Continuous Synthesis of Zn2Al-CO3 Layered Double Hydroxides for the Adsorption of Reactive Dyes from Water

Clark, Ian; Smith, Jacob; Gomes, Rachel L.; Lester, Edward

Abstract

A novel pilot scale approach to continuous synthesis of layered double hydroxides (LDHs) was used to produce Zn2Al-CO3. The Zn2Al-CO3 was calcined and used in the adsorption of Reactive Black 5 (RB5) and Reactive Orange 16 (RO16) from water. The specific surface area of the LDH was 50.1 m2 g-1, while the surface area of the calcined LDH (MMO) was 57.8 m2 g-1. X-ray diffraction indicated complete breakdown of the LDH at 500 °C for 4 hours, with amorphous Al2O3 or AlOOH alongside ZnO. Reaction variables in the adsorption system; temperature, adsorbent dose, pH, initial concentration and the effect of competing anions were investigated across four temperatures from 10 °C to 40 °C. Maximum adsorption capacity calculated from the Langmuir isotherm was 895 mg g-1 and 589 mg g-1 at 20 °C, for RB5 and RO16, respectively. Intercalation of dye molecules was the main mode of adsorption, as indicated by shifts in (003) reflection from 11.5° to 4.5° and 3.2° for RB5 and RO16 respectively. Adsorption was best modelled by the pseudo 2nd order kinetic model. The intra-particle diffusion model indicated multiple stages of adsorption; surface adsorption occurs initially, followed by, intra-particle diffusion of dye molecules into the interlayer region. Regeneration through calcination resulted in an adsorption equal to 99 ± 2%.

Citation

Clark, I., Smith, J., Gomes, R. L., & Lester, E. (2019). Continuous Synthesis of Zn2Al-CO3 Layered Double Hydroxides for the Adsorption of Reactive Dyes from Water. Journal of Environmental Chemical Engineering, 7(3), Article 103175. https://doi.org/10.1016/j.jece.2019.103175

• Journal Article Type: Article
• Acceptance Date: May 24, 2019
• Online Publication Date: May 24, 2019
• Publication Date: 2019-06
• Deposit Date: Jun 26, 2019
• Publicly Available Date: May 25, 2020
• Journal: Journal of Environmental Chemical Engineering
• Print ISSN: 2213-2929
• Electronic ISSN: 2213-2929
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 7
• Issue: 3
• Article Number: 103175
• DOI: https://doi.org/10.1016/j.jece.2019.103175
• Keywords: Continuous Flow Synthesis; Layered Double Hydroxides; Reactive Dyes; Adsorption Kinetics; Thermodynamics
• Public URL: https://nottingham-repository.worktribe.com/output/2231067
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S2213343719302982?via%3Dihub
• Additional Information: This article is maintained by: Elsevier; Article Title: Continuous Synthesis of Zn2Al-CO3 Layered Double Hydroxides for the Adsorption of Reactive Dyes from Water; Journal Title: Journal of Environmental Chemical Engineering; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.jece.2019.103175; Content Type: article; Copyright: © 2019 Published by Elsevier Ltd.