Congo Red Removal from Aqueous Solution Using 2-Mercaptopropionic Acid Functionalized Fe₃O₄ Magnetic Nanoparticles

Year 2025, Volume: 7 Issue: 3, 361 - 369, 30.09.2025

Ümit Can Erim

https://doi.org/10.51435/turkjac.1766160

Abstract

In this study, magnetic Fe₃O₄ nanoparticles were synthesized and were modified with 2-mercaptopropionic acid (MPA). This was done to enhance their adsorption performance toward Congo Red (CR) in aqueous solution. FTIR spectroscopy was used to characterize the resulting MPA-functionalized nanomaterial (Fe₃O₄@MPA), confirming the successful attachment of -SH and -COOH functional groups. To investigate the effects of pH, initial dye concentration, contact period and temperature, the batch adsorption technique was conducted. Since the adsorption capacity was not significantly affected by pH, pH adjustment was continued for minimal chemical and time savings. This finding indicates that the surface charge and functional groups of Fe₃O₄@MPA interact most favorably with CR molecules under near-neutral conditions. The adsorption data were fitted to isotherm models, and the optimal model was found to be the Langmuir model (R² = 0.9901), which shows single-layer adsorption with a maximum capacity of 120.48 mg/g. Analysis of the kinetic data revealed a correlation with the pseudo-second-order kinetic model, confirming the chemical adsorption mechanism with a determination coefficient (R²) greater than 0.99. Thermodynamic parameters further confirmed the process to be spontaneous and endothermic, with negative ΔG°, positive ΔH° (6.92 kJ/mol), and positive ΔS° (0.029 kJ/mol·K). More than 60% removal was achieved in real sample applications. This work presents a new approach using MPA-functionalized Fe₃O₄ nanoparticles, which both increases adsorption efficiency and magnetic recoverability, providing a sustainable and pH-independent method for Congo Red purification from real matrices.

Keywords

2-Mercaptopropionic acid , Adsorption isotherms , Congo Red , Magnetic nanoparticles

Thanks

The author gratefully acknowledges Büşra Şahin Kurt and Mehmet Enes Tezçakar for their valuable assistance, and Nursu Aylin Kasa and Selim Gürsoy for their critical review of the manuscript.

2-Merkaptopropiyonik Asit ile Fonksiyonelleştirilmiş Fe₃O₄ Manyetik Nanopartiküller Kullanılarak Sulu Çözeltiden Kongo Kırmızısının Uzaklaştırılması

Abstract

Bu çalışmada, manyetik Fe₃O₄ nanopartiküller sentezlenmiş ve 2-merkaptopropiyonik asit (MPA) ile modifiye edilmiştir. Bu, sulu çözeltide Kongo Kırmızısı (CR) üzerindeki adsorpsiyon performansını artırmak için yapılmıştır. FTIR spektroskopisi, elde edilen MPA-fonksiyonelleştirilmiş nanomalzemeyi (Fe₃O₄@MPA) karakterize etmek için kullanılmış ve -SH ve -COOH fonksiyonel gruplarının başarılı bir şekilde bağlandığını doğrulamıştır. pH, başlangıç boya konsantrasyonu, temas süresi ve sıcaklığın etkilerini araştırmak için toplu adsorpsiyon tekniği uygulandı. Adsorpsiyon kapasitesi pH'dan önemli ölçüde etkilenmediğinden, kimyasal ve zaman tasarrufu için pH ayarlaması devam ettirildi. Bu bulgu, Fe₃O₄@MPA'nın yüzey yükü ve fonksiyonel gruplarının, neredeyse nötr koşullar altında CR molekülleriyle en uygun şekilde etkileşime girdiğini göstermektedir. Adsorpsiyon verileri izoterm modellerine uydurulmuş ve optimal modelin, maksimum kapasitesi 120,48 mg/g olan tek katmanlı adsorpsiyonu gösteren Langmuir modeli (R² = 0,9901) olduğu bulunmuştur. Kinetik verilerin analizi, 0,99'dan büyük bir belirleme katsayısı (R²) ile kimyasal adsorpsiyon mekanizmasını doğrulayan, sözde ikinci dereceden kinetik model ile bir korelasyon olduğunu ortaya koymuştur. Termodinamik parametreler, negatif ΔG°, pozitif ΔH° (6,92 kJ/mol) ve pozitif ΔS° (0,029 kJ/mol·K) ile sürecin spontan ve endotermik olduğunu daha da doğruladı. Gerçek numune uygulamalarında %60'ın üzerinde bir giderim oranı elde edildi. Bu çalışma, MPA ile işlevselleştirilmiş Fe₃O₄ nanopartiküllerini kullanan yeni bir yaklaşım sunmaktadır. Bu yaklaşım, hem adsorpsiyon verimliliğini hem de manyetik geri kazanılabilirliği artırarak, gerçek matrislerden Kongo Kırmızısı saflaştırması için sürdürülebilir ve pH'dan bağımsız bir yöntem sağlamaktadır.

Keywords

2-merkaptopropiyonik asit , adsorpsiyon izotermleri , kongo kırmızısı , manyetik nanopartiküller

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