High efficiency adsorption of boron by sodium alginate/ polyethyleneimine/polysiloxane composite aerogel

In this work, a new biomass boron adsorbent of N-methyl-D-glucosamine embedded sodium alginate/polyethyleneimine/polysiloxane composite aerogel (SKPN) was reported. Relevant characterization proved that the aerogel exhibited 3D porous structure with plenty of hydroxyl and amino functional groups, which was beneficial to the diffusion of boron and the chelation between boron and SKPN. Various parameters affecting the adsorption performance including pH value, contact time initial concentration, temperature and reusability were investigated. The maximum adsorption capacity was found at pH 8.0, and the adsorption capacity reached equilibrium within 3.75-5.75 h. Adsorption kinetics were more in line with the pseudo-second order kinetic model, suggesting the predominance of chemisorption. The adsorption isotherm was more in line with the Langmuir model, and the maximum adsorption capacities were calculated up to 38.41-49.39 mg/g (3.55-4.57 mmol/g) within the temperature range of 298 to 318 K, which were higher than most of the previous works. In addition, SKPN still showed good resistance to external ion interference and good reusability. The adsorption mechanism proved that the chelation interactions between boron and cis-diol and amino groups were the main driving forces. These results instructed that the adsorbent exhibited a good application prospect for boron adsorption, with the advantages of high adsorption performance, simple preparation process and environmental friendliness.