Research Article :
The inhibitive and adsorption properties of ethanol extract of Bryophyllum pinnatum leaves were studied using weight loss, potentiodynamic polarization, Scanning Electron Microscopy (SEM) and Fourier transformed infra-red spectroscopy (FTIR) methods of monitoring corrosion. The results obtained, indicated that ethanol extracts of Bryophyllum pinnatum leaves is a good adsorption inhibitor for the corrosion of zinc in sulphuric acid solutions. The adsorption of the inhibitor on zinc surface was found to be spontaneous and supported the Langmuir adsorption model. From the calculated values of free energy of adsorption, the activation energy and the variation of inhibition efficiency with temperature, a physical adsorption mechanism has been proposed for the adsorption of ethanol extract of Bryophyllum pinnatum leaves on zinc surface. Results from potentiodynamic polarization study indicated that Bryophyllum pinnatum is a mixed-type corrosion inhibitor. Analysis of spectra obtained from Fourier transformed infra-red spectrophotometer (FTIR) revealed that some functional groups presence in the spectra of the inhibitors were missing in the spectra of the corrosion products which also indicated that there is an interaction between zinc and the inhibitor. The consequences of corrosion
are enormous in the metallurgical
industries where metal components or their alloys are used in the fabrication
of different materials or components for engineering and other
industrial use. Zinc
metal for instance is applied in many areas some of which includes reaction
vessels, pipes, tanks, etcetera which are known to corrode invariably in
contact with various solvents. The study of corrosion of zinc is a matter of
tremendous theoretical and practical concern, and as such has received a
considerable amount of interest. Acid solutions widely used in industrial acid
cleaning, acid de-scaling, acid pickling and oil well acidizing, require the
use of corrosion inhibitors in order to restrain their corrosion attack on
metallic materials. Inhibitors are chemicals that react with the surface of a
material decreasing the materials corrosion rate, or interact with the
operating environment to reduce its corrosivity (Abiola et al, 2007). Most of
the corrosion inhibitors available are synthetic chemicals, expensive and very
hazardous to the environment.
Therefore, it is desirable to source for environmentally safe, economical,
green inhibitors (El-Etre, 2003; Bouklah, 2006; Oguzie, 2005). There has been a
wide spread research on the use of plant extracts and
their isolates as corrosion inhibitors. Hence, a vast number of natural plants
are continuously been investigated as profitable alternatives to synthetic
inhibitors because of their obvious advantages which include among other
things, their ready availability, biodegradability, non-toxicity, non-
pollutancy and eco-friendliness (Abiola et al, 2007; Eddy & Mamza, 2009;
Nwankwo, 2013; Hadi, 2015). Leave extracts of Bryophyllum pinnatum are
tested for the first time as corrosion inhibitors in this work. Hence, this
research work is aimed at investigating the inhibitive and adsorptive
properties of ethanol extract of Bryophyllum pinnatum leaves
for the corrosion of zinc in 0.1M H2SO4 which will be achieved through the
following objectives (i)
Evaluation
of corrosion of zinc in H2SO4 by gravimetric-based mass loss. (ii)
Phytochemical
composition of ethanol extract of Bryophyllum pinnatum leaves in the
chemical laboratory using various standard phytochemical screening methods. (iii)
Undertake
potentiodynamic polarization studies of the inhibition of zinc by the Bryophyllum
pinnatum leaves extract. (iv)
Using
Fourier Transform Infrared (FTIR) spectroscopy to investigate the functional
groups in the plant extract and the corrosion product. (v)
Characterization
of the test coupons before and after the corrosion tests using Scanning
Electron Microscopy (SEM). (vi)
Proposition
of model/mechanism of inhibition by the ethanol extract of Bryophyllum
pinnatum leaves from generated parameters Materials The sheets of zinc, A72357 type
used for this study were obtained from the Novara group Limited England. The
composition of the zinc metal in (% wt) as determined by quantitative method of
analysis, using Xray fluorescence spectrometer of PANALYTICAL model MagiX) is
Zn (99.548), Pb (0.004), Al (0.001), Cu (0.347), Cd (0.013), Sn (0.001), Fe
(0.001) and Ni (0.085). Each sheet was 0.4 mm in thickness and were
mechanically pressed cut into 5 x 4 cm coupons. The coupons were degreased by
washing in absolute ethanol, dried in acetone and stored in moisture free
