Tetrakis hydroxymethyl phosphonium sulfate (THPS) with biopolymer as strategy for the control of microbiologically influenced corrosion in a dynamic system

Abstract In this study, satisfactory efficacy was found from the combination of the biocide THPS with the xanthan biopolymer for the control of microbiologically influenced corrosion in SAE 1010 carbon steel. The effectiveness of this combination was compared with three systems: without treatment and using THPS and xanthan in isolation. The experiments were carried out in a turbulent flow looping, in which the circulating medium was seawater. Quantification of microbial groups, corrosion rate measurements through mass loss, quantification of biomass and extracellular polymeric substances (EPS) of the biofilm were performed. The biofilm on the coupons was analyzed using the scanning electron microscope (SEM), and X-ray diffraction (XRD) was used to identify the crystallographic phases of the corrosion products. The results showed that, even with low concentration of xanthan added, the THPS + xanthan system had a greater reduction of microbial groups in relation to the other systems. This combination also reduced biomass and extracellular polymeric substances. Despite the presence of grooves, SEM indicated that xanthan forms a more adherent film on steel due to its dispersant property. And, finally, the lepidocrocyte phase was not found in the corrosion products from systems with THPS, whereas mackinawite phase was found.