Water-soluble carboxymethylchitosan used as corrosion inhibitor for carbon steel in saline medium

Biodegradability and ecotoxicity of products used in oil industry are of great relevance and corrosion inhibitor could not be an exception. In earlier reports, chitosan and some derivatives were evaluated as corrosion inhibitors at acid pH, mainly due to polymer solubility.

Carbohydrate Polymers 205 (2019) 371–376 Contents lists available at ScienceDirect Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol Water-soluble carboxymethylchitosan used as corrosion inhibitor for carbon steel in saline medium T Ruza Gabriela Medeiros de Arẳjo Macedoa, Nívia Nascimento Marquesa, Josealdo Tonholob, ⁎ Rosangela de Carvalho Balabana, a b Universidade Federal Rio Grande Norte – UFRN, Natal, RN, Brazil Universidade Federal de Alagoas – UFAL, Maceió, AL, Brazil A R T I C LE I N FO A B S T R A C T Keywords: Carboxymethylchitosan Corrosion inhibitor Carbon steel Chlorides Polarization EIS Biodegradability and ecotoxicity of products used in oil industry are of great relevance and corrosion inhibitor could not be an exception In earlier reports, chitosan and some derivatives were evaluated as corrosion inhibitors at acid pH, mainly due to polymer solubility An eco-friendly corrosion inhibitor with water solubility in all pH range should be ideal, as well as that could act under the high salinity of oil field environment Thus, herein is presented the performance of a water-soluble carboxymethylchitosan (CMC) as corrosion inhibitor in presence of chlorides (3.5% NaCl) in 1020 carbon steel, without any addition of acid or base CMC showed good properties as corrosion inhibitor in media containing Cl−, and behaved as an anodic inhibitor CMC exhibited inhibitory efficiency of about 80% and 67%, according to Tafel curve and electrochemical impedance, respectively, which was attributed to chemisorption mechanism (ΔGads ≈ −45 kJ/mol) Introduction Crude oil, a complex mixture of hydrocarbons, is the basis for energy savings around the world In many cases, the presence of these liquid hydrocarbons may help to reduce corrosion as a result of their ability to form highly adherent films on the metal surface (Heakal, Fouda, & Radwan, 2011) However, in other cases, the presence of impurities such as H2S, CO2, naphthenic acids and chlorides can promote the corrosion of steel pipes and equipment used in the exploration, production, transportation and petroleum refining process (Ghassem Mahjani, Neshati, Parvaneh Masiha, & Jafarian, 2007; Heakal et al., 2011) The main cause of corrosion in carbon steel by pitting is related to the presence of chloride ions (Ghassem Mahjani et al., 2007), due to its aggressive nature that is attributed to its small ionic radius, which allows a greater diffusion between the monolayers formed in the metal surface Corrosion in the petroleum industry can be generally mitigated by the use of inhibitors, which are chemicals that retard the rate of corrosion of the metal (Heakal et al., 2011) In general, the chemicals used as inhibitors contain in their structure phosphonates and sulfonates, which, although efficient, have low biodegradability (Frenier & Ziauddin, 2008) Therefore, frequent use can result in damage to the environment One of the great challenges of the industry has been to develop chemicals that are environmentally ⁎ safe and effective in inhibiting corrosion under the conditions of each well The efficiency of these organic inhibitors of corrosion is related to the presence of polar functions containing S, O or N atoms, which are centers for the adsorption process In addition to these compounds, there are also polymers or macromolecules that function as good corrosion inhibitors, not only by the presence of functional groups (eOH, eCOOH, eNH2, etc.) but also by the size of the polymer chains, which favors the adsorption in the surface (Benchikh, Aitout, Makhloufi, Benhaddad, & Saidani, 2009; Darmokoesoemo, Suyanto, Anggara, Amenaghawon, & Kusuma, 2018; Eduok, Ohaeri, & Szpunar, 2018; Mobin & Rizvi, 2017; Sun, Wang, Wang, & Yan, 2018; Umoren, AlAhmary, Gasem, & Solomon, 2018) The most common corrosion inhibitor polymers are derivatives of polyamines, polyvinylamides, polyaspartates and other amino acids, polyaniline, polycarboxylates/polycarboxylic acids and polysaccharides (Tiu & Advincula, 2015) In general, corrosion inhibitor selection criteria are not limited to their chemical structure but also to their