desiccators before use. Analar grade reagents were used. These included concentrated
tetraoxosulphate
(vi) acid, ethanol and Zinc dust. The concentration of acid (H2SO4) used for
the study was 0.1M while the concentrations of the inhibitor (Bryophyllum
pinnatum) were 0.1, 0.2, 0.3, 0.4 and 0.5 g (per liter of the acid solution). Preparation of samples Bryophyllum pinnatum leaves were obtained from the Botanical garden of
Department of plant Biology, Bayero University Kano, Kano State, Nigeria. The
plant was identified with the Herbarium Accession Number BUKHAN 0014. The leaves
were washed with water; shade dried, grinded and soaked in a solution of
ethanol for 48 hours. After 48 hours, the sample was filtered. The filtrate was
further subjected to evaporation at 338K (65ºC) in other to ensure the sample
was free of ethanol. The plant extract obtained was used in preparing different
concentrations of the extract by dissolving 0.1, 0.2, 0.3, 0.4 and 0.5g of the
extract in 250ml of 0.1M H2SO4 for the gravimetric
analysis. Corrosion monitoring Weight
loss method: A previously weighed
metal (zinc sheet) was completely immersed in 250 ml of the test solution
(different concentrations of acid, inhibitors: as described in the section
above) in an open beaker. The beaker was inserted into a water bath maintained
at a temperature of 303 K. Similar experiments were repeated at 313, 323 and
333 K. In each case, the weight of the sample before immersion was measured
using Scaltec high precision balance (Model SPB31). After every 24 hours, each
sample was removed from the test solution, washed in 5 % chromic acid solution
(containing 1% silver nitrate) and rinsed in de ionised water. Potentiodynamic polarisation:
The potentiodynamic current-potential
curves were recorded by changing the electrode potential (Ecorr automatically
with a scan rate 0.33 mV s-1 from a low potential of -800 to -300 mV (SCE).
Before each run, the working electrode was immersed in the test solution for 30
min to reach steady state. The corrosion rate of the structure shall be
calculated through corrosion current density lcorr. The linear Tafel segments
of the anodic and cathodic curves obtained were extrapolated to corrosion
potential to obtain the corrosion current densities (icorr). Chemical analysis Phytochemical analysis of
ethanol extracts of Bryophyllum pinnatum leaves (EEBPL) was carried out
according to the method reported by Eddy (2009). For the identification of
saponin, frothing and Na2CO3 tests were adopted. For the identification of
tannin, bromine water and ferric chloride tests were used. For the identification
of cardiac glycodises, Lebermans and Salkowskis tests were adopted and for the
identification of alkaloid, dragendorf, Hagger and Meyer reagents were used. FTIR analysis FTIR ((Fourier Transform Infra-red) analysis of
EEBPL and those of the corrosion products (in the presence of the inhibitor)
were carried out using Cary-630 Agilent Fourier transform infra-red
spectrophotometer The analysis was carried out by scanning the sample through a
wave number range of 650cm to 4000cm-1. Scanning electron microscopy
studies A scanning electron microscope
(SEM) model JSM-5600 LV, was used to analyze the morphology of the zinc surface
without and with inhibitor added. The sample was mounted on a metal stub and
sputtered with gold in order to make the sample conductive, and the images were
taken at an accelerating voltage of 10 kV using different magnifications. Weight loss method
(Gravimetry) Figures 1 to 4 shows plots for
the variation of weight loss with time during the corrosion of zinc in 0.1 M H2SO4 containing
various concentrations of EEBPL at 303 to 333 K respectively. The plots
generally reveal that; weight loss of zinc increases with time, but decreases
with increase in the concentration of EEBPL, indicating that the corrosion rate
of zinc increases with increase in the period of contact of the metal with the
acid. The results also reveal that EEBPL retarded the corrosion of zinc in
solution of 0.1 M H2SO4 hence a good adsorption inhibitor, since the corrosion
rate decreases with increase in concentration. Comparing Figure s. 4.1, 4.2, 4.3 ad
4.4, it is evident that the weight loss of zinc
increases with increase in temperature indicating that the corrosion rate of
zinc also increases with increase in temperature. Table 1 presents values of
corrosion rates of zinc at various temperatures in the absence and presence of
various concentrations of EEBPL. The results indicated that in the presence EEBPL,
the corrosion rate is decreased, even as the concentration of the extract increases.
