TECHNOLOGY FOR THE PRODUCTION OF A CORROSION INHIBITOR BASED ON GUANIDINE AND LOCAL RAW MATERIALS

ABSTRACT

This article analyzes an improved conceptual technology for obtaining a corrosion inhibitor based on guanidine derivatives, which are considered industrial waste. The technological process takes into account the ratio of products and the sequence of reactions. In order to control the efficiency of the process, separators and extractors are considered for removing unreacted substances. The proposed technology is designed for continuous operation, ensuring a precisely ordered progression of the process. Each stage allows for controlled execution of chemical reactions, enabling accurate regulation of transformation steps. A laboratory-scale prototype of this system was used to synthesize a corrosion inhibitor, which was subsequently tested under laboratory conditions in accordance with established standards. The results demonstrated a high level of protective efficiency, confirming the system’s potential for practical application. Gravimetric analysis revealed that GCMA acts as an effective corrosion barrier, achieving up to 93.3% protection on St-20 steel at 300 mg/L. This high efficiency fully meets the SST (RH 39.0-051:2007) standard, turning corrosion risk into controlled resistance.

АННОТАЦИЯ

В данной статье рассматривается усовершенствованная концептуальная технология получения ингибитора коррозии на основе производных гуанидина, которые рассматриваются как промышленный отход. Технологический процесс предусматривает строгое соблюдение соотношения реагентов и последовательности химических реакций. Для повышения эффективности процесса предусмотрены использование сепараторов и экстракторов, обеспечивающих удаление непрореагировавших веществ. Предлагаемая технология рассчитана на непрерывный режим работы и обеспечивает чёткую поэтапную реализацию процесса. Каждый этап позволяет осуществлять контролируемое проведение реакций, что способствует точному управлению всеми стадиями превращения. На основе лабораторного прототипа данной системы был синтезирован ингибитор коррозии, который прошёл испытания в лабораторных условиях в соответствии с установленными стандартами. Результаты показали высокий уровень защитной эффективности, подтверждая перспективность технологии для практического применения. Согласно гравиметрическому анализу, соединение ГХМА продемонстрировало эффективность в качестве антикоррозионного барьера, обеспечивая до 93,3% защиты стали марки St-20 при концентрации 300 мг/л. Данная эффективность полностью соответствует требованиям стандарта ГОСТ (PH 39.0-051:2007), превращая риск коррозии в контролируемый процесс.

Keywords: guanidine rhodanide (GR), guanidine chloride (GC), methanal, formalin, acrylic acid, pump, separator

Ключевые слова: роданид гуанидина (РГ), хлорид гуанидина (ХГ), метанал, формалин, акриловая кислота, насос, сепаратор

Introduction

Metals and their alloys are among the most widely used materials in industry. However, in acidic and aggressive environments, these materials corrode rapidly, leading to technical failures, production downtime, and economic losses. Therefore, preventing corrosion is a critical issue, especially in the oil and gas industry, as well as in the chemical and metallurgical sectors[1-3].

One of the effective and economically viable chemical methods for preventing corrosion is the use of corrosion inhibitors. This article provides an in-depth analysis of the technology for producing guanidine chloride methyl acrylate (GCMA) based on local raw materials. It discusses the production stages, technological advantages, economic efficiency, and environmental safety of the process[4-5].

Materials and methods

The technology for synthesizing the new corrosion inhibitor consists of four main stages:

- Preparation of raw materials

- Chemical synthesis

- Extraction and purification of the substance

- Packaging of the final product

Each of these stages has a direct impact on product quality and the economic efficiency of the synthesis process.

In this study, the production waste of the "Navoiyazot" JSC enterprise was selected as the primary raw material. Guanidine rhodanide was extracted from this waste using a cooling method. This approach enables the recycling of industrial waste, reduces environmental load, and ensures the rational use of economic resources[6, 7].

The extracted guanidine rhodanide was treated with 34–36% hydrochloric acid in reactor R1. During this stage, the temperature is strictly maintained at 30–35 °C. As a result of the reaction, impurities in the substance precipitate out, while guanidine chloride, rhodanide acid, and excess HCl remain in the solution. The principal technological scheme of the process is illustrated in Figure 1.

Figure 1. Principal technological scheme for obtaining the GCMA corrosion inhibitor. 1 – reactor; 2 – settler; 3 – tank; 4 – pumps

After the precipitate is separated, the filtrate is transferred to reactor R2, where it is treated with a CuCl₂ (copper(II) chloride) solution. Under controlled chemical reactions, a dark brown Cu(SCN)₂ precipitate is formed. At this stage, guanidine chloride remains in the solution[8]. Next, the guanidine chloride solution is transferred to reactor R3, where it is processed with 38–40% formalin (methanal) at 50–60 °C. As a result of the reaction, dimethylol guanidine (GCDM) precipitate is formed and separated. In the final stage, the GCDM solution is transferred to reactor R4, where it reacts with acrylic acid. The reaction is conducted at a temperature of 70–75 °C and is accelerated using concentrated sulfuric acid as a catalyst. This reaction yields guanidine chloride monomethacrylate (GCMA).  The resulting GCMA is obtained in the form of a homogeneous solution, with a concentration typically ranging from 50% to 63%. This concentration is sufficient for either direct use or further processing.

The corrosion inhibitor obtained was analyzed under laboratory conditions using the gravimetric method. The results of the gravimetric analysis are presented in Table 1.

Table 1.

Dependence of corrosion-inhibiting characteristics of GCMA on its concentration. The experiment was conducted on St-20 steel.

Results and discussion

In this study, guanidine chloride methyl acrylate (GCMA), synthesized from local raw materials, was tested as an effective corrosion inhibitor for steel in acidic environments. Experimental results confirmed that the adsorption properties of the active groups in the synthesized GCMA onto metal surfaces are directly related to its high efficiency. According to corrosion rate analyses conducted using the gravimetric method, GCMA demonstrated a protective efficiency of up to 93.3% on St-20 steel surfaces at a concentration of 300 mg/L, fully complying with SST (RH 39.0-051:2007) standards. Furthermore, at this concentration, the corrosion rate was observed to decrease by a factor of 15. The technological approach offers several advantages, including import substitution, low production cost, enhanced environmental safety, easy adaptability to existing industrial facilities, and the synthesis of a competitive corrosion inhibitor.

Conclusion

Based on the above-described technological process, a highly effective GCMA corrosion inhibitor was successfully synthesized using local raw materials. This technology is characterized by low waste generation, environmental safety, and economic feasibility, making it suitable for application in the oil and gas, chemical, and metallurgical industries.

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