Kinetic and equilibrium study of the removal of reactive dye using modified walnut shell

• Published in: Water science and technology Vol. 80; no. 5; pp. 874 - 883
• Main Authors: Li, Shenmaishang, Zeng, Zuoxiang, Xue, Weilan
• Format: Journal Article
• Language: English
• Published: England IWA Publishing 01.09.2019
• Subjects: Acids; Adsorbents; Adsorption; Aqueous solutions; Aspartic acid; Caustic soda; Chemisorption; Diffusion; Dyes; Engineering; Epichlorohydrin; Equilibrium; Fourier transforms; Hydrogen-Ion Concentration; Isotherms; Juglans; Kinetics; Organic chemistry; Reaction kinetics; Scanning electron microscopy; Sodium; Spectrum analysis; Textiles; Thermodynamics; Walnuts; Water Pollutants, Chemical; Water treatment; Japan
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2019.324

Modified walnut shell (EAWNS) was prepared by reaction with epichlorohydrin and alkaline solution of aspartic acid and used to remove reactive dye (Reactive Brilliant Blue (KN-R)) from aqueous media. The isotherms, kinetics and thermodynamics of KN-R adsorption onto EAWNS were studied at 298-318 K. The isotherm data of KN-R adsorption onto EAWNS agreed closely with the Langmuir model. The theoretical monolayer adsorption capacity for KN-R was 224.42 mg/g at 318 K. The result from the Dubinin-Radushkevich model showed that the KN-R adsorption onto EAWNS is chemisorption. The adsorption rate of KN-R onto EAWNS conformed to the pseudo-second-order model. The diffusion mechanism was investigated by the intraparticle diffusion model. The mass-transfer coefficient calculated by the surface mass-transfer coefficient model was in range of 2.95 × 10 to 2.93 × 10 cm/s. The thermodynamic results suggested that the adsorption of KN-R onto EAWNS is spontaneous and endothermic in nature. The design of a single-stage batch adsorption process based on EAWNS adsorbent was carried out. Furthermore, the recycled EAWNS maintains high adsorption capacity despite four cycles.