The trend for the decrease is presented graphically in Fig. 5. The plots
generally reveal that the decrease in corrosion rate varies with the
concentration of EEBPL. Values of inhibition efficiency of EEBPL calculated
from equation 1 are also presented in Table 2. From the results obtained, the
inhibition efficiency is seems to increase with concentration of EEBPL. This
may be attributed to the decrease in the protective nature of the inhibitive
film formed on the metal surface (or desorption of the inhibitor molecules from
the metal surface) at higher temperatures. This suggests that the mechanism of
inhibition of Bryophyllum pinnatum leaves extract for the corrosion of
zinc in solution of 0.1M H2SO4 is physical adsorption. According to Ameh (2015), a
physical adsorption mechanism is characterised with a decrease in inhibition
efficiency with temperature as opposed to chemical adsorption mechanism, where
inhibition efficiency is expected to increase with increase in temperature. The
inhibitive action of the Bryophyllum pinnatum leaves extract is due
mainly to the presence of saponins, terpenes, flavanoids, phlobatanins,
anthraquinones, cardiac glycosides and alkaloids present in the plant extracts.
These compounds contain heteroatoms such as oxygen, nitrogen or aromatic rings
with π bonds in their molecules, which serve as centres for adsorption onto the
metal surface. Table 1: Corrosion rate of zinc in the presence and absence of various concentrations of EEBPL. Electrochemical
measurement The results obtained from the
potentiodynamic polarization
(PDP) (anodic and cathodic) study for the corrosion of zinc in 0.1 M H2SO4 solution in the
presence and absence of the various concentration of the inhibitor are
presented in Figure 6. The electrochemical
parameters derived from these plots are presented in Table 3. In Table 3, the values of
corrosion current density (Icorr) also decreased in the presence of increased
concentration of EEBPL which suggests that the rate of electrochemical reaction
was reduced due to the formation of a barrier layer over the zinc metal surface
by the inhibitor (Ameh et al, 2015). The inhibition efficiency results
of the inhibitor were calculated from the corrosion current values according to
equation 5, and the values are presented in Table 3. From the values, it can be
seen that the inhibition efficiency showed a steady increase following
increased inhibitor concentration from 0.1 g/L to 0.5 g/L. This increase in
inhibition efficiency (from 0 to 89.10 %) as compared to the blank value
indicates a reduction in zinc metal corrosion rate through the formation of
adsorbed protective film against corrosion attack at the metal/electrolyte
interface (Ameh, 2015 ). Effect of temperature Temperature affects the rate of any chemical reaction
including corrosion reaction. Where CR is the corrosion rate
of zinc in solution of H2SO4.A is the Arrhenius constant or pre-exponential factor,
Ea is
the minimum energy needed for the corrosion reaction to start (i.e activation
energy), R is the universal gas constant and T is the absolute temperature. The implication of equation 7 is
that a plot of log (CR) versus 1/T should be linear with slope equals to –Ea/R and intercept
equals to ln(A). Figure 7 shows the Arrhenius plots for the corrosion of zinc in
the absence and presence of various concentrations of EEBPL. Values of Arrhenius
parameters calculated from the plots are presented in Table 4. From the results
obtained, it is evident that excellent degree of linearity (R2 ranged from
0.9922 to 0.9999) were obtained in all cases indicating the application of the
Arrhenius model to the inhibited and uninhibited corrosion reaction of zinc. Value of the activation energy
for the blank was 27.70 J/mol. In the presence of 0.1, 0.2, 0.3, 0.4 and 0.5 g
/L of the inhibitor (EEBPL), values of Ea were found to be; 36.73, 38.29, 40.54,
41.60 and 44.41kJmol-1 respectively. The inhibitor (EEBPL), thus increases the
corrosion activation energies for zinc in 0.1 M H2SO4 thereby slowing the corrosion
process. Therefore, the corrosion of zinc is retarded by the presence of EEBPL,
and the ease of adsorption
of the inhibitor on the surface of the metal increases with increasing
concentration. According to Ameh 2015, values of activation energy less than 80
kJ/mol is associated with the mechanism of physical adsorption while those more
than 80 kJ/mol points toward the mechanism of chemical adsorption. Hence the
mechanism of adsorption of EEBPL on the surface of zinc is consistent with
charge transfer from charged inhibitor to charged metal surface, which favours
physical adsorption (Eddy, 2010). Thermodynamic parameters
(including enthalpy and entropy of adsorption) for the adsorption of EEBPL on
the surface of zinc was investigated using Eyring transition state equation,
which can be expressed as follows (Eddy, 2010); From equation 4.3, a plot of
ln(CR/T) versus 1/T should be linear with slope and intercept equal to Δ𝐻𝑎𝑑𝑠0𝑅 and 𝑙𝑛(𝑅𝑁ℎ) + Δ𝑆𝑎𝑑𝑠0𝑅 respectively.
