A good activated carbon adsorbent, KC-8, was used to
remove residual p-xylene (PX) effectively after the
extraction process of
treating pure terephthalic acid (PTA) wastewater. The adsorption thermodynamics
and kinetics of PX on activated carbon KC-8 were investigated completely
and systematically. A series of adsorption equilibrium experiments
were conducted under temperatures of (313.15, 323.15, and 333.15)
K. The adsorption equilibrium data were fitted to Langmuir and Freundlich
isothermal equations. The results showed that the adsorption equilibrium
data were agreed with the Freundlich isothermal equation well. Thermodynamic
analysis suggested ΔH > 0, ΔG < 0, and ΔS > 0. The adsorption
of PX
on KC-8 was a spontaneous physical and endothermic adsorption process.
Kinetic studies indicated that the adsorption process of PX on activated
carbon KC-8 could be described well by the pseudosecond-order kinetic
model, and particle diffusion was the main rate-controlling step in
the adsorption process.
Photocatalytic syntheses of gem-difluoroolefins were performed using the B-TiO hybrid catalyst during the C[double bond, length as m-dash]C bond reduction of α-trifluoromethyl styrenes with C-F bond cleavage at room temperature under nitrogen. The gem-difluoroolefins were used as synthetic precursors for fluorinated cyclopropanes.
Flat band potential (Vfb) is one of the most important physical parameters to study and understand semiconductor materials. However, the influence of surface states on the evaluating Vfb of titanium oxide (TiO2) and other semiconductor materials through a Mott-Schottky plot is ignored. Our study indicated that the influence of surface states should be introduced into the corresponding equivalent circuit even when the kinetic process did not occur. Ignoring the influence of surface states would lead to an underestimation of the space charge capacitance. Our paper would be beneficial for accurate determination of Vfb of semiconductor materials. We anticipate that this preliminary study will open new perspectives in understanding the semiconductor-electrolyte interface.
A visible light induced three-component catalytic system with the cobalamin derivative (B) as a catalyst, the cyclometalated iridium(iii) complex (Irdfppy, Irppy, Irpbt and [Ir{dF(CF)ppy}(dtbpy)]PF) as a photosensitizer and triethanolamine as an electron source under N was developed. This catalytic system showed a much higher catalytic efficiency than the previous catalytic system using [Ru(ii)(bpy)]Cl as the photosensitizer for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT). Noteworthy is the fact that the remarkable high turnover number (over ten thousand) based on B, which ranks at the top among the reported studies, was obtained when Irdfppy was used as a photosensitizer. This photocatalytic system was also successfully applied to the B enzyme-mimic reaction, i.e., the 1,2-migration of the phenyl group of 2-bromomethyl-2-phenylmalonate. The plausible reaction mechanism was proposed, which involved two quenching pathways, an oxidative quenching pathway and a reductive quenching pathway, to be responsible for the initial electron transfer of the excited-state photosensitizers during the DDT dechlorination reaction. Transient photoluminescence experiments revealed that the oxidative quenching of the photosensitizer dominated over the reductive quenching pathway.
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