Modeling batch kinetics of cesium, cobalt and strontium ions adsorption from aqueous solutions using hydrous titanium oxide

Abstract

Hydrous titanium oxide was chemically synthesized and tested as adsorbent material for the removal of cesium, cobalt and strontium ions from chloride waste solutions using batch technique. The influences of pH, contact time, and temperature have been reported. The uptake of both strontium and cobalt ions was found to be greater than that of cesium and the apparent sorption capacity of each ion increases with increase in temperature. Thermodynamic parameters such as changes in Gibbs free energy (Δ

LTA zeolite monoliths with hierarchical trimodal porosity as highly efficient microreactors for strontium capture in continuous flow

“…The mechanistic homogeneous particle diffusion model (HPDM) [29,32], was attempted following the method presented by Metwally et al [29] (Fig. S7).…”

“…Rates of cation-exchange can be calculated by using different kinetic models as pseudo-first-order or pseudo-second-order rate models [29]. In the case of LTA powders and LTA-monolith M0 (featuring no mesoporosity), it has already been shown that a pseudo second-order model describes accurately the kinetics of cation adsorption [9].…”

“…Comparison with literature results is not straight forwards due to different experimental conditions. However, Metwally et al [29] used quite similar conditions as us for Sr 2þ adsorption measurements using hydrous titanium oxide, a new promising sorbent for strontium removal. At pH 6 this material features an adsorption capacity of 3.3 meq g À1 at 25 C and as high as 6.5 meq g À1 at 35 C, in comparison to 5.4 meq g À1 for LTA zeolites independently of temperature and shape.…”

“…Consequently, the two diffusion limiting steps are external mass transfer (film diffusion) and intraparticle diffusion. Different models have been proposed to quantify diffusion limitations: empirical models as the one proposed for molecules by Weber and Morris [31], which is to attempt to fit the experimental data to a simple functional form, which not possesses any theoretical basis, or mechanistic model named homogeneous particle diffusion model (HPDM) [29,32], which attempt to use detailed physical concepts to describe the process. However, this may lead to prohibitively complex models that may be difficult to apply in practice [33].…”

Effect of the synthesis temperature of sodium nonatitanate on batch kinetics of strontium-ion adsorption from aqueous solution

“…According to the literature, the presence of two linear zones in these plots can be explained by two sorption processes: external mass transfer, such as boundary-layer diffusion, and intra-particle diffusion. The initial curve zone is attributed to the external diffusion, and the second linear zone is defined as the intra-particle diffusion (Crini et al 2007;Metwally et al 2007). Moreover, the slope of this second linear zone can be considered the intradiffusion coefficient.…”