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An elaborate structural and chemical depth profile of the thin film composite (TFC)-forward osmosis (FO) membrane is indispensable to the complete understanding of how the substrate structures influence the in-situ polyamide (PA) layer formation and ultimately the wastewater concentration performance of the resultant TFC-FO membrane. Herein, the X-ray photoelectron spectroscopy paired with Ar2500+ gas cluster ion beams sputtering is introduced for the first time to conduct the depth profiling analysis of the PA-based TFC-FO membrane. The fine chemical and structural properties of the TFC-FO membranes were successfully reconstructed from the depth profiles, which revealed that the sponge-like substrate with small surface pores favored the formation of a smooth and thin PA layer with a highly cross-linked inner layer, while the macroporous substrate with large surface pores facilitated the development of a rough and defective PA layer with deep formation inside substrate pores. Benefiting from the thin effective thickness and dense inner selective layer, the PA layer formed on sponge-like substrate exhibited superior water permeability and salt selectivity. Besides, even suffered from more serious internal concentration polarization within substrate, the smooth PA layer surface with fewer carboxylic groups endowed the sponge-like substrate supported TFC-FO membrane with much higher anti-fouling capacity and average water flux than its counterpart. However, the TFC-FO membrane with highly cross-linked PA layer still exhibited poor NH4+-N rejections (56.93 ± 0.95%). This work opens up a frontier for depth profiling of the ultrathin PA layer and provides theoretical guidance for the preparation of high-performance and anti-fouling TFC-FO membrane.

The development of cost-effective preparation routes for high-quality graphene is important for its large scale application. Here, we propose an one-step scalable preparation method of few-layer graphene (FLG) by the exfoliation of flake graphite in a novel binary-component system comprised of peroxyacetic acid and sulfuric acid. This provides a ∼100% yield of FLGs from the starting graphite in 4 h at room temperature. The as-prepared FLG sheets behave a few-layer feature (average layer number

Bromate is a highly carcinogenic disinfection by-product in drinking water. Catalytic reduction is an emerging technology that can effectively remove bromate from water without forming additional brines and sludges. In this study, Pd and Pt nanoparticles supported on SBA-15 were prepared for catalytic bromate reduction. The activity investigation results showed that the Pt/SBA-15 catalysts exhibited higher activities than the Pd/SBA-15 catalysts and the commercial 5% Pd/C catalyst, and the highest catalytic activity of 24.72 mg·min−1·gcat−1 was obtained using 4% Pt/SBA-15 as the catalyst. This activity is approximately 2.33- and 6.50-fold higher than the activities of the 4% Pd/SBA-15 and 5% Pd/C catalysts, respectively. Analysis of the intrinsic mechanism revealed that the activation energy of bromate reduction over the 4% Pt/SBA-15 catalyst was 47.31 kJ·mol−1, and the reaction followed the Langmuir-Hinshelwood mechanism, suggesting that the reduction of adsorbed bromate on the Pt surface rather than the diffusion process controlled the overall reaction rate. Catalytic bromate reduction was strongly dependent on the reaction pH, and the catalytic activity increased with decreasing pH. Bromate reduction was suppressed in the presence of coexisting anions, including PO43−, SO42−, and Cl−, and the inhibition effects followed the order of PO43− > SO42− > Cl−. Surprisingly, bromate removal was obviously enhanced when a low concentration (

