Green anticorrosive oilfield chemicals from seeds and leave eextracts of Griffonia simplicifolia for mild stel

See discussions, stats, and author profiles for this publication at: /publication/305503002 Green anticorrosive oilfield chemicals from seed and leave extracts of Griffonia simplicifolia for mild steel. Article July 2016 CITATIONS 3 READS 180 1 author: Some of the authors of this publication are also working on these related projects: Novel multifunctional materials for simultaneous inhibition of corrosion, scales, wax and hydrates in oil and gas production View project Ekemini Ituen University of Uyo 29 PUBLICATIONS 33 CITATIONS SEE PROFILE All content following this page was uploaded by Ekemini Ituen on 29 July 2016. The user has requested enhancement of the downloaded file. Journal of Chemistry and Materials Research Vol. 5 (3), 2016, 4557 ISSN: 2381-3628 JCMR Journal of Chemistry and Materials Research ORICPublications /jcmr Original Research Green Anticorrosive Oilfield Chemicals from Seed and Leave Extracts of Griffonia Simplicifolia for Mild Steel Ekemini B. Ituen1,2, *, Onyewuchi Akaranta2,3, Abosede O. James3, Shuangqin Sun1 1 Materials Physics and Chemistry Research Laboratory, China University of Petroleum, Qingdao. 2 African Centre of Excellence in Oilfield Chemicals Research, Institute of Petroleum Studies, University of Port Harcourt, Nigeria. 3 Department of Pure and Industrial Chemistry, University of Port Harcourt, Nigeria. Received 29 April 2016; accepted 15 June 2016 Abstract Extracts from Griffonia simplicifolia (EGS) were investigated as eco-friendly alternative oilfield chemical for protection of mild steel (MS) surface in corrodible fluids associated with petroleum production. Corrosion rate was calculated in both 1M HCl and 15% HCl with and without different concentrations of the seed (SEGS) and leave (SEGS) extracts using gravimetric and electrochemical measurements. The extracts function as mixed type inhibitor and by spontaneous physical adsorption mechanism. Results from FTIR, UV-visible, SEM-EDS support possible involvement of O and N sites in adsorption by formation of surface complex protective film of EGS molecules within 60 days effective shelf life. Keywords: Acid corrosion, Adsorption, Corrosion inhibitor, EIS, EFM, Griffonia simplicifolia, Oilfield chemicals, SEM-EDS. 1. Introduction Production of hydrocarbons requires the use of a number of chemicals referred to as oilfield chemicals. When existing wells deplete, the use of chemistry to maintain production through well stimulation and enhanced oil recovery operations, becomes very crucial. Oilfield chemicals also include those used as additives for the drilling mud, fluid loss additives, clay stabilizers, lubricants, biocides, corrosion inhibitors, scale inhibitors, gelling agents, filter cake removal agents, hydrate control agents, cement additives, etc. Many fluids such as fracturing, flooding, stimulation, and pickling contain acid which stimulates corrosion of associated metallic materials. * Corresponding author: E-mail address: (Ekemini B. Ituen). All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of ORIC Publications, . Steel corrosion is a major industrial problem because steel is used as structural material for production, transport, storage, etc. Since corrosion gulps a major part of production cost in the oil and gas industry, corrosion inhibitors are an important class of oilfield chemicals 1. The National Association of Corrosion Engineers (NACE) estimated the direct cost of corrosion in U.S.A. at $276 billion in 1998 which was approximately 3.1 % of the gross domestic product (GDP) but exceeded $1trillion in 2012 2. Globally, the annual cost of corrosion worldwide has been estimated at $ 2.2trillion (2010), believed to have been roughly 3% of worlds GDP 3. According to Obot 3, such funds could have been channeled to providing food for the poor as part of the Millennium Development Goals (MDGs), hence the need for something to be done to control corrosion and cut down the associated cost. The use of corrosion inhibitors has been considered an easy and cost effective approach to combating oilfield corrosion. They can be used as additives in drilling, acidizing, fracture, stimulation, and enhanced oil recovery fluids which contain corrodible agents like acid (HCl), water and carbon (iv) oxide 4 to reduce the rate of