查看更多>>摘要：A heterogeneous extracting route of 4-ethylguaiacol is constructed using the intermediate of the reaction between 4-ethylguaiacol and Ca~(2+) as the extracting agent. In this work, 4-ethylguaiacol with different concentrations (70, 80, 90, 95%) is prepared using 40 v/v% ethanol aqueous solution as the mother liquor. The extraction parameters optimization, cycle extraction and 4-ethylguaiacol purification are studied, respectively. Extracting parameters investigated are reaction temperature (4-80 °C), extraction time (5-60 min), and pH value (6.5-13). 4-ethylguaiacol extraction efficiency keeps above 90% at the optimum extracting conditions at the reaction temperature of 4-20 °C, the extraction time of 30 min, and the pH value of 6.5-10. Further cycle extraction experiments are carried out under the optimal extraction parameters using the intermediate as the extracting agent. After 36 cycle extraction times, the extraction efficiency of 4-ethylguaiacol can still reach 91.7%. Guaiacol has similar physical and chemical properties to 4-ethylguaiacol, thus it is used as an impurity to test the extraction and purification effect of the heterogeneous extracting method. With increasing the cycle extraction times from 1 to 4, 4-ethylguaiacol purity reaches more than 99% for all four mother liquors with different initial concentrations. 4-ethylguaiacol purity of 99.57% is achieved through twice cycle extraction when its initial content in the mother liquor is 95%.
查看更多>>摘要：A series of multiblock polydimethylsiloxane-b-polyimides copolymers, including non-fluorinated (PDMS-b-PI) and fluorinated polyimides (PDMS-b-FPI), were successfully prepared from pyromellitic dianhydride and 4,4'-(4-aminophenoxy) biphenyl, 4,4'-(hexafluoroisopropyl) diphenyl dicarboxylic anhydride and 2,2'-bis(trifluoromethyl)benzidine, respectively. The chemical structures of these block polymers were determined with FTIR. Self-supporting membranes were prepared from the copolymers using a solution coating method. The physicochemical properties, pervaporation properties and thermal stability of the block polymer membranes were studied. The results showed that the mechanical properties of PDMS-b-FPI and PDMS-b-PI membranes increased with an increase in the FPI or PI content in the copolymer, where the tensile strengths and moduli increased, and the elongations at break decreased. The swelling of the PDMS-b-FPI and PDMS-b-PI membranes in ethyl acetate increased with an increase in the PDMS content, and membranes with PDMS contents of less than 50% were stable. TEM showed that the block copolymers formed microphase separated structures. SAXS showed that the chain segment spacing increased with the increase of PDMS content, and the chain segment spacing of PDMS-b-FPI was larger than that of PDMS-b-PI. In the pervaporation tests using a feed solution containing 5 wt% ethyl acetate at 40 °C, the separation factor(a) of the PDMS-b-PI-50 membrane was 31, and the total flux(J) was 924 g·m~(-2)·h~(-1). Using the same pervaporation test conditions, the a of the PDMS-b-FPI-50 membrane was 31, and the J was 1267 g·m~(-2)·h~(-1). Both the PDMS-b-PI-50 and PDMS-b-FPI-50 membranes were found to be stable during the separation tests, and the a and J did not change significantly after 150 min of operation.
查看更多>>摘要：As a typical sulfonamide antibiotic, sulfamethoxazole (SMX) will cause serious harm to human health and ecological environment. In this study, CoFe-N doped C was prepared as cathode catalyst of electro-Fenton for degrading SMX, and 91% of SMX could be removed within 5 h under optimum conditions (pH = 1, U = -0.7 V). In order to understand degradation mechanisms, Density Functional Theory (DFT) was combined with Liquid Chromatography-Mass Spectrometry (LC-MS), four pathways were proposed, and benzene ring fracture was the most important step. Concomitantly, the toxicity of degradation intermediates was predicted by ECOSAR sofrware and the toxicity of most intermediates was lower than that of SMX. Therefore, this study has a certain reference value for removing the pollution of persistent organic pollutants in water.
