Description:FIELD OF THE INVENTION
The present invention relates to the field of corrosion protection and green chemistry. More particularly, it pertains to the development of an eco-friendly anti-corrosive liquid composition derived from natural waste materials, which provides sustainable and non-toxic protection of metallic surfaces against corrosion, thereby offering an environmentally safe alternative to conventional synthetic and chemical-based corrosion inhibitors.
BACKGROUND OF THE INVENTION
References which are cited in the present disclosure are not necessarily prior art and therefore their citation does not constitute an admission that such references are prior art in any jurisdiction. All publications, patents and patent applications herein are incorporated by reference to the same extent as if each individual or patent application was specifically and individually indicated to be incorporated by reference.
Corrosion is a critical issue affecting the durability and functionality of materials, particularly metals, leading to economic and structural losses. Conventional anti-corrosive agents are often synthetic, toxic, and environmentally hazardous. Recent advancements emphasize the need for sustainable, biodegradable alternatives. Natural waste materials, rich in phenolics, flavonoids, and essential oils, possess inherent corrosion-inhibiting properties. However, their systematic application in anti-corrosive formulations remains underexplored. This invention aims to develop an eco-friendly, bioactive liquid from plant-based waste for broad-spectrum corrosion protection.
Existing anti-corrosive formulations largely rely on synthetic chemicals, such as chromates and phosphates, which are effective but present significant environmental and health concerns due to their toxicity and non-biodegradability. While some prior patents have explored plant-based or natural corrosion inhibitors, these inventions often fail to provide a comprehensive, scalable solution that leverages widely available and sustainable waste materials. Additionally, most existing formulations are limited in their ability to protect a broad range of materials, including metals, alloys, and ceramics. There remains a need for a cost-effective, eco-friendly anti-corrosive liquid derived from natural waste, capable of offering efficient corrosion resistance across diverse material types. This invention surpasses prior patents by utilizing a synergistic blend of multiple natural waste-derived sources rich in bioactive compounds, thereby enhancing corrosion inhibition efficiency and ensuring broader material compatibility.
Several patents issued for corrosion inhibitor but none of these are related to the present invention. Patent US6117364A relates to an acid corrosion inhibitor composition is provided for petroleum wells and water wells subjected to stimulation with acid solutions. The inhibitor combines cinnamaldehyde and an organo-sulfur compound. The inhibitor provides a reduced rate of corrosion and fewer instances of pitting than inhibitors which include cinnamaldehyde alone. The inhibitor does not suffer from the well-known oil field aldehyde/polyacrylamide crosslinking incompatibility. The enhanced performance by the inhibitor of the present invention is provided by a synergistic action between the cinnamaldehyde and an organo-sulfur compound.
Another patent US6800594B2 describes an environmentally friendly corrosion inhibiting formulation for the oil-water interface of pipe lines and oil well drilling systems which is prepared pursuant to a process including the steps of reacting an acid selected from the group consisting of a fatty acid anhydride and a 21 carbon dibasic acid with an amine or imidazoline to form a corrosion inhibitor consisting essentially of a fatty acid derivative; dissolving the inhibitor in a fatty acid oil or ester selected from the group consisting of soybean oil or methyl soya ester; adding water dispersing agents consisting of sulfonates and a long chain ethoxylated alcohol; and adjusting the viscosity with an alcohol comprising isopropanol.
Another patent US7241391B1 relates to a biodegradable scale and corrosion inhibiting composition includes between about 50 and about 90% by weight of a protein polymer that is derived from a natural source, and between about 10 and about 20% by weight of the alkali salts of gluconic acid.
Another patent US5849220A discloses a corrosion inhibiting composition for use in inhibiting corrosion of metallic surfaces, the composition comprising a first surfactant wherein the first surfactant includes at least one sorbitan fatty acid ester and a second surfactant wherein the second surfactant includes at least one polyoxyethylene derivative of a sorbitan fatty acid ester.
Another patent US6511613B1 provides the reaction of propargyl alcohol and iodine gives 2,3di-iodo-2-propen-1-ol, and it has been discovered that this compound is effective as an intermediate in a corrosion inhibitor for metals in acid media, particularly halogen acids. The compound provides iodine to the media in a stable form that does not appear to degrade over time.
Another patent US5763368A provides corrosion inhibited well acidizing compositions and methods of using the compositions to acidize wells. The compositions basically comprise an aqueous acid solution, a corrosion inhibitor comprising at least one quaternary ammonium compound and a corrosion inhibitor intensifier comprised of aliphatic carboxylic acids, crude tall oil, tall oil fatty acids, rosin acids and mixtures thereof.
