A combination of citric acid-dopamine-epichlorohydrin polymer and linear carboxymethyl β-cyclodextrin-epichlorohydrin polymer as an eco-friendly scale inhibitor in artificial seawater

Currently, reducing the formation of calcium scale is an important challenge for seawater utilization in the cooling water system of offshore oil and gas platforms. The combination of linear carboxymethyl β-cyclodextrin-epichlorohydrin polymer (L-CM-β-CD-EP) and citric acid-dopamine-epichlorohydrin polymer (CA-DA-EP) as an eco-friendly scale inhibitor was studied by the static experiments. We observed that L-CM-β-CD-EP/CA-DA-EP displayed excellent scale inhibition efficiency of 94.6 % and 92.5 % against CaCO3 and CaSO4, respectively, at the 19.2 mg/L inhibitor (Ca2+ = CO32- = 2400 mg/L, Ca2+ = SO42- = 800 mg/L). XRD and SEM images of scale crystal exhibited that CaCO3 and CaSO4 crystals were deformed and transformed by L-CM-β-CD-EP/CA-DA-EP, which was attributed to multiple inhibition effects, including lattice distortion, chelation, and host–guest synergistic effects. More importantly, the host–guest synergistic effects of L-CM-β-CD-EP and CA-DA-EP can significantly improve the scale inhibition performance of L-CM-β-CD-EP/CA-DA-EP. Besides, the TOC results analysis showed that L-CM-β-CD-EP/CA-DA-EP possessed excellent biodegradability, low bioaccumulation, and ecotoxicity.