corrosion. In the selection Online available since 2016/ July /26 at (2016) Copyright ORIC Publications 46 Ekemini B. Ituen et al. / Journal of Chemistry and Materials Research 5 (2016) 4557 of the corrosion inhibitor, important factors such as sources and cost of raw materials, its chemistry, and environmental impacts, are considered. Plant biomasses afford cheap, sustainable and eco-friendly source of corrosion inhibitors. However, it has been claimed that they degrade easily at high temperature and cannot be stored for long (i.e. they have short shelf life) 5. The effects of temperature on the effectiveness of some corrosion inhibitors derived from plant materials have been demonstrated in some reports 613. Nevertheless, the shelf life within which these extracts can remain efficient has not been reported in literature. In this paper, we report results of our investigation of EGS as alternative eco-friendly anti-corrosive oilfield chemical for inhibition of mild steel corrosion for the first time. The effectiveness and efficient shelf life of EGS is estimated. Experiments were simulated in acid solutions with different corrosive strengths to estimate its suitability in different oilfield fluids from the less aggressive to highly aggressive acidizing and stimulation fluids. The corrosion process was monitored by weight loss and electrochemical (EIS, PDP, LPR and EFM) techniques; surface morphology of the protected metal was characterized using SEM/EDS and the corrosion products using UV/VIS and FTIR spectroscopy. Hydrochloric acid is the most frequently used acid in the field, which informed our choice. The choice of concentration of 15% was particularly motivated by its application in acidizing fluids. In most parts of Nigeria, Griffonia simplicifolia (see Fig. 1) is not edible; hence using it for production of corrosion inhibitors would not compete with food. The plant is rich in various alkaloids like 5-hydroxytryptophan, melatonin, fluvoxamine, amitriptyline, griffonin, clomipramine, 5-hydroxytryptamine, etc 1416. These alkaloids contain potential adsorption sites like nitrogen, oxygen, multiple bonds and aromatic systems, which are key active functionalities present in many efficient industrial organic corrosion inhibitor molecules 1721. 2. Experimental procedure 2.1. Materials Mild steel used for this study was purchased from construction materials market in Uyo, Akwa Ibom state of Nigeria. Mature seeds and leaves of the plant were harvested in large quantities from a local forest in Ikot Ambon Ibesikpo, Uyo, Nigeria. Some of the materials used in the study are given in Table 1. 2.2. Preparation metal specimens surface Mild steel sheet was mechanically press-cut into coupons of sizes 4cm x 4cm and 1cm x 1cm for weight loss and electrochemical measurements respectively. The surface was treated as provided by NACE Recommended Practice RP- 0775 and ASTM G-1 Counter platinium electrode; Working mild steel UV/VIS 756PG Spectrum, Shanghai Spectrum Instruments Co., Ltd FTIR TENSOR II SEM/EDAX AMETEX S4800 EDAX TSL Ekemini B. Ituen et al. / Journal of Chemistry and Materials Research 5 (2016) 4557 47 and weighed coupons in acetone and allowing to air-dry, they were used immediately for experiments. In addition, coupons for electrochemical study were abraded with different grades of silicon carbide papers; one exposed surface area (about 1cm2) was finished to mirror surface using CC-3000 electro- coated grade paper. 2.3. Preparation of EGS and test solutions The corroding media were simulated using both 15% HCl and 1M HCl prepared by diluting 37 % stock solution in distilled water. The leaves and seeds of Griffonia simplicifolia (Fig. 1) were washed convincingly in distilled water and air- dried. The dried samples were grounded to powder and extrac- ted in acetone by maceration, percolation and infusion 22. Appropriate weights of the extract corresponding to concentrations 100, 500 and 1000 ppm were prepared in 1M HCl while 1000, 5000 and 10000 ppm were prepared in 15% HCl. Distilled water was used for all solution preparations. 2.4. UV-visible spectroscopic technique The UV-vis spectrum was first obtained using the solution containing 1000 ppm SEGS in 1M HCl prior to immersion of MS. Another spectrum was obtained using a solution resulting from immersing MS in 1M HCl for 24 hours. The spectral profiles were then compared. 