Another patent US7662241B2 provides a corrosion-inhibiting composition for application to a metal substrate, such as aluminum or steel, and in connection with a paint, and the synthesis of the composition. The active inhibitor constituent of the composition can be selected from the group consisting of 2,5-dimercapto-1,3,4 thiadiazole (DMTD), 2,4-dimercapto-s-triazolo-[4,3-b]-1,3-4-thiadiazole, trithiocyanuric acid (TMT), and derivatives of DMTD and TMT, including various N- or S- and N, N-, S- and N-,S-substituted derivatives of DMTD, including salts of DMTD of the general formula: M(DMTD)n, where n=1,2 or 3, and M is a metal cation and preferably M=Zn(II), Bi(III), Co(II), Ni(II), Cd(II), Pb(II), Ag(I), Sb(III), Cu(II), Li(I), Ca(II), Sr(II), Mg(II), La(III), Ce(III), Pr(III), Al(III) or Zr(IV). DMTD, TMT, and their derivatives may also be combined with phosphates, molybdates, borates, silicates, tungstates, phosphotungstates, phosphomolybdates, cyanamides, carbonates, SiO2 and mixtures thereof.
OBJECTS OF THE INVENTION
Main object of the present invention is to development of eco-friendly anti-corrosive liquid from natural waste materials.
Another object of the present invention is to develop an eco-friendly anti-corrosive liquid utilizing natural waste materials as the primary source of active ingredients.
Another object of the present invention is to provide a sustainable, biodegradable, and non-toxic alternative to synthetic and chemical-based corrosion inhibitors.
Another object of the present invention is to ensure effective protection of metallic surfaces against corrosion under varied environmental and industrial conditions.
Another object of the present invention is to promote value-added utilization of natural waste materials, thereby reducing environmental pollution.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention.
This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings.
The present invention provides an eco-friendly anti-corrosive liquid composition formulated from natural waste materials, offering a sustainable alternative to conventional synthetic corrosion inhibitors. The invention utilizes bioactive compounds present in selected plant-based and organic waste residues, which exhibit inherent corrosion-inhibiting properties. By converting low-cost natural waste into a high-value protective formulation, the invention not only minimizes environmental hazards caused by chemical inhibitors but also promotes waste valorization. The developed liquid is biodegradable, non-toxic, and effective in preventing the deterioration of metallic surfaces exposed to corrosive environments. Furthermore, the invention ensures cost-effectiveness, industrial scalability, and wide applicability in sectors such as automotive, construction, marine, and infrastructure, thereby addressing the dual challenge of corrosion control and eco-friendly waste management.
Herein enclosed a method for preparing an eco-friendly anti-corrosive liquid, comprising the steps of:
Selecting botanical waste residues including citrus peels, garlic peels, onion peels, eucalyptus leaves, pine needles, wheat straw, and rice husk based on their antioxidant, chelating, silica-rich, and film-forming properties;
Extracting the bioactive components such as flavonoids, polyphenols, lignin, organosulfur compounds, tannins, terpenoids, resin acids, hemicellulose, essential oils, and silica from said residues;
Formulating the extracts in defined proportions to prepare three anti-corrosive formulations (F1, F2, and F3); and
Applying the formulated liquid onto metallic substrates including iron and mild steel to inhibit corrosion under atmospheric and aqueous environments.
Citrus peels are present in the range of 10–20%, garlic peels in the range of 10–15%, onion peels in the range of 10–15%, eucalyptus leaves in the range of 15–20%, pine needles in the range of 10–20%, wheat straw at 15%, and rice husk in the range of 10–15%.
The corrosion inhibition mechanism comprises adsorption of polyphenols, flavonoids, lignin, tannins, and silica onto the metal surface, chelation of free metal ions to reduce anodic dissolution, scavenging of reactive oxygen species to suppress redox reactions, and formation of a hydrophobic film to minimize moisture penetration.
Hydrophobic constituents including limonene, essential oils, and resin acids contribute to the formation of a water-repellent protective barrier on the metal surface.
Silica derived from rice husk enhances the structural stability and durability of the protective surface film, thereby improving resistance to corrosion.
