Synthesis and study of composite materials based on apple pectin and copper cations

The paper presents the results of synthesis the metal-composite materials based on apple pectin and divalent metal cations - Cu2+; determining the degree of esterification and the content of free carboxyl groups of the native pectin by acid-base titration, determining the degree of inclusion of the specified cation in the polysaccharide macromolecule and studying by IR spectroscopy and fungicidal activity of native pectin and copper complexes against Penicillum sp According to the results of titration, it was found that apple pectin has a high degree of esterification (DE = 50.7%) and a low content of carboxyl groups (Kc = 2.79%), which suggests its low gelling activity. It was found that the increase in salt concentration is above 0.005 g-eq/l. leads to a decrease in the proportion of the resulting water-soluble complex. The optimal concentration of CuSO4 5H2O, at which the largest mass of the water-soluble complex is formed, is 0.005 g-eq/l. According to IR spectroscopy, the degree of substitution of sodium cations for copper cations was calculated, which amounted to 18%. It was shown that the native apple pectin does not have fungicidal activity, while the copper complex based on it is able to suppress the growth of the culture already under the action of 10 µl of the substance, and with an increase in volume to 50 µl, an even more active fungicidal activity of the copper complex appears.