Shengxia Duan

Dual shelled Fe3O4/polydopamine hollow microspheres as an effective Eu(III) adsorbent

A facile method was developed to synthesize Fe3O4/polydopamine (PDA) dual shelled microspheres with a hollow interior. Since the final product was obtained by in situ polymerization of dopamine (DA) on the surface of a hollow Fe3O4 spherical template, the average size of the hybrid microspheres was tunable by manipulating both the Fe3O4 size and the PDA shell thickness. Due to the hollow interior and the compatible surface, the Fe3O4/PDA demonstrated excellent adsorption performance for Eu(III) ion removal (151.05 mg g−1) in aqueous solution. In comparison to pristine Fe3O4 hollow spheres, the dual shelled particles exhibited a faster adsorption dynamic process and a higher adsorption capacity for Eu(III) entrapment. Simultaneously, the Fe3O4/polydopamine (PDA) also exhibits a higher adsorption capacity for Eu(III) entrapment compared with that of other magnetic materials. This method was also effective for synthesizing other kinds of PDA shell encapsulated core/shell nanoparticles.

Highly enhanced adsorption performance of U(VI) by non-thermal plasma modified magnetic Fe3O4 nanoparticles

In this study, magnetic Fe3O4 nanoparticles (MNP) modified with O-phosphorylethanolamine (O-PEA) were successfully prepared by non-thermal plasma induced method with different treatment times. The raw and modified MNP were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrophotometer (FT-IR), and vibration sample magnetometer (VSM). The modified MNP samples show higher adsorption capacity for U(VI) removal and longer treatment time results in higher adsorption capacity and efficiency. The experimental parameters were optimized by means of the response surface methodology to improve the removal efficiency of U(VI) by the modified adsorbents from aqueous solutions. The O-PEA modified MNP with 120 min treatment time shows the highest adsorption capacity with 228.17 mg⋅g-1 among the five samples at 293.15 K. Thermodynamic studies reveal that the adsorption process of U(VI) onto O-PEA modified MNP is endothermic and spontaneous. XPS studies indicate that the U(VI) removal is fulfilled through the binding interactions between U(VI) and NH2, OH and phosphate groups on the modified MNP surface. This work not only provides a simple, convenient and cost-effective way for water treatment by plasma modification, but also provides a new insight into preparing promising adsorbents to achieve magnetic separation from aqueous solution.

A Valuable Biochar from Poplar Catkins with High Adsorption Capacity for Both Organic Pollutants and Inorganic Heavy Metal Ions

In this paper, biochar derived from poplar catkins was used as an economical and renewable adsorbent for adsorption organic and inorganic pollutants such as, dyes, organic compounds, and heavy metal ions from wastewater. Mesoporous activated carbonized poplar catkins (ACPCs) were produced from char as a by-product by carbonized poplar catkins (CPCs). With their high surface area, ACPCs exhibited the maximum adsorption capacities of 71.85 and 110.17 mg/g for the removal of inorganic U(VI) and Co(II). Compared other biochars adsorbents, ACPCs can also adsorb organic pollutants with the maximum adsorption capacities of 534, 154, 350, 148 and 384 mg/g for methylene blue (MB), methyl orange (MO), Congo red (CR), chloramphenicol (CAP) and naphthalene. The adsorption of organic pollutants was fitted with pseudo-first order, pseudo-second order, and intra-particle diffusion kinetic models figure out the kinetic parameters and adsorption mechanisms. Langmuir adsorption isotherm was found to be suitable for Co(II) and U(VI) adsorption and thermodynamic studies indicated adsorption processes to be endothermic and spontaneous. The adsorption process includes both outer-sphere surface complexes and hydrogen-bonding interactions. The results showed that biochar derived from poplar catkins was a potential material to remove pollutants in wastewater.

UV-curable ladder-like diphenylsiloxane-bridged methacryl-phenyl-siloxane for high power LED encapsulation

A UV curable ladder-like diphenylsiloxane-bridged methacryl-phenyl-siloxane (L-MPS) was synthesized from phenyltrichlorosilane, diphenylsilanediol and methacryloxypropyldimethylmethoxysilane via dehydrochlorination precoupling, supramolecular architecture-directed hydrolysis-condensation and end-capping reactions. The L-MPS has a condensation degree of ∼100%, and can be complete crosslinked by UV curing. XRD, TEM and molecular simulation suggest that the ladder-like molecules are close packed with a periodic distance of ca. 1.2 nm. The L-MPS shows transmittance of 98% and a refractive index of ca. 1.61 at 450 nm. The cured L-MPS with a Td5% value of 465.5 °C showed excellent anti-yellowing and anti-sulfidation properties. The cured L-MPS film and the encapsulated LED samples were compared with those of Dow Corning OE-6630 and OE-7662. It is believed that the dense nano-ladder unit also contributes to the thermal, gas barrier and even optical properties. L-MPS shows promising potential as a high power LED encapsulant and optical coating for use in harsh environments. This work provides an approach to integrate this novel ladder structure with advanced properties.

Interaction between Al2O3 and different sizes of GO in aqueous environment

Although the aggregation of graphene oxide (GO) has been widely researched, the influence of the GO size on the homoaggregation behavior and its interaction with environmental media are still unexplored. In this work, critical coagulation concentration (CCC) values for GO with different sizes, from micro to nanosheet, were measured with NaCl and CaCl2 electrolytes, and the results indicated that GO with the largest size presented the smallest CCC value. Aluminum oxide (Al2O3) was selected as a natural solid particle representative to mimic the interaction between GO and environmental media. Batch experiments were conducted in solution with different pH and ionic strength. Results indicated that the attachment capacity of large GO onto Al2O3 particles was greater than that of small GO. The experimental data were well fitted with Freundlich model. The electrostatic attraction and hydrogen-bonding interaction dominated the interaction process between GO and Al2O3. These findings are important for better understanding in the environmental fate and transport of GO.

Formation of C60 fullerene-bonded-CNTs using radio frequency plasma

C60 fullerene-bonded-CNTs (CNBs) were successfully synthesized by radio frequency plasma (RF plasma) treatment for the first time. High-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy were used to confirm the formation of the CNB structure. A possible mechanism was also proposed to explain the formation of CNBs. This RF plasma treatment may inspire a novel method to potentially overcome the synthetic difficulty of CNBs.