BRIEF DESCRIPTION OF THE TABLES
Table 1. Botanical waste materials selected for anti-corrosive formulation, their key bioactive components, corrosion-inhibiting roles, and percentage composition in three experimental formulations (F1, F2, and F3)
Table 2. Corrosion rate and inhibition efficiency of formulations on iron and mild steel coupons
DETAILED DESCRIPTION OF THE INVENTION
The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
In addition, the descriptions of "first", "second", “third”, and the like in the present invention are used for the purpose of description only, and are not to be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In some embodiments of the present invention, the development of an eco-friendly anti-corrosive liquid prepared from botanical waste residues selected for their abundance, sustainability, and high content of corrosion-inhibiting compounds.
In some embodiments of the present invention, agro-industrial and household wastes including citrus peels, garlic peels, onion peels, eucalyptus leaves, pine needles, wheat straw, and rice husk were utilized as the primary raw materials, as they are rich in flavonoids, polyphenols, organosulfur compounds, tannins, terpenoids, lignin, resin acids, hemicellulose, and silica, all of which contribute to corrosion prevention through diverse mechanisms.
In some embodiments of the present invention, these natural bioactives act synergistically by adsorbing onto metal surfaces, forming protective antioxidant and hydrophobic layers, chelating free metal ions, scavenging reactive oxygen species, and enhancing barrier properties against moisture, oxygen, and chloride ions, which are the primary agents of corrosion in metals such as iron and mild steel.
In some embodiments of the present invention, to optimize performance, three formulations (F1, F2, and F3) were developed by varying the proportions of each botanical residue, where the balanced contributions of citrus peels (10–20%), garlic peels (10–15%), onion peels (10–15%), eucalyptus leaves (15–20%), pine needles (10–20%), wheat straw (15%), and rice husk (10–15%) ensured effective surface coverage and film stability.
In some embodiments of the present invention, the presence of silica from rice husk further reinforced the protective film’s durability, while hydrophobic components such as limonene and essential oils reduced water penetration, thereby extending protection in humid environments. Overall, the invention provides a biodegradable, non-toxic, and sustainable anti-corrosive liquid that effectively mitigates corrosion in iron and mild steel substrates, while simultaneously addressing waste valorization and reducing dependence on synthetic chemical inhibitors.
Herein enclosed a method for preparing an eco-friendly anti-corrosive liquid, comprising the steps of:
Selecting botanical waste residues including citrus peels, garlic peels, onion peels, eucalyptus leaves, pine needles, wheat straw, and rice husk based on their antioxidant, chelating, silica-rich, and film-forming properties;
Extracting the bioactive components such as flavonoids, polyphenols, lignin, organosulfur compounds, tannins, terpenoids, resin acids, hemicellulose, essential oils, and silica from said residues;
Formulating the extracts in defined proportions to prepare three anti-corrosive formulations (F1, F2, and F3); and
Applying the formulated liquid onto metallic substrates including iron and mild steel to inhibit corrosion under atmospheric and aqueous environments.
Citrus peels are present in the range of 10–20%, garlic peels in the range of 10–15%, onion peels in the range of 10–15%, eucalyptus leaves in the range of 15–20%, pine needles in the range of 10–20%, wheat straw at 15%, and rice husk in the range of 10–15%.
The corrosion inhibition mechanism comprises adsorption of polyphenols, flavonoids, lignin, tannins, and silica onto the metal surface, chelation of free metal ions to reduce anodic dissolution, scavenging of reactive oxygen species to suppress redox reactions, and formation of a hydrophobic film to minimize moisture penetration.
Hydrophobic constituents including limonene, essential oils, and resin acids contribute to the formation of a water-repellent protective barrier on the metal surface.
Silica derived from rice husk enhances the structural stability and durability of the protective surface film, thereby improving resistance to corrosion.
EXAMPLE 1
Materials and Methods
Detailed Description of the Invention
1. Selection of Botanical Residues and Formulation
For the development of the eco-friendly anti-corrosive liquid, selected plant waste materials were chosen based on their high content of antioxidant, chelating, silica-rich, and film-forming compounds with proven corrosion-inhibiting activity. The selection was guided by sustainability, availability as agro-industrial and household waste, and their potential to protect commonly used substrates such as iron and mild steel, which are highly prone to corrosion in atmospheric and aqueous environments. The botanical residues used in this invention include citrus peels, garlic peels, onion peels, eucalyptus leaves, pine needles, wheat straw, and rice husk. These materials are rich in natural bioactives such as polyphenols, lignin, essential oils, and silica, which contribute to corrosion inhibition by forming protective surface layers, reducing metal ion dissolution, and suppressing oxidation reactions. To evaluate performance, three different formulations (F1, F2, and F3) were prepared using varied proportions of the selected botanical extracts. Each formulation is designed to be tested specifically on iron and mild steel coupons under controlled conditions to assess their corrosion-inhibiting effectiveness. The selected residues and their corrosion-related bioactive properties are summarized in Table 1.
