3. Results and discussion
3.1. Dithizone adsorption onto silica surface
The adsorption of H2Dz onto SG and SP from chloroform, toluene, hexane and their mixtures was studied.
The best reagent adsorption was observed in the case of hexane.
The kinetics experiments have shown that the equilibrium of H2Dz adsorption onto SG and SP (0.02 g) surface from hexane solution (10 ml) was reached in 15 and 30 min, respectively.
The isotherms are represented in Fig. 1. The values of H2Dz maximum adsorption onto SP and SG were 46 and 40 mmol g−1, respectively. In the present work H2Dz-SG and H2Dz-SP with this reagent content on the surface were used.
3.2. Zn(HDz)2 adsorption onto SP surface
The adsorption of Zn(HDz)2 onto SP surface from chloroform and its mixtures with hexane was studied.
The best complex adsorption was observed in the case of mixture with the ratio chloroform:hexane=1:9.
The kinetics experiments have shown that the equilibrium of Zn(HDz)2 adsorption onto SP (0.01 g) surface from this mixture (5 ml) was reached in 5 min.
The shape of isotherm of zinc dithizonate adsorption (Fig. 1(b)) testifies the stronger complex binding with the SG surface, in contrast to H2Dz.
It is caused probably by its plane fixation. In the present work SP containing 8 mmol g−1 Zn(HDz)2 was used.