Laminated porous diatomite monoliths for adsorption of dyes from water

Abstract

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

Preparation and Superstrong Adsorption of a Novel La(Ⅲ)-Crosslinked Alginate/Modified Diatomite Macroparticle Composite for Anionic Dyes Removal from Aqueous Solutions

“…Hence, CPAM-Dia/SA-La gel spheres have the benefits of green environmental protection, superstrong adsorption capacity, good selectivity and easy separation from the water and without secondary pollution. At the same time, the q max (mg/g) values of other Dia-based adsorbents for the dyes are shown in Table 4 [ 61 , 62 , 63 , 64 , 65 , 66 ]. By comparing the reported research results, the CPAM-Dia/SA-La gel composite is confirmed to have extremely significant adsorption advantages for dyes.…”

Porous Strontium Chloride Scaffolded by Graphene Networks as Ammonia Carriers

“…Particularly, as ammonia carriers for the automotive SCR system, the porosity, pore size, SrCl 2 loading, and the volumetric efficiency can be tailored by the processing parameters such as suspension concentration, freezing rate, and shape of the molds, to obtain porous structured SrCl 2 -rGO composites with a hierarchy of pores for efficient ammonia delivery while fitting to the automotive components without modifications, such as dosing pipelines, shape, and size of the storage cartridges. [38,[47][48][49] Furthermore, the porous SrCl 2 -rGO composite structures exhibit a wide SrCl 2 loading range from 0 to 96 wt% with a theoretical porosity over 90%, which compensates for the volume swing associated with the ammonia absorption-desorption cycles. A series of porous SrCl 2 -rGO composites with SrCl 2 loading of 20, 50, 80, and 96 wt% (denoted as PS20, PS50, PS80, and PS96, respectively) as well as the SrCl 2 pellet (denoted as SP100) were designed and fabricated for comparison.…”

Macroporous ceramics for the sustainable development goals (SDGs): Review

“…Significant research efforts have been also made for the decontamination of wastewater from dyes. Nikjoo et al 29 . prepared laminated porous diatomite monoliths by controlled freeze‐casting of aqueous suspensions of diatomite powders for the adsorption of dyes from water.…”

“…28 Significant research efforts have been also made for the decontamination of wastewater from dyes. Nikjoo et al 29 prepared laminated porous diatomite monoliths by controlled freeze-casting of aqueous suspensions of diatomite powders for the adsorption of dyes from water. Directional freezing of suspensions with solids loading of 25-37 wt% at cooling rates of .5-5 K/min resulted in a formation of lamellar pores and solid walls with thickness of 12-30 and 14-39 μm, respectively.…”