heavy metals, dyes or surfactants, a standard protocol of adsorption
was developed. Samples of aqueous solutions with the corresponding
pollutants (Zn2+,MB or CTAB) were put into 100 mL-flask under
strict thermal control. A fixed amount of tanningel was added to
each flask (20 mg) with different volumes of contaminated aqueous
solutions. Kinetic data were obtained in previous researching
stages (data not shown) and they supported the equilibrium period
of 2 weeks. Magnetic stirring was applied and the concentration of
the model compound before and after the trial were determined.
Metal concentration analysis was carried out by a spectrophotometric
method [36] while dye concentration was determined by
direct visible spectrophotometric measure at 665 nm. CTAB was
determined according to a non-extracting method referred in previous
literature [37].
An HELIOS UV/vis spectrophotometer was used for all the measures.
PANREAC supplied all the reagents in analytical grade.