Application of Walnut Shell Biowaste as an Inexpensive Adsorbent for Methylene Blue Dye: Isotherms, Kinetics, Thermodynamics, and Modeling

Separations

article

Sabrina Farch¹  Madiha Melha Yahoum³  Selma Toumi⁴  Hichem Tahraoui¹  Sonia Lefnaoui¹  Mohammed Kebir⁵  Meriem Zamouche⁶  Abdeltif Amrane⁷  Jie Zhang⁸  Amina Hadadi⁹  Lotfi Mouni⁹ 

[1] Laboratory of Experimental Biology and Pharmacology, Faculty of Sciences, University Yahia Fares of Medea;Laboratory Advanced Materials and Physical Chemistry for Environment and Health, Faculty of Exact Sciences, University Djillali Liabes of Sidi Bel Abbes;Materials and Environmental Laboratory ,(LME), University of Medea;Faculty of Sciences, University Yahia Fares of Medea;Research Unit on Analysis and Technological Development in Environment;Laboratory of Research on Drug Developpement and Sustainable Developpement ,(ReMeDD), Faculty of Process Engineering, University of Salah BOUBNIDER Constantine 3;University Rennes, Ecole Nationale Supérieure de Chimie de Rennes;School of Engineering, Merz Court, Newcastle University;Laboratory of Management and Valorization of Natural Resources and Quality Assurance, SNVST Faculty, Akli Mohand Oulhadj University

关键词: walnut shells;    methylene blue;    adsorption;    analytical approaches;    isotherms;    kinetic models;   

DOI  :  10.3390/separations10010060

学科分类：社会科学、人文和艺术（综合）

来源: mdpi

【 摘 要 】

This research aimed to assess the adsorption properties of raw walnut shell powder (WNSp) for the elimination of methylene blue (MB) from an aqueous medium. The initial MB concentration (2–50 mg/L), the mass of the biomaterial (0.1–1 g/L), the contact time (10–120 min), the medium’s pH (2–12), and the temperature (25–55 °C) were optimized as experimental conditions. A maximum adsorption capacity of 19.99 mg/g was obtained at an MB concentration of 50 mg/L, a medium pH of 6.93 and a temperature of 25 °C, using 0.2 g/L of WNSp. These conditions showed that the MB dye elimination process occurred spontaneously. Different analytical approaches were used to characterize the WNSp biomaterial, including functional groups involved in MB adsorption, the surface characteristics and morphological features of the WNSp before and after MB uptake, and identification of WNSp based on their diffraction pattern. The experimental isotherm data were analyzed by the Langmuir and Freundlich models for the adsorption of MB dye. The corresponding values of parameter RL of Langmuir were between 0.51 and 0.172, which confirmed the WNSp’s favorable MB dye adsorption. The experimental kinetic data were examined, and the pseudo-second-order model was shown to be more suitable for describing the adsorption process, with an excellent determination coefficient (R2 = 0.999). The exchanged standard enthalpy (H° = −22.456 KJ.mol−1) was calculated using the van ‘t Hoff equation, and it was proven that the adsorption process was exothermic. The spontaneous nature and feasibility of the MB dye adsorption process on WNSp were validated by negative standard enthalpy values (G°) ranging from −2.580 to −0.469 at different temperatures. It was established that WNSp may be employed as a novel, effective, low-cost adsorbent for the elimination of methylene blue in aqueous solutions.

【 授权许可】

CC BY