Jinglan Feng

Recent developments in heterogeneous photocatalytic water treatment using visible light-responsive photocatalysts: a review

Visible light-responsive photocatalytic technology holds great potential in water treatment to enhance purification efficiency, as well as to augment water supply through the safe usage of unconventional water sources. This review summarizes the recent progress in the design and fabrication of visible light-responsive photocatalysts via various synthetic strategies, including the modification of traditional photocatalysts by doping, dye sensitization, or by forming a heterostructure, coupled with π-conjugated architecture, as well as the great efforts made within the exploration of novel visible light-responsive photocatalysts. Background information on the fundamentals of heterogeneous photocatalysis, the pathways of visible light-responsive photocatalysis, and the unique features of visible light-responsive photocatalysts are presented. The photocatalytic properties of the resulting visible light-responsive photocatalysts are also covered in relation to the water treatment, i.e., regarding the photocatalytic degradation of organic compounds and inorganic pollutants, as well as photocatalytic disinfection. Finally, this review concludes with a summary and perspectives on the current challenges faced and new directions in this emerging area of research.

Distribution of Polycyclic aromatic hydrocarbons (PAHs) in Henan Reach of the Yellow River, Middle China

The distribution and source of 16 polycyclic aromatic hydrocarbons (PAHs) in Henan Reach of the Yellow River, Middle China, has been investigated. summation sigmaPAHs levels ranged from 144.3 to 2361 ng L(-1) in water, from 506.6 to 10,510 ng g(-1) in suspended particulate matters (SPMs) and from 16.4 to 1358 ng g(-1) in sediment, respectively. The compositional profile of PAHs revealed that 2-3-ring PAHs were predominated in water and 2-4-ring PAHs were abundant in SPMs. Whereas the PAHs in sediment were composed mainly of 3-5-ring PAHs. The spatial distribution of PAHs indicated that concentrations of PAHs in water and SPMs in dry season were much higher than those in flooding season. It may be attributed to a high flow rate in flooding season. The ratios of phenanthrene/anthracene (Phe/Ant) and fluoranthene/pyrene (Flua/Pyr) reflected a pattern of pyrogenic input. The potential ecosystem risk assessment indicated that the ecosystem risk of PAHs was relatively low in Henan Reach of the Yellow River.

Residues of organochlorine pesticides (OCPs) in upper reach of the Huaihe River, East China.

Residues of HCHs and DDTs in surface water and suspended particulate matter (SPM) from upper reach of the Huaihe River, East China, were investigated. Levels of total HCHs (∑HCH) and total DDTs (∑DDT) in water detected by GC-ECD ranged from 0.85 to 12.77 ng L⁻¹ and from 3.54 to 33.59 ng L⁻¹, respectively. According to European and America water quality guidelines, HCHs were within safe levels while DDT would pose adverse biological effects. Distribution of OCPs in water indicated that input of tributaries was important factor for the Huaihe River. For OCPs in SPM, concentrations varied from 1.01 to 25.22 ng g⁻¹ for ∑HCH and not detected to 4.74 ng g⁻¹ for ∑DDT. Compared with sediment quality guidelines, HCHs and DDTs might have an ecological risk. The main reason for OCPs residues in the Huaihe River was usage of lindane and technical DDT. Furthermore, composition of DDTs reflected fresh inputs of dicofol mixture in some sites.

Seasonal and Particle Size-Dependent Variations of Hexabromocyclododecanes in Settled Dust: Implications for Sampling

Particle size is a significant parameter which determines the environmental fate and the behavior of dust particles and, implicitly, the exposure risk of humans to particle-bound contaminants. Currently, the influence of dust particle size on the occurrence and seasonal variation of hexabromocyclododecanes (HBCDs) remains unclear. While HBCDs are now restricted by the Stockholm Convention, information regarding HBCD contamination in indoor dust in China is still limited. We analyzed composite dust samples from offices (n = 22), hotels (n = 3), kindergartens (n = 2), dormitories (n = 40), and main roads (n = 10). Each composite dust sample (one per type of microenvironment) was fractionated into 9 fractions (F1-F9: 2000-900, 900-500, 500-400, 400-300, 300-200, 200-100, 100-74, 74-50, and <50 μm). Total HBCD concentrations ranged from 5.3 (road dust, F4) to 2580 ng g(-1) (dormitory dust, F4) in the 45 size-segregated samples. The seasonality of HBCDs in indoor dust was investigated in 40 samples from two offices. A consistent seasonal trend of HBCD levels was evident with dust collected in the winter being more contaminated with HBCDs than dust from the summer. Particle size-selection strategy for dust analysis has been found to be influential on the HBCD concentrations, while overestimation or underestimation would occur with improper strategies.

Ultrasonic-assisted rational design of uniform rhombus-shaped ZnMoOx on graphene for advanced sunlight-driven photocatalysts, functional supercapacitor electrodes, and antibacterial platforms

To date, growing interest has been devoted to fabricating graphene–metal oxide hybrid composites for a plethora of applications including photocatalysis. However, controllable synthesis of such composite materials by virtue of facile and rational routes still remains challenging. Herein, we report, for the first time, the design of an in situ, ultrasonic-assisted growth strategy for the tailored production of well-dispersed, rhombus-shaped ZnMoOx/reduced graphene oxide (RGO) composites. The resultant composites exhibit a superior and recyclable natural-sunlight-driven photocatalytic activity toward the degradation of Rhodamine B, where the highest photocatalytic degradation efficiency can be achieved for the ZnMoOx/RGO composites with 3 wt% RGO dosage. In addition, the synthesized hybrids possess a high areal capacitance with a good cycling performance, as well as an interesting noticeable antibacterial activity, offering special insights into the usage of such composites for a wide range of applications.

Oxidation of ofloxacin by Oxone/Co 2+ : identification of reaction products and pathways

Oxidative degradation of ofloxacin (OFX) by sulfate free radicals (SO4−•) in the UV/Oxone/Co2+oxidation process was investigated for the first time, with a special focus upon identifying the transformation products as well as understanding the reaction pathways. Thirteen main compounds were identified after the initial transformation of OFX; the detailed structural information of which were characterized by high-performance liquid chromatography–high resolution mass spectrometry and MS fragmentation analysis. The degradation pathways mainly encompassed ring openings at both the piperazinyl substituent and the quinolone moiety, indicating that the usage of SO4−• aided the oxidative degradation of OFX to undergo more facile routes compared to those in previous reports by using OH•/h+ as the oxidant, where the initial transformation attacks were mainly confined to the piperazine moiety. Moreover, in this study, smart control over the pH conditions of the oxidation system via different modes of Oxone dosage resulted in the selective degradation of the functional sites of OFX molecule, where it was shown that the SO4−•-driven destruction of the quinolone moiety of OFX molecule favored the neutral pH conditions. This would be beneficial for the reduction of bacterial resistance against quinolones in the aqueous environment.

Ecological and health risks of DDTs and HCHs in surface water from the upper reaches of the Huaihe River

Based on the available toxicity data and the concentrations of DDTs and HCHs in surface water from the upper reaches of the Huaihe River, overlapping areas of probability density and margin of safety (MOS10) were used to estimate the risk levels of DDTs and HCHs to aquatic organisms. The overlapