As the key material of the adsorption method used for
practical
uranium extraction from seawater, the adsorbent should have a high
uranium adsorption capacity and long service life. Polyethylene nanofibrous
membranes (PENFMs) using a one-step grafting strategy to prepare scalable
membrane adsorbents are reported with supreme uranium uptake capacity
and long service life. A series of amidoximated polyethylene nanofibrous
membrane (called amidoximated membrane or AM) adsorbent materials
with different degrees of grafting (DGs) are modified by one-step
radiation-induced graft polymerization (RIGP) of acrylonitrile (AN)
and acrylic acid (AA) and an amidoximation reaction. The AM adsorbents
prepared from the PENFM show outstanding hydrophilicity, good adsorption
capacity, and excellent affinity for uranium. The highest uranium
uptake capacity of AM adsorbents is 115.32 mg/g in simulated seawater
for 24 h and 6.03 mg/g in natural seawater for 10 weeks. The AM adsorbents
are reusable for more than 10 cycles of continuous adsorption–desorption–regeneration
tests, showing the long service life. In addition, the AM adsorbent
adsorption results in natural seawater indicate that only prolonging
time to pursue high adsorption capacity is not conducive to the acquisition
of benefits. The AM adsorbents have broad potential application in
the industrialization of uranium extraction from seawater by choosing
the best adsorption efficiency to achieve high adsorption amount.
The adsorption is widely used to remove dyes from wastewater because of its low cost, simple preparation, and environmental friendliness. However, the existing adsorbents suffer from difficult recycling, inconvenient use, and low regeneration rate. In this study, polyacrylonitrile (PAN) and graphene oxide (GO) was mixed for electrospinning GO/PAN nanofiber membrane and then chitosan (CS) was grafted to obtain CS-GO/PAN nanofiber membrane. CS-GO/PAN membrane were characterized with FE-SEM, EDX, FT-IR and, WCA. The effects of membrane types, dosage, solution pH on the removal of dye sunset yellow (SY) were systematically investigated. The results showed that more than 80% of SY were removed within 15 min at pH 2 using 100 mg CS-GO/PAN membrane.Adsorption kinetic data were fitted well with the pseudo-second-order model and adsorption equilibrium achieved within 240 min. The isotherm study followed the Langmuir model with the actual maximum adsorption capacity of 211.54 mg/g. After 5 adsorption-desorption cycles, the adsorption efficiency and the desorption efficiency of CS-GO/PAN were over 90% and 93%, respectively. Moreover, the membrane recovered easily from the water while its integrity was still maintained. The CS-GO/PAN membrane demonstrates the virtue of high adsorption capacity, easy operation, and good reusability, which could be considered as a promising material for adsorbing dyes in wastewater.
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