environmental impact, which should be low Due to the worldwide interest in environmental safety, the use of toxic chemicals and the operations in which they are generated have been minimized For this reason, natural products such as organic acids, vitamins, plant extract and natural water-soluble polymers have been studied as corrosion inhibitors (Bello et al., 2010; El-Haddad, 2014; Jenkins & Harris, Corresponding author E-mail address: balaban@supercabo.com.br (R.d.C Balaban) https://doi.org/10.1016/j.carbpol.2018.10.081 Received 15 June 2018; Received in revised form 23 October 2018; Accepted 23 October 2018 Available online 26 October 2018 0144-8617/ © 2018 Elsevier Ltd All rights reserved Carbohydrate Polymers 205 (2019) 371–376 R.G.M.d.A Macedo et al 2011; Umoren & Eduok, 2016) In particular, many papers have been describing the performance of chitosan or its derivatives as corrosion inhibitors and the obtained results have been considered very promising (Cheng, Chen, Liu, Chang, & Yin, 2007; Eduok et al., 2018; El-Haddad, 2013; Giuliani et al., 2018; Menaka & Subhashini, 2017; Sangeetha, Meenakshi, & Sundaram, 2016; Srivastava et al., 2018; Umoren et al., 2018; Wan, Feng, Hou, & Li, 2016) Chitosan is a polymer generally obtained by desacetylation of chitin, a polysaccharide extracted from the shells of crustaceans, exoskeleton of many arthropods and some fungi Mainly due to polymer solubility, the studies have been restricted to acid-induced conditions, mostly in sweet water However, in order to avoid poor solubility or precipitation, which would lead to inefficient inhibition, financial loss and reduction of petroleum production, oil industry requires a corrosion inhibitor water-soluble in all pH range and that could be applied under typical high salinity encountered in the field Thus, the main objective of this work is to evaluate the behavior of a water-soluble carboxymethylchitosan as a preventive inhibitor of the corrosion processes in pipelines used in the oil well installations of Brazil, considering the high salinity of 3.5% NaCl in the medium Fig (a) Polarization curves obtained with the 1020 C-steel electrode in 3.5% NaCl in the presence and absence of different concentrations of the CMC inhibitor at 25 °C and υ = mVs−1; (b) Curve of corrosion potential as a function of CMC concentration Experimental calculated the corrosion current density and corrosion rate EIS measurements were carried out using AC signals of amplitude 10 mV peak to peak at the open circuit potential in the frequency range 10 kHz a 100 mHz The electrical equivalent circuit was estimated from the EIS Spectrum Analyser software, which uses the method of complex nonlinear least squares to approximate the theoretical data of experimental The quality of the treatment of experimental data was evaluated through a parameter set to Chi-square, x2, which indicates a good approximation the smaller its value For this study, all the approaches were estimated with values in the order 2.1 Chemical and materials ¯ v = 2.28 × 104 g/mol The water-soluble carboxymethylchitosan (M and degree of carboxymethylation = 0.55) was prepared as described by Chen and Park (2003), however, with some changes The temperature was fixed at 10 °C and the water/isopropanol ratio used was 2/8 (Fig 1) The chemical composition of carbon steel used in the study is the following (weight %) C – 0.18, S – 0.05, P – 0.04, Mn – 0.85 The coupon was embedded in epoxy resin in a glass tube and the electrical count was performed through a copper wire Prior to all measurements, the exposed surface area of the electrode (0.308 cm2) was abraded with series of emery papers up to 1200 grade, rinsed with double distilled water, ethanol and dried air This was used as the working electrode during the electrochemical methods The aggressive solution used was 3.5% NaCl diluted in double distilled water Stock solution of carboxymethylchitosan (1 g/L) was prepared in double distilled water The concentration range of CMC used in this work was 10–80 ppm Results and discussion 3.1 Electrochemical measurements 3.1.1 Potentiondynamic polarization Potentiondynamic polarization curves for 1020 C-steel in 3.5% NaCl in absence and presence of different concentrations of CMC at 25 °C are shown in Fig The percentage inhibition efficiency (ε %) and the degree of surface coverage (θ), were calculated from the Eq (1) (Wang, Liu, & Xin, 2004; Zhang, Gong, Yu, & Du, 2011) 2.2 Electrochemical measurements