A novel copper oxide/titanium membrane integrated with peroxymonosulfate activation for efficient phenolic pollutants degradation.

Herein, a novel CuO catalyst functionalized Ti-based catalytic membrane (FCTM) was prepared via the regulated electro-deposition technique followed with low-temperature calcination. The morphology of CuO catalyst and oxygen vacancy (OV) content can be controlled by adjusting the preparation conditions, under optimal condition (400 °C, electrolyte as sulfuric acid), the fern-shaped CuO catalyst was formed and the OV content was up to its highest level. Under the optimal treatment condition, the 4-chlorophenol (4-CP) removal of the membrane filtration combined with peroxymonosulfate (PMS) activation (MFPA) process was up to 98.2% (TOC removal of 88.2%). Mechanism studying showed that the enhanced performance in this system was mainly due to the increased production of singlet oxygen (1O2) via the co-effect of fern-shaped CuO (increased specific surface area) and its fine-tuned OV (precursor of 1O2), which not only synergistically enhanced adsorption ability but also offered more active sites for PMS activation. Theoretical calculations showed that the OV-rich CuO displayed high adsorption energy for PMS molecule, leading to the change in OO and OH bond (tend to 1O2) of the PMS molecule. Finally, the possible three degradation pathways of 4-CP were formed by the electrophilic attacking of 1O2.

Carbon electrochemical membrane functionalized with flower cluster-like FeOOH catalyst for organic pollutants decontamination.

Decorating active catalysts on the reactive electrochemical membrane (REM) is an effective way to further improve its decontamination performance. In this work, a novel carbon electrochemical membrane (FCM-30) was prepared through coating FeOOH nano catalyst on a low-cost coal-based carbon membrane (CM) through facile and green electrochemical deposition. Structural characterizations demonstrated that the FeOOH catalyst was successfully coated on CM, and it grew into a flower cluster-like morphology with abundant active sites when the deposition time was 30 min. The nano FeOOH flower clusters can obviously boost the hydrophilicity and electrochemical performance of FCM-30, which enhance its permeability and bisphenol A (BPA) removal efficiency during the electrochemical treatment. Effects of applied voltages, flow rates, electrolyte concentrations and water matrixes on BPA removal efficiency were investigated systematically. Under the operation condition of 2.0 V applied voltage and 2.0 mL·min-1 flow rate, FCM-30 can achieve the high removal efficiency of 93.24% and 82.71% for BPA and chemical oxygen demand (COD) (71.01% and 54.89% for CM), respectively, with only a low energy consumption (EC) of 0.41 kWh·kgCOD-1, which can be ascribed to the enhancement on OH yield and direct oxidation ability by the FeOOH catalyst. Moreover, this treatment system also exhibits good reusability and can be adopted on different water background as well as different pollutants.

Effect of Graphene Sheets Embedded Carbon Films on the Fretting Wear Behaviors of Orthodontic Archwire-Bracket Contacts.

Carbon films were fabricated on the orthodontic stainless steel archwires by using a custom-designed electron cyclotron resonance (ECR) plasma sputtering deposition system under electron irradiation with the variation of substrate bias voltages from +5 V to +50 V. Graphene sheets embedded carbon (GSEC) films were fabricated at a higher substrate bias voltage. The fretting friction and wear behaviors of the carbon film-coated archwires running against stainless steel brackets were evaluated by a home-built reciprocating sliding tribometer in artificial saliva environment. Stable and low friction coefficients of less than 0.10 were obtained with the increase of the GSEC film thickness and the introduction of the parallel micro-groove texture on the bracket slot surfaces. Particularly, the GSEC film did not wear out on the archwire after sliding against three-row micro-groove textured bracket for 10,000 times fretting tests; not only low friction coefficient (0.05) but also low wear rate (0.11 × 10-6 mm3/Nm) of the GSEC film were achieved. The synergistic effects of the GSEC films deposited on the archwires and the micro-groove textures fabricated on the brackets contribute to the exceptional friction and wear behaviors of the archwire-bracket sliding contacts, suggesting great potential for the clinical orthodontic treatment applications.

High performance polypyrrole coated carbon-based electrocatalytic membrane for organic contaminants removal from aqueous solution.

