In this report, we studied the formation mechanism of cagelike polymer microspheres fabricated conveniently and efficiently through a swelling-osmosis process of sulfonated polystyrene (SPS) microspheres in a ternary mixed solvent (water/ethanol/heptane). The scanning electron microscopy and transmission electron microscopy observations indicated that the morphology of the final cagelike SPS microspheres is mainly controlled by the composition of the mixed solvent and the swelling temperature. Considering the solubility parameters of related reagents and the low interface tension of heptane and the aqueous solution of ethanol (only 6.9 mN/m), we confirm that the porogen procedure starts from the swelling of SPS microspheres by heptane, followed by the osmosis process of water molecules into the swollen SPS microspheres forced by the strong hydrophilicity of -SO3H group. The water molecules permeated into SPS microspheres will aggregate into water pools, which form the pores after the microspheres are dried. These prepared cagelike SPS microspheres are further served as the scaffold for the in situ generated CdS nanoparticles under γ-ray radiation. The CdS/SPS composite microspheres show good fluorescence performance. This work shows that the cagelike SPS microspheres have a wide industrial application prospect due to their economical and efficient preparation and loading nanoparticles.
The recovery of precious
metals like palladium (Pd) from secondary resources has enormous economic
benefits and is in favor of resource reuse. In this work, we prepared
a high efficiency pyridine-functionalized reduced graphene oxide (rGO)
adsorbent for selective separation of Pd(II) from simulated electronic
waste leachate, by one-pot γ-ray radiation-induced simultaneous
grafting polymerization (RIGP) of 4-vinylpyridine (4VP) from graphene
oxide (GO) and reduction of GO. The poly(4-vinylpyridine)-grafted
reduced graphene oxide (rGO-g-P4VP) exhibits fast
adsorption kinetics and high maximum adsorption capacity. The adsorption
capacity is 105 mg g–1 in the first minute and reaches
equilibrium within 120 min. The adsorption process follows the Langmuir
model, from which the maximum adsorption capacity of Pd(II) is estimated
to be 177 mg g–1. We also proved that the adsorption
mechanism of Pd(II) on rGO-g-P4VP involves both ion
exchange and coordination adsorption by XPS analysis. Most importantly,
the loss of oxygen-containing groups due to reduction of GO not only
facilitates the separation of adsorbent from aqueous solution but
also reduces the electrostatic repulsion toward Pd(II)Cl4
2– in hydrochloric acid solution, leading to a
higher adsorption selectivity of Pd(II) over some common metal cations
in electronic waste including Fe(III), Cu(II), and Al(III) compared
with poly(4-vinylpyridine)-grafted graphene oxide (GO-g-P4VP) prepared by atom transfer radical polymerization. Other precious
metals like Pt(IV) and Au(III) can also be recovered easily and selectively
by rGO-g-P4VP. This work demonstrates that rGO-g-P4VP prepared by the facile RIGP is a promising adsorbent
for recovery of precious metals from secondary resources like electronic
waste leachate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.