A conventional three-electrode cell, composed of a working electrode carbon steel 1020, Ag/AgCl reference electrode and contra-electrode was used for electrochemical measures The experiments were performed in a Metrom Instrument Autolab PGSTAT 30 Potentiostat/ Galvanostat with FRA – Frequency Response Analyzer, which were held the following electrochemical techniques: Linear Voltammetry and Electrochemical Impedance Spectroscopy Initially, the electrode was preconditioned on open circuit potential (OCP) for 30 at a temperature of ± 25 °C for all trials Potentiodynamic polarization measurements were performed in a range of ± 100 mV of OCP with nearstationary scanning of mVs−1 From the polarization curve, were I ε (%) = θ * 100 = ⎡ ⎢ ⎣ corr − Icorr ⎤ ⎥ I corr ⎦ * 100 (1) Where I°corr and Icorr are the corrosion current densities in the absence and the presence of the inhibitor, respectively In Fig is possible to observe a displacement in the corrosion potential by the addition of the carboxymethylchitosan to the medium, indicating that the polymer has a strong potential for inhibition of corrosion by chloride The corrosion potential of NaCl 3.5% was −501 mV When 10 ppm of CMC was added, this potential was shifted to −484 mV And at each concentration increase, that potential was shifted to more positive regions, Fig Synthesis of carboxymethylchitosan 372 Carbohydrate Polymers 205 (2019) 371–376 R.G.M.d.A Macedo et al Table Electrochemical parameters acquired from Tafel extrapolation for 1020 C-steel processes in the absence and presence of carboxymethylchitosan, at 25 °C CMC concentration (ppm) Ecorr (mV) Icorr (μA/cm2) T (mm/year) θ ε (%) 10 20 40 80 −501 −484 −472 −467 −444 2.604 2.102 1.579 0.468 0.458 8.258e−3 4.070e−3 3.024e−3 1.501e−3 1.191e−3 – 0.507 0.521 0.818 0.855 – 50.71 52.07 81.82 85.57 reaching −444 mV at the concentration of 80 ppm This result suggests an anodic behavior From these curves, it was possible to estimate, through the extrapolation of the Tafel curve, the electrochemical parameters related to this system, such as current density and corrosion rate, which are presented in Table The obtained data indicated that the corrosion rate reduces with increasing concentration of CMC in the system, reaching times less than pure brine for the maximum concentration of inhibitor The corrosion current is also reduced with increasing inhibitor concentration, thus suggesting the formation of a protective layer that hinders the permeation of ions through the electric double layer in order to reach the metal surface Therefore, it is suggested that CMC shows a good performance as a corrosion inhibitor Table shows the electrochemical parameters that give evidences that the degree of coverage of the metal rise with increasing concentration of the CMC, suggesting a possible chemical adsorption on metal surface 3.1.2 Electrochemical impedance spectroscopy (EIS) The impedance responses of 1020 c-steel in solutions of 3.5% NaCl in absence and presence of CMC in various concentrations, at 25 °C, are represented in Fig 3, at Nyquist and Bode plots The Nyquist diagram is typical for a system of carbon steel corrosion in 3.5% NaCl solution (ElHaddad, 2014) Although it is not formed a perfect semi-circle, can be seen that the addition of CMC causes the formation of a bow more capacitive, compared to the curve of 3.5% NaCl solution, which induces an increase in diameter of the arc The intersection of the curve with the x-axis (Zr) provides data of polarization resistance, it can be said that the relationship between diameter and increase resistance to polarization is direct It is observed that the polarization resistance increases with the increase of CMC concentration The Bode curves represented in Fig 3(c) show that the addition of the inhibitor did not cause a significant displacement to a region of greater impedance when compared to the curve of the electrolyte, however a slight increase in the polarization resistance of 1020 carbon steel was observed with the increase of CMC concentration, with the highest displacement reached when using the polymer concentration of 80 ppm, which suggests a higher adsorption on the metal surface The cross of the line, which determines the slope of the curve, with Log ω = gives the electric double layer capacitance through Eq (2) (Umoren, Obot, Madhankumar, & Gasem, 2015; Wang, Liu, Bin, & Xin, 2004) |Z| = Cdl Fig Nyquist plots (a) and Bode plots (b,c) of 1020 c-steel in uninhibited