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A study on green corrosion inhibitors for inhibiting corrosion on mild steel in oil well simulating brine

2024-06-01T00:00:00Z

Title: A study on green corrosion inhibitors for inhibiting corrosion on mild steel in oil well simulating brine Authors: Koundal, Minakshi Abstract: Corrosion causes early failure of construction materials due to degradation and destruction of the metal in contact with corrosive ions. Mild steel is widely utilized in industries such as oil and gas wells because it is inexpensive, has high strength, and is readily available. In the oil and gas exploration and production section, the corrosion cost is $1.37 billion each year. Furthermore, chloride ions present in the formation water of oil wells, which cause pitting attacks on mild steel, are the most corrosive of the ions found in oil and gas well formation waters. Literature survey revealed that less work has been carried out to inhibit the localized corrosion of mild steel in the presence of chloride ions after more prolonged exposure. The current study focused on the use of inhibitors such as surfactants (organic compounds), surfactants and ionic liquids (organic organic combination), rare earth metal salts (inorganic compounds), and rare earth carboxylate compounds (inorganic-organic combination) to inhibit the localized corrosion of mild steel in corrosive NaCl solution. Chapter 1: Introduction and Literature Review This thesis chapter covers the fundamentals of corrosion, its history, and its adverse effects on metal. Furthermore, it describes its economic influence in various industries and research studies that offer multiple methods of corrosion control. A review of the literature survey shows that application of corrosion inhibitors are mostly applied and among the least costly techniques to inhibit corrosion from pipes. The review reveals few gaps in the field of corrosion inhibition, which serves as motivation to conduct the investigation. Finally, the established research objectives were defined to steer the thesis logically. Chapter 2: Materials, Methods, and Theories This chapter comprises the amalgamation of all the materials (i) commercially available and (ii) synthesized in the lab. Also included are the methods followed in various corrosion testing, weight loss, electrochemical polarization, electrochemical impedance, etc. methods for corrosion rate identification and the associated theories. After the exposure of mild steel in NaCl solution without and with the addition of an inhibitor, the layer formed above the metal was characterized through various techniques like FESEM coupled with EDS, XRD, FTIR, and Raman i spectroscopy, which are explained in details. Further, the isotherms present the adsorbent application, which includes Langmuir adsorption isotherm. Chapter 3: Synergistic Inhibition Effect of Imidazolium Ionic Liquid and Sodium Dodecyl Sulfate (SDS) for Mild Steel in NaCl Solution This chapter investigates the effect of varying concentrations of SDS, DMImCl, and a mixture of SDS and DMImCl. Weight loss and electrochemical polarization techniques were employed to calculate the corrosion rate, and experimental results reveal that adding a mixture of 200 ppm SDS/200 ppm DMImCl inhibitors sufficiently minimizes the corrosion rate. Chapter 4: Comparison Study of Inhibition Efficiency of Cerium Nitrate with Cerium Tartrate for Mild Steel in NaCl Solution The current chapter investigates the effect of adding an organic component (tartrate) on the inhibition efficiency of cerium nitrate. This study produces cerium tartrate (CeTar) by precipitating cerium nitrate with potassium sodium tartrate (KNaTar). Weight loss tests and electrochemical testing indicated that the inhibition efficiency decreased by adding cerium nitrate. Still, the cerium tartrate inhibitor demonstrated a nearly constant inhibition efficiency for up to 30 days. Chapter 5: Investigate the Effect of Cation on the Inhibition Efficiency of Various Rare Earth Tartrates This section of the chapter investigates the effect of rare earth metals (RE- Y, La, and Nd) on the inhibitory efficacy of synthesized rare earth tartrate (RETar) compounds against mild steel corrosion in neutral NaCl solution. These compounds hinder mild steel corrosion by forming bimetallic complexes and metal oxides/hydroxides. The experimental results demonstrate that CeTar imparts the most inhibition, while YTar offers the least. Therefore, the examined rare earth metal has the following order of inhibitory efficiency: Ce>Nd>La>Y. Chapter 6: Summary and Future Prospects This chapter summarizes the significant findings of this thesis. The 3rd chapter of the thesis illustrates the efficacy of the mixture of organic compounds. The result shows that the mixture ii of two compounds synergistically inhibits the corrosion more effectively than the single components. Then, in the 4th chapter, inhibition efficacy was studied by the mixture of inorganic and organic compounds. The outcomes of these studies show that the mixture of organic and inorganic inhibitors gives more promising results than the inorganic and organic-organic inhibitors. This is because the organic and inorganic compounds follow different adsorption mechanisms. The study's findings on rare earth carboxylate compounds offer valuable insights into utilizing inhibitors in NaCl corrosive solutions for industrial applications and propose potential areas for future research in the presence of another corrosive environment in the oil well.

