Co-reporter:Cailong Zhou, Huijing Li, Jing Lin, Kun Hou, Zhijie Yang, Pihui Pi, Shouping Xu, Xiufang Wen, and Jiang Cheng
The Journal of Physical Chemistry C September 14, 2017 Volume 121(Issue 36) pp:19716-19716
Publication Date(Web):August 22, 2017
DOI:10.1021/acs.jpcc.7b03645
We fabricated a matchstick-like Cu2S@CuxO nanowire film on copper mesh by applying a Cu(OH)2 nanowires template-sacrificial method, which can transformed from superhydrophilic to superhydrophobic just after storage in air for a certain period without any further organic modification. The surface morphology, chemical composition and the wettability were investigated by Scanning Electron Microscopy (SEM), X-ray diffractometer (XRD), Raman, X-ray Photoelectron Microscopy (XPS), and contact angle measurement. Results showed that the change of surface chemical composition and the trapped air among the matchstick-like structures were the decisive factors for the wettability transition. Therefore, on-demand oil/water separation was achieved, which was performed by using the superhydrophilic–underwater superoleophobic mesh for separating light oil/water mixtures and the superhydrophobic one for separating heavy oil/water mixtures.
Langmuir May 2, 2017 Volume 33(Issue 17) pp:4172-4172
Publication Date(Web):April 11, 2017
DOI:10.1021/acs.langmuir.7b00227
We demonstrate a facile method to induce water droplet motion on an wedge-shaped superhydrophobic copper surface combining with a poly(dimethylsiloxane) (PDMS) oil layer on it. The unbalanced interfacial tension from the shape gradient offers the actuating force. The superhydrophobicity critically eliminates the droplet contact line pinning and the slippery PDMS oil layer lubricates the droplet motion, which makes the droplet move easily. The maximum velocity and furthest position of droplet motion were recorded and found to be influenced by the gradient angle. The mechanism of droplet motion on the shape gradient surface is systematically discussed, and the theoretical model analysis is well matched with the experimental results.
Phytic acid, which is a naturally occurring component that is widely found in many plants, can strongly bond toxic mineral elements in the human body, because of its six phosphate groups. Some of the metal ions present the property of bonding with phytic acid to form insoluble coordination complexes aggregations, even at room temperature. Herein, a superhydrophobic cotton fabric was prepared using a novel and facile nature-inspired strategy that introduced phytic acid metal complex aggregations to generate rough hierarchical structures on a fabric surface, followed by PDMS modification. This superhydrophobic surface can be constructed not only on cotton fabric, but also on filter paper, polyethylene terephthalate (PET) fabric, and sponge. AgI, FeIII, CeIII, ZrIV, and SnIV are very commendatory ions in our study. Taking phytic acid–FeIII-based superhydrophobic fabric as an example, it showed excellent resistance to ultraviolet (UV) irradiation, high temperature, and organic solvent immersion, and it has good resistance to mechanical wear and abrasion. The superhydrophobic/superoleophilic fabric was successfully used to separate oil/water mixtures with separation efficiencies as high as 99.5%. We envision that these superantiwetting fabrics, modified with phytic acid–metal complexes and PDMS, are environmentally friendly, low cost, sustainable, and easy to scale up, and thereby exhibit great potentials in practical applications.Keywords: fabrics; oil/water separation; PDMS; phytic acid metal complexes; superhydrophobic;
Environmental Science and Pollution Research 2017 Volume 24( Issue 24) pp:19807-19815
Publication Date(Web):07 July 2017
DOI:10.1007/s11356-017-9615-z
Gasification has gained advantage as an effective way to dispose domestic solid waste in mountainous rural of China. However, its toxic emissions such as PCDD/Fs and heavy metals, as well as their potential environmental risks, were not well studied in engineering application. In this study, an updraft fixed bed gasifier was investigated by field sampling analysis. Results showed that low toxic emissions (dust, SO2, NOx, HCl, CO, H2S, NH3, PCDD/Fs and heavy metals) in the flue gas were achieved when the rural solid waste was used as feedstock. The mass distribution of heavy metals showed that 94.00% of Pb, 80.45% of Cu, 78.00% of Cd, 77.31% of Cr, and 76.25% of As were remained in residual, whereas 86.58% of Hg was found in flue gas. The content of PCDD/Fs in the flue gas was 0.103 ngI-TEQ·Nm−3, and the total emission factor of PCDD/Fs from the gasifier was 50.04 μgI-TEQ·t-waste−1, among which only 0.04 μgI-TEQ·t-waste−1 was found in the flue gas. The total output of PCDD/Fs was1.89 times as high as input, indicting the updraft fixed bed gasifier increased emission of PCDD/Fs during the treatment domestic solid waste. In addition, the distribution characteristics of PCDD/Fs congeners reflected that PCDD/Fs was mainly generated in the gasification process rather than the stage of flue gas cleaning, suggesting the importance to effectively control the generation of PCDD/Fs within the gasifier chamber in order to obtain a low PCDD/Fs emission level.
