In the present study, SWCNH–COOH and SWCNH–TETA were fabricated using single-walled carbon nanohorns (SWCNHs) via carboxylation and grafting with triethylenetetramine (TETA) for uranium (VI) ion [U­(VI)] removal. The morpho-structural characterization of as-prepared adsorbing materials was performed by transmission electron microscopy, X-ray diffractometry, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Several parameters including the pH value of the aqueous solutions, contact time, temperature, and U­(VI) concentration were used to evaluate the sorption efficiency of SWCNH–COOH and SWCNH–TETA. The Langmuir isotherm model could well represent the as-obtained adsorption isotherms, and the kinetics was successfully modeled by pseudo-second-order kinetics in the adsorption process. The maximum adsorption capacity of SWCNH–TETA was calculated as 333.13 mg/g considering the Langmuir isotherm model. Thermodynamic studies showed that adsorption proved to be a spontaneous endothermic process. Moreover, SWCNH–TETA exhibited excellent recycling performance and selective adsorption of uranium. Furthermore, the possible mechanism was investigated by XPS and density functional theory calculations, indicating that the excellent adsorption was attributed to the cooperation capability between uranium ions and nitrogen atoms in SWCNH–TETA. This efficient approach can provide a strategy for developing high-performance adsorbents for U­(VI) removal from wastewater.

This paper presents a novel wet flue gas desulfurization (FGD) technology based on a basic aluminum sulfate (BAS) desorption regeneration process, in which ethylene glycol (EG) was first employed to inhibit the byproduct oxidation. The operating parameter effect on SO2 absorption efficiency and oxidation efficiency of sulfite was thoroughly examined in a lab-scale bubbling column. The results indicated that both the amount of aluminum and basicity play important roles on the desulfurization time with above 90% absorption efficiency. The BAS-based desulfurization process was more suitable for a low temperature and low gas flow rate. High inlet SO2 concentrations may contribute to the mass-transfer rate of SO2, and the SO2 absorption efficiency remained above 90% when the pH value was over 3.10. With the addition of 1% (v/v) EG in BAS solution, the oxidation efficiency dropped dramatically from 86 to below 10% (in 120 min). On the basis of the two-film theory, a model of the SO2 absorption process was developed and the mass-transfer characteristics were analyzed. The calculation results indicated that the SO2 absorption process for this system was decided by a combination of both the gas- and liquid-phase diffusion controls.

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Improving the catalytic efficiency in the hydration of olefins to alcohols is an important yet challenging issue in acid catalysis. Herein, a series of novel superacidic polyoxometalate-based ionic hybrids were prepared and employed as catalysts for highly efficient indirect hydration of olefins to corresponding alcohols. Several characterization techniques such as FT-IR spectra, XRD, SEM, and 31 P MAS NMR spectroscopy were performed to characterize the structures of these superacid hybrids and their acid properties. The results show that the catalytic performances of ionic hybrids were closely related to their acidic strength. The superacidic ionic hybrid [BPy-SO 3 H-OTf]PW was found to be the best active catalyst to obtain the corresponding alcohols with good yields. The catalytic efficiency in indirect hydration process using superacidic ionic hybrid catalysts is obviously superior to that of direct hydration, which thus opens up a new way to improve the efficiency of the current hydration process.

Basic aluminum sulfate (BAS) wet flue gas desulfurization (FGD) is a promising renewable process used to remove sulfur dioxide (SO2) from flue gas, in which the regeneration of BAS SO2-loaded solution is of great importance for the reuse of BAS solution. In this paper, a novel regeneration method by vacuum desorption was developed to achieve superior regeneration performance for a BAS-rich solution. The operating parameter effect on SO2 desorption performance was thoroughly investigated in a lab-scale reactor. The experimental results demonstrated that the great decrease of pressure could significantly improve the regeneration performance, and high desorption temperature was favorable for SO2 desorption. Furthermore, it is worth determining the optimum components of a BAS-rich solution and initial sulfite concentration, considering the contradiction between the SO2 absorption performance and the regeneration performance. The increase of stirring speed in the liquid had a considerable positive effect on SO2 desorption efficiency. In addition, through a simple comparison with direct heating regeneration, it indicates that the utilization of vacuum regeneration could have the potential to improve the regeneration rate and lower the total energy consumption. Finally, the recycling experiments of the absorption–desorption process show that the BAS solution could be reused successfully to capture SO2 from flue gas by vacuum regeneration, while SO2 absorption efficiency would decrease to below 90% after 11 cycles, attributed to the inevitable oxidation of byproduct in the desulfurization process.