Flocculation of sodium alginate combined with AlCl3/PAC on fine calcite: An in-situ experimental and calculation study

In this study, in-situ flocculation kinetics tests, fourier transform infrared spectroscopy and DFT theoretical calculation were used to analyze flocs properties of calcite flocs under combination of sodium alginate and AlCl 3 /polyaluminum chloride (PAC) and their adsorption mechanism. The results showed that the average size of calcite flocs treated with AlCl 3 -sodium alginate was smaller than that of flocs treated with PAC-sodium alginate. The number of residual fine particles in the slurry treated with AlCl 3 -sodium alginate was more than that in the slurry treated with PAC-sodium alginate. However, the fractal dimension of calcite flocs treated with AlCl 3 -sodium alginate was larger than those treated with PAC-sodium alginate. The sodium alginate and Al 3+ could form chemical adsorption on the calcite surface. AlCl 3 has a higher content of Ala than PAC. Ala could form chemical adsorption between sodium alginate and calcite, resulting in a high strength and fractal dimension of calcite flocs. Alb and Alc was not easily able to form metal bridges between calcite and sodium alginate. The sweep effect of PAC and sodium alginate leads to the formation of large-sized flocs. This work can promote the supplication of sodium alginate as a green flocculant.