VARIANTS OF METHOD OF FUNDAMENTAL SOLUTIONS FOR INVERSE HEAT CONDUCTION PROBLEM

2020-06-01T00:00:00Z

Title: VARIANTS OF METHOD OF FUNDAMENTAL SOLUTIONS FOR INVERSE HEAT CONDUCTION PROBLEM Authors: Arora, Surbhi Abstract: In this study, we propose and investigate an application of the variants of the method of fundamental solutions (MFS) to the parabolic inverse heat conduction problems (IHCP). The focus lies on three schemes, in particular, application of heat polynomial based variant of MFS introduced by Malihe Rostamian and Alimardan Shahrezaee (2017); the application of energy MFS, introduced by Chein-Shan Liu and Fajie Wang (2018); and a combination study of the heat polynomial based MFS and energy MFS newly developed in this thesis. The MFS being a collocation based meshless scheme offers a great deal of flexibility in the building of novel meshfree schemes. For starters, we extend the idea of Malihe Rostamian and Alimardan Shahrezaee for two-dimensional IHCP in an anisotropic medium and for the steady state inverse heat conduction in an anisotropic medium. Next, we extend the algorithm of Chein-Shan Liu and Fajie Wang for a two dimensional inverse Cauchy problem of heat conduction. Lastly, we culminate these two schemes and introduce a novel meshfree scheme, which is tested for its efficiency and accuracy for a two dimensional IHCP set in an isotropic medium. The study also includes theoretical properties and results, along with discussions around the optimal placement of source points and numerical investigations on the efficiency and accuracy of these schemes. Owing to the illposed nature of an inverse problem, truncated singular value decomposition (TSVD) regularization in conjunction with the L-Curve criteria, for parameter determination, is used to solve the obtained ill conditioned system of equations. A list of references related to the study is also incorporated at the end of this thesis.

