Industrial Chemistry
Open Access

Catalytic ozonation; Carbon-coated catalysts; Copper-alumina core-shell; High-salinity wastewater; Petrochemical effluents; Advanced oxidation process

Introduction

Industrial wastewater, particularly from the petrochemical sector, poses significant environmental challenges due to its high salinity and complex mixture of organic contaminants. Traditional treatment methods often fall short in addressing these pollutants effectively, leading to a pressing need for innovative and efficient treatment technologies. Advanced oxidation processes (AOPs) have emerged as a promising solution due to their ability to degrade a wide range of organic pollutants into harmless end-products [1,2]. This article explores the application of carbon-coated copper-alumina (C/Cu-Al2O3) core-shell catalysts in catalytic ozonation, a type of AOP, for the treatment of high-salinity petrochemical wastewater. The petrochemical industry is a cornerstone of modern society, providing essential raw materials for a multitude of products. However, the wastewater generated by petrochemical processes presents substantial environmental challenges due to its high salinity and complex mixture of organic pollutants [3,4]. Traditional wastewater treatment methods, such as biological treatment and conventional chemical oxidation, often prove inadequate in effectively degrading these contaminants [5]. As a result, there is a growing need for more efficient and sustainable treatment technologies. Advanced oxidation processes (AOPs) have emerged as a promising solution for the treatment of recalcitrant industrial wastewater. These processes rely on the generation of highly reactive species, such as hydroxyl radicals (•OH), which can non-selectively oxidize a wide range of organic pollutants into harmless end-products. Among the various AOPs, catalytic ozonation has garnered significant attention due to its enhanced efficiency in generating reactive species and its ability to operate under mild conditions [6,7]. In catalytic ozonation, catalysts play a crucial role in accelerating the decomposition of ozone (O3) to produce more hydroxyl radicals. This study focuses on the use of carbon-coated copper-alumina (C/Cu-Al2O3) core-shell catalysts for the catalytic ozonation of high-salinity petrochemical wastewater [8]. The unique design of these catalysts combines the high surface area and stability of carbon, the protective and supportive properties of the alumina shell, and the active catalytic sites provided by the copper core. This synergistic combination aims to overcome the limitations of conventional catalysts and enhance the overall treatment efficiency. This research delves into the synthesis, characterization, and application of C/Cu-Al2O3 catalysts in the remediation of high-salinity petrochemical effluents [9]. By exploring the mechanisms of pollutant degradation and evaluating the performance of these catalysts, this study aims to demonstrate their potential in providing a robust, efficient, and environmentally friendly solution for industrial wastewater treatment [10].

Understanding advanced oxidation processes (AOPs)

AOPs are a set of chemical treatment procedures designed to remove organic and inorganic materials in water and wastewater through oxidation reactions. The cornerstone of AOPs is the generation of highly reactive species, primarily hydroxyl radicals (•OH), which have a high oxidation potential and can non-selectively oxidize most organic compounds. Catalytic ozonation is an advanced variant where catalysts are used to enhance the generation and efficiency of these reactive species.

Catalytic ozonation and its advantages

Ozonation involves the use of ozone (O3) as an oxidizing agent. Ozone itself is a powerful oxidant, but its efficiency can be significantly improved through catalytic ozonation. The introduction of a catalyst accelerates the decomposition of ozone to generate more hydroxyl radicals, thereby enhancing the degradation of contaminants. The use of catalysts like carbon-coated copper-alumina (C/Cu-Al2O3) brings several advantages:

Increased reaction rates: Catalysts promote faster ozone decomposition, leading to increased production of reactive species.

Selective oxidation: Catalysts can aid in selectively targeting specific pollutants.

Reduced ozone consumption: Enhanced efficiency means less ozone is required, making the process more cost-effective and environmentally friendly.

Carbon-coated copper-alumina core-shell catalysts

Structure and properties

The C/Cu-Al2O3 core-shell catalysts are composed of a copper-based core with an alumina shell, all coated with a layer of carbon. This unique structure offers several benefits:

High surface area: The carbon coating increases the surface area, providing more active sites for ozone decomposition.

Enhanced stability: The alumina shell protects the copper core, enhancing the catalyst's stability and resistance to harsh conditions found in high-salinity wastewater.

Synergistic effects: The combination of copper, alumina, and carbon results in synergistic effects that improve the overall catalytic performance.

Synthesis of c/cu-al2o3 catalysts

The synthesis of C/Cu-Al2O3 catalysts involves several steps:

Preparation of copper core: Copper nanoparticles are synthesized using a reduction method.

Formation of alumina shell: The copper nanoparticles are coated with an alumina layer through a sol-gel process.

Carbon coating: The alumina-coated copper particles are then coated with carbon using chemical vapor deposition (CVD) or other suitable techniques.

Application in high-salinity petrochemical wastewater treatment

High-salinity petrochemical wastewater contains a complex mix of organic pollutants and salts, which complicate the treatment process. The effectiveness of C/Cu-Al2O3 catalysts in catalytic ozonation for such wastewater can be attributed to several factors:

Robustness in high-salt environments

The carbon coating and alumina shell provide excellent resistance to corrosion and fouling by salts, maintaining the catalyst's activity over prolonged use. This durability is crucial for the economic viability of the treatment process.

High efficiency in organic pollutant degradation

Studies have shown that C/Cu-Al2O3 catalysts significantly enhance the degradation rates of various organic pollutants commonly found in petrochemical wastewater, including hydrocarbons, phenols, and other toxic compounds. The high surface area and active sites ensure that even trace contaminants are effectively targeted.

Mechanism of action

The mechanism by which C/Cu-Al2O3 catalysts enhance catalytic ozonation involves several key steps:

Ozone adsorption: Ozone molecules adsorb onto the catalyst surface.

Ozone decomposition: The catalyst facilitates the decomposition of ozone into reactive oxygen species, primarily hydroxyl radicals.

Pollutant oxidation: These reactive species then non-selectively oxidize the organic pollutants in the wastewater.

Advantages over conventional methods

The use of C/Cu-Al2O3 catalysts in catalytic ozonation offers several advantages over conventional treatment methods such as biological treatment, coagulation-flocculation, and traditional ozonation:

Broader range of contaminant removal: Capable of degrading a wider range of organic pollutants.

Higher treatment efficiency: More efficient at lower ozone doses, reducing operational costs.

Environmental benefits: Produces fewer harmful by-products compared to traditional methods.

Conclusion

The application of carbon-coated copper-alumina core-shell catalysts in catalytic ozonation represents a significant advancement in the treatment of high-salinity petrochemical wastewater. This technology combines the strengths of advanced oxidation processes with innovative catalyst design, offering a robust, efficient, and environmentally friendly solution to one of the most challenging industrial wastewater problems. Continued research and development in this field hold the potential to further improve the effectiveness and economic viability of this promising treatment method.

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