Table 1. Botanical waste materials selected for anti-corrosive formulation, their key bioactive components, corrosion-inhibiting roles, and percentage composition in three experimental formulations (F1, F2, and F3)

Botanical Waste Key Bioactive Components Corrosion-Inhibiting Role Formulations (%)
F1 F2 F3
Citrus peels Flavonoids, limonene, ascorbic acid Antioxidant, metal-chelating, film-forming 15 20 10
Garlic peels Organosulfur compounds, phenolics Oxidation inhibition, barrier layer formation 10 10 15
Onion peels Quercetin, sulfur compounds ROS scavenging, protective coating 10 15 10
Eucalyptus leaves Eucalyptol, tannins, terpenoids Antioxidant, hydrophobic film formation 20 15 20
Pine needles Resin acids, lignin, polyphenols Surface binding, water repellency, antioxidative action 15 10 20
Wheat straw Lignin, hemicellulose, phenolic acids Physical barrier, oxidative suppression 15 15 15
Rice husk Silica, lignin, ferulic acid Passive layer formation, mechanical surface protection 15 15 10
2. Mode of Action
The anti-corrosive liquid developed from natural waste-derived botanical residues acts through a synergistic combination of physical and chemical mechanisms. Upon application, bioactive compounds such as polyphenols, flavonoids, lignin, tannins, essential oils, and silica adsorb onto the metal surface, forming a stable protective layer that prevents direct contact with corrosive agents like moisture, oxygen, and chloride ions. Chelating agents present in the extracts bind with free metal ions, reducing anodic metal dissolution, while natural antioxidants scavenge reactive oxygen species, thereby inhibiting electrochemical redox reactions responsible for corrosion. Additionally, hydrophobic constituents such as limonene and essential oils create a water-repellent barrier, further reducing corrosion in humid environments. Silica from rice husk contributes to the structural integrity and durability of the protective film. These combined actions effectively mitigate corrosion in iron and mild steel substrates.
Example 2
Experimental Data & Results
Experimental Methods
To assess the anti-corrosive performance of the natural waste-derived formulations (F1, F2, F3), the following methods were employed using iron and mild steel coupons.
1.1. Weight Loss Method: Metal coupons (iron and mild steel) were mechanically polished, cleaned, and weighed accurately to obtain the initial weight (W1). Each coupon was immersed separately in 100 ml of 3.5% NaCl solution, with and without the test formulations, and kept undisturbed at room temperature for 72 hours. After exposure, the coupons were cleaned, dried, and reweighed to determine the final weight (W2). The corrosion rate (CR) was calculated using the formula:
CR (mg/〖cm〗^2.day)=(W_1-W_2)/(A×T)
1.2. Inhibition Efficiency: The effectiveness of each formulation in reducing corrosion was quantified by calculating the Inhibition Efficiency (IE%). Two equivalent formulas were applied depending on whether corrosion rate or direct weight loss was used:
Based on corrosion rate:
IE (%)=(〖CR〗_Control-〖CR〗_Treated)/〖CR〗_Control
Based on weight loss:
IE (%)=(W_Control-W_Treated)/W_Control
Results and Interpretation
The experimental evaluation of corrosion inhibition performance revealed notable differences in the weight loss, corrosion rate, and inhibition efficiency across the three formulations (F1, F2, F3). The results are summarized in Table 2.
Table 2 Corrosion rate and inhibition efficiency of formulations on iron and mild steel coupons

Material Parameter Control F1 F2 F3
Iron Weight Loss (mg) 124.6 42.5 21.9 33.1
Corrosion Rate (mg/cm2.day) 1.73 0.59 0.30 0.46
Inhibition Efficiency (%) — 65.9 82.4 73.4
Mild Steel Weight Loss (mg) 118.2 46.4 25.0 37.3
Corrosion Rate (mg/cm2.day) 1.64 0.64 0.35 0.52
Inhibition Efficiency (%) — 60.7 78.9 68.4
Formulation F2 demonstrated the highest inhibition efficiency on both iron (82.4%) and mild steel (78.9%), indicating superior anti-corrosive performance. This is attributed to the synergistic action of bioactive compounds like polyphenols, flavonoids, lignin, and silica in the selected botanical residues. The trend (F2 > F3 > F1) confirms that optimized combinations of natural waste materials can effectively inhibit corrosion in an eco-friendly manner.