Co-reporter:Cailong Zhou, Jiang Cheng, Kun Hou, Zhengting Zhu, Yanfen Zheng
Chemical Engineering Journal 2017 Volume 307(Volume 307) pp:
Publication Date(Web):1 January 2017
DOI:10.1016/j.cej.2016.08.119
•CuWO4@Cu2O film was prepared on copper mesh by a one-step electrochemical anodization method.•Various oil/water mixtures can be separated using the as-prepared mesh with high separation efficiency.•The mesh could purify the aqueous pollutant in the water phase under visible light illumination.•This work may provide a potential simple route to prepare other metal tungstates or composites.CuWO4@Cu2O film was prepared on copper mesh by a one-step electrochemical anodization method for efficiently separating oil/water mixtures and photodegrading organic pollutants in the water phase. The as-prepared mesh displayed superhydrophilicity and good underwater superoleophobicity due to the hierarchical cauliflower-like structure. The mesh possessed high separation efficiency up to 99.3% for oil/water separation. During the oil/water separation process, water passed through the mesh rapidly by gravity, while oils stayed above due to its underwater superoleophobicity. After the separation, the mesh could be used for degrading the aqueous pollutant in the separated water phase under visible light illumination, which significantly amplifies the utilization of solar energy. Methylene blue and rhodamine B were successfully photodegraded by the as-prepared mesh in the presence of Na2S2O8 with a maximum degradation efficiency of 96.4%.Download high-res image (277KB)Download full-size image
The emission, mass balance, and distribution characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) as well as those of heavy metals (Hg, Cd, Pb, Cr, and Cu) were investigated during the cocombustion of 5%, 10%, 15%, and 20% sewage sludge (SS) in a pulverized coal power plant. The PCDD/F emissions increased from 7.00 to 32.72 pg I-TEQ/Nm3 as the amount of SS in the mixed fuel (MF) increased. High sulfur content and relatively low chlorine levels in MF resulted in lower PCDD/F emissions. SS exhibited a remarkable difference in congener profiles compared with flue gas, bottom ash, and fly ash. The negative dioxin mass balance indicated that the cofiring of SS with coal in power plants was not a source but a sink of dioxins. The concentrations and emission factors of heavy metals in flue gas and bottom ash, as well as fly ash, all exhibited a tendency to increase with increasing input values of heavy metals in MF. The distribution characteristics of the investigated heavy metals were primarily dependent on the evaporative properties of these metals. The availability of chlorine could alter the heavy metal distribution behavior. The emitted pollutants in the power plant were below the legal limits.
