Investigation of the Adsorption of Eosin B Dye with Graphene Oxide: Effect of Synthesis Methods and Adsorption Conditions

Uluslararası İleri Doğa Bilimleri ve Mühendislik Araştırmaları Dergisi Sayı 9, S. 457-463, 10, 2025 © Telif hakkı IJANSER’e aittir Araştırma Makalesi https://as-proceeding.com/index.php/ijanser ISSN:2980-0811 International Journal of Advanced Natural Sciences and Engineering Researches Volume 9, pp. 457-463, 10, 2025 Copyright © 2025 IJANSER Research Article 457 Investigation of the Adsorption of Eosin B Dye with Graphene Oxide: Effect of Synthesis Methods and Adsorption Conditions Mahad Quesleyeh ALI1, Mücahit UĞUR1, Haluk KORUCU1* 1 Chemical Engineering Department, Faculty of Engineering, Çankırı Karatekin University, Çankırı *([email protected]) (Received: 25 October 2025, Accepted: 26 October 2025) (7th International Conference on Engineering and Applied Natural Sciences ICEANS 2025, October 25-26, 2025) ATIF/REFERENCE: Ali, M. Q., Uğur, M. & Korucu, H. (2025). Investigation of the Adsorption of Eosin B Dye with Graphene Oxide: Effect of Synthesis Methods and Adsorption Conditions, International Journal of Advanced Natural Sciences and Engineering Researches, 9(10), 457-463. Abstract – The contamination of industrial wastewater with dyes causes toxic effects on aquatic organisms and poses risks to human health. Among existing wastewater treatment methods, adsorption stands out due to its simplicity, efficiency, and low cost. Graphene oxide (GO) is one of the most studied materials due to its high specific surface area, good stability in aqueous environments, and oxygenated functional groups (hydroxyl, carboxyl, and epoxide) that facilitate interactions with organic molecules. In this study, GO was synthesized using three different methods (Staudenmaiermaier, StaudenmaiermaierHummers, and Hummers) and subsequently used for the adsorption of eosin B in aqueous solutions. Furthermore, the effects of the type of base (NaOH, KOH, NH₄OH) and different pH values (pH: 2, 5, and 9) on the adsorption process were investigated. Samples were analyzed in terms of % eosin B adsorbed and the amounts of eosin B (mg)/GO (g). Experiments were conducted at 25 °C, at an initial concentration of 300 ppm, using 0.1 g of GO and stirring for 24 h. The results show that the Hummers method has the highest adsorption capacity. Adsorption efficiency reaches its maximum value, particularly in the basic environment created by using NaOH, and the highest efficiency under pH influence was obtained at pH 2. These findings confirm the critical role of surface functionalization and electrostatic charges in the GO-dye interaction and demonstrate the promising potential of GO as an effective absorbent in the treatment of colored wastewater. Keywords – Graphene Oxide, Eosin B, Adsorption, Dye, pH. I. INTRODUCTION With the rapid development of industry, synthetic dyes, widely used especially in the textile, cosmetics, biological, and plastic industries, pose a significant threat to environmental pollution. These substances are chemicals that are not readily biodegradable [1-3]. When mixed with wastewater systems, they can create toxic effects in aquatic ecosystems and adversely affect human health [4,5]. Synthetic dyes, especially eosin B, are major components of colored wastewater in the textile industry, and the effective removal of these substances is crucial for water treatment processes [6]. Eosin B is an organic dye widely used in the textile industry due to its strong color-imparting properties [7]. This compound is highly soluble in water and contributes significantly to color pollution due to its International Journal of Advanced Natural Sciences and Engineering Researches 458 characteristic structure (Figure 1). However, the contamination of water resources with eosin B and similar dyes leads to deterioration of water quality and pollution of ecosystems. Direct release of eosin B into the environment threatens aquatic life and has long-term effects on ecosystems [8]. Therefore, various water treatment methods are needed to eliminate such contaminants [4]. Figure 1. Structure of Eosin B Among wastewater treatment techniques, biological, chemical, and physical methods are available. However, most of these methods are characterized by high costs and low efficiency [9]. In this context, the adsorption method stands out as a low-cost, effective, and environmentally friendly solution [3]. Adsorption