Fig. 8 shows the transition state plot for the corrosion of zinc in 0.1 M H2SO4 containing
various concentrations of EEBPL. Thermodynamic parameters deduced from the
plots are presented in Table 5. From the results obtained, R2 values are very
close to unity indicating the application of the Transition state model to the
studied corrosion reaction. Values of standard enthalpy change deduced from the
plots were found to be negative and ranged from -35.22 to -42.90J/mol. These
values are greater than that of the blank (enthalpy change for the blank =
-26.18 J/mol) and tend to increase with increase in concentration of EEBPL.
Therefore, the corrosion of zinc in H2SO4 solution is strongly retarded by EEBPL and that the
ease of adsorption of the inhibitor on the metal surface increases with
increasing concentration. On the other hand, the entropy of activation is
positive both in the absence and presence of inhibitor (EEBPL). This is an
indication that for the adsorption of EEBPL to be spontaneous, the enthalpy values should
be negative as found in the present study. The increase in entropy implies
disordering that took place in going from reactants to the activated complex.
The negative sign of enthalpy of adsorption indicated the exothermic nature of
zinc metal dissolution process. Adsorption considerations
The adsorption characteristics
of EEBPL for zinc was investigated using adsorption isotherms including
Langmuir, Fruendlich, Flory-Huggins, El awardy et al., Bockris-Swinkel
and Temkin isotherms. Fitness of the data obtained for the degree of surface
coverage reveals that Langmuir model best described the adsorption of EEBPL on
the surface of zinc. Fig. 9 shows the Langmuir plots
developed through equation 4.4, while adsorption parameters (including values
of Δ𝐺𝑎𝑑𝑠0, calculated from equation 10) deduced from the
Langmuir plots are presented in Table 6. The constant value of 55.5 is the
concentration of water in solution in mol/l.; since ΔGads are below
40kJ/mol (ΔGads threshold value), it corroborates that the adsorption
process is physisorption (Ebenso, 2004). The negative values of ΔGads indicated
spontaneous adsorption of the inhibitor on the zinc metal surface. Slope values
are seen to proximate unity, which suggest that there is little or no
interaction between the inhibitor and the metal. Excellent correlations
obtained for the different temperatures studied confirm the application of
Langmuir isotherm to the adsorption of EEBPL on zinc. Calculated values of the
free energy are within the range of values expected for the mechanism of
physical adsorption, hence the adsorption of EEBPL on the surface of zinc is
consistent with the mechanism of physical adsorption (Eddy, 2011). Figure 8: Transition state plot for the inhibition of the corrosion of zinc in 0.1 M H2SO4 by various concentrations of EEBPL. Table 7 presents the
phytochemical constituents of EEBPL. From the results, it is significant to
note that the extract studied contain saponin, terpenes, tannins, flavanoid,
phlobatanins, anthraquinones, cardiac glycoside and alkaloids. From, the
point of view of corrosion inhibition, these phytochemicals are expected to be
good corrosion inhibitors, since they contain long chain of carbon-carbon
single and double bonds having π bonds that contain π electrons for bond formation
with the zinc metal, thereby preventing corrosion of the zinc metal. Umoren et
al., (2008) have reported that saponins, tannins and alkaloids are active
constituents of most green inhibitors. Hence, the inhibition efficiency of the Bryophyllum
pinnatum leaves extract observed may be due to the presence of some or all
of the mentioned phytochemicals. This is because they are organic compounds
that are characterized by the presence of heteroatoms (Eddy et al.,
2009). Therefore, the inhibition of the corrosion of zinc by EEBPL is due to
the formation of chelates between zinc and some phytochemicals constituents of
the extract. Table 7: Phytochemical constituents of EEBPL. In this study, ethanol extract
of Bryophyllum pinnatum leaves (EEBPL) has been found to be a good
corrosion inhibitor for zinc metal. The inhibition potential of the extract can
be explained in terms of interaction between the metal and the inhibitor. Most
efficient corrosion inhibitors are long-carbon chain or aromatic compounds that