Gradient wettability surface was prepared on copper substrate via a facile alkali assistant surface oxidation technique. It was based on the control of cupric hydroxide (Cu(OH)2) nanoribbon arrays growth from the upper part to lower part along the vertically placed copper substrate in an aqueous solution of NaOH and (NH4)2S2O8. Thus the gradient wettability functionalized Cu(OH)2 nanoribbon arrays were directly fabricated on copper substrate by varying the immersing time of different positions along the substrate surface. By using a relative dilute NaOH solution (0.75 mol/L) and (NH4)2S2O8 solution (0.03 mol/L), and regulating dropping speed, the surface gradient wettability changing from the original contact angle of copper substrate (90.5°) to surperhydrophilicity (3.0°) was prepared. The surface fabricated on copper substrate may keep its gradient wetting property after immersed in water bath at 100 °C for 10 h. The water contact angle measurement (CA), Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed to analyze the wettability, morphologies, crystal structure, and surface chemical compositions of the Cu(OH)2 nanoribbon arrays on copper substrate. This research is expected to be significant in providing a new strategy for the preparation of novel gradient wettability material with potential industrial applications on copper substrate.
A superhydrophobic and superoleophilic coating for oil filter paper was synthesized based on waterborne bisphenol-A novolac epoxy emulsion. The benzoic acid (BA) and maleic anhydride (MA) were used as modification agents to give the epoxy resin hydrophilic groups (carboxyl) and CC double bonds. And the fluorinated waterborne epoxy emulsion was prepared by free radical solution polymerization of dodecafluoroheptyl methacrylate (DFMA) monomer. The covalent bound low free energy fluorinated chains in the monomer reduce the surface energy of solidification polymers sufficiently to give rise to superhydrophobic behavior while conserving superoleophilicity. Surfaces prepared show a sticky property, which exhibits a static water contact angle of 152° for a 5 μL droplet that does not slid off even when the sample is held upside down. This synthetic emulsion is simple and convenient as impregnating agent for filter paper, which can be considered as a suitable candidate for various substrates such as cotton textiles, E-glass and artificial fiber, and so on.
Surface and Coatings Technology 2012 Volume 213() pp:90-97
Publication Date(Web):December 2012
DOI:10.1016/j.surfcoat.2012.10.025
A method to fabricate wettability gradient surface with raspberry-like composite microspheres was described. The synthesis of composite microspheres was through the ethanol sol–gel processing of TEOS on carboxyl functionalized polystyrene (PS) template particles. The factors influencing the raspberry-like morphology and the deposition efficiency of SiO2 onto templates were discussed, including the surface carboxyl density, TEOS amount and water amount, and the optimal formulation of synthesis was given. The wettability gradient surface was built up by coating the suspension prepared on substrate and putting it in thermal gradient field for heat treatment. The resultant surface demonstrated wettability gradient from hydrophobic to superhydrophilic with the increasing of calcination temperature, which was because the physical topography of surface changed gradually from spike-type into pore-type and the main chemical compositions changed from polystyrene into SiO2.Highlights► We prepared composite microspheres via sol–gel process on carboxyl functionalized templates. ► Wettability gradient surface was fabricated with gradual temperature field. ► Ideal gradient wetting could range from hydrophobic to superhydrophilic. ► Three temperature segments were divided with wettability. ► Suitable theoretical models were selected for explanation.
Separation and Purification Technology 2003 Volume 31(Issue 1) pp:97-104
Publication Date(Web):1 April 2003
DOI:10.1016/S1383-5866(02)00152-1
The removal rate(s) of one or several organic pollutant(s) from water by ozonation and the chemical mass transfer coefficient of ozone in an agitated semi-batch reactor are predicted simultaneously using the explicit expression of enhancement factor in ozone absorption relating to the surface renewal theory presented elsewhere by this study group (Chinese J. Chem. Eng. 8 (2000) 236–240). By comparing with the iteration method proposed by Kuo (Environ. Prog. 1 (1982) 189–195) based on the film theory, no significant deviation has been found in simulating ozone absorption into the solution of 2,4-dichlorophenol (2,4-DCP). The predicted results also agree well with the measured data.
