2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
ged, and thereby very attractive for flocculation and different
kinds of binding applications. Since most natural colloidal
particles, including bacteria and macromolecules, are negatively
charged, attractive electrostatic interactions may lead
to flocculation 1,2,4 .
Experimental
C h i t o s a n S o l u t i o n s
Chitosan is partially soluble in dilute mineral acids such
as HnO 3 , HCl, H 3 PO 4 . We have used 0.5% solutions of chitosan
TM 324 (Primex, Island) diluted in 0.1M HCl. The
solution was prepared fresh before each set of experiments
for consistency.
M e t a l - B a s e d C o a g u l a n t s
Ferric sulphate [Fe 2 (SO 4 ) 3 ] and aluminium sulphate
[Al 2 (SO 4 ) 3 . 18H2 O], supplied by Kemifloc a.s. (Přerov,
Czech Republic) or Kemwater ProChemie s.r.o., (Bakov
nad Jizerou, Czech Republic) respectively were used for the
experiments.
Fig. 2. Turbidity removal comparison between different initial turbidity levels
s393
M o d e l H u m i c W a t e r s
Tests were made with model humic water. Model water
was mixtures of distilled water, tap water and natural concentrate
of humic substances sampled from a peatbog near
Radostín. Selected model humic water parameters are given
in Table I.
Turbidity was formed by addition of bentonit. Absorbance
at 254 nm was measured in 1-cm cell and absorbance at
387 nm and at 820 nm were measured in 5-cm cell 7 .
C o a g u l a t i o n T e s t s
Coagulation test using centrifugation as the separation
method was employed. This test did allow us to study formation
of nOM particles by Brownian motion (perikinetic
coagulation) and has the highest possible degree of reproducibility
(in any place in the world) as temperature is the
only parameter influencing the kinetics of particles formation.
Aggregation time was 10 and 40 minutes. Absorbance at
254 nm, 387 nm and 820 nm were evaluated.