查看更多>>摘要：In this study, numerical and experimental studies of ice directional crystallization for the NaCl, Na2SO4, MgCl2, and MgSO4 solutions were investigated. The comparison of energy consumption between freezing-centrifugal desalination and the conventional method was discussed. The phase-field method was employed to simulate the ice directional crystallization process. A microscope experimental setup was established to observe the morphology of dendrites and verify the theoretical model in the directional crystallization process. The absolute deviations of the average width of the brine channel between numerical and experimental results are less than 15%, which indicates that the phase-field method can present the performance of ice directional crystallization well. The results also showed that in the directional crystallization process, the solutions with SO4~(2-) (Na2SO4 and MgSO4 solutions, and their mixtures) form narrower brine channels than that of NaCl and MgCl2 solutions due to their low diffusion coefficient. Moreover, the impacts of ions and brine channel on the freezing-centrifugal desalination were investigated by the experiments. When the rotation speed and centrifugal time were set at 5000 rpm and 2.0 min, respectively, the salt removal efficiency of NaCl and MgCl2 was higher than 96%, while they were less than 13% for the Na2SO4 and MgSO4 solutions. Hence, the SO4~(2-) ion plays a significant role in preventing sea ice desalination due to narrower brine channels.
查看更多>>摘要：Waste printed circuit boards (PCBs), a common electronic waste, contain a high content of Cu. For environmental sustainability and economic benefit, it is necessary to recover the Cu as high value-added product instead of discarding it. In this work, Cu from PCBs was successfully recovered as CuO particles with high specific surface area and rich oxygen vacancies through cyclic leaching, chemical precipitation, low temperature aging, and calculation. Compared with CuO prepared from commercial Cu(NO3)2 · 5H2O, the PCBs-derived CuO (PCBs-CuO) exhibited comparable performance in activating peroxymonosulfate to degrade reactive blue 19, although its crystallinity and phase purity were relatively lower. Additionally, PCBs-CuO had an outstanding pH tolerance (2-12), confirming the practical application potential of PCBs-CuO in the removal of organic contaminants in various wastewater. Moreover, the quenching experiments, electrochemical measurements and electron paramagnetic resonance analysis suggested that ~1O2 and · OH played a significant role in PCBs- CuO/peroxymonosulfate system. The =Cu(II) and oxygen vacancies on the surface of PCBs-CuO was mainly responsible for the activation of peroxymonosulfate. This work provides a promising method for recycling metal from waste PCBs into high-effective peroxymonosulfate activator and simultaneously achieving environmental remediation.
查看更多>>摘要：The key to efficient treatment of organic pollutants in water is to improve their mass transfer efficiency and reaction efficiency. Herein, a one-step construction of new metal-organic frameworks (MOFs) using 4,4', 4", 4"-(pyrene-1, 3, 6, 8-tetrayl) tetra-benzoic acid as a photosensitizer ligand and Ti-In as bimetallic centers has been constructed. The results exhibited that increased specific surface area was obtained by Ti-In-MOF(1:1), which improved the adsorption performance of 50 ppm bisphenol A to 38% and facilitated it complete degradation upon light irradiation in 20 min, being much faster than that of single In/Ti-MOFs. For Ti-In-MOF(1:1), the In-MOF parts enhanced the adsorption capability, meanwhile the Ti-MOF parts based on infinite Ti-O chains realized the effective separation of photogenerated carriers. A synergistic role of adsorption and degradation achieved rapid mass transfer and excellent catalytic degradation performance. This investigation will provide a novel MOF construction strategy for efficient catalytic application in environmental pollutants.
查看更多>>摘要：At present, the Li4SiO4 sorbents have been getting widespread attention for mitigating the release of CO2 gas owing to its stable cyclic property, higher capturing ability, and lower regeneration temperatures. In this work, a facile rolling ball method is first proposed to fabricate Li4SiO4 sorbent pebbles, which overcomes the low production efficiency, poor adsorption stability, and high production cost adopted in the previous literature. In the rolling ball process, the spray granulation process was involved to decrease the specific surface area of ceramic powder, which makes it easier for powder self-agglomerate to form pebbles via the centrifugal force with the assistance of PVA polymer solution. Moreover, the phase composition, the specific surface area, the shaping principle, and the microstructure of Li4SiO4 sorbent pebbles were studied, respectively. The result shows that the Li4SiO4 pebbles sintered at 900 °C for 2 h present a superior comprehensive performance with a homogeneous diameter of 1.2 mm, good sphericity of 0.95, high crushing load of 65 N, and suitable porosity of 6.28 %. Compared with Li4SiO4 powder, the spherical pebbles performed superior CO2 adsorption ability (0.304 g CO2/g sorbent) and excellent cyclic stability in a 100% CO2 environment owing to its large number of uniform pores channels produced by binder solution at high temperature. Therefore, the rolling ball process is a potential method for the batch production of Li4SiO4 pebbles to capture CO2 stably in the future.
