production of selected secondary metabolites in transformed ...

STUDY OF THE COPPER(II) IONS NON–STATIONARY DIFFUSION
IN HUMIC GEL
Ing. Petr Sedláček, 1 st year of study
Supervisor: doc. Ing. Martina Klučáková, PhD.
Brno University of Technology, Faculty of Chemistry, Institute of Physical and Applied
Chemistry, Purkyňova 118, 612 00 Brno, e–mail: sedlacek@fch.vutbr.cz
INTRODUCTION
Severe reduction of use of solid fossil fuels in the power–producing industry has markedly
encouraged the investment to alternative applications of these materials. Humic acids (HA),
which are one of their key components, are because of their rich natural sources, simple
isolation methods and profitable chemical ad physical behavior predetermined for the wide–
spread use in different industrial and agricultural branches. Although the intensive study of
this material lasts for several decades the knowledge level (mainly concerning the structure of
HA) is still quite low (it is often compared with the knowledge of proteins fifty years ago).
Application of HA in a form of humic gel (see [1]) is quite new and unexplored field of
their study. The gel form of HA is easy to prepare, suitable for the exploration of transport
phenomena and mainly simulates the natural conditions; HA are usually found in the highly
humid environment (water sediments, peat etc.) and thus in the swollen form.
One of most famous and promising HA properties is the ability to bind metal ions. They
can form stable complexes among others with heavy metals, which influences their toxicity in
environment and this fact encourages potential applications of humic substances mainly in
environmental industry, in the production of fertilizers and in pharmacy. Most important
binding sites in HA molecule are carboxylic and phenolic groups and aromatic cycles.
Besides the lower mobility of metal ions in humic gels comparing water solution, the
diffusion in gels are influenced also by the retention or immobilization of the ions, both
caused by chemical reaction between metals and HA. The result is that mathematical
apparatus used in the description of diffusion phenomena is very complicated.
Copper(II) ion is well–known for its high affinity to humic substances [2]. Besides this the
HA–Cu(II) binding is among the highest strengths. Therefore and also because of easy
quantification of copper content by means of
spectroscopy, the copper(II) ions has been chosen
as model metal ions for this work.
The main aim of this research was the study of
copper(II) ions diffusion from solutions with
different Cu 2+ concentration into humic gel across
the phase interface and the diffusion in the gel
itself. Other experiment interested in the influence
of other properties of the copper(II) source
solution, namely the type of anion of copper salt,
solution pH and ionic strength.
EXPERIMENTAL PART
HA were obtained from South-Moravia lignite by means of the alkaline extraction (see
[2]). Humic gel was prepared by the technique optimized in [3]: HA were diluted in 0.5 M
NaOH in the 8 g HA in 1 dm 3 Fig. 1 Humic gel sample
NaOH ratio. This sodium humate solution was acidified by
Sborník soutěže Studentské tvůrčí činnosti Student 2006 a doktorské soutěže O cenu děkana 2005 a 2006
Sekce DSP 2006, strana 223