Novel CuMgAlTi-LDH Photocatalyst for Efficient Degradation of Microplastics under Visible Light Irradiation.

Microplastics (MPs) in the water system could easily enter the human body and pose a potential threat, so finding a green and effective solution remains a great challenge. At present, the advanced oxidation technology represented by photocatalysis has been proven to be effective in the removal of organic pollutants, making it a feasible method to solve the problem of MP pollution. In this study, the photocatalytic degradation of typical MP polystyrene (PS) and polyethylene (PE) by a new quaternary layered double hydroxide composite photomaterial CuMgAlTi-R400 was tested under visible light irradiation. After 300 h of visible light irradiation, the average particle size of PS decreased by 54.2% compared with the initial average particle size. The smaller the particle size, the higher the degradation efficiency. The degradation pathway and mechanism of MPs were also studied by GC-MS, which showed that PS and PE produced hydroxyl and carbonyl intermediates in the process of photodegradation. This study demonstrated a green, economical, and effective strategy for the control of MPs in water.

The effect of sludge retention time (SRT) on the Nitrifier typical kinetics at ambient temperature under the low ammonia density.

Sludge retention time (SRT) regulation is one of the essential management techniques for refined control of the main-sidestream treatment process under the low ammonia density. It is indispensable to understand the effect of SRTs changes on the Nitrifier kinetics to obtain the functional separation of the Nitrifier and the refined control of the nitrification process. In this study, Nitrifier was cultured with conditions of 35 ± 0.5 °C, pH 7.5 ± 0.2, DO 5.0 ± 0.5 mg-O/L, and SRTs were controlled for 40 d, 20 d, 10 d, and 5 d. The net growth rate (µm), decay rate (b), specific growth rate (µ), the yield of the Nitrifier (YA), temperature parameter (TA), and inhibition coefficient (KI) have been measured and extended with the SRT decreases. Instead, the half-saturation coefficient (KS) decreased. In addition, the limited value of pH inhibition occurs (pHUL), and the pH of keeping 5% maximum reaction rate (pHLL) was in a relatively stable state. The trade of kinetics may be induced by the change of species structure of Nitrifier. The Nitrosomonas proportion was increased, and the Nitrospira was contrary with the SRT decreasing. It is a match for the functional separation of Nitrifier when SRTs was 20 d at ambient temperature under the low ammonia density. The kinetics of ammonia-oxidizing organisms (AOO) and nitrite-oxidizing organisms (NOO) in Nitrifier under different SRT conditions should be measured respectively to the refined control of the partial nitrification process in future study.

Efficient Removal of Bisphenol A Using Nitrogen-Doped Graphene-Like Plates from Green Petroleum Coke.

Green petroleum coke, a form of industrial waste produced in the oil-refining process, was used to synthesize nitrogen-doped graphene-like plates (N-GLPs) together with melamine. In this study, characterization and batch experiments were performed to elucidate the interaction mechanism of N-GLPs and bisphenol A (BPA). Structural analysis of N-GLPs, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS), showed an obvious graphene-like structure and successful nitrogen doping. In addition, compared with 8.0 m2/g for green petroleum coke, the BET surface area of N-GLPs markedly increased to 96.6 m2/g. The influences of various factors, including contact time, temperature, and initial pH on BPA removal efficiency were investigated. It was found that 92.0% of BPA was successfully removed by N-GLPs at 50 °C. Based on the adsorption experiments, it was shown that electrostatic attraction, hydrogen bonding, and π-π interaction enhanced the adsorption capacity of N-GLPs for BPA. According to the thermodynamic data, the adsorption process was spontaneous, physical, and endothermic in nature. Therefore, N-GLPs are efficient adsorbent material to remove BPA from wastewater.

Copolymer of Pyrrole and 1,4-Butanediol Diglycidyl as an Efficient Additive Leveler for Through-Hole Copper Electroplating.

