Preparation And Properties Of Hydrophobically Associated Cationic Starch-nano-SiO 2 Composite Flocculant

With the continuous development of prospecting and exploitation in oil and gas field, the environmental pollution and formation damage due to the drilling wastewater is becoming more and more prominent, which seriously restricts the rapid development of oil and gas industry. As the main additive in drilling wastewater treatment, the properties of the flocculant were directly related to flocculation efficiency. With the excellent flocculability, the cheap and abundant raw materials and the biodegradability as the starting point, this study designed and synthesized a hydrophobically associating cationic starch-nano SiO2 composite polymer flocculant CSSADD.The hydrophobic monomer dimethyl hexadecyl (2-methylacryloylamide propyl (DHAB) was prepared by quaternization reaction, using amino propyl intermediates dimethyl aminopropyl methacrylamide (DMAPMA) and cetyl bromide, then the chemical structure of DHAB was demonstrated by IR and 1HNMR; Then the CSSADD was synthesized by aqueous solution polymerization using soluble starch, the functional cationic monomer DMDAAC, hydrophobic monomer DHAB and nano-SiO2, and the optimum synthesis condition was selected by single factor and orthogonal experiments referring to the industry standard evaluation method:the graft monomers molar ratio was n(AM): n(DMDAAC):n(DHAB)= 84.6:15:0.4, theNa2SiO3 and starch quality ratio scale was 1:3, the starch and monomers quality ratio scale was 1:4.5, the mass of initiator was 0.5%of total monomers, the reaction temperature was 70?, the reacting time was 6 hours. And then the chemical structure of CSSADD was characterized by IR, XRD, TG and SEM.With the decreasing rate of absorbance of the simulated water as the index, the investigation reviewed the factors influencing the flocculability by single factor experiment, the study found that when the flocculant dosage was 4mg/L, acidity control in pH value was 6, flocculating temperature was 55?, subsidence time was 0.5h, the decreasing rate of absorbance can reach 95.9%, and the experimentation was further analyzed to explore the flocculate mechanism of CSSADD preliminary.Then the product was used in drilling waste-water from PetroChina Huabei Oilfield Company treatment, we found that under the same test conditions, the flocculability of CSSADD including settling velocity, the water content of solids, the upper transparent rate, the solids removal rate, organic matter removal rate, oil removal rate and CODCr removal rate was better compared with PAM, SSAD, CSADD and CSSAD.