Removal Efficiency of Textile Dyes from Aqueous Solutions Using Calcined Waste of Eggshells as Eco-friendly Adsorbent: Kinetic and Thermodynamic Studies

R. Slimani et al., Removal Efficiency of Textile Dyes from Aqueous Solutions…, Chem. Biochem. Eng. Q., 35 (1) 43–56 (2021) Removal Efficiency of Textile Dyes from Aqueous Solutions Using Calcined Waste of Eggshells as Eco-friendly Adsorbent: Kinetic and Thermodynamic Studies 43 This work is licensed under a Creative Commons Attribution 4.0 International License R. Slimani,a I. El Ouahabi,b S. Benkaddour,b H. Hiyane,b M. Essoufy,a Y. Achour,c S. El Antri,b S. Lazar,b,* and M. El Haddadc a Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Water & Environment-CERNE2D, Faculty of Sciences, Mohammed V University in Rabat, BP 1014RP, Rabat, Morocco b Laboratory of Biochemistry, Environment &Agroalimentary URAC36, Faculty of Sciences and Techniques, Hassan II University doi: https://doi.org/10.15255/CABEQ.2020.1872 of Casablanca, BP 146, 20650, Mohammedia, Morocco c Laboratory of Analytical & Molecular Chemistry, Original scientific paper Faculty Poly-Disciplinary of Safi, University Received: September 29, 2020 of Cadi Ayyad, BP4162, 46000 Safi, Morocco Accepted: January 25, 2021 This research investigates the removal of textile dyes (Rhodamine B and Alizarin Red S) from aqueous solution by a low-cost adsorbent prepared from eggshell waste. Batch adsorption experiments were conducted in order to determine the effect of different parameters such as pH, dye concentration, contact time, adsorbent dosage, particle size, and temperature. The best correlation was found by Langmuir model, and the maximum adsorption capacity was 175.58 mg g–1 for Rhodamine B and 156.56 mg g–1 for Alizarin Red S. Thermodynamic studies showed that the adsorption of Rhodamine B and Alizarin Red S were feasible, spontaneous, and exothermic in nature. Regeneration study conducted to test the reusability (five cycles) and comparison of adsorption capacities of Rhodamine B and Alizarin Red S showed that calcined eggshell adsorbent could potentially be used for the removal of dyes from aqueous solutions. Keywords: calcined eggshells, dye, adsorption, kinetics, isotherms Introduction Dyes are widely used in different manufacturing industries, of which the textile industry is their largest consumer, and a large producer of dye-loaded wastewater. During the dyeing process, about 10–15 % of unfixed dye is lost in the water, which comes out as a colored effluent from the industries1. Additionally, dyes are thermally stable compounds that are light-resistant and non-biodegradable because of their complex molecular structures. Most dyes and their degradation products cause serious damage to the ecosystem and biological life due to their toxicity2,3; therefore, it is necessary to remove dyes from the wastewater to protect the eco-system and human health. There are various studies on the physicochemical strategies for removal of dyes from aqueous systems; and among the available methods, adsorption is a well-known separation Corresponding author at: E-mail address: / (S. Lazar) Tel : +212 5 23 31 47 05/Fax : +212 5 23 31 53 53 * technique in terms of initial cost, simplicity, design, ease of separation, and ability to treat dyes in a more concentrated form4. Activated carbon is the most preferred adsorbent for dye removal because of its excellent adsorption ability. However, an extensive usage of activated carbon is restricted because of its high cost. Alternative adsorbents are required to be of low cost when minimal processing is required, abundant in nature, or derived from an industry by-product5. Some of the potential alternative adsorbents studied by a number of researchers include Cerastoderma lamarcki shell6, watermelon seeds7, calcined cow leather8, animal bones9, mussel shells10, Ensissiliqua shell11, and conch shells12. Rhodamine B is a highly water soluble, cationic dye of the xanthene class, and widely used in biological, analytical and optical sciences. It is reported that Rhodamine B is harmful to the environment13,14. Alizarin Red S is an anionic dye of the anthraquinon class, which is widely used in woven fabrics, wool, and cotton textiles15,16. Many re- R. Slimani et al., Removal Efficiency of Textile Dyes from Aqueous Solutions… 43–56 44 R. Slimani et al., Removal Efficiency of Textile Dyes from Aqueous Solutions…, Chem. Biochem. Eng. Q., 35 (1) 43–56 (2021) searchers have been interested in the removal of these dyes from aqueous solutions; and in fact, Ra phiahookeri fruit’s epicarp removed Rhodamine B from an aqueous solution with a maximum adsorption capacity of 666.67 mg g–1 17. Zamouche et al. reported the adsorption of Rhodamine B onto cedar cone by studying the effect of calcination and chemical activation18. Adsorption of Rhodamine B has also been studied on iron-pillared bentonite, and the maximum monolayer adsorption capacity of 98.62 mg g–1 19 was attained. Mustard husk removed Alizarin Red S with a multilayer adsorption mechanism20, which was also achieved on olive stone by-product giving 16 mg g–1 as adsorption capacity21. Roosta et al. developed an Alizarin Red S adsorption process from aqueous solution onto gold nanoparticles by the application of ultrasound, giving a high adsorption capacity of 123.4 mg g–1 22. The aim of the present study was to evaluate and investigate the performance of a newly developed adsorbent, i.e., eggshell powder. This adsorbent was chosen according to its daily presence in domestic waste worldwide. It is an abundant waste, and currently not used in any way. It can be thermally activated for the rapid removal and fast adsorption of Rhodamine B and Alizarin Red S from aqueous solutions with initial dye concentration (20 mg L–1 – 50 mg L–1), which exceeds the actual discharge limit rates. The developed adsorbent was well characterized using various analytical techniques, such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The impact of several influential parameters, such as solution pH, initial dye concentration, contact time, adsorbent dosage, and temperature were well investigated and optimized using batch adsorption study. Moreover, kinetics and thermodynamics of adsorption of Rhodamine B and Alizarin Red S were studied and discussed. Materials and methods Chemicals All chemicals used were of analytical reagent grade and used without further purification. All solutions were prepared using double distilled water. Rhodamine B and Alizarin Red S dyes were supplied by Sigma Aldrich. Some of the data on both dyes are listed in Table 1. The stock solutions of Rhodamine B and Alizarin Red S dyes (1 g L–1) were prepared by dissolving the required amount of dyes in distilled water. Preparation of calcined eggshell adsorbent Preparation of the obtained calcined eggshell (CES) absorbent was achieved by collecting eggshell waste from a restaurant. Firstly, the eggshells were washed several times with tap water and distilled water, and then left in open ai (...truncated)