermo Scientific (England)device. X-ray fluorescence (XRF) method was used to analyze
the initial and spent sorbent samples. Detection limits were (mg/l): 0.001 for Cd, Cr, Cu, Zn, Sr; 0.002 for
Zn; 0.01 for K, Na, Ca and 0.03 for Pb.
The values of the sorption parameters (distribution coefficients and kinetic characteristics) were studied.
The distribution coefficients (ml/g) were for H⁺ ion 6·103, for K⁺_- (1-5)·103, for Cu^2+_{_} (2.6-3.1)·103, for
Cr²O^2-₇ - >1.8·10³, for Pb - >(3.2-5.8)·10³ , for Ca²⁺ and Sr²⁺- (200-400), and even lower for Cd, Ni, Zn.
HM sorption kinetics was estimated from the shapes of the dynamic output curves. For Cd²⁺, Cr₂O₇^2-,
Cu²⁺, Zn²⁺ were limited by film diffusion kinetics. The dependences of the kinetic coefficients β HM of the
linear flow rate were received. The kinetic coefficients β for the anion Cr₂O^2-₇  at pH3.7 цуку significantly
lower than the corresponding data for the anion CrO^2-₄  at pH6.7. The kinetic sorption of H⁺, K⁺ were described
by the particle diffusion; the corresponding values of the particle diffusion coefficients were for H⁺-10^-8, for K⁺ - 5.10^-10 sm²/с. On the example of H⁺, Cu²⁺, Cr₂O^2-₇  ions the possibility of calculating the dynamics
of sorption on PEI–CLT from surface water with pH 3.6 was shown.