Investigation of biodegradable surfactant as a corrosion inhibitor to the cold rolled steel in the membrane separation device process.

[Display omitted] • The biodegradable surfactant-dodecyl dimethyl betaine (BS-12) was used as metal inhibitor. • Traces of BS-12 (10 mg·L−1) showed high inhibition efficiency (95.3 %) to cold-roll steel (CRS). • The MD simulations showed that the BS-12 adsorbed on the CRS surface horizontally. • The density of state proved that the electron transfer within BS-12 and CRS. • Adding BS-12 had no side effect on the performance of the nanofiltration membrane. The membrane process is an effective way to realize resource reutilization. Most membrane devices are made of cold-roll steel (CRS), which is easy to corrode when operating in acid conditions. Herein, the biodegradable surfactant dodecyl dimethyl betaine (BS-12) was used as the inhibitor to protect the CRS in the trichloroacetic acid (TCA) solution. The long-term stability membrane tests showed that adding BS-12 will not harm the membrane performance. The weight loss experiments proved that adding BS-12 with trace amount (10 mg·L−1) endowed the CRS with good inhibition efficiency (95.3 %). The electrochemical tests indicated that the mixed inhibitor- BS-12 works by inhibiting the anode and cathode simultaneously, and the polarization resistance increased to 21 times. The SEM, AFM, and CLSM tests proved that adding BS-12 enabled the CRS surface to remain stable. The FTIR and XPS tests proved that BS-12 adsorbed on the CRS surface via physical and chemical adsorption. The theoretical calculations proved the horizontal adsorption of BS-12 on the CRS surface and the existence of the electron transfer within the BS-12 and CRS. The BS-12 showed great potential in the CRS inhibition of the membrane separation and purification processing. [ABSTRACT FROM AUTHOR]