HINDU MYTHS IN POST-INDEPENDENCE INDIAN WRITINGS IN ENGLISH

2020-03-01T00:00:00Z

Title: HINDU MYTHS IN POST-INDEPENDENCE INDIAN WRITINGS IN ENGLISH Authors: Jhanjhnodia, Shankar Lal Abstract: While myths have been an inseparable part of human existence, the mythical stories associated with them have been recognized as the most significant tools towards comprehending the human predicament. With a critical survey and analysis of myths in general, this thesis intends to examine the nature of Hindu myths in particular and their creative employment in the writings of Bankim Chandra Chatterji, Raja Rao, Dharamvir Bharati, Shivaji Sawant, Shashi Tharoor and Chitra Banerjee Divakaruni among others. The thesis attempts a critical evaluation of the conflicting as well as complementing nature of the dichotomous and confounding relationship between Myths and Science as the two different ways of human communication. With its six distinct chapters, the present study begins with the first, the Introduction, which presents a detailed analysis of mythology as a discipline with its roots in antiquity and discusses its functions and interconnectedness with other disciplines. It examines the role of myths in giving ‗shape and significance‘ to the ideals of a given society while arguing how the ‗primitive humans‘ had been ‗myth-makers‘ even during the times as early as the Palaeolithic Era of human civilization. Through a brief and critical employment of the findings of the anthropologists and cultural theorists including Bronislaw Malinowski, Joseph Campbell and Claude Levi-Strauss among others, the thesis attempts to resolve the perceived conflict between history and mythology as two different and often contradicting concepts with their roots in the philosophical writings of Plato, a dichotomy which proceeded into the formation of strict hierarchies favouring the one over the other––history over myth––during the heydays of European colonization. In the light of arguments put forth by the mythologists including Joseph Campbell, Robert A. Segal, Claude Levi-Strauss, Bultmann among others, the chapter serves as the expository background to the ongoing discussion related to the work. The second chapter, Nation and its Narration: Mythography as Literature, discusses the role of narratives in formation the idea of ‗nation‘. In the light of the propositions of some of the important theorists including Ernest Renan, Benedict Anderson and Homi K. Bhabha among others, the chapter examines the western notion of ‗nation‘ as fraught with the risk of a gross generalization of the term. In the light of the findings of these critics, the chapter presents a discussion around the term ‗nation‘ and the act of the ‗narration‘ as an inseparable agent towards its formation and dissemination as a cultural construct. The relatively more distant yet a relevant one, the idea of ‗rashtra‘ finds a detailed critical analysis in the study as a coterminous to the idea of ‗nation‘ as an ‗imagined community‘ or even ‗spiritual entity‘. The colonization of India, like several other countries of the world, has played a significant role in i defining the concept of nation, and the chapter aptly deals with the issue while employing the ideological construct of ‗rashtra‘ as the counterpart of ‗nation‘. Further, the literary writings of ancient Indian scholars like Kalidas, Bhavabhuti and Bhasa have been juxtaposed along with creative writings of some of the contemporary writers like Maithili Sharan Gupt, Jaishankar Prasad, Bharati, Shivaji Sawant, Shashi Tharoor, Devdutt Pattanaik and Chitra Divakaruni in order to underline the formation of what we can arguably quote, a Hindu mythography. The study also discovers the role of the two Hindu epics, the Mahabharata and the Ramayana, as the metaphorical rudder and reservoir of the Indian writings. The figuratively entitled third chapter, They Write Back: Bankim Chandra and Raja Rao, aptly presents a critical evaluation of the works of Bankim Chandra Chatterji and Raja Rao and analyses them as an act of resistance against the ruling dispensation i.e. the British colonizers. In the immediate context of the country‘s Freedom Struggle, these writings carry a significant space in that they were able to influence not only the revolutionaries but also the writers of successive generations. Bankim Chandra‘s political novel Anandamath established itself as a source for inspiration to the generations of revolutionaries in their rebellion against the oppressors. Written in the backdrop of the important though lesser known Sannyasi Rebellion during the eighteenth century famines and the eventual uprising, the novel attempts to capture the contemporary scene of chaos and anarchy with the help of the myth of Goddess as Bharat Mata (Mother India). The creative employment of the myth of Goddess is intended to depict the plight of Indians, ravished by the colonial subjugators and oppressors. It can be argued that the writer attempts to establish the role of a pious deity as the protector of impoverished Indians who have been left to fend for themselves in the aftermath of the great famine caused by the faulty policies of the emperors of the day. However, the Mother India (Bharat Mata) has been aptly portrayed in tattered garbs only to symbolize the decrepit state of the nation. Similarly, Raja Rao‘s Kanthapura falls back upon the myth of Ram as saviour and connects it with the image of Gandhi as the liberator of Nation. The Freedom Struggle of the Indians finds its counterpart in the myth of exile, struggle and the final repatriation of Ram to his kingdom in Ayodhya. With a similar verbal figuration as that of the previous one, the fourth chapter entitled The Hope that Was: Myths in Post-Independence Era, examines the use of myth as a literary device to give expression to the growing disenchantment against the political system in the country. With the works of Dharamvir Bharati (Andha Yug–The Dark Ages) and Shivaji Sawant (Mrityunjaya), the two notable authors writing in Indian languages, the chapter discusses their ii works in the light of modern theories including Neo Historicism. The text and tropes used in each of these works serve to highlight the socio-political milieu prevailing during the post Independence days thus encapsulating the entire scene of rising aspirations and crashing hopes of the citizens of a newly found country marked by the scars of the Partition and the frustration of the masses. The failure of governments and the resultant disillusionment and despondency among the masses, the futility of the successive wars with the neighboring countries like Pakistan as well as the internal strife and the abysmal situation of general hopelessness finds a mythological parallel in the Mahabharata. The subaltern and marginalized voices find a creative representation in Sawant‘s novel Mrityunjaya. The fifth chapter, The Hindu Myths in Contemporary Indian Writings, analyzes the literary representation of socio-political events in the Post-emergency India. Shashi Tharoor‘s The Great Indian Novel interrogates and dismantles the Eurocentric notion of ‗history‘ as well as their historiography. Other than this novel, the chapter also analyses Chitra Divakaruni‘s The Forest of Enchantments (2019) in the light of some of the most relevant theories. While the concluding chapter, entitled Conclusion, advocates the relevance of the study in present times, it also attempts to resolve some of the basic questions and tensions that seem to have emerged during the following discussion around the theme of use of Hindu myths in Indian writings in English.

