SYNOPSISParticle nucleation in the polymerization of styrene microemulsions was found to take place throughout the polymerization as indicated by measurements of the particle number as a function of conversion. A mechanism based on the nucleation in the microemulsion droplets was proposed to explain the experimental findings although homogeneous nucleation and coagulation during polymerization were not completely ruled out. A thermodynamic model was developed to simulate the partitioning of monomer in the different phases during polymerization. The model predicts that the oil cores of the microemulsion droplets were depleted early in the polymerization ( 4 % conversion). Due to the high monomer/ polymer swelling ratio of the polymer particles, most of the monomer resides in the polymer particles during polymerization. The termination of chain growth inside the polymer particles was attributed to the chain transfer reaction to monomer. The low ii (less than 0.5) of the microemulsion system was attributed to the fast exit of monomeric radicals.

The introduction of oxygen vacancies (Ov) has been regarded as an effective method to enhance the catalytic performance of photoanodes in oxygen evolution reaction (OER). However,t heir stability under highly oxidizing environment is questionable but was rarely studied. Herein, NiFe-metal-organic framework (NiFe-MOFs) was conformally coated on oxygen-vacancy-richB iVO 4 (Ov-BiVO 4 )a st he protective layer and cocatalyst, forming ac ore-shell structure with caffeic acid as bridging agent. The as-synthesized Ov-BiVO 4 @NiFe-MOFs exhibits enhanced stability and aremarkable photocurrent density of 5.3 AE 0.15 mA cm À2 at 1.23 V( vs. RHE). The reduced coordination number of Ni(Fe)-O and elevated valence state of Ni(Fe) in NiFe-MOFs layer greatly bolster OER, and the shifting of oxygen evolution sites from Ov-BiVO 4 to NiFe-MOFs promotes Ov stabilization. Ovs can be effectively preserved by the coating of at hin NiFe-MOFs layer,l eading to ap hotoanode of enhanced photocurrent and stability.

Initiation of polymerization in styrene oil‐in‐water microemulsions by water‐soluble potassium persulfate of oil‐soluble 2,2′‐azobis‐(2‐methyl butyronitrile) at 70°C gave stable latexes which were bluish and less translucent than the original microemulsions. The effects of initiator concentration, polymerization temperature, and monomer concentration on the kinetics, particle size distributions, and molecular weight distributions were investigated. The kinetics of polymerization were measured by dilatometry. In all cases, the polymerization rate shows only two intervals, which increased to a maximum and then decreased. There was no apparent constant rate period and no gel effect. A longer nucleation period was found for polymerizations initiated by potassium persulfate as compared to 2,2′‐azobis‐(2‐methyl butyronitrile). The small latex particle size (20–30 nm) and high polymer molecular weight (1–2 × 106) implies that each latex particle consists of two or three polystyrene molecules. The maximum polymerization rate and number of particles varied with the 0.47 and 0.40 powers of potassium persulfate concentration, and the 0.39 and 0.38 powers of 2,2′‐azobis‐(2‐methyl butyronitrile) concentration, respectively. This is consistent with the 0.4 power predicted by Smith–Ewart Case 2 kinetics. Microemulsion polymerizations of styrene–toluene mixtures at the same oil‐water phase ratio gave lower polymerization rates and lower molecular weights, but the same latex particle size as with styrene alone. A mechanism is proposed, which comprised initiation and polymerization in the microemulsion droplets, by comparing the kinetics of microemulsion polymerization with conventional emulsion and miniemulsion polymerization systems.

A mathematical model was developed to simulate the polymerization kinetics of styrene oil‐in‐water microemulsions. Nucleation of particles in microemulsion droplets was assumed to account for the number of particles generated. It was found that the entry rate coefficient of radicals into microemulsion droplets is much smaller than the entry rate coefficient into monomer‐swollen particles. All particles contain at most one growing radical. Various radical entry mechanisms were evaluated using the simulation. The possibility of flocculation between particles during the later stages of the polymerization and the high desorption rate of monomeric radicals was suggested by the simulation results. The likelihood of re‐entry of desorbed radicals was den onstrated.

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The enhancement of electron-and-hole separation efficiency and facile generation of reactive oxygen species are significant factors for performance improvement of photocatalysts in selective toluene photocatalytic oxidation. Heterojunction and defect construction have been regarded as valid methods to boost photocatalytic activity of semiconductors. Herein, the CdIn2S4-CdS composite with compact heterojunctions and defect-induced sulfur vacancies was fabricated by a one-step hydrothermal process. The sheet-to-sheet heterojunctions and the abundant sulfur vacancies facilitate separation and migration of photoinduced charge carriers. Benefited from the compositional and structural synergy, the prepared CdIn2S4-CdS-140 composite boosted photocatalytic oxidation activity for toluene conversion into benzaldehyde (remarkable toluene conversion of 80.3% and benzaldehyde selectivity of 99% in 6 h) under visible light irradiation. It is noteworthy that the composite can perform well when pure O2 was replaced with air.

PADB was a highly efficient cationic flocculant, which was synthesized through the copolymerization of acrylamide (AM), acryloyloxyethyl trimethyl ammonium chloride (DAC), and butylacrylate (BA) with ultraviolet initiation by micellar polymerization technology. The PADB was the terpolymer of AM, DAC, and BA. In order to observe this flocculant's structural characteristics, nuclear magnetic resonance hydrogen spectroscopy ( 1 H NMR), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA) were used. The most important study was to analyze its physicochemical parameters during dewatering of activated sludge. These tested parameters included residual turbidity of supernatant, dry solid content (DS), extracellular polymeric substances (EPS), specific resistance to filtration (SRF), ζ-potential, floc size, and settling rate. Results demonstrated that the PADB have a superiority over both poly(acrylamide-acryloyloxyethyl trimethyl ammonium chloride) (PAD) and commercially available cationic polyacrylamide (CPAM). However, it was dependent on pH and dosage. A favorable pH was in the neutral range while the appropriate dosage (20 mg·L −1 -60 mg·L −1 ) was crucial to the conditioning process. For the PADB at40 mg·L −1 and pH at 7, the residual turbidity of supernatant, DS, SRF, and settling rate could reach 5.5 NTU, 32.2%, 5.51 × 10 12 m·kg −1 , and 3.318 cm·min −1 , respectively. During the sludge flocculation process, the charge neutralization mechanism and bridging flocculation played an important role in floc's formation and settlement.

Temperature is generally considered as a key factor controlling algal bloom formation. Previous studies have indicated that the bloom-forming cyanobacteria Microcystis spp. overwinters near the sediment surface and does not actively grow below 158C. However, satellite images and field collections from Lake Taihu, China have shown that Microcystis spp. blooms persisted when water temperatures were below 108C during winter, although their magnitudes were smaller than during periods of higher temperature. Winter Microcystis cells maintained low activity and were able to grow again when exposed to elevated temperatures (12.58C). Hence, cyanobacterial blooms may appear year-round in eutrophic lakes. Temperature increases coupled with nutrient enrichment promoted the growth of cyanobacteria, while low temperature decreased the loss rate of Microcystis, allowing winter blooms to persist. High concentrations of overwintering vegetative cells may provide a large inoculum for blooms during warmer seasons. Controlling winter blooms may reduce their magnitude during the warmer seasons.