Yunbai Luo

Studies of Benzotriazole and Tolytriazole as Inhibitors for Copper Corrosion in Deionized Water

The inhibition efficiencies of benzotriazole (BTA) and tolytriazole (TTA) on copper in deionized water were investigated. The inhibition effects of BTA and TTA were evaluated from polarization curves. Coupon tests established that the inhibition efficiency was concentration, temperature, and time-dependent. Effective inhibition to copper was observed when TTA or BTA (>6 ppm) was added to deionized water. TTA showed more effeciency and persistence for inhibiting the corrosion of copper under selected conditions, which may be attributed to its increased film hydrophobicity. The thermodynamic parameters of BTA and TTA adsorption were calculated.

Relating organic fouling of reverse osmosis membranes to adsorption during the reclamation of secondary effluents containing methylene blue and rhodamine B.

Dyes fouling of reverse osmosis (RO) membranes and its relation to adsorption had been investigated by using a crossflow RO filtration setup. Methylene blue (MB) and rhodamine B (RB) were used as model organic foulants. The calculated amount of the irreversible sorption was related to the irreversible flux decline. The characteristic fouling kinetics was accounted by Langmuir-Hinshelwood (L-H) kinetics model for initial fouling, with the fouling rate constant k=0.0556μm s(-1)min(-1) and k=0.0181μm s(-1)min(-1) for MB and RB fouling RO membrane CPA2, respectively. And the subsequent fouling was attributed to the growth of a dye cake. A remarkable correlation was obtained between the quantified irreversible sorption and irreversible flux decline under the solution chemistries investigated. In the presence of divalent cation, the extent of flux decline was related to the competition model.

A superhydrophobic 3D porous material for oil spill cleanup

Oil spills are a serious threat to environment and marine ecosystems; hence, it is urgent to identify an economic and efficient countermeasure to deal with them. In this work, a kind of superhydrophobic 3D porous material is fabricated for oil spill cleanup. Oil is selectively absorbed in the material at first, and then sucked by a pump. The superhydrophobicity and factors influencing oil collection rates are studied. The results show that the water contact-angle is 155°, and the oil collection rate can reach 2.8 g s−1 under appropriate conditions. A plurality of these materials can be connected to a similar pump simultaneously, forming a network for oil cleanup. As the 3D material together with the pumping method can realize a continuous cleanup with high efficiency, it can be thought of as a promising candidate for oil spill cleanup applications.

Large-Scale Synthesis of Metal-Ion-Doped Manganese Dioxide for Enhanced Electrochemical Performance

One-dimensional (1D) MnO2 was widely applied in areas of enzyme biosensors, industrial sieves, and energy storage materials owing to its excellent thermal, optical, magnetic, and chemical features. However, its practical application into energy storage devices is often hindered by the bad electronic conductivity (from 10(-5) to 10(-6) S cm(-1)). As is widely known, doping with hetero elements is an efficient way to enhance the electronic conductivity of metal oxides. Herein, a novel and simple molten-salt method is developed to achieve a large-scale preparation of 1D MnO2 nanowires. Such an approach also realizes the easy tuning of electrical properties through doping with different transition metal ions. On the basis of first-principle calculation as well as four-probe measurement, we determined that the conductivity of the doped MnO2 nanowires can be promoted efficiently by utilizing such protocol. Meanwhile, a possible doping route is discussed in detail. As a result, a superior electrochemical performance can be observed in such metal ions (M(+))-doped nanowires. Such high-quality M(+)-doped MnO2 nanowires can satisfy a broad range of application needs beyond the electrochemical capacitors.

Polyvinylidene fluoride (PVDF)/hydrophobic nano-silica (H-SiO2) coated superhydrophobic porous materials for water/oil separation

The separation of water and oil is a promising work due to the increasing worldwide oil pollution and leakage of chemical solvents. Superhydrophobic porous materials were prepared for their separation. In this work, various porous substrates of copper meshes, filter papers and polyurethane (PU) sponges were chosen to obtain superhydrophobic surfaces. Superhydrophobic surfaces were fabricated by polyvinylidene fluoride (PVDF) and hydrophobic nano-silica particle coatings through a spraying approach. The superhydrophobicity, stability of coatings and oil/water separation effect of these as-coated materials were studied. The results demonstrated that all the surfaces showed high water contact angles (>150°), good reusability and excellent oil selectively. Moreover, the coated filter paper was scaled up for practical use of removing trace water from mineral insulating oil in our group. It is promising that this superhydrophobic coating could be used in more applications.

