Study of the toluene absorption capacity and mechanism of ionic liquids using COSMO-RS prediction and experimental verification

As green solvents,ionic liquids(ILs)are quite suitable for the absorption of volatile organic compounds(VOCs)such as benzene and its homologues.However,solvent selection is the key to the VOC absorption process.In the present study,a rapid solvent screening tool,Conductor-like Screening Model for Real Solvents(COSMO-RS),was used to predict the solubility of toluene in 816 ILs.The effects of four structure characters,namely,the type and alkyl chain length of the cations and anions on the solubility of toluene were discussed.The following conclusions were drawn from the results:(1)ILs with pyrrolidinium-based cations showed better solubility than pyridinium-and imidazoliumbased ones.(2)The solubility of toluene in PF6-based ILs increased with the increasing alkyl chain length,while its solubility in Ac-based ILs exhibited the opposite trend.(3)Toluene showed greater solubility in Cl-based ILs than those based on other anions.(4)The solubility of toluene increased with the anion alkyl chain length.Ac-based ILs were chosen as the most promising potential solvents,and further studied to determine the relationship between various interaction energy parameters and toluene solubility.The results showed that the misfit energy played a dominant role during the absorption process.Furthermore,several ILs were selected for experimental verification of the predicted solubility behavior using liquid and gaseous toluene.The results demonstrated that COSMO-RS could be used to semi-quantitatively and qualitatively predict the solubility of toluene,and this model had promising prospects in screening ILs for VOCs absorption.In summary,this study provided a fundamental basis and practical data for the control and treatment of VOCs.

Ellipsoidal Thermal Concentrator and Cloak with Transformation Media

Thermal concentrators and cloaks with ellipsoidal shapes are designed by utilizing the transformation thermotics method and finite element simulations.The thermal conductivities for the concentrator and cloak are directly derive in Cartesian coordinates.The simulation results show that the ellipsoidal thermal concentrator can focus heat flux into a central region and that the ellipsoidal thermal cloak can guide heat flux around the cloaked region smoothly without disturbing the external temperature distribution and heat flux.The present method can be extended to design arbitrarily shaped thermal metadevices with novel properties.

Highly efficient energy harvest via external rotating magnetic field for oil based nanofluid direct absorption solar collector

Nanofluids based direct absorption solar collectors(DASCs) are considered as the important alternative for further improve the utilization of solar energy. However the low-quality energy and aggregation of nanoparticles obstructs their large-scale application. In this work, a new method of using magnetic nanofluids in DASCs is proposed. By this method, not only high-quality energy is got as well as the problems of blockage and corrosion in heat exchanger are well avoided. The result shows that the maximum temperature can reach 98℃ under 3 solar irradiations and the photothermal conversion efficiency can be further increased by 12.8% when the concentration is 500 ppm after adding an external rotating magnetic field. The highest viscosity of working fluid reduced by 21% when the concentration is 500 ppm at 95℃ after separating the Fe_(3)O_(4)@C nanoparticles from the nanofluids via magnetic separation technology. Meanwhile, the obtained pure base liquids with high temperature flow to heat exchanger, which also reduces the flow resistance in pipeline and avoids the problems such as blockage and corrosion in heat exchanger. This research promotes a new way for the efficient utilization of solar energy.

Synthesis of nitrogen-doped carbon nanotubes-FePO_4 composite from phosphate residue and its application as effective Fenton-like catalyst for dye degradation

Phosphate residue is regarded as a hazardous waste, which could potentially create significant environmental and health problems if it is not properly treated and disposed of. In this study, nitrogen-doped carbon nanotubes-FePO_4(NCNTs-FePO_4) composite was successfully synthesized from phosphate residue, and its application as an effective catalyst was explored. Firstly, an effective method was developed to recover FePO_4 from phosphate residue, achieving an impressive FePO_4 mass recovery rate of 98.14%. Then, the NCNTsFePO_4 catalyst was synthesized from the recovered FePO_4 by two main reactions, including surface modification and chemical vapor deposition. Finally, the synthesized NCNTs-FePO_4 was applied to photo-degrade 15 mg/L Rhodamine B(RhB) in a Fenton-like system. The results showed that 98.9% of RhB could be degraded in 60 min, closely following the pseudofirst-order kinetics model. It was found that even after six consecutive cycles, NCNTs-FePO_4 still retained a high catalytic capacity(>50%). Moreover, ·OH radicals participating in the RhB degradation process were evidenced using quenching experiments and electron paramagnetic resonance analysis, and a rational mechanism was proposed. It was demonstrated that the materials synthesized from hazardous phosphate residue can be used as an effective catalyst for dye removal.

Preparation and optical properties of three-dimensional navel-like Bi_2WO_6 hierarchical microspheres

Three-dimensional(3D) navel-like Bi_2WO_6(BWO) hierarchical microspheres(HMSs) were successfully prepared using a simple hydrothermal method. The as-obtained BWO samples were characterized by a variety of techniques. XRD result indicated that the as-synthesized samples were well-crystallized orthorhombic phase Bi_2WO_6 structure. SEM observations revealed that the hierarchical microspheres with an average diameter of 2 μm were built from several dozen of nanosheets. UV-vis diffuse reflectance spectrum study revealed that the obtained BWO sample had band gap energy of about 3.3 eV.Photoluminescence(PL) result showed that the sample had weak emission intensity. The BET specific surface area of the BWO sample was about 35.40 m^2/g. The photocatalytic efficiency of the as-obtained BWO was evaluated by the degradation of norfloxacin(NOR) antibiotic. The result showed an about 67%NOR degradation in 8 h.

Enhanced photothermal conversion and thermal conductivity of phase change n-octadecane microcapsules shelled with nano-SiC doped crosslinked polystyrene

Microcapsules incorporating phase change material n-octadecane(ODE)shelled with crosslinked polystyrene(CLPS)were prepared via the suspension polymerization.SiC nanoparticles(nano-SiC)were employed to modify the shell to improve the heat transfer and photothermal conversion of the microcapsules.The scanning electron microscopic analysis revealed the microcapsules of a general spherical shape.The surface components and chemical composition of the microcapsule samples were evaluated by the energy-dispersive X-ray and Fourier transform infrared spectroscopy,confirming that the nano-SiC have been embedded in the CLPS shell.Results show that the microcapsule sample with 1.25 wt.%nano-SiC(denoted as MPCM3)exhibits the best heat property among the four kinds of samples prepared with various nano-SiC dosages,and all the nano-SiC doped samples have improved thermal conductivity and photothermal conversion as compared to the microcapsule sample without doping(denoted as MPCM1).Compared to the MPCM1,the thermal conductivity of the MPCM3 is increased by 65.3%,reaching 0.124±0.005 W·m^(−1)·K^(−1).The MPCM3 has excellent thermal stability as well.Differential scan-ning calorimetry examination shows that the MPCM3 has higher melting and crystallization enthalpies than the MPCM1,achieving 106.8±0.3 J·g^(−1) and 104.9±0.2 J·g^(−1),respectively.In the photothermal conversion experi-ments,the MPCM3 exhibited great photothermal conversion capability,with a 54.91%photothermal conversion efficiency,which is 145.68%higher than that of the MPCM1.