is based on the principle of removing pollutants by binding to the adsorbent surface and is widely preferred, especially for the removal of organic substances and dyes. This method offers advantages such as high efficiency, low energy consumption, and easy applicability [10,11]. In recent years, graphene oxide (GO) has become a popular material for adsorption applications [12]. GO is a carbon material with a high surface area and enriched with oxygen-containing functional groups. Thanks to these properties, it is used as a highly effective adsorbent for the adsorption of organic pollutants [13]. GO has the capacity to adsorb organic pollutants such as dyes through mechanisms such as hydrogen bonds, Van der Waals interactions, and electrostatic interactions [14]. The adsorption capacity of GO varies depending on environmental factors such as the synthesis method used, pH value, and ionic strength of the solution [15]. Graphene oxide is attracting attention as a potential adsorbent for the removal of dyes such as Eosin B, particularly those used in the textile industry, from aqueous solutions. However, optimization of various parameters is necessary to maximize GO's adsorption capacity [16]. Among these parameters, factors such as the synthesis method, pH, ionic strength of the solution, and the type of base used play important roles. Oxygenated functional groups on the surface of GO can affect adsorption efficiency by varying their charge distributions depending on pH and the type of base [16]. Therefore, the methods used in GO synthesis have a decisive impact on its adsorption capacity [17]. This study aims to investigate the effects of different synthesis methods and adsorption parameters to increase the effectiveness of graphene oxide (GO) in the adsorption of Eosin B dye. The literature indicates that GO has a high adsorption capacity, and this property can vary depending on pH conditions [18]. In this context, this study will compare the adsorption performance of GO forms obtained from three different synthesis methods (Staudenmaiermaier, Staudenmaiermaier-Hummers, and Hummers) in aqueous solutions of Eosin B dye. Furthermore, the effects of factors such as pH (2, 5, 9) and base type (NaOH, KOH, NH₄OH) on the adsorption process will be evaluated. The findings will contribute scientifically to the potential use of graphene oxide as an adsorbent in the treatment of colored wastewater. International Journal of Advanced Natural Sciences and Engineering Researches 459 II. MATERIALS AND METHOD For graphene oxide synthesis using the Staudenmaier, Staudenmaier-Hummers, and Hummers methods, all chemicals; including graphite, potassium permanganate, 37% hydrochloric acid, ethanol, 35% hydrogen peroxide, acetone, phosphoric acid, potassium chlorate, sulfuric acid, nitric acid, sodium hydroxide, potassium hydroxide, and ammonium hydroxide, were of analytical grade and were supplied by various suppliers. Additionally, the Eosin-B dye used for adsorption studies was also supplied in analytical grade. 2.1. Graphene Oxide Synthesis Graphene oxides have been synthesized using three different methods: The Staudenmaier Method: This method is based on the reaction of graphite with a mixture of concentrated nitric and sulfuric acids under the oxidizing effect of potassium chlorate. The reaction process is carried out at an initial temperature of approximately 5°C and under prolonged stirring. Water is then added to the medium, raising the temperature to 95°C. In the final stages of the process, metal ions and various impurities are removed with hydrochloric acid. Remaining oxidizing residues are neutralized with hydrogen peroxide (H₂O₂). Finally, the product is subjected to washing, centrifugation, and drying. Staudenmaier–Hummers Combined Method: This method is considered a modified procedure that combines the key features of the Staudenmaier and Hummers approaches.In addition to nitric and sulfuric acids, phosphoric acid is also included in the reaction medium to enhance oxidation efficiency. Potassium chlorate and potassium permanganate are used together as oxidizing agents. The reaction conditions and purification steps are similar to those in the Staudenmaier method; however, the combined use of these two oxidizers increases the degree of oxidation and improves the quality of the synthesized graphene oxide. The Modified Hummers Method: In this method, a mixture of sulfuric and phosphoric acids forms the reaction medium, while potassium permanganate serves as the sole oxidizing agent. The process generally follows a similar procedure to other methods: initial stirring at a low temperature, followed by an increase in temperature by adding water. After the reaction, purification with hydrochloric acid is performed, residual oxidants are removed with hydrogen peroxide, and finally, washing and drying are completed. 