The influence of the ligands nature on the sorption of copper ions (II) by activated carbons and ion exchange resins

Abstract

At present-day industry rate of development the sustainable use of water resources is one of the most
crucial ecological tasks. The essential role in the developing water treatment technologies directed on the
removal of heavy-metal ions, copper in particular, is assigned to the sorption methods. In present work an
attempt to estimate the degree of influence of organic and nonorganic ligands nature presented in waste water
on the sorption capacity of activated carbons and synthetic ion exchange resins has been done. The investigations
were fulfilled on model systems with Cu (II) ion’s concentrations 0.01 – 10000 mg/dm3
in the presence/absence
of ammonia and EDTA. The content of Cu(II) ions in the solution has been controlled spectrophotometrically
in the presence/absence of diethyldithiocarbamate and by AAS method. As sorbents were
used activated carbon NWC and synthetic ion-exchange resin Dowex 50wx8. The kinetic and thermodynamic
characteristics of the sorption process have been observed. For mathematical description of statical equilibrium
for ion-exchange process Langmuir and Freundlich models have been used. It has been detected that in
all considered systems in the presence of ligands the decrease of holding capacity has been observed. The
degree of decrease ranges from 15 – 45%. Such difference, probably, is due to the influence of ligands and
sorbent nature on the sorbent – ligand – metal complex formation. It has been stated that the presence of ligands
leads to the sorption process rate decrease. In general, the sorption process passes in the mixed diffusion
mechanism and can be sufficiently described by the kinetic model of pseudo second order.