2 research outputs found
The univariate and multivariate Cox analysis of risk score and clinical features.
The univariate and multivariate Cox analysis of risk score and clinical features.</p
Introduction of Bifunctional Groups into Mesoporous Silica for Enhancing Uptake of Thorium(IV) from Aqueous Solution
The potential industrial application
of thorium (Th), as well as the environmental and human healthy problems
caused by thorium, promotes the development of reliable methods for
the separation and removal of ThÂ(IV) from environmental and geological
samples. Herein, the phosphonate-amino bifunctionalized mesoporous
silica (PAMS) was fabricated by a one-step self-assembly approach
for enhancing ThÂ(IV) uptake from aqueous solution. The synthesized
sorbent was found to possess ordered mesoporous structures with uniform
pore diameter and large surface area, characterized by SEM, XRD, and
N<sub>2</sub> sorption/desorption measurements. The enhancement of
ThÂ(IV) uptake by PAMS was achieved by coupling of an access mechanism
to a complexation mechanism, and the sorption can be optimized by
adjusting the coverage of the functional groups in the PAMS sorbent.
The systemic study on ThÂ(IV) sorption/desorption by using one coverage
of PAMS (PAMS12) shows that the ThÂ(IV) sorption by PAMS is fast with
equilibrium time of less than 1 h, and the sorption capacity is more
than 160 mg/g at a relatively low pH. The sorption isotherm has been
successfully modeled by the Langmuir isotherm and D-R isotherm, which
reveals a monolayer homogeneous chemisorption of ThÂ(IV) in PAMS. The
ThÂ(IV) sorption by PAMS is pH dependent but ionic strength independent.
In addition, the sorbed ThÂ(IV) can be completely desorbed using 0.2
mol/L or more concentrated nitric acid solution. The sorption test
performed in the solution containing a range of competing metal ions
suggests that the PAMS sorbent has a desirable selectivity for ThÂ(IV)
ions