Synthesis Of Humic Acid Graft Copolymer And Its Scale And Corrosion Inhibition Properties

Humic acid is a cheap,safe,non-toxic and abundant material.It is rich in function groups,like hydroxyl,carboxyl,amino,ether and benzene rings.Therefore,it should have a good inhibition performance of scale and corrosion after modification.In this paper,two kinds of monomer were synthesized and characterized,and these monomers were grafted with sodium humate,epoxy succinic acid,etc.to obtained three kinds of humic acid graft copolymer,and it scale inhibition and corrosion inhibition have been researched.The mainly research results are as follows:(1)The 3-(acrylamidomethyl)-2-hydroxy-5-sulfobenzoic acid(recorded as SAM)w hich contains a double bond was synthesized by sulfosalicylic acid,acrylamide and for maldehyde.Then,N-vinylpyrrolidone(NVP),phosphorous acid(H3PO3),phosphorus ox ychloride(POCl3)as a reaction raw material to obtain a monomer Sodium(2-(diethyla mino)-1-vinylpyrrolidin-2-yl)phosphonate(recorded as MVP)which has double bond.Fi nally the structure of SAM and MVP was characterized by FT-IR and NMR 1H spectr a.(2)The balck copolymer HA-g-SAM(i.e.HS-01)was synthesized by sodium humate and SAM.The HA-g-SAM-PESA polymer(i.e.HS-02)was synthesized by SAM,epoxy succinic acid(ESA)and sodium humate.Finally,the HA-g-MVP-PESA(i.e.HS-03)polymer,was synthesized by MVP,ESA and sodium humate.The structure of three kinds of graft copolymers was characterized by FT-IR and NMR 1H spectra.(3)According to the performance evaluation standard of anti-scaling agent for oilfield(SY/T 5673-93),the inhibition performance of CaCO3 and CaSO4 of three kinds of humic acid graft copolymers were evaluated by static test.The results showed that the scale inhibition efficiency of CaCO3 and CaSO4 were 73.0%and 80.1%,respectively,at the constant temperature was 70? when the dosage of HS-01 was 800 mg/L.When the dosage of HS-02 was 400 mg/L,the scale inhibition efficiency of CaCO3 and CaSO4 were 84.5%and 88.2%,respectively.When the dosage of HS-03 was 400 mg/L,the scale inhibition efficiency of CaCO3 and CaSO4 were 83.6%and 86.7%,respectively.(4)The Micro-morphological scanning of CaCO3 and CaSO4 deposits were performed by SEM and the crystal phase were analyzed by X-ray diffraction.The result showed that three kinds of graft copolymers can block the normal growth of CaCO3 and CaSO4 crystals,and lead to lattice distortion and deformation,thus it can prevent the formation of scale effectively.(5)According to the Technical specifications and evaluating methods of corrosion inhibitors for oiled profucted water,the corrosion inhibition performance of the three-graft copolymer was evaluated by static weight loss method and electrochemical test.The results show that HS-01 and HS-02 have poor corrosion inhibition performance on N80 steel sheets,and the corrosion inhibition efficiency was 50%.When the dosage of HS-03 was 1200 mg/L,the corrosion inhibition efficiency of N80 steel sheet reached above 80%at 60?.This data is consistent with the fitting data obtained by electrochemical polarization curve and AC impedance diagram.(6)The SEM and EDS was used to analysis the surface topography and elements of N80 steel in different corrosion media.The result showed that the surface of the N80 steel sheet has many corrosion marks and more pitting without HS-03.The surface is smooth and has no obvious pitting after adding HS-03.The EDS showed that HS-03 adsorbs on the surface of the N80 steel sheet to form a film,which plays an important role in corrosion inhibition.