and inhibited 3.5% NaCl solutions containing various concentrations of CMC, at 25 °C (2) Table Data of the load transfer resistance (Rtc) and the electric double layer capacitance (Cdl) for CMC after treatment of the experimental data It is possible to extract from this curve the data concerning the resistance of the electrolytic solution (Re) and resistance to polarization (Rp) The difference between these two provides the load transfer resistance (Rtc) The load transfer resistance (Rtc) and the electric double layer capacitance (Cdl) obtained experimentally after treatment of the data with specific software are presented in Table It is evidenced that the addition of CMC causes an increase in the transfer resistance of charge and consequently a reduction in the capacitance of the double electric layer These low Cdl values may be associated with an increase in the thickness of the electric double layer (Zhang et al., 2011), 373 Inhibitor Concentration (ppm) Rtc (Ωcm2) Cdl (μF/cm2) 10 20 40 80 67.74 110.07 117.39 146.21 210.68 0.142 0.0921 0.0871 0.0708 0.0500 Carbohydrate Polymers 205 (2019) 371–376 R.G.M.d.A Macedo et al suggesting that the inhibitor molecules adsorb at the metal/solution interface In the Bode (Log ω vs phase angle) curves for CMC at different concentrations is possible to observe the existence of two phase constants when CMC is added because the diagram shows two distinct peaks The first peak, located in the low frequency region, can be attributed to the metal/electrolyte interaction It is possible to observe that the increase in the concentration of CMC increases the phase angle, which contributes to a better protection of the metal The second peak, a region of high frequency, can indicate a higher resistance of the steel, associated to the process of adsorption of the film The maximum point of the curve is related to the polarization resistance, according to Eq (3) (Umoren et al., 2015; Wang et al., 2004) By the Eq (3), if Rp (polarization resistance) is increased and Re (solution resistance) is kept constant, θmax will increase Thus, it is observed that the concentration of 80 ppm presents greater polarization resistance and probably higher adsorption power, compared to the other concentrations, thus making the steel more protected θmáx = arctg Table Data on efficiency (ε) and degree of coverage (θ) of the CMC inhibitor obtained by extrapolation of the Tafel curve and Electrochemical Impedance, at 25 °C CMC TAFEL 10 20 40 80 EIS 10 20 40 80 C (M) θ C (M)/θ 4.386e−7 8.772e−7 1.754e−6 3.508e−6 0.507 0.521 0.818 0.855 8.6508e−7 1.6836e−6 2.1447e−6 4.1038e−6 4.386e−7 8.772e−7 1.754e−6 3.508e−6 0.384 0.423 0.536 0.678 1.1421e−6 2.0737e−6 3.2731e−6 5.1751e−6 Electrochemical technique Inhibitor kads (M−1) ΔGads (KJ/mol) Tafel EIS CMC 1.8219e6 1.2143e6 −45.666 −44.661 (3) Inhibition efficiency was computed from the electrochemical impedance spectroscopy measurements using the Eqs (4) and (5) Rtc0 Rtc (4) %ε = θ * 100 (5) θ=1− C (ppm) Table Data of adsorption constant (kads) and free energy of Gibbs (ΔGads) for the inhibitor CMC in NaCl 3.5% obtained by extrapolation of the Tafel curve and electrochemical impedance, at 25 °C Rp R e (R e + Rp) Inhibitor θ = kads C θ−1 (6) Rearranging, C =C+ θ K ads Where, Rtc° and Rtc correspond to the charge transfer resistance without and with inhibitor, respectively The impedance spectra were analyzed by fitting an equivalent electric circuit using the EIS Spectrum Analyzer Software, as shown in Fig CMC followed the same mechanism of action for all concentrations studied In this way, we have that R1 represents the resistance of the solution, CPE1 is the electric double layer capacitance, R2 is the charge transfer resistance and Ws1 is the semi-finite linear diffusion resistance (Warburg) (7) Where C is the concentration of the inhibitor and θ is the fraction of the surface covered Eq (7) provides a linearity between the values of C/θ and C Since ΔGads is the free energy of adsorption and kads the equilibrium adsorption constant, it is possible to calculate this energy through Eq (8) (Umoren & Eduok, 2016; Umoren et al., 2015) These parameters were calculated and are described in Table exp −ΔG RT 55,5 ( ) 3.2 Adsorption isotherm kads = To obtain more information on the mode of adsorption of CMC on the metal surface, the data acquired from the extrapolation of the Tafel curve and electrochemical impedance spectroscopy were tested by several models, and the best