Enhancement in membrane performances of a commercial polyamide reverse osmosis membrane via surface coating of polydopamine followed by the grafting of polyethylenimine

Membrane fouling and chlorine degradation are two of the major challenges the reverse osmosis (RO) membrane industry is facing in recent years. In the present study, a commercial aromatic polyamide RO membrane (XLE-400, DOW Co., Ltd.) was modified via surface coating of polydopamine (PDA) followed by the grafting of polyethylenimine (PEI). The successful modification was confirmed by X-ray photoelectron spectroscopy (XPS). Membrane surface properties were characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), zeta potential and contact angle. The results showed that modification enhanced the surface hydrophilicity, moved the surface charge towards the positive side and made the surface slightly rougher without damaging the surface peak-and-valley substrate. The influence of modification on the permselectivity of the membrane was also examined. The modified membrane had a higher salt rejection and a slightly lesser water flux than the unmodified membrane. Furthermore, the chlorination, fouling and simulated biofouling experiments were done. The results showed that, due to the abundant presence of grafted amino groups coming from PEI, the modified membrane exhibited higher chlorine resistance, anti-fouling and antibacterial properties.

Novel water treatment process - combined cationic ion-exchange bed and degasifier in a three-phase fluidized bed

A novel water treatment process, combining cationic ion exchange and bicarbonate removal in a countercurrent three-phase fluidized bed, was explored. The study was based around a laboratory scale bed. The different operating conditions and effluent quality were investigated. The results showed that concentrations of sodium and carbon dioxide in effluent decreased with increasing height of resin static layer and greater airflow velocity. The concentration of sodium and carbon dioxide in the effluent was lower than 0.1 mg/l and 5 mg/l respectively. Instantaneous conductivity that illustrated effluent quality was measured in different sections of the bed. A mathematical modeling which can simulate the changing of conductivity was built, the validity and applicability of the model for future prediction of effluent properties have been verified by the good agreement between the experimental and predicted values.

A facile dip-coating approach to stable superhydrophobic SiO2/epoxy resin membrane preparation for micro-water separation in transformer oil liquids

In this study, a facile one-step dip-coating approach was reported for superhydrophobic membrane fabrication, in which only epoxy resin and silica nanoparticles were needed. In addition, the surface microstructure and wettability of the membrane were closely related to the content of silica nanoparticles. When the content of silica nanoparticles was 4 wt%, the membrane exhibited optimum surface roughness and superhydrophobicity, by which water was blocked, while oil was allowed to permeate. Through the application of water contact angle, scanning electron microscopy, energy dispersive spectroscopy, thermal gravimetric analysis and Karl Fischer moisture titrator measurements, the membrane examination indicated that the micro/nanostructures enhanced the water repellency, which was similar to the lotus leaf effect. Furthermore, this method is suitable for large-scale production and employed for micro-water separation in transformer oil. This is possible because environmentally friendly and inexpensive materials are adopted and harsh operations, sophisticated equipment and a special atmosphere are avoided.

Synthesis and characterization of a polyamide thin film composite membrane based on a polydopamine coated support layer for forward osmosis

In this study, a facile method has been developed to prepare high performance thin film composite (TFC) forward osmosis (FO) membranes, which was conducted by coating the surface of a polysulfone (PSf) substrate with polydopamine (PDA) prior to the interfacial polymerization of trimesoyl chloride and m-phenylenediamine. The PDA coating layer was investigated by ATR-FTIR, XPS, FESEM and contact angle measurements. Results showed that the PDA layer played the following roles: (1) endowing the PSf substrate with catechol and ethylamino groups to enhance the hydrophilicity, which resulted in a significant increase in water flux; (2) facilitating the formation of a denser selective polydopamine layer during the interfacial polymerization process to enhance salt rejection. The TFC membrane based on PDA coated dual PSf surfaces showed a water flux of 43.4 LMH and a salt flux of 6.46 gMH in pressure retarded osmosis (PRO) mode using 2 M NaCl as draw solution.

Fabrication of BaSO4-based mineralized thin-film composite polysulfone/polyamide membranes for enhanced performance in a forward osmosis process

Novel BaSO4-based mineralized thin-film composites (TFC) as forward osmosis (FO) membranes were fabricated through depositing barium sulfate on the surface of the prepared polysulfone/polyamide (PSf/PA) membranes by adopting an approach named surface mineralization. BaSO4 particles were deposited by an alternate soaking process (ASP) with aqueous solutions of barium chloride (BaCl2) and sodium sulfate (Na2SO4), separately. Membranes with different mineralization degrees were prepared by changing the number of ASP cycles. The mineralized TFC PSf/PA FO membranes were characterized by a variety of methods in accordance with membranes structure and surface properties. It turned out that the mineral coating made of BaSO4 particles was evenly distributed on the membrane surface and the existence of this coating made the membrane surface became more hydrophilic and negatively charged after mineralization. The FO performances of the mineralized TFC membranes were also tested and compared with the original PSf/PA membrane and the commercial CTA-W FO membrane with pure water as the feed solution and a 1 M NaCl solution as the draw solution. The mineralized TFC PSf/PA membranes displayed better water permeability and salt rejection than the original PSf/PA membrane and the commercial FO membrane. The results revealed that mineralized TFC PSf/PA membranes showed great potential for further development of FO applications.