查看更多>>摘要：Low temperature flue gas evaporation is an effective method for low-cost and efficient treatment of desulfurization wastewater (DW). However, due to the influence of low flue gas temperature and high salt content, it is easy to lead to scaling and blockage of evaporation flue, affect the stable operation of the system. In order to effectively use the waste heat of flue gas to treat DW and avoid the corrosion of DW to the flue, the falling film evaporation treatment technology of DW with synergistic particle removal is proposed. The effects of different operating parameters on the falling film evaporation and deposition characteristics of DW, and particle removal efficiency are studied. The results show that the increase of the electrostatic field voltage is conducive to the evaporation of DW, and inhibits its crystal deposition. The increase of the Cl~- concentration is inconducive to the evaporation and crystal deposition of DW without electrostatic field, but is conducive to the evaporation and crystal deposition of DW in the electrostatic field. In the experiment of 120 °C flue gas, the evaporation capacity of liquid film decreases by 17.9% with Cl~- concentration increasing from 0% to 5% without the voltage; but the evaporation capacity of liquid film increases by 30.9% with Cl~- concentration increasing from 0% to 5% after applying 40 kV voltage. Replacing water with DW is conducive to the removal of particles by electrostatic field. The efficiency of particle removal increases from 79.9% to S4.8% with Cl~- concentration increasing from 0% to 5% at 120 °C and 40 kV. In addition, increase on flue gas temperature is also conducive to the DW evaporation and particles removal by electrostatic field. Compared with other wastewater treatment technologies, this technology has the advantage of low treatment cost.
查看更多>>摘要：Herein, the enhanced performance of the VUV process run in a helical-baffle reactor (VUV@HBR) compared with an annular reactor in degrading the antiviral remdesivir (RDV) was scrutinized. 67.9% degradation of RDV was achieved within 10 min in the VUV@HBR system, compared to 54.1% of that in the annular reactor under similar conditions. The addition of peroxymonosulfate (PMS) or hydrogen peroxide (H2O2) to the VUV@HBR considerably improved the degradation of RDV; the rate of RDV degradation for the initial 10-min reaction period in the VUV@HBR system improved from 0.124 min~(-1) in the absence of oxidants to 0.350 and 0.572 min~(-1) in the presence of optimum level of PMS and H2O2 oxidants, respectively. Selecting the VUV/H2O2@HBR as the best performing process, over 90% of RDV was eliminated within 10 min. Scavenger studies identified HO· as the main reactive species leading to RDV degradation, with a k = 4.6 x10~9 M~(-1) s~(-1); a plausible RDV degradation pathway was proposed. In addition, tap water and a municipal wastewater treatment spiked with RDV were efficiently treated by VUV/H2O2@HBR (90% RDV and 45% TOC removal in 10 min and 30 min, respectively). In continuous-flow mode, >99% degradation of 1 mg/L of RDV was achieved at hydraulic retention times of 1 and 5 min, for VUV/H2O2@HBR and VUV@HBR, respectively, simultaneously with a 6-log inactivation E. coli (3 min) or the favipiravir antiviral drug (1.5 min). In overall, the developed VUV/H2O2@HBR is considered an attractive and promising technology for water and wastewater treatment.
查看更多>>摘要：In this study, a novel plate-on-plate hollow structured BiOBr/Bi2MoO6 p-n heterojunction with rich oxygen vacancies (OVs) was systematically constructed by an in-situ ion exchange method. The structure, morphology, photoabsorption ability, and surface properties of BiOBr/BiMoO6 were characterized, showing an etching process of BiOBr nanoplates (NPs) by molybdate to form BiOBr/Bi2MoO6 plate-on-plate hollow heterostructures (BM PHs). A feasible formation mechanism was proposed by regulating the concentration of molybdate and reaction times. The introduction of Bi2MoO6 in BiOBr NPs was proved to play a significant role in affecting the crystal growth and photocatalytic activity of BM PHs, which displayed a greatly enhanced photocatalytic antibacterial performance under visible light irradiation compared to pure BiOBr and Bi2MoO6. The highly efficient photocatalytic performance can be attributed to the synergistic effects of the fabricated p-n heterojunction combined with massive OVs, leading to the fast separation of photoinduced charge carriers, which were subsequently verified by the photoelectrochemistry (PEC) and photoluminescence (PL) measurements. In addition, the photocatalytic mechanism was discussed and deduced based on the active spices trapping and electron spin resonance (ESR) tests as well as DFT theory calculation, illustrating the primary roles of ·OH, ·O2~- and h~+ and charge migration route during the photocatalytic process of BM PHs. This study provides a promising strategy for constructing novel heterojunctions with highly efficient photocatalytic performance.
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