have heteroatoms such as; N, S, P, and O in their system. The presence of π-electron
rich functional groups has also been found to enhance inhibition efficiency of
a corrosion inhibitor (Ameh, 2015). Figure 10 shows IR spectrum of
EEBPL while Fig. 11 shows the IR spectrum of the corrosion product of zinc when
0.5 g/L of EEBPL was used as an inhibitor. Table 8: Wave number and Intensity of FTIR of EEBPL (Bryophyllum pinnatum leaves extract). Figure 12: Scanning electron micrographs of (A) Pure Zinc metal, (B) Zinc metal in Corredent(0.1M H2SO4), (C) Zinc Metal in Corredent in the presence of EEBPL(as an inhibitor) at magnification of 1500×. Corrosion inhibition of zinc
metal by ethanol extract of Bryophyllum pinnatum leaves (EEBPL) is as a
result of the phytochemical constituents of the plant extract. These
phytochemicals facilitated the adsorption behaviour of the inhibitor onto the
metal (zinc) surface. The adsorption of EEBPL on the surface of zinc is best
described by the Langmuir adsorption model. All values of the standard Gibbs
energy of adsorption are negative (spontaneous adsorption process) and lower in
absolute values than 40kJ mol-1. Also, the activation energies, Ea, of the inhibited
systems increased considerably as the concentration of the inhibitor increased
progressively. These results confirm that physisorption mechanism controls the
adsorption phenomenon. The corrosion product of zinc metal in the presence of
EEBPL is IR active, whereas the corrosion product of zinc metal is not IR
active. The IR spectrum of the corrosion product of zinc metal in the presence
of EEBPL confirmed that the extract actually inhibited the corrosion of zinc by
being adsorbed onto the surface of the zinc metal and indicating interaction
between the inhibitor and the surface. Inhibition efficiency of the inhibitor
correspondingly increased with an increase in the concentration of EEBPL in
0.1M H2SO4. The results of
the analysis revealed that both the inhibition efficiency and degree of surface
coverage decreases as temperature increases. The negative values of ΔGads show that
adsorption of inhibitor on surface of the zinc metal is spontaneous. Conclusively, the ethanol
extract of Bryophyllum pinnatum leaves (EEBPL) is a good, economical,
biodegradable and eco-friendly adsorption inhibitor for the corrosion of zinc
metal in 0.1M H2SO4. 1.
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10.1108/03699420810860455Corrosion Inhibition Potential of Ethanol Extract of Bryophyllum pinnatum Leaves for Zinc in Acidic Medium
Alhaji Modu Kolo, Sunusi Idris, Oloyede Martins Bamishaiye
Abstract
Full-Text
Introduction
Materials and Methods
Results and Discussions
Figure 1: Variation of weight loss with time for the corrosion of zinc in 0.1 M H2SO4 containing various concentrations of EEBPL as inhibitor at 303 K.
Figure 2: Variation of weight loss with time for the corrosion of zinc in 0.1 M H2SO4 containing various concentrations of EEBPL as inhibitor at 313 K.
Figure 3: Variation of weight loss with time for the corrosion of zinc in 0.1 M H2SO4 containing various concentrations of EEBPL as inhibitor at 323 K.
Figure 4: Variation of weight loss with time for the corrosion of zinc in 0.1 M H2SO4 containing various concentrations of EEBPLas inhibitor at 333 K.
Figure 5: Variation of corrosion rate of zinc with concentration of EEBPL at various temperatures.
Table 2: Degree of surface coverage and Inhibition efficiency of various concentrations of EEBPL for Zinc.
Also, in Table 2 for the values
of degree of surface coverage, the results show similar trend to those of
inhibition efficiencies, this is because the degree of surface coverage is
directly proportional to the inhibition efficiency. It can be seen that the
degree of surface coverage increases as the concentration of the inhibitor
increases. This is as result of the EEBPL forming compact layer on the zinc
metal, preventing further corrosion of the zinc. However, as the temperature
increases, the degree of surface coverage decreases. This is due to the fact
that desorption of the inhibitor from the surface of the zinc metal took place
under this condition.
Table 3: Potentiodynamic polarization resistant data for the corrosion of zinc in 0.1 M H2SO4 containing various concentrations of EEBPL at 303K.