ADVANTAGES OF THE INVENTION:
The invention offers several notable advantages, primarily by utilizing low-cost and abundantly available botanical waste materials to develop an eco-friendly anti-corrosive liquid. It provides a sustainable and non-toxic alternative to conventional synthetic inhibitors, with high inhibition efficiency demonstrated on both iron and mild steel surfaces. The formulation uses the natural presence of polyphenols, flavonoids, lignin, and silica, which contribute to forming a protective barrier that minimizes metal degradation. Being biodegradable and environmentally safe, the invention reduces ecological impact and health hazards while supporting circular economy goals through green chemistry and effective waste-to-value conversion.
References
Al-Amiery, A., Salman, T. A., Alazawi, K. F., Shaker, L. M., & Kadhum, A. A. H. (2020). Quantum chemical elucidation on corrosion inhibition efficiency of Schiff base: DFT investigations supported by weight loss and SEM techniques. International Journal of Low-Carbon Technologies, 15(2), 202-209. https://doi.org/10.1093/ijlct/ctz073
Ishak, A., Adams, F. V., Madu, J. O., Joseph, I. V., & Olubambi, P. A. (2019). Corrosion inhibition of mild steel in 1M hydrochloric acid using Haematostaphis barteri leaves extract. Procedia Manufacturing, 35, 1279-1285. https://doi.org/10.1016/j.promfg.2019.06.072
Kaur, J., Daksh, N., & Saxena, A. (2022). Corrosion inhibition applications of natural and eco-friendly corrosion inhibitors on steel in the acidic environment: An overview. Arabian Journal for Science and Engineering, 47(1), 570-74. https://doi.org/10.1007/s13369-021-05877-6
Legut, D., Kądzielawa, A. P., Pánek, P., Marková, K., Váňová, P., Konečná, K., & Langová, Š. (2021). Inhibition of steel corrosion with imidazolium-based compounds—Experimental and theoretical study. arXiv preprint, arXiv:2102.02006. https://arxiv.org/abs/2102.02006
Onuegbu, T. U., Umoh, E. T., & Ehiedu, C. N. (2019). Emilia sonchifolia extract as green corrosion inhibitor for mild steel in acid medium using weight loss method. Measurement, 3, Article 100008. https://doi.org/10.1016/j.measen.2019.100008
 
, Claims:1. A method for preparing an eco-friendly anti-corrosive liquid, comprising the steps of:
a) selecting botanical waste residues based on their antioxidant, chelating, silica-rich, and film-forming properties;
b) extracting the bioactive components such as flavonoids, polyphenols, lignin, organosulfur compounds, tannins, terpenoids, resin acids, hemicellulose, essential oils, and silica from said residues;
c) formulating the extracts in defined proportions to prepare three anti-corrosive formulations (F1, F2, and F3); and
d) applying the formulated liquid onto metallic substrates including iron and mild steel to inhibit corrosion under atmospheric and aqueous environments.
2. The anti-corrosive liquid as claimed in claim 1, wherein botanical waste residues are citrus peels, garlic peels, onion peels, eucalyptus leaves, pine needles, wheat straw, and rice husk.
3. The anti-corrosive liquid as claimed in claim 1, wherein citrus peels are present in the range of 10–20%, garlic peels in the range of 10–15%, onion peels in the range of 10–15%, eucalyptus leaves in the range of 15–20%, pine needles in the range of 10–20%, wheat straw at 15%, and rice husk in the range of 10–15%.
4. The anti-corrosive liquid as claimed in Claim 1, wherein the corrosion inhibition mechanism comprises adsorption of polyphenols, flavonoids, lignin, tannins, and silica onto the metal surface, chelation of free metal ions to reduce anodic dissolution, scavenging of reactive oxygen species to suppress redox reactions, and formation of a hydrophobic film to minimize moisture penetration.
5. The anti-corrosive liquid as claimed in claim 1, wherein hydrophobic constituents including limonene, essential oils, and resin acids contribute to the formation of a water-repellent protective barrier on the metal surface.
6. The anti-corrosive liquid as claimed in claim 1, wherein silica derived from rice husk enhances the structural stability and durability of the protective surface film, thereby improving resistance to corrosion.