Removal of methylene blue dyet from aqueous solutions using magnetic nanoclays: Kinetic, equilibrium and thermodynamic studies

Water pollution is defined as the contamination of water by any pollutant that comes into contact with water and has harmful effects on living organisms. One of the major water pollutants is organic and chemical dyes. Organic dyes are extensively used in facilities that produce leather, paint, paper, cosmetics, and textiles. However, dyes are among the significant wastewater pollutants since their presence can be observed even at very low concentrations in water. Approximately 5-10% of the dyes produced for painting and printing are discharged into the receiving environment along with wastewater. Various methods are available for removing dyes from aqueous solutions. Chemical and biological treatment methods are the first methods that come to mind. These methods include chemical precipitation, solvent extraction, membrane filtration, coagulation, reverse osmosis, and adsorption. These methods have disadvantages such as high cost, generation of additional pollutants, and low efficiency. However, adsorption is one of the most effective methods for removing dyes from wastewater and enabling their recycling. In the adsorption process, several physicochemical factors, such as pore structure, dye-adsorbent interaction, surface area of the adsorbent, pH, particle size, temperature, and contact time, influence the process. Adsorption is the process of a substance binding to the surface of another substance or particles. This process is widely used in various applications such as pollution removal, chemical separation, catalysis, and gas purification. The adsorption method is performed using a material called an adsorbent. The adsorbent should have specific properties to attract or bind the targeted substance. Materials such as activated carbon, zeolites, silica gel, and polymeric resins are commonly used as adsorbents. During the adsorption process, the targeted substances are drawn to the surface of the adsorbent and adhere through physical or chemical bonds. This binding process can rely on various mechanisms such as attractive forces, electrostatic interactions, or chemical interactions. The effectiveness of adsorption can depend on factors such as surface area of the material, temperature, pressure, and solution composition. The adsorption method offers several advantages. These include high efficiency, a wide range of applications, scalability, and low cost. Additionally, the adsorption process can be suitable for recovery or recycling purposes. However, there are certain limitations to the adsorption method. These limitations can include saturation of the adsorbent material, process duration, regeneration costs, and disposal of the adsorbent material. In conclusion, the adsorption method is an effective technique for pollution control and separation in various industrial and environmental applications. It is preferred due to its high efficiency, versatility, and cost-effectiveness. The textile industry relies on the use of dyes to achieve vibrant and diverse colors in fabrics. Dyes are substances that chemically bond with textile fibers, resulting in the desired coloration of the materials. These dyes can be classified into two main categories: organic and inorganic compounds. Organic dyes are derived from carbon-based compounds and can be obtained from both natural and synthetic sources. Natural organic dyes are extracted from plants, insects, or other naturally occurring substances. For instance, indigo, obtained from the indigo plant, and cochineal, derived from the cochineal insect, are examples of natural organic dyes. On the other hand, synthetic organic dyes are produced through chemical processes in laboratories. Synthetic dyes offer a broader spectrum of colors, enhanced colorfastness, and greater stability compared to natural dyes. Inorganic dyes, as the name suggests, are comprised of metal-based compounds. These dyes are created through various chemical reactions between the metal ions and the textile fibers. Inorganic dyes often consist of metal oxides or salts. Common examples include chromium-based dyes, iron oxides, and titanium dioxide. Inorganic dyes are valued for their ability to produce bright and intense colors that exhibit excellent lightfastness and chemical stability. The usage of dyes in the textile industry is not limited solely to achieving aesthetic appeal. It also plays a crucial role in meeting the demands of consumers who seek a wide array of colors and designs in their clothing and other textile products. However, it is important to consider the environmental impact associated with the production and application of dyes. The textile industry has faced concerns regarding the environmental footprint of dyes, particularly in terms of water pollution and waste generation. Some dyes contain harmful chemicals that can leach into water bodies during the dyeing process, posing