Preparation And Properties Of Cationic Acrylamide-Nanoparticle Composite Flocculant

The development of unconventional oil and gas resources is an important way to ensure China’s oil and gas security.Hydraulic fracturing is a key technology for unconventional oil and gas development,but it consumes a lot of water and produces a lot of fracturing flowback fluid.Treatment of fracturing flowback fluid is the key to improve the economic benefits of unconventional oil and gas development.Cationic polyacrylamide flocculant is a commonly used chemical flocculant in water treatment at present.It has the advantages of high efficiency,economy and energy saving.The combination of cationic polyacrylamide flocculant with nanoparticles can greatly improve the flocculation effect and has a wide application prospect in the field of water treatment.This paper is mainly divided into the following three parts:Cationic polyacrylamide flocculant（CPAM）was synthesized in ammonium sulfate aqueous solution with acrylamide（AM）and methylacryloyl ethoxy trimethylammonium chloride（DMC）as monomer,PDMC as dispersive stabilizer,ammonium persulfate（APS）and sodium bisulfite（RH）as initiator.Fourier infrared spectroscopy was used to characterize the successful preparation of CPAM.The effects of molecular weight and dosage of dispersion stabilizer,salt concentration,initiator dosage,monomer mass ratio and monomer mass on CPAM polymerization were investigated by single factor method to determine the optimal reaction conditions.The highest relative molecular weight of CPAM was 4.13×106.And the stability,fluidity and solubility are good.On the basis of the first part,the water dispersion polymerization method was used to introduce the nano-SiO₂ modified by KH570 to prepare CPAM-SiO₂-KH570composite flocculant.FT-IR and SEM analysis proved that SiO₂-KH570 was successfully introduced into CPAM,and the influence of the amount of SiO₂-KH570 on the flocculating effect of CPAM-SiO₂-KH570 composite flocculant was investigated.When the amount of SiO₂-KH570 accounted for 12%-14%of the monomer,the flocculating effect of composite flocculant was the best.The Zeta potential of the two flocculants was tested at different p H.With the increase of p H,the potential decreased,and the flocculation effect was better under acidic condition.Kaolin suspension was used as simulated sewage,and the self-made CPAM/CPAM-SiO₂-KH570 flocculant was used in the flocculation experiment.The influence of dosage,p H and temperature on the flocculation effect was explored.It was used to treat the fracturing flowback fluid produced in shale gas exploitation,and the light transmission rate after treatment was 98.9%.The results show that the flocculation effect of composite flocculant is better than that of traditional CPAM flocculant.