2.5. FTIR spectroscopic technique The spectrum of the pure sample and that of the film formed on the mild steel surface after immersion (both mixed with potassium bromide) were recorded. 2.6. SEM-EDS study Mild steel coupons of size 1 cm x 2 cm were abraded to mirror finish as described above. The SEM images were recorded in the vacuum mode before and after immersion in HCl. This was repeated with a coupon immersed in HCl containing 1000 ppm EGS solution. The instrument operated at 5 kV. EDS profiles of the surfaces were also recorded. 2.7. Electrochemical measurements Electrochemical impedance spectroscopic (EIS) measure- ments were conducted at frequency of 105 to 102 Hz with amplitude AC voltage of 10 mV and open circuit delay for 30 minutes at 303 K. The voltage was set from 0.15 to +0.15 V vs. EOC at scan rate of 1 mV/s at the same temperature for potentiodynamic polarization (PDP) measurements. Linear polarization resistance (LPR) was measured at 0.20 to +0.20 V vs. EOC at 1 mV/s. Electrochemical frequency modulation (EFM) measurements were conducted at 0.1 Hz and peak voltage of 10 mV. Gamry Echem software package was used for data fitting and analyses. 2.8. Weight loss technique Pre-weighed mild steel coupons were immersed in the test solutions in the absence and presence of the EGS for required time interval maintained at 303 K in a water bath. They were retrieved, washed in mild detergent solution and distilled water, rinsed in acetone, air-dried and weighed to determine the weight loss. By denoting the initial and final weights of the coupons as w1 and w2 respectively, corrosion rate of iron, percentage inhibitor effectiveness (inhibition efficiency), WL and degree of surface coverage (), were calculated as follows: At wwR )(6.87 21 (1) b ibWL R RR )(100 (2) inh 01.0 (3) where bR and iR are the corrosion rates (mmpy) in the absence and presence of the inhibitor, is the density of iron and A is the surface area (cm2) of the metal specimens. 3. Results and discussion 3.1. Weight loss measurement The effectiveness of an anti-corrosive additive can be influenced by the medium of application. For crucial jobs like stimulation, cooling systems, drilling muds, pipelines protection, refinery units, oil storage tanks, production units and decaling treatments, the key factors that influence inhibitor performance include concentration, pH, temperature, contact time, shelf life of inhibitor and grade/metallurgy of steel material. Since it is difficult to reproduce the exact field conditions in the laboratory, weight loss experiment were used to probe these factors. In this report, we consider the influences of concentration, shelf life, and contact time of the inhibitor as well as concentration/pH of aggressive fluid. The effects of temperature and grade of steel are under investigation. 3.1.1. Effects of extract source Same concentrations of both SEGS and LEGS were invest- tigated under the same experimental conditions. SEGS provided better inhibitive effect than LEGS as can be seen in Table 2. In literature, EGS has been reported to be effective for folk medicine and health products because of the active ingredient, 5-hydroxytryptophan, 5-HTP 23,24. Chromatographic assay 48 Ekemini B. Ituen et al. / Journal of Chemistry and Materials Research 5 (2016) 4557 has also revealed that naturally occurring 5-HTP is more abundant insides and leaves extract 2527. The better performance exhibited by SEGS can be attributed to the higher 5-HTP composition than in LEGS. 3.1.2. Effects of extract concentration The effect of amount of the inhibitor solution was also investigated. Results obtained using SEGS are shown in Table 3. Corrosion inhibition efficiency increased with increase in inhibitor concentration. The 1000 ppm sample was about 34 and 28 % more efficient than 100 and 500 ppm respectively. This implies that the performance of EGS can be improved by increasing the concentration. Apart from 5-HTP, other alkaloid compounds like amitriptyline, fluvoxamine, clomipramine, phenelzine, melatonin, imipramine, hydritioerectine, 5-hydrox- ytryptamine, griffonin, trigonneline, etc, are also present in EGS 14. The anti-corrosive effect of EGS can also be attributed to the presence of these compounds because they possess electron donor functionalities (see Fig. 2) which are potential active sites for adsorption on the steel surface. The relative influence of each of these compounds on the EGS inhibitive effect is still under investigation. 