correlation was obtained with the Langmuir isotherm According to this isotherm, θ is related to concentration through Eqs (6) and (7) (Abdallah, El-Etre, Soliman, & Mabrouk, 2006; El-Haddad, 2014; Wang et al., 2004) The values of C and C/θ are represented in Table for each technique studied Fig shows the adsorption isotherms according to the Langmuir model obtained by the two experimental techniques used in the study According to the Fig 4, it is possible to observe linearity between C/θ and C for both techniques, with correlation values of 0.9902 and 0.9925 for Tafel and EIS, respectively, indicating an optimal correlation For a corrosion inhibitor to exhibit good adsorption and thus promote good inhibition, it must be adhered spontaneously to the metal surface As the spontaneity is determined by the value of ΔGads, which (8) Fig (a) Overlap of experimental and theoretical fitting of Nyquist curves, at 10, 40 and 80 ppm of CMC, and (b) proposed equivalent electric circuit for the validation of the impedance curves of the system under study R1 = solution resistance, CPE1 = electric double layer capacitance, R2 = charge transfer resistance and Ws1 = semi-finite linear diffusion resistance 374 Carbohydrate Polymers 205 (2019) 371–376 R.G.M.d.A Macedo et al groups or oxygen atoms in the hydroxyl and carboxyl groups and the empty 3d orbitals of iron atoms on the metallic surface (Fig 6) (Yoo, Kim, Chung, Kim, & Kim, 2013; Wan et al., 2016) This result indicates that the inhibitor molecules can form a protective layer at the metal/ solution interface Conclusions The water-soluble CMC is an excellent corrosion inhibitor in media of 3.5% NaCl, since the efficiency results were 85%, determined by the extrapolation of the Tafel curve, at the maximum concentration studied (80 ppm) According to data from the extrapolation of the Tafel curve, the CMC behaves as an anodic inhibitor, as the polarization curves were shifted to a region of more positive potentials The values of ΔGads obtained by the extrapolation techniques of the Tafel curve and electrochemical impedance are consistent and suggest a mechanism of chemisorption, since this energy is greater than |40| kJmol−1, which suggests a strong adsorption of the organic molecule, carboxymethylchitosan, on the metallic surface The performance exhibited under NaCl medium, coupled to the water solubility of CMC, indicates that it has great potential as corrosion inhibitor of carbon steel in oil field environment Acknowledgement Fig Langmuir model adsorption isotherm and correlation curve obtained by the extrapolation of Tafel (a) and EIS (b) for the different concentrations of CMC in 1020 C-steel and 3.5% NaCl, at 25 °C This study was financed in part by the Coordenaỗóo de Aperfeiỗoamento de Pessoal de Nớvel Superior - Brasil (CAPES) Finance Code 001 References Abdallah, M., El-Etre, A Y., Soliman, M G., & Mabrouk, E M (2006) Some organic and inorganic compounds as inhibitors for carbon steel corrosion in 3.5% NaCl solution Anti-Corrosion Methods and Materials, 53(2), 118–123 Bello, M., Ochoa, N., Balsamo, V., López-Carrasquero, F., Coll, S., Monsalve, A., et al (2010) Modified cassava starches as corrosion inhibitors of carbon steel: An electrochemical and morphological approach Carbohydrate Polymers, 82(3), 561–568 Benchikh, A., Aitout, R., Makhloufi, L., Benhaddad, L., & Saidani, B (2009) Soluble conducting poly(aniline-co-orthotoluidine) copolymer as corrosion inhibitor for carbon steel in 3% NaCl solution Desalination, 249(2), 466–474 Chen, X G., & Park, H J (2003) Chemical characteristics of O-carboxymethyl chitosans related to the preparation conditions Carbohydrate Polymers, 53(4), 355–359 Cheng, S., Chen, S., Liu, T., Chang, X., & Yin, Y (2007) Carboxymethylchitosan + Cu2+ mixture as an inhibitor used for mild steel in M HCl Electrochimica Acta, 52(19), 5932–5938 Darmokoesoemo, H., Suyanto, S., Anggara, L S., Amenaghawon, A N., & Kusuma, H S (2018) Application of carboxymethyl chitosan-benzaldehyde as anticorrosion agent on steel International Journal of Chemical Engineering, 2018 4397867 Eduok, U., Ohaeri, E., & Szpunar, J (2018) Electrochemical and surface analyses of X70 steel corrosion in simulated acid pickling medium: Effect of poly (N-vinyl imidazole) grafted carboxymethyl chitosan additive Electrochimica Acta, 278, 302–312 El-Haddad, M N (2013) Chitosan as a green inhibitor for copper corrosion in acidic medium International Journal of Biological Macromolecules, 55, 142–149 El-Haddad, M N (2014) Hydroxyethylcellulose used as an eco-friendly inhibitor for 1018 c-steel corrosion in 3.5% NaCl solution Carbohydrate Polymers, 112, 595–602 Frenier, W W., & Ziauddin, M (2008) Formation, removal, and inhibition of inorganic scale in the oilfield environment In N Wolf, & R Hartman (Eds.) 