MICROBIAL INFLUENCED CORROSION DUE TO METAL OXIDIZING BACTERIA

2020-11-01T00:00:00Z

Title: MICROBIAL INFLUENCED CORROSION DUE TO METAL OXIDIZING BACTERIA Authors: Sachan, Reena Abstract: Corrosion involves the series of chemical, physical, and biological processes and leads to the destruction of materials (metals). Corrosion is a serious problem with societal and economic consequences. Microbial influenced corrosion (MIC) or biocorrosion is the result of electrochemical reactions influenced by metabolic activities of microorganisms. It is one of the major concerns in industries due to huge economic losses the industry has to bear as a result of maintenance, premature failure of the material of construction of its machinery, process equipment, and related factors. Accordingly, it has been a subject of extensive studies over the past decades. Sulfate-reducing bacteria (SRB) are well studied and highly corrosive. However, the MIC mechanism, especially by iron-oxidizing bacteria (IOB), is not yet elucidated completely. In this context, this study presents experiments performed on microbial influenced corrosion due to IOB‗s on mild steel and other allied tests so as to investigate the correlation between the extent of MIC and nature of bacteria, its biofilm through the extracellular polymeric substances (EPS) exuded by IOB strains, nature of corrosion products and the related electrochemical reactions as a key part of the mechanism for MIC of mild steel. In this research, laboratory based studies have been undertaken to investigate the corrosion behavior of mild steel in the presence of iron-oxidizing bacteria. The findings from this research will help to understand the possible mechanism of MIC. Towards this direction, efforts have been made through a series of short and relatively longer-term microbiological corrosion studies. The results from these studies are being presented in SIX (6) chapters of this thesis. Chapter 1: Introduction and review literature - This chapter introduces basic aspects of corrosion followed by details on MIC, different corrosion influencing microbes, and its proposed mechanisms. The literature survey shows various materials and industries affected by MIC. Some case studies related to MIC in different industry sectors have been described briefly. A review of the literature revealed that most of the studies on MIC are related to sulfate-reducing bacteria but very few related to MIC due to other bacteria. Out of them, metal oxidizing bacteria, namely iron-oxidizing bacteria are important bacteria to study for their microbial corrosion effects due to their wide and varied prevalence and deteriorating effect on various metal structures/industrial machinery, etc. as outlined above. v IOB are the dominant part of aerobic bacteria influencing corrosion and their metabolic activities are the main perpetrator of the deterioration of metals. However, not much literature exists related to MIC and EPS constituents of metal oxidizing bacteria. Accordingly, the work done in the present study has been described in the following given Chapters Chapter 2: Materials and Methods with the description of isolating and identifying metal oxidizing bacteria, corrosion experiments, and their set-up, other allied techniques used in the present work for analyzing the results. Chapter 3: To investigate microbial influenced corrosion in Winogradsky media due to two bacterial isolates and test their dependence on the nature of biofilm, etc. produced by them on mild steel. MIC due to the two strains has also been attempted and described (Chapter 3A, 3B, and 3C). Chapter 4: To investigate microbial influenced corrosion in nutrient broth due to two bacterial isolates and test their dependence on the nature of biofilm etc. produced by them on mild steel. MIC due to the two strains has also been attempted and described (Chapter 4A, 4B, and 4C). Chapter 5: To investigate the effect of host media, namely Winogradsky media (inorganic media) and nutrient broth media (organic media), on MIC due to bacterial isolates. Chapter 2: Materials and methods - This chapter deals