Synthesis, properties, and application of a graphitized magnetic carbon composite made from FeCl3-activated flax shive

Magnetic graphitized materials were synthesized in the temperature range T = 600–1000° With the method of single-stage pyrolysis of microcrystalline flax cellulose (MCC) modified with citric acid and homogeneously impregnated with FeCl3. The modification of the MCC with citric acid and the use of FeCl3 as a graphitization catalyst reduces the graphitization temperature from 800 to 600 °C and increases the degree of graphitization to 95%. Morphological and physicochemical properties of carbon composites were studied by scanning electron microscopy, infrared spectroscopy with Fourier transform, low-temperature adsorption-desorption of N2, X-ray diffraction analysis and zeta potential. A possible mechanism of pyrolysis of the cellulose matrix has been established by thermogravimetry. The carbon composite obtained at 700 °C has the highest adsorption capacity of the dyes methylene blue (МВ) and methyl orange (МО) was 127.4 mg/g and 23.7 mg/g, respectively. MO molecules have a monolayer character of the adsorbent surface coating, and for MВ, the character of the adsorbent surface coating depends on the pyrolysis temperature. It is established that the physical adsorption of dyes is due to the interaction between delocalized graphite π-electrons and free electrons in the aromatic rings of dye molecules, electrostatic and adsorption interactions. The resulting composites may be potential candidates as dye adsorbents for wastewater treatment.