Abstract:

Hydroxymethylated lignin/cellulose composite aerogel particles were prepared by freeze-drying with NaOH/urea aqueous solution as the solution system using hydroxymethylated lignin and cellulose as raw materials. The structure of the product was characterized by scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD), specific surface area and aperture analyzer. The results showed that the methylated lignin was attached to the cellulose skeleton by hydrogen bonding, and the aerogel still maintained three-dimensional network structure. The aerogel surface shrank significantly with the introduction of methylated lignin, and the density of the network structure gradually decreased with the increase of the content of methylated lignin. At the same time, aerogel particles had cellulose Ⅱ type infrared absorption peak and XRD diffraction peak; the particles showed Ⅱ isothermal adsorption/stripping isotherm, and the apertures were all below 15 nm, and with hydroxymethyl lignin content increasing, the specific surface area, entrance reduced, and the specific surface area of HKL-4 was 105.3 m²/g, entrance was 0.336 6 cm³/g, pore size was 13.67 nm. The adsorption performance analysis showed that the unit adsorption capacities of HKL-4 aerogel particles to auramine O, methylene blue and rhodamine B at 25℃ for 5 h were 33.06, 96.06 and 43.26 mg/g, respectively, and the saturated adsorption capacity of methylene blue was up to 208.7 mg/g. The adsorption process was more consistent with the Langmuir isothermal adsorption model, mainly monolayer adsorption.

Key words: hydroxymethylated lignin, cellulose, aerogel, adsorption