Table 4: Arrhenius parameters for the inhibition of the corrosion of zinc by various concentrations of EEBPL.
Figure 6: Polarization curve for the corrosion of zinc in 0.1 M H2SO4 in the presence and absence of various concentration of EEBPL at 303K.
Figure 7: Arrhenius plot for the corrosion of zinc in the presence of Bryophyllum pinnatum leaves extract as an inhibitor at various temperatures.
From the results
presented, it can be seen that both the corrosion potential (Ecorr) and
corrosion current densities (icorr) decrease on addition of the inhibitor (EEBPL) to 0.1
M H2SO4. When the
inhibitor concentration was increased progressively from 0.1 g/L to 0.5g /L,
values of corrosion potential (Ecorr) were shifted more negatively .This is an indication
of a mixed-type corrosion inhibition mechanism (Ameh et al., 2015). The
calculated IE% obtained follows similar trend as that in weight loss
measurement, indicating that the plant extracts inhibited the corrosion of the
zinc metal.
Table 5: Transition state parameters for the inhibition of the corrosion of zinc by various concentrations of EEBPL.
Table 6: Langmuir parameters for the adsorption of EEBPLThermodynamics
considerations
Figure 9: Langmuir isotherm for the adsorption of EEBPL on the surface of zinc.
Photochemical constituents
of the inhibitor (EEBPL)
FTIR study
Figure 10: FTIR spectrum of EEBPL (Bryophylllum pinnatum leaves extract).
Figure 11: FTIR spectrum of the corrosion product of zinc when 0.5 g/L of EEBPL was used as an inhibitor.
Table 8 presents frequencies and
functional group assignments that are associated with the absorption of IR by
EEBPL, while Table 9 presents frequencies and functional group assignments that
are associated with the absorption of IR by the corrosion product .From
the IR spectrum of EEBPL, OH stretch at 3257 cm-1, CN stretch at 1365 cm-1, NH bend at
1514 cm-1, CH stretch at 2936 cm-1- , C=C stretch at 1640 cm-1, CC stretch at
2121 cm-1, CH rock at 1365 cm-1, C-O stretch at 1037 cm-1, CH bend at 821 and at 925 cm-1 were
identified. The corrosion product of the studied metal in the presence of
inhibitor revealed that that CH bend at 821 and 925 cm-1 were shifted to
799 and 914 cm-1, the C-O stretch at 1037 cm-1 were shifted to
1030 cm-1, the C=C Stretch at 1640 cm-1 was shifted to 1655 cm-1, C≡C stretch at 2121 cm-1 was shifted to
2117 cm-1, the OH stretch at 3257 cm-1 was shifted to 3298 cm-1. The shifts in the frequencies
of vibration indicate that there is interaction between the inhibitor and the
metal surface. Also, the N-H bend scissoring at 1514 cm-1 was absent in
the spectrum of the corrosion product of zinc suggesting that this functional
groups were used in the adsorption of the inhibitor to the metal surface. On
the other hand the C – H bend at 665 cm-1, C=O stretch at 1834cm-1, the C-H stretch at 1990 cm-1, the C-N
stretch at 2206 cm-1, the OH stretch free hydroxyl at 3618 cm-1 and the NH
stretch at 3361 cm-1 were new to the spectrum of the corrosion product
indicating that new bonds were formed.
Figure 12 (A), shows the scanning
electron micrograph of pure zinc metal, while Fig. 12 (B) and (C), show the
scanning electron micrograph of zinc metal in the absence and presence of EEBPL
respectively. For the zinc metal (B) in H2SO4, a great degree of corrosion was observed when
compared to the pure zinc metal in (A). This can be evidently seen as the
surface was rough and coarse, due to the distortion of the surface layer by the
corrodent (acid). The degree of corrosion however reduced drastically in zinc
metal (C) which was in contact with the acid solution in the presence of EEBPL
as inhibitor. This shows that the leave extract inhibited the corrosion of zinc
in H2SO4. This was as a
result of the leaves extract forming multiple films on the zinc surface for
adsorption. Therefore, EEBPL prevented the corrosion of zinc by forming a
protective layer on its surface.Conclusion
Table 9: Wave number and Intensities of FTIR of corrosion product of Bryophyllum pinnatum extract as inhibitor of zinc in 0.1M H2SO4.References
