Cancrinite is the key substance that affects the adsorption effect of phosphate from red mud(RM) . Therefore, cancrinite in RM was modified to improve its adsorption performance. Based on density functional theory(DTF), this paper optimized the structure of cancrinite, the main component of red mud, modified the cancrinite with sodium dodecyl benzene sulfonate, and studied the surface wettability changes of cancrinite before and after modification through dynamics relaxation. The effects of wetting modification on the adsorption properties of cancrinite were studied by molecular dynamics simulation of radial distribution function, adsorption site , adsorption energy and mean square displacement. Research shows that modified cancrinite Surface wettability increased by 77%, also has more adsorption sites, adsorption energy is smaller, diffusion process is accelerated, so the adsorption capacity is stronger. This study lays a theoretical foundation for enhancing the adsorption of phosphate from wastewater by RM.

The adhesion of β-phosphogypsum product (M-β-PG) to mold is one of the factors affecting its mildew，and the possible structure and mechanism of the interaction between mold adsorbed on M-β-PG surface remain unclear. From the point of view of the interaction between the main biomolecular (Z) on the surface of mold cell wall and the main component of M-β-PG gypsum (G), the adsorption characteristics and interaction mechanism of Z on G surface were studied by means of molecular simulation and experiment. Using X-ray diffraction, gypsum phase composition analysis, X-ray fluorescence spectroscopy, scanning electron microscopy, microbial diversity detection and other tests, the object of molecular simulation modeling was determined. By analyzing the fourier infrared spectroscopy (FTIR) functional group test, the geometric optimization, the band structure and the density of states calculated by quantum mechanics; the adsorption heat, interaction energy, adsorption isotherm, adsorption bond length and mean square displacement calculated by molecular mechanics, the interaction mechanism between G and Z is studied. The results showed that the adsorption occurred primarily between the hydroxyl and carboxyl O atoms and amino N atoms of Z and Ca, S and H atoms in G. The forms of interaction were hydrogen bonding and van der Waals force interaction, which belonged to physical adsorption. On the surface of G, the most and least adsorbed were β-glucan and galactosamine, respectively, whereas the strongest and weakest adsorbed were galactomannan and galactosamine, respectively. This study provides some indication for the interaction mechanism between mold and phosphogypsum surface.

Red mud (RM) alone as an adsorbent for phosphorus shows unsatisfactory adsorption performance. This paper studied the wettability of katoite (the main component of RM) and its adsorption of phosphate. We also analysed the adsorption law of phosphate-containing water clusters on the katoite surface from bond length changes of the unit cell, adsorption equilibrium conformation, radial distribution function, interaction energy, adsorption isotherm and adsorption heat. found that kattenite has good wettability and the adsorption of phosphate is the result of van der Waals force and hydrogen bond.