Polydentate Adsorbent Based on Flax Cellulose Modified by Hyperbranched Polyester Polybenzoylthiocarbamate

A highly efficient hybrid adsorbent has been synthesized, which is based on an industrially available biodegradable nontoxic flax cellulose modified with hyperbranched polyester polybenzoylthiocarbamate. The synthesis has been carried out using toluene diisocyanate (TDI) as a linker. The second-generation hyperbranched polyester polybenzoylthiocarbamate contains eight terminal benzoylthiocarbamate and eight hydroxyl groups according to 1 H NMR, 13 C NMR, and IR spectroscopy. In the first stage, the reaction of TDI with flax cellulose has been carried out, which provided 27% content of TDI according to potentiometric titration. The resulting modified flax cellulose has reacted with hyperbranched polyester polybenzoylthiocarbamate. The content of hyperbranched polymer in cellulose (5%) has been evaluated by the weight method. The unreacted isocyanate groups have been neutralized with isobutyl alcohol. The structure of the hybrid material has been proven by IR spectroscopy. The adsorption properties of the polydentate adsorbent have been studied with for the Cu(II) ions. It has been found that the adsorption capacity of the adsorbent is 6.93 mg/g. The methods of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been used to evaluate the temperature characteristics, thermal effects, and mass loss of the obtained polydentate compound and its complexes. Desorption of the Cu(II) and Co(II) ions with the regeneration of the hybrid adsorbent has been shown to occur in an acidic medium at pH 3–4.