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Laminated porous diatomite monoliths for adsorption of dyes from water
Author(s) -
Nikjoo Dariush,
Perrot Virginie,
Akhtar Farid
Publication year - 2019
Publication title -
environmental progress and sustainable energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.495
H-Index - 66
eISSN - 1944-7450
pISSN - 1944-7442
DOI - 10.1002/ep.13064
Subject(s) - monolith , adsorption , chemical engineering , materials science , aqueous solution , porosity , mass transfer , rhodamine b , porous medium , diffusion , composite material , chromatography , chemistry , organic chemistry , catalysis , photocatalysis , engineering , physics , thermodynamics
Structured laminated diatomite monoliths with superior mechanical properties were prepared by controlled freeze‐casting of the aqueous suspensions of diatomite powders for wastewater treatment. The directional freezing of suspensions with solids loading of 25, 30, and 37 wt % at cooling from 0.5 to 5 K/min resulted in the formation of lamellar pores and solid walls with the thickness of 12–30 and 14–39 μm, respectively. The increase in solid loading and freezing rate resulted in refinement of the porous structure. Durable monoliths with the mechanical strength of 5.3 MPa were obtained by thermal treatment of the freeze‐dried green bodies at 1,373 K. Diatomite monoliths with a pore size of 29.6 μm showed the removal of model dye pollutant Rhodamine B from water by adsorption and long‐term water stability. The dye uptake capacity of monolith changed from 1.38 to 17.04 mg/g for the initial dye concentrations between 1.0 and 12.5 mg/L at 298 K and pH = 6, respectively. The adsorption data analysis using Lagergren's pseudo‐first‐order, pseudo‐second‐order, and intra‐particle diffusion models revealed that diatomite monoliths offered efficient mass transfer in the porous laminated scaffold and to the adsorption sites and bulk diffusion of dye molecules in water was the rate‐limiting mechanism for dye removal. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S377–S385, 2019