with the materials and methodology used in the present study. Iron-oxidizing bacteria (IOB), isolated from the rust deposited on the surface of mild steel (ms), exposed to local river water and identified as Pseudomonas sp. strain DASEWM1 and DASEWM2. Mild steel was tested for studying MIC and its performance against corrosion. Winogradsky media and nutrient broth media were used as test solutions for corrosion studies (electrochemical tests and immersion tests). Biofilm formed on the corroded metal surface was analyzed for EPS constituents using UV-Vis spectroscopy. The extent of localized corrosion was determined by optical microscope, and the corroded steel surface was analyzed by Field Emission Scanning Electron Microscope / Energy Dispersive X-Ray Analysis (FESEM)/EDAX) techniques. Corrosion products deposited on the corroded steel surface were identified using XRD and FTIR techniques. vi Chapter 3: The microbial influenced corrosion studies on mild steel in the presence of iron-oxidizing bacteria (Pseudomonas sp. strain DASEWM1) in Winogradsky media are described in part (A) of this chapter and those due to Pseudomonas sp. strain DASEWM2 in Winogradsky media are described in part (B). The comparison of the corrosivity of both iron-oxidizing bacteria Pseudomonas sp. strain DASEWM1 and DASEWM2 in Winogradsky media is discussed in section (C) of this chapter. Part A - Corrosion behavior of steel due to iron oxidizing bacteria (DASEWM1 strain) in Winogradsky media: This chapter describes the corrosion behavior of mild steel due to iron-oxidizing bacteria (DASEWM1 strain) in Winogradsky media (inorganic media). In this work, electrochemical polarization tests, immersion tests, and surface analysis were carried out to estimate the extent of uniform and localized corrosion. Corrosion products deposited on the steel surface were identified using X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. Biofilm formed on the corroded metal surface was analyzed by UV- visible spectroscopy for the constituents of extracellular polymeric substances. Results showed that inoculated Winogradsky media accelerate the corrosion of mild steel. Uniform and localized corrosion increases with increased bacterial concentration and EPS constituents of biofilm. Higher corrosion of steel exposed to inoculated media can be attributed to the presence of wider cracks, carbohydrates of EPS, and corrosion product iron sulfite. Whereas fine cracks, absence of EPS, and protective type corrosion product iron hydrogen phosphate on steel exposed to control media may be responsible for lesser corrosion. A mechanism of microbial corrosion has been proposed considering corrosion products and pH of the solution during the corrosion test. (Work published: Sachan, R., and Singh, A.K., 2019. Corrosion of steel due to iron oxidizing bacteria, Anti-corrosion methods and materials, Vol 66 (1) pp.19-26). Part B - Corrosion of steel due to iron-oxidizing bacteria (DASEWM2 strain) in Winogradsky media: In this section, the corrosion behavior of mild steel was investigated in the presence of another IOB strain (DASEWM2) in Winogradsky media. In this part, the same methodology was used, vii as mentioned in part (a). The corrosion rate obtained by Tafel plots was higher when the concentration of sessile cells and constituents of extracellular polymeric substances were high. Lower pitting potential, repassivation potential, and the large area under hysteresis loop were observed in the cyclic polarization curves of steel exposed to inoculated media. These results indicate a higher susceptibility of steel to localized corrosion due to bacteria. Immersion tests also show a higher corrosion rate and large deep pits (open area and under crevice) on the steel surface, indicate a higher degree of corrosion in inoculated media. Corrosion products formed on the corroded steel samples were analyzed using XRD and FTIR techniques. Goethite and lepidocrocite are the main corrosion products in the case of inoculated media. In contrast, lepidocrocite and iron hydrogen phosphate are the main corrosion products in the