Electrocatalytic filtration process adopting the electrocatalytic membrane as both filtration membrane and active electrode showed great prospect on the organic pollutant removal from water. In this work, a high-performance metal-free polypyrrole (PPy) coated carbon-based electrocatalytic membrane (PPy@CCM) was developed through the facile and controllable electro-polymerization deposition method. Structural properties and electrochemical performance of the prepared PPy@CCM were characterized systematically. The influences of preparation parameters and operational parameters on water treatment performance of PPy@CCM were also investigated. Results indicates that the spherical PPy particles uniformly distributed on the surface of PPy@CCM. Coating with PPy particles can significantly improve the hydrophilicity and electrochemical activity of CCM, therefore PPy@CCM has lower hydraulic resistance and higher water treatment performance than CCM. The phenol and chemical oxygen demand (COD) removal rates obtained by PPy@CCM are up to 99.51% and 89.90%, respectively, under the optimal condition of 2.0 V cell potential, 2.50 g·L-1 Na2SO4, 1.5 ml·min-1 flow rate and 50 mg·L-1 phenol, and only 0.5 kWh·kgCOD-1 energy consumption is consumed. In addition, PPy@CCM also exhibits good treatment performance in different water matrixes. Moreover, PPy@CCM has good stability for several cycle operation and considerable applicability for different types of organic pollutants removal. The oxidation mechanism study reveals that PPy@CCM has both direct and indirect oxidation activity during the electrocatalytic filtration treatment, and the coating of PPy can improve the direct oxidation ability and ·OH yield of CCM.

Preparation and application of high-performance and acid-tolerant TiO2/carbon electrocatalytic membrane for organic wastewater treatment.

Acidic organic wastewater with toxic and carcinogenic properties has long been a tough problem for industrial treatment. To break down the barrier of poor acidic stability as well as the high cost of materials and reactors, a novel strategy of utilizing a high-performance and acid-tolerant TiO2/carbon electrocatalytic membrane (TiO2/CEM) for acidic organic wastewater treatment was proposed. Study results showed that high concentrations of organic pollutants were separated and degraded by the synergistic effects of membrane separation and electrocatalytic oxidation simultaneously on the TiO2/CEM. The great treatment performance with membrane removal efficiency of >97.4% was obtained by treating acidic rhodamine B (RhB) dye wastewater under optimized applied voltage. Treatment experiments under various pH and electrochemical tests demonstrated the outstanding acid-tolerant property and long service life of TiO2/CEM. Furthermore, the feasibility of TiO2/CEM for industrial application and various acidic organic wastewater treatment was proved by treating typical organic pollutants (phenol, tetracycline and oil) under high acidic circumstances.

Insights into the impact of polydopamine modification on permeability and anti-fouling performance of forward osmosis membrane.

Forward osmosis (FO) has drawn wide attention as a promising method to address world-wide water crisis due to the advantages of low-energy consumption and easy separation operation. Unfortunately, the trade-off between permeability and selectivity as well as membrane fouling hindered the application of forward osmosis. Surface modification is a feasible method to address these issues. However, there is a lack of systematic evaluation about the effect of modification position on FO performance due to the asymmetric structure of thin film composite (TFC) FO membrane. To provide new insights into the design of FO membrane with satisfied permeability and fouling resistance, novel TFC FO membranes were fabricated by introducing polydopamine (PDA) on the support layer (TFC-I) or active layer (TFC-S), respectively. The surface morphology, chemical composition and wettability of the fabricated membrane were studied. It was found that the surface wettability of the modified membrane was improved greatly compared to pristine TFC membrane (TFC-C). Moreover, TFC-S membrane displayed a rougher surface than that of TFC-I membrane. As a result, a superior TFC-S membrane with a water flux of 60.95 ± 3.15 L m-2h-1 in AL-DS mode was obtained, which was 72.61% and 17.87% higher than that of TFC-C and TFC-I membrane, respectively. In addition, the TFC-S membrane also presented an excellent fouling resistance and membrane regeneration performance during the three organic fouling cycle experiments. The results indicated that the introduction of PDA as a surface coating for TFC membranes modification guaranteed the high-performance and fouling resistance. Especially, the PDA coating on the support layer surface resulted in an enhancement in permeability, while both the permeability and anti-fouling performance were significantly improved with the PDA coating on the polyamide active layer surface. This study provides new insights into the development of modification TFC-FO membranes for practical applications in water treatment.