risks to aquatic ecosystems and human health. In response to these concerns, there has been a growing emphasis on developing eco-friendly or sustainable dyeing methods. Efforts are underway to promote the use of natural dyes derived from renewable resources such as plants, fruits, and vegetables. Natural dyes offer the advantage of being biodegradable and non-toxic, minimizing the environmental impact. Furthermore, advancements in dyeing technologies and processes aim to reduce water consumption, energy requirements, and the generation of hazardous byproducts. Techniques like digital printing and "dyeing in supercritical carbon dioxide" are gaining traction due to their potential for reducing water usage and chemical waste. Additionally, regulations and certifications have been implemented to encourage responsible dye usage in the textile industry. Standards such as the Global Organic Textile Standard (GOTS) and the Oeko-Tex Standard ensure that textile products meet specific criteria regarding environmental and social sustainability. In conclusion, dyes are essential components of the textile industry, providing vibrant colors and aesthetic appeal to fabrics. While dyes enhance the visual and creative aspects of textiles, the industry must address the environmental challenges associated with their production and application. By embracing sustainable practices, exploring eco-friendly alternatives, and implementing stringent regulations, the textile industry can minimize its ecological impact and work towards a more sustainable future. The production, use, and disposal stages of dye substances can cause various environmental impacts. One primary concern is that dyes can lead to water pollution. The chemicals used during the dyeing process can seep into water sources through wastewater, causing harm to aquatic ecosystems. Some dyes can be toxic or carcinogenic, resulting in the death of aquatic organisms, water contamination, and disruption of ecosystem balance. Furthermore, the production and use of dyes increase water and energy consumption. The significant amount of water usage can contribute to water scarcity and depletion of water sources, while energy consumption, often relying on fossil fuels, can contribute to greenhouse gas emissions and climate change. Harmful chemical emissions into the air can also occur during the production and application of dyes, compromising air quality and negatively affecting human health. Additionally, some dyes may be difficult or impossible to recycle, exacerbating the environmental impact of waste. Therefore, the textile industry should embrace sustainable and eco-friendly practices, explore alternative dyeing methods, and exercise careful waste management to reduce the environmental effects of dye substances. This study investigates the relationship between our adsorbent material and dye pollution, how much dye load the adsorbent material can carry, and what behaviors it develops against this pollution through the adsorption process. The aim of this study is to observe the impact of dyes released into the environment consciously or unconsciously on the receiving medium. Additionally, this study examines how much load the adsorbent material can carry and analyzes its response to the incoming pollution. The removal efficiency of different parameters will be investigated using the adopted adsorption process. The effects of parameters such as pH, temperature, adsorbent quantity, initial dye concentrations, and contact time on the adsorption process were studied. In this study, the aim is to evaluate the effectiveness of Fe3O4-based clay as a low-cost material for the removal of MM dye from aqueous solutions. The effects of various parameters such as pH (3-10), contact time (5-120 minutes), initial dye concentration (50-100-200 mg/L), adsorbent quantity (0.05-0.1-0.2-0.3-0.4-0.5-0.75-1 g), and process temperature (303-313 K) on the adsorption capacity were investigated. The results of the study indicate that optimum adsorption efficiency is achieved at pH 7, 25 °C, 0.2 grams of adsorbent quantity, and 100 mg/L initial dye concentration. The clay's structural characteristics before and after adsorption were analyzed using SEM, XRF, BET, XRD, FTIR, and TGA methods. Calculations based on experimental results revealed that the adsorption outcomes are more in line with the Langmuir model. The maximum adsorption capacity (qm) was calculated as 52.63 mg/g at 25°C, 53.48 mg/g at 30°C, and 54.64 mg/g at 35°C. According to adsorption kinetic analyses, it was observed to conform to the pseudo-second-order model. Negative ΔG° values indicate the spontaneity of the adsorption process, and the positive ΔH° value suggests that the process is endothermic. In light of the obtained data, it is believed that, under optimal conditions, K- Fe3O4-based clays investigated in this study have the potential to be an effective and cost-efficient adsorbent for the removal of MM dye from different industrial environments.