A copolymer comprising of pyrrole and 1,4-butanediol diglycidyl ether (PBDGE) was designed and synthesized as a leveler to improve the throwing power for printed circuit board (PCB) through-hole electroplating. The results of linear sweep voltammetry (LSV), galvanostatic measurements (GMs), and cyclic voltammetry (CV) reveal the strong coordination effect of PBDGE with other additives and confirm the advantageous performance of PBDGE to effectively assist the electroplating of through-hole. An increment of 35.5% in the throwing power was achieved under the addition of PBDGE in through-hole plating. Additionally, the reaction mechanism was studied by quantum chemical calculations and molecular dynamics (MD) simulations, indicating that the pyrrole rings of the PBDGE molecule are adsorbed on the copper surface as the adsorption sites to balance the copper plating regardless of the through-hole position differences.

Polypropylene Glycol-Polyoxytetramethylene Glycol Multiblock Copolymers with High Molecular Weight: Synthesis, Characterization, and Silanization.

The high crystallization at room temperature and high cost of polyoxytetramethylene glycol (PTMG) have become obstacles to its application. To overcome these problems, a segment of PTMG can be incorporated into a block copolymer. In this work, polypropylene (PPO) glycol-polyoxytetramethylene (PPO-PTMG) multiblock copolymers were designed and synthesized through a chain extension between hydroxyl (OH)-terminated PPO and PTMG oligomers. The chain extenders, feed ratios of the catalyst/chain extender/OH groups, reaction temperature, and time were optimized several times to obtain a PPO-PTMG with low crystallization and high molecular weight. Multiblock copolymers with low crystallization and high average molecular weight (Mn = 1.0-1.4 × 104 Dalton) were harvested using m-phthaloyl chloride as the chain extender. The OH-terminated PPO-PTMG multiblock copolymer with high Mn and a functionality near two was further siliconized by 3-isocyanatopropyltrimethoxysilane to synthesize a novel silyl-terminated polyether. This polyether has an appropriate vulcanizing property and potential applications in sealants/adhesive fields.

Control of Uniform and Interconnected Macroporous Structure in PolyHIPE for Enhanced CO2 Adsorption/Desorption Kinetics.

The highly uniform and interconnected macroporous polymer materials were prepared within the high internal phase hydrosol-in-oil emulsions (HIPEs). Impregnated with polyethylenimine (PEI), the polyHIPEs were then employed as solid adsorbents for CO2 capture. Thermodynamic and kinetic capture-and-release tests were performed with pure CO2, 10% CO2/N2, and moist CO2, respectively. It has shown that the polyHIPE with suitable surface area and PEI impregnation exhibits high CO2 adsorption capacity, remarkable CO2/N2 selectivity, excellent adsorption/desorption kinetics, enhanced efficiency in the presence of water, and admirable stability in capture and release cycles. The results demonstrate the superior comprehensive performance of the present PEI-impregnated polyHIPE for CO2 capture from the postcombustion flue gas.

Effect of chain topology of polyethylenimine on physisorption and chemisorption of carbon dioxide.

Polyethylenimine (PEI) is a promising candidate for CO2 capture. In this work, the physisorption and chemisorption of CO2 on various low-molecular-weight PEIs are investigated to identify the effect of chain architecture on sorption. The reliability of theoretical calculations are partially supported by our experimental measurements. Physisorption is calculated independently by the reference interaction-site model integral equation theory; chemisorption is distinguished from the total sorption given by the quantum density functional theory. It is shown that, as the chain length increases, both chemisorption and physisorption drop off nonlinearly, but the decay amplitude of chemisorption is more apparent. Conversely, as the amine group approaches the central triamine unit of each oligomer, the sorption capacity decreases, affecting the sorption equilibrium in a complex way. This arises from the cooperative contribution of an increased steric effect and renormalized electronic distribution.

Seaweed to dendrite transition in directional solidification.

We simulate directional solidification using a phase-field model solved with adaptive mesh refinement. For small surface tension anisotropy directed at 45 degrees relative to the pulling direction we observe a crossover from a seaweed to a dendritic morphology as the thermal gradient is lowered, consistent with recent experimental findings. We show that the morphology of crystal structures can be unambiguously characterized through the local interface velocity distribution. We derive semiempirically an estimate for the crossover from seaweed to dendrite as a function of thermal gradient and pulling speed.