Design of SiO2-TiO2-PAM composite flocculant with self-degrading characteristics and optimization of the flocculation process using a combination of central composite design and response surface methodology

Nowadays, the polymer flocculation technology has been widely used in the treatment of oil sand tailings pollutants. However, the most commonly used polyacrylamide flocculant has encountered some problems, such as low flocculation efficiency and severe secondary pollution. In this paper, an organic-inorganic composite high-efficiency flocculant with self-degradation was designed and prepared. Furthermore, in order to analyze the synthesis mechanism of the composite material, the functional groups of the material were investigated by Fourier transform infrared spectroscopy (FTIR). At the same time, the morphology and structure were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Meanwhile, the crystal structure was recorded by XRD. In addition, the flocculation efficiency of the composite flocculant was determined by measuring the turbidity removal of the kaolin suspension. Apart from this, the flocculation parameters were optimized by central composite design (CCD) experimental design and response surface methodology (RSM). Finally, the self-degrading property of the flocculant was tested under light conditions. The characterization data of the material indicated that the synthesis mechanism is that under the ultraviolet light condition, the acrylamide monomer undergoes free radical polymerization under the action of active free radicals on the surface of the core-shell structure SiO2-TiO2 to form an organic-inorganic composite flocculant. In addition, the optimized experimental results showed that the optimal turbidity removal conditions were followed: V-TBOT/M-SiO2 of 6.66 mL/g, flocculant dosage of 50 ppm and kaolin suspension concentration of 1.5 wt%. Ultimately, the degradation experiment showed that the prepared organic-inorganic composite flocculant has nice self-degradation performance, and the self-degradation efficiency reaches over 90% within two hours. In summary, this work has greatly enriched the knowledge of oil sand tailings treatment.