3.1.3. Effects of corrodible medium aggressiveness Many field operations employ HCl of concentration up to 15 % hence the effect of concentration of the aggressive fluid was also investigated. Results (SEGS only) reveal that the extract was effective in both 1M HCl and 15 % HCl, with better effectiveness in 1M HCl. This can be attributed to sensitivity of the phyto-compounds to changes in pH. As concentration of the acid increases, less phyto-compounds of SEGS are capable of displacing initially adsorbed chloride ions and/or water molecules on the steel surface resulting in reduced inhibition efficiency. The 1000 ppm extract was about 28% less effective in 15 % HCl than in 1M HCl. To optimize this performance, its concentration was increased by ten folds and this resulted in an increase in inhibition efficiency by about 54 % as shown in Table 4. This demonstrates that SEGS can be an effective alternative corrosion inhibitor additive in well acid treatment fluids. Table 2 Weight loss results for mild steel corrosion inhibition by SEGS and LEGS Test solution Initial weight (g) Final weight (g) Weight loss (g) Corrosion rate (mpy) Inhibition efficiency (%) 1M HCl 9.83725 9.64504 0.19221 26.72 - 1000ppm SEGS 9.70883 9.65699 0.01584 2.21 91.73 1000ppm LEGS 9.87204 9.83306 0.03898 5.43 79.68 Table 3 Effect of concentration on the inhibition of mild steel corrosion by SEGS Test solution Initial weight (g) Final weight (g) Weight loss (g) Corrosion rate (mpy) Inhibition efficiency (%) 1M HCl 9.83725 9.64504 0.19221 26.72 - 100ppm SEGS 9.81401 9.75305 0.06096 8.49 68.23 500ppm SEGS 9.76215 9.73783 0.02432 3.39 87.31 1000ppm SEGS 9.70883 9.65699 0.01584 2.21 91.73 Table 4 Effects of corrodible fluid concentration on performance of SEGS as mild steel corrosion inhibitor Corroding fluid Amount of Inhibitor Initial weight (g) Final weight (g) Weight loss (g) Corrosion rate (mpy) Inhibition efficiency (%) 1M HCl 0ppm SEGS 9.83725 9.64504 0.19221 26.72 - 100ppm SEGS 9.81401 9.75305 0.06096 8.49 68.23 500ppm SEGS 9.76215 9.76215 0.02432 3.39 87.31 1000ppm SEGS 9.70883 9.70883 0.01584 2.21 91.73 15% HCl 0ppm SEGS 9.84207 8.73695 1.10512 153.94 - 1000ppm SEGS 9.76483 9.16840 0.59643 82.78 46.22 5000ppm SEGS 9.89142 9.49468 0.39674 55.27 64.10 10000ppm SEGS 9.77614 9.46063 0.31551 43.95 71.45 Ekemini B. Ituen et al. / Journal of Chemistry and Materials Research 5 (2016) 4557 49 3.1.4. Effect of contact time The performance of a corrosion inhibitor can be influenced by the duration of contact with the system. To determine this influence, the immersion tests were conducted in 1000 ppm SEGS at different contact intervals of 1 h, 5 h, 12 h and 24 h. The variation of inhibition efficiency and corrosion rate with contact time is shown in Fig. 3. The highest inhibition efficiency (which corresponds to lowest corrosion rate) was obtained at 5 hrs. Variation of inhibition efficiency with contact time followed the trend 24h d500ppm d100ppm d0ppm) which corresponds with the trend of inhibition efficiency. The Nyquist plot also produced imperfect single depressed semicircles which can be attributed to surface roughness of the mild steel 28. The single capacitive loop obtained indicates that the corrosion process is mainly controlled by charge transfer process. The shapes of the plots were similar without and with SEGS demonstrating that the presence of the extracts does not change the steel corrosion Fig. 5. Nyquist and Bode plots for inhibition of mild steel corrosion in 1M HCl by SEGS at 303K using EIS measurement Fig. 6. Electrochemical equivalent circuit model used for data fitting Table 5 Some parameters obtained from EIS technique used to monitor the inhibition of mild steel corrosion by SEGS and LEGS EIS Parameters SEGS LEGS 0ppm 100ppm 500ppm 1000ppm 100ppm 500ppm 1000ppm Rct (cm2) 102.30 385.50 1089.00 1144.00 304.20 911.30 977.00 Rs (cm2) 1.035 0.999 0.873 1.138 0.804 0.823 0.806 Y0 (106) (1sncm1) 157.70 81.62 80.50 60.20 77.52 78.00 67.90 (103) 898.50 888.60 859.90 845.00 889.30 858.40 821.10 Goodness of fit (x10-6) 351.80 683.10 999.00 720.40 347.90 894.70 38.50 n 0.572 0.566 0.547 0.538 0.566 0.546 0.523 Cdl (1010 F) 12.770 6.221 0.999 0.338 6.814 1.036 0.202 WL (%) - 73.46 90.61 91.06 66.37 86.80 87.68 Ekemini B. Ituen et al. / Journal of Chemistry and Mate