Nanocomposites and nanomaterials 

Comparative characteristics of sorption properties of silica gels with in situ immobilized azopolymers for Cu (II), Pb (II) Cd (II) and Fe (III) ions

Savchenko1, E. Yanovska1,  D. Sternik2, O. Kychkyruk3

1 National Taras Shevchenko University of Kyiv,
60, Volodymyrska str., 01601 Kyiv, Ukraine
E-mail: iras@univ.kiev.ua
2 Maria Curie-Skłodowska University, pl. Maria Curie-Skłodowskiej 3, 20‑031 Lublin, Poland
3 Ivan Franko Zhytomyr State University, 40 Velyka Berdychivska St., 10008 Zhytomyr, Ukraine

To increase the efficiency of sorbents against transition metal ions on the surface of porous inorganic carriers, it is advisable to fix polymers with complexing properties. Previously, we synthesized and investigated the sorption properties of a number of organo-mineral composites, by in situ immobilization on the surface of mesoporous silica gels and natural macroporous aluminosilicate minerals of Ukraine, in particular with such amino- and az-containing homopolymers as poly [4- (methacryloylaminophenyl) -2-methacrylate], poly [p- (4-carboxyphenyl) -methacrylamide, poly [4-methacryloyloxy- (4'carboxy) -azobenzene], poly [4-methacryloyloxy- (4'carboxy) -3-chloro) -azobenzene] and poly [4-methacryloyloxy- (4'carboxy-2-nitro-5-methyl) -azobenzene] and poly [8-methacroyloxy-quinoline]. 
Studies of the sorption properties of the synthesized composites on Cu (II), Pb (II), Mn (II), Fe (III), Cd (II) ions showed that all synthesized composites show better sorption properties on the microquantities of the studied toxic metal ions in neutral aqueous environment compared to the original carriers. It was found that the sorption capacity of Fe (III) ions among the synthesized composites based on silica gels with immobilized azo-containing polymers is higher than that of composites with immobilized amine-containing homopolymers.
This paper is devoted to the synthesis and study of sorption properties of Cu (II), Cd (II), Pb (II), Fe (III) ions of new organo-mineral composites obtained by in situ immobilization on the surface of mesoporous silica gel of poly [5- (p -nitrophenylazo) -8-methacryloxyquinoline] (SiO2-AzoQN), poly [1-methacryl- [4 - ((E) - {4 - [(E) - (4-aminophenyl) diazenyl) -phenyl} -diazenyl) - phenyl] ethanone] (SiO2-BazoN) and poly [1-4 - (E) - {4 - [(E) - (4-nitrophenyl) diazenyl] -phenyl} -diazenyl) -phenylamine] (SiO2-BazoN). 
Immobilization of the synthesized azopolymers on the surface of silica gels was confirmed using IR spectroscopy and thermogravimetric analysis combined with mass spectroscopy. Using thermogravimetric analysis, their mass fractions in the synthesized composites were determined. From the analysis of photographs of the surface of the synthesized composites obtained by scanning electron microscopy, it was found that the polymers on the surface of silica gels are in the form of agglomerates of various shapes, covering most of the surface of the carrier particles.
As a result of research and comparison of the sorption capacity of the synthesized composites with respect to Cu (II), Cd (II), Pb (II) and Fe (III) ions, it was found that none of them showed sorption activity against Cd (II) and Pb (II) ions. However, their sorption capacity in comparison with that for the original silica gel increases significantly relative to Fe (III) ions, in particular for SiO2-AzoQN - 4.5 times, for SiO2-BazoN - 4.2 times, for (SiO2-BazoM) in - 6.4 times. In addition, in contrast to other synthesized composites, the chemical activity of SiO2-AzoQN against Cu (II) ions was recorded with an increase in sorption capacity compared to the original carrier by 5.3 times.