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Darmokoesoemo et al., 2018; Eduok et al., 2018; Mobin & Rizvi, 2017; Sun et al., 2018; Umoren et al., 2018) and, consequently, a corrosion inhibition efficiency of 85%, for the 80 ppm concentration of the inhibitor, since it has a high value of kads (1.8219e6) According to Hu, Zhang, Li, and Hou, (2010) and Wang et al (2004), when the absolute value of ΔGads is below 20 kJmol−1, a physisorption process occurs; and an absolute value of ΔGads above 40 kJ mol−1 indicates a chemisorption process, and between the two values there are two processes In this way, it can be inferred that the CMC follows the mechanism of chemisorption, since the values of ΔGads are greater than |40| kJmol−1 Thus, it is suggested a sharing or transfer of organic molecules to the metal surface forming a coordinate-like bond This phenomenon was confirmed by both techniques studied Literature states that the chemisorption force derives from the interaction between the lone electron pairs of nitrogen atoms of amino 375 Carbohydrate Polymers 205 (2019) 371–376 R.G.M.d.A Macedo et al inhibitors for metal substrates in different media: A review Carbohydrate Polymers, 140, 314–341 Umoren, S A., Obot, I B., Madhankumar, A., & Gasem, Z M (2015) Performance evaluation of pectin as ecofriendly corrosion inhibitor for X60 pipeline steel in acid medium: Experimental and theoretical approaches Carbohydrate Polymers, 124, 280–291 Wan, K., Feng, P., Hou, B., & Li, Y (2016) Enhanced corrosion inhibition properties of carboxymethyl hydroxypropyl chitosan for mild steel in 1.0 M HCl solution RSC Advances, 6(81), 77515–77524 Wang, H L., Liu, R., Bin, & Xin, J (2004) Inhibiting effects of some mercapto-triazole derivatives on the corrosion of mild steel in 1.0 M HC1 medium Corrosion Science, 46(10), 2455–2466 Yoo, S.-H., Kim, Y.-W., Chung, K., Kim, N.-K., & Kim, J.-S (2013) Corrosion inhibition properties of triazine derivatives containing carboxylic acid and amine groups in 1.0 M HCl solution Industrial & Engineering Chemistry Research, 52(32), 10880–10889 Zhang, J., Gong, X L., Yu, H H., & Du, M (2011) The inhibition mechanism of imidazoline phosphate inhibitor for Q235 steel in hydrochloric acid medium Corrosion Science, 53(10), 3324–3330 inhibitor for carbon steel in M HCl solution Carbohydrate Polymers, 160, 172–183 Sangeetha, Y., Meenakshi, S., & Sundaram, C S (2016) Interactions at the mild steel acid solution interface in the presence of O-fumaryl-chitosan: Electrochemical and surface studies Carbohydrate Polymers, 136, 38–45 Srivastava, V., Chauhan, D S., Joshi, P G., Maruthapandian, V., Sorour, A A., & Quraishi, M A (2018) PEG-functionalized chitosan: A biological macromolecule as a novel corrosion inhibitor ChemistrySelect, 3(7), 1990–1998 Sun, H., Wang, H., Wang, H., & Yan, Q (2018) Enhanced removal of heavy metals from electroplating wastewater through electrocoagulation using carboxymethyl chitosan as corrosion inhibitor for steel anode Environmental Science Water Research & Technology, 4, 1105–1113 Tiu, B D B., & Advincula, R C (2015) Polymeric corrosion inhibitors for the oil and gas industry: Design principles and mechanism Reactive & Functional Polymers, 95, 25–45 Umoren, S A., AlAhmary, A A., Gasem, Z M., & Solomon, M M (2018) Evaluation of chitosan and carboxymethyl cellulose as ecofriendly corrosion inhibitors for steel International Journal of Biological Macromolecules, 117, 1017–1028 Umoren, S A., & Eduok, U M (2016) Application of carbohydrate polymers as corrosion 376 ... and testing of scale inhibitors Chemical Engineering, 118(4) Menaka, R., & Subhashini, S (2017) Chitosan Schiff base as effective corrosion inhibitor for mild steel in acid medium Polymer International,... Du, M (2011) The inhibition mechanism of imidazoline phosphate inhibitor for Q235 steel in hydrochloric acid medium Corrosion Science, 53(10), 3324–3330 inhibitor for carbon steel in M HCl solution... behavior of a water-soluble carboxymethylchitosan as a preventive inhibitor of the corrosion processes in pipelines used in the oil well installations of Brazil, considering the high salinity of 3.5%