case of control media. Absence of iron hydrogen phosphate, a protective type of corrosion product, on steel exposed to inoculated media was suggested for the higher degree of corrosion due to bacteria. (Work Published: Sachan, R., and Singh, A.K., Negi, Y.S., “Study of microbial influenced corrosion in presence of iron oxidizing bacteria (Strain DASEWM2)” in Journal of Bio and Tribo corrosion, 6:109). Part C - Comparison of microbial influenced corrosion due to iron-oxidizing bacteria (strains DASEWM1 and DASEWM2) in Winogradsky media: In this segment, a comparison of microbial influenced corrosion due to iron-oxidizing bacteria (strains DASEWM1 and DASEWM2) in Winogradsky media was investigated. It was observed that inoculated media is more corrosive than control media. The results obtained by this study show higher corrosion of mild steel in the presence of DASEWM2 strain than DASEWM1 strain. It may be due to higher carbohydrate concentration and the absence of iron hydrogen phosphates (protective) in the case of DASEWM2 strain. Chapter 4: Part A - Corrosion behavior of steel due to iron-oxidizing bacteria (strain DASEWM1) in nutrient broth media: In this chapter, the corrosion behavior of mild steel was investigated in the presence of IOB strain DASEWM1 in nutrient both media (organic media). In this work, the same methodology was adopted, as in chapter 3rd. Experimental results revealed that the degree of corrosivity depends upon bacterial concentration and the amount of EPS constituents due to which higher viii degree of corrosion is observed in the presence of bacteria. A lesser amount of vivianite (protective in nature) was observed in the case of inoculated media, which might be responsible for increased corrosion. Corrosion products deposited on the steel surface were identified using XRD and FTIR techniques. Corrosion of steel in inoculated media appears to be associated with (i) oxidation of Fe2+ to Fe3+ by bacteria, thereby resulting in a lesser amount of Fe2+ available for the formation of vivianite (ii) some Fe3+ bound to EPS thereby making available some electrons for the oxygen reduction. This overall leads to the increased alkalinity of the media. Considering all these reactions, a possible mechanism of MIC been proposed. [Work communicated (Minor revision): Sachan, R., and Singh, A.K., “Corrosion behavior of Carbon Steel in the presence of Pseudomonas sp. strain DASEWM1” in Environmental sustainability]. Part B - Corrosion behavior of steel due to iron-oxidizing bacteria (strain DASEWM2) in nutrient broth media: In this part, the corrosion behavior of mild steel due to iron-oxidizing bacteria (DASEWM2 strain) in nutrient broth media was investigated. Experimental results showed that the corrosion rate (obtained by Tafel plots) was higher when bacterial (sessile cells) concentration and EPS constituents were high. In the case of inoculated media, lower pitting potential, and repassivation potential was observed with increasing incubation time. Higher corrosion rate and deep pits on the carbon steel surface were observed in the case of inoculated media. Corrosion of steel in inoculated media appears to be associated with (i) oxidation of Fe2+ to Fe3+ by DASEWM2 strain, thereby resulting in a lesser amount of Fe2+ available for the formation of vivianite (ii) more anionic functional groups of EPS (higher concentration of carbohydrates) bind with ferric ions and making available some electrons for the oxygen reduction. Part C - Comparison of microbial influenced corrosion due to iron-oxidizing bacteria (strains DASEWM1 and DASEWM2) in nutrient broth media: Part c of this chapter describes the comparison of microbial influenced corrosion due to iron- oxidizing bacteria (strains DASEWM1 and DASEWM2) in nutrient broth media. This study presented the co-relation of extracellular polymeric substances exuded by IOB strains as a key mechanism for MIC of mild steel. A comparative study using surface analysis, electrochemical tests, and immersion tests in nutrient broth media revealed a higher degree of corrosion in inoculated media (strain DASEWM1