Yang Man,Huang Yun,Cao Haijun,Lin Yuanhua,Cheng Xiaowei,Wang Xia
The organic–inorganic self-doped poly (vinyltrimethoxy silane-ethylene glycol dimethacrylate) (VE resin) was
synthesized by solution polymerization, hydrolysis and dehydration condensation. In this method, ethylene glycol dimethacrylate (EGDMA) was used as cross-linked reagent to form a three-dimensional network structure. Then, the system was prepared by radical polymerization in the presence of the hydrolysis of –OCH 3 and the dehydration condensation of Si–OH. The maximum adsorption capacity 75.68 mg g −1 was achieved when pH was 6, the contact time 60 min, the adsorbent dose 0.1 g, the initial concentration 3000 mg L −1 and the temperature 293 K. The adsorption kinetics followed the pseudo-second-order kinetic model, and the intra-particle diffusion was but not the only rate-limiting step. Adsorption isotherms of phenol were linearly correlated and found to be well represented by the Freundlich model. Thermodynamic parameters such as changes in the enthalpy (Δ H ), free energy (Δ G ) and entropy (Δ S ) indicated that the adsorption process of phenol on VE resin were physical and exothermic. After four regeneration recycles, the adsorption capacity of VE resin remained at 95.04 % of the initial value, which illustrated that it possessed good regeneration capacity.
The interaction details of phenol with transition metal oxides are important for understanding the mechanisms of organic pollutant degradation as well as functionalization of oxide semiconductors through organic chromophores. In this work, we apply low-temperature scanning tunneling microscopy in combination with density functional theory calculations to explore the adsorption structures and interface charge transfer of phenol on a ZnO(101̅0) surface. Distinct adsorption configurations of phenol are clearly determined. For low coverage conditions, the less-stable standing-up configuration of phenol prevails both at 77 K and room temperature (RT), but all transform into more stable lying-down configurations and assemble into a linear chain structure orientating along the [0001] direction at increased coverage. The lying-down phenols dominate in the two-dimensional structures formed at either RT or 400 K, presenting a c(2 × 2) periodicity at medium coverage or a p(2 × 1) superstructure at saturation coverage. Because different phenol configurations have distinct charging characteristics, their aggregation state hence plays a critical role in switching phenol from electron acceptors to electron donors relative to the ZnO surface. These results are believed to provide important inputs for the deepened understanding of catalytic removal of phenol pollutes as well as for the design of new ZnO–organic functional systems.
Mesoporous manganese dioxide(meso-MnO2) fibers were synthesized in high yields in a simple, templatefree manner by localized Ostwald ripening under hydrothermal conditions. The adsorption behavior of 2,4-dinitrophenol on meso-MnO2 fibers was well described by Langmuir
isotherm equation, Dubinin-Radushkevich and pseudo-second-order kinetic equation, so the adsorption mechanism maybe a chemical and monolayer adsorption. Meso-MnO2 fibers have potential for use as a high-performance adsorbent.
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