Modifying cellulose with metaphosphoric acid and its efficiency in removing brilliant green dye

In this study, cellulose was chemically modified through the addition of the phosphorylating agent, metaphosphoric acid in order to obtain a new material (MPCel) with higher adsorptive properties than the starting material. Both materials were characterized by infrared spectroscopy, X-ray diffraction, solid-state phosphorus-31 nuclear magnetic resonance spectroscopy and thermogravimetric analysis. Maximal adsorption capacity, at 45°C for pure cellulose, was 90.5mgg^-1, at pH=10 and contact time of 40min, with experimental isotherms better adjusted to the Langmuir model. MPCel at the same temperature conditions showed contact time of 10min, pH=10, and maximal adsorption capacity of 150.0mgg^-1, being better adjusted to the Temkin model. The kinetic study of both materials followed the pseudo-second-order model. Modification successfully occurred and both adsorbents were shown able to be capable of removing the brilliant green dye, but MPCel was more efficient for purpose, when compared to the pure cellulose.