This study aimed to evaluate the properties, nutrients removal and microbial community dynamics of algal–bacterial granules in a lab-scale photobioreactor treating synthetic domestic wastewater. Two identical bioreactors were operated under non-phototrophic (Rc, the control) and phototrophic (Rp) conditions (12 h/12 h dark–light cycles). The results showed that aggregation of algal and bacterial biomass occurred rapidly in Rp, possibly as a granule nucleus, which favored aerobic granulation. Mature algal–bacterial granules had a compact structure and large size as well as exhibited excellent settling properties. In addition, increased biomass production was facilitated in Rp compared to Rc. Notably, increased production of extracellular polymeric substances (EPS) was induced in Rp, especially aromatic and tryptophan-like substances, implying that proteins significantly contributed to the formation and stability of the algal–bacterial granules. Further investigations revealed that algal–bacterial granules provided resistance to temperature fluctuations and enhanced the removal efficiencies of organics and nutrients (nitrogen and phosphorus), probably attributable to the enrichment of the Betaproteobacteria, Gammaproteobacteria and Flavobacterium bacterial classes, and Chlorophyta, Trebouxiophyceae and Bacillariophyceae algae classes, whereas Cyanobacteria only occupied a small proportion. These findings demonstrated that the algal–bacterial consortium was conducive to accelerating aerobic granulation, enhancing system stability and improving nutrient removal efficiency.

Eco-friendly exfoliation of two-dimensional nanosheets from their layered bulks is very attracting but still remains a big challenge. Here, we report a novel preparation route of two-dimensional nanosheets through soaking the bulk layered material in the C2H4O3-based chemical exfoliation system followed by microwave irradiation. This route has demonstrated the effective exfoliation of two-dimensional nanosheets (graphene nanosheets, BNNS and MoS2NS) from their layered bulks in a green and eco-friendly way. The average layer-number of the obtained graphene nanosheets, BNNS and MoS2NS is 4, 6 and 5, respectively, behaving a few-layer feature. Interestingly, when the graphene paper is prepared from the exfoliated graphene nanosheets by simple vacuum filtration and mechanical pressing, its average electrical conductivity is up to 7.36 × 105 S/m and the EMI SE value reaches to 61 dB, both among the highest for the graphene papers reported previously. Since there exists no serious fragmentation of layered materials during the whole exfoliation, the present exfoliation strategy is more competent in preparing the large-sized two-dimensional nanosheets over those conventional green routes.

The Pd–Cu/γAl 2 O 3 catalysts were prepared by impregnation method and introduced into the cathode chamber of a divided electrochemical denitrification cell with two graphite plates as the cathode and anode, to enhance the nitrate removal efficiency and N 2 selectivity. The Pd–Cu/γAl 2 O 3 catalysts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), specific surface area measurements (BET) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). In the rationally designed electrochemical-catalytic (ECC) system, the as-prepared catalyst could significantly enhance the nitrate degradation rate to 1.08 mg/L at current density of 10 mA/cm 2 , which was approx. 2.5 times compared with the electrochemical (EC) system without catalysts adding in. Additionally, a higher nitrogen selectivity of 80.37% was obtained under the same experiment condition. The improved performances were likely due to the presence of a catalytic reduction reaction of nitrate with the appropriate amount of hydrogen generated by electrolysis as reductant. Significantly, the current efficiency was calculated and enhanced value of 20–40% (depended on current density) was obtained in the ECC process with a catalyst content of 1.0 g/L.

Scalable preparation of graphene with both large size and high quality is an important prerequisite for fully realizing its commercial use. Herein, we propose a high-efficient route for preparing few-layer graphene, in which the chemical exfoliation of graphite to ~100% few-layer graphene can be realized within only about 15 min by using a novel two-step microwave irradiation strategy. The as-obtained graphene sheets behave a few-layer feature (average layer number ≤5 layers) and possess large size (the average area size is up to 256.8 μm2). The graphene film prepared from the obtained graphene sheets exhibits an excellent electrical conductivity of up to 2.03 × 105 S m−1, among the highest ones reported so far for the graphene, suggesting the high quality of the prepared graphene. Most importantly, no water-washing and effluent-treatment are needed during the whole preparation process, which will greatly reduces the consumption of water resource and alleviates the environmentally detrimental impact caused by the effluent of used chemicals compared with those conventional chemical exfoliation routes. Benefiting from its simplicity, high-efficiency and high-quality, the present method will show great promise for the mass production of high-quality graphene sheets.