2.2. Adsorption Experiments The adsorption of eosin B on graphene oxide (GO) was investigated in three stages, as described below: First Stage: To determine the effect of the GO synthesis method on adsorption, 0.1 g of GO, synthesized using the Staudenmaier, Staudenmaier-Hummers, and Hummers methods, was mixed with 100 mL of eosin B solution at a concentration of 300 ppm. The samples were stirred at 25°C for 24 hours and then centrifuged at 3750 rpm for 5 minutes. The remaining eosin B content was measured using a UV-Vis spectrophotometer at 514 nm, and the adsorption rate was calculated based on the decrease in absorbance. Second Stage: In this stage, the effect of the type of base on adsorption was investigated. 0.05 g of GO, synthesized using the Hummers method, was exposed to 300 ppm eosin B solutions. The pH of the solutions was adjusted to 10 using NaOH, KOH, and NH₄OH, respectively. The mixtures were kept at 25°C for 24 hours. After this period, the mixtures were centrifuged, and the resulting supernatants were analyzed using a UV-Vis spectrophotometer. Third Stage: In the final stage, the effect of pH on adsorption capacity was investigated. 0.05 g of GO, synthesized using the Hummers method, was mixed with a 250 ppm eosin B solution. The pH of the solution was adjusted to 2, 5, and 9 using NaOH or HCl. After stirring for 24 hours at 25°C, the samples were centrifuged, and the remaining dye content was measured using a UV-Vis spectrophotometer. The schematic representation of the three-stage experimental study is given in Figure 2. International Journal of Advanced Natural Sciences and Engineering Researches 460 Figure 2. Adsorption test setup and post-test solutions 2.3 Analysis The percentage dye removal and the amount of adsorption were calculated using the following equations: %𝑅𝑒𝑚𝑜𝑣𝑎𝑙 = 𝐶𝑜−𝐶𝑒 𝐶𝑜×100 (1) 𝑞𝑒(𝑚𝑔/𝑔) = (𝐶𝑜− 𝐶𝑒) × 𝑉 𝑊 (2) Where C0 (mg/L) represents the initial dye concentration, Ce (mg/L) represents the equilibrium concentration of the dye solution, W(g) represents the mass of the adsorbent, and V(L) represents the volume of the dye solution. Calibration Curve – Eosin B To create a calibration curve for eosin B, standard solutions were prepared at concentrations between 5 and 300 ppm. Absorbance values at 514 nm, the maximum adsorption wavelength of the dye, were measured using a UVVis spectrophotometer. The calibration curve derived from the obtained data is shown in Figure 3. Figure 3. Calibration curve for eosin B solutions prepared at different concentrations y = 0,0031x - 0,004 R² = 0,999 0 0,2 0,4 0,6 0,8 1 050 100 150 200 250 300 Absorbance Eozin-B (mg/L) International Journal of Advanced Natural Sciences and Engineering Researches 461 III. RESULTS AND DISCUSSION The aim was to evaluate the effects of graphene oxide synthesized using various methods on the adsorption capacity of eosin B dye. In this context, the effects of the graphene oxide synthesis method, the type of base used, and the pH on adsorption performance were investigated. The removal amounts and adsorption percentages obtained under the experimental conditions are presented in Table 1. Table 1. Eosin B removal results under different experimental conditions Experiment Feature Co Ce The amount of absorbed Eosin-B mgEozinB/gGO % Eosin B Adsorption Efficiency Staudenmaier 300 275 25 50 8,33 St-Hummers 300 245 55 110 18,33 Hummers 300 185 115 230 38,33 KOH 300 284 16 32 5,33 NaOH 300 268 32 64 10,67 NH4OH 300 271 29 58 9,67 pH2 250 14 236 472 94,4 pH5 250 219 31 62 12,4 pH9 250 234 16 32 6,4 %Eosin= (Absorbed Eosin B/Co)*100= (25/300)*100 = 8.333% Effect of Synthesis Method on Eosin B Adsorption Capacity The effect of the synthesis method of graphene oxide (GO) on eosin B adsorption was investigated by comparing the Staudenmaier, Staudenmaier–Hummers, and Hummers methods. As shown in Table 1, the highest adsorption capacity was obtained in GO synthesized by the Hummers method (230 mg/g; 38.33%). GO produced by the Staudenmaier–Hummel method exhibited lower adsorption (110 mg/g; 18.33%), while the lowest value was observed in GO synthesized by the Staudenmaier method (50 mg/g; 8.33%). These findings indicate that the Hummers method results in a higher rate of oxidation of graphite layers and creates a greater number of oxygenated functional groups (hydroxyl, carboxyl, epoxy, etc.) on the surface. These functional groups increase adsorption capacity by facilitating the adhesion of eosin B molecules to the surface via electrostatic attraction or hydrogen bonds. Similarly, the literature reports that GO synthesized using the Hummers method exhibits higher oxygen content and surface activity than samples obtained using other methods [19,20]. These findings support the claim that GO produced using the Hummers method is a more effective adsorbent for the removal of anionic dyes such as eosin B. Effect of Base Type on Eosin B Adsorption The effect of base type on the adsorption capacity of eosin B dye was investigated using NaOH, KOH, and NH₄OH at pH 10. As shown in Table 1, the highest adsorption capacity was obtained in the system using NaOH (64 mg/g; 10.67%). This result was followed by NH₄OH (58 mg/g; 9.67%) and KOH (32 mg/g; 5.33%). The findings indicate that the base type significantly affects the ionic character of the solution and the charge distribution of the GO surface. A high OH⁻ ion concentration in NaOH caused greater negative charge accumulation on the GO surface, strengthening the electrostatic interaction with eosin B molecules. In contrast, the ionization effect was weaker in KOH and especially NH₄OH environments, and the attractive forces between the adsorbent and the dye were limited. It has also been International Journal of Advanced Natural Sciences and Engineering Researches 462 reported in the literature that base type and pH conditions are determinants of GO surface charge and adsorption efficiency [21]. pH and ionic species affect the degree of ionization of functional groups on the GO surface; [22] reported that GO prepared in NaOH medium exhibited higher adsorption capacity than other bases. In this regard, the use of NaOH provided the most efficient base condition for eosin B removal by creating a higher negative charge density on the GO surface, consistent with trends reported in the literature. Effect of pH on Adsorption Initial pH is an important parameter in the adsorption of eosin B by graphene oxide (GO). In this study, experiments conducted at pH 2, 5, and 9 showed that the adsorption capacity is strongly dependent on pH. The highest capacity was obtained at pH 2 (472 mg/g; 94.4%), while a significant decrease was observed at pH 5 (62 mg/g; 12.4%) and pH 9 (32 mg/g; 6.4%). Similarly, Sangashekan, Asan, and Gilani (2019) reported a capacity of 68.027 mg/g for eosin B adsorption by GO at pH 4 and showed that low pH increased adsorption [8]. This is due to the strong electrostatic attraction between the protonated functional groups on the GO surface and the anionic dye in acidic media [8]. Tang et al. (2017) investigated the effect of pH on the adsorption of ionized compounds on the GO surface and reported that strong interactions occurred at low pH, while these interactions weakened at high pH due to deprotonation. These findings support the pH-dependent adsorption change observed in the present study [23]. IV. CONCLUSION This study evaluated the effects of the synthesis method, the type of base used, and the pH of the solution on the removal of eosin B dye using graphene oxide (GO). The results showed that all three factors significantly influence the adsorption capacity. When comparing the synthesis methods, the GO obtained using the Hummers method achieved the highest adsorption capacity (230 mg/g; 38.33%). This can be attributed to the method's ability to promote the formation of more oxygen-containing functional groups on the GO surface. In the section investigating the effect of base type, the system using NaOH showed the highest adsorption (64 mg/g; 10.67%). This is likely due to the increased OH⁻ ions in the NaOH medium, which cause a stronger negative charge on the GO surface, enhancing the interaction with eosin B molecules. Regarding the pH factor, the highest adsorption was observed under acidic conditions (pH = 2) (472 mg/g; 94.4%). The capacity decreased as the pH increased, which can be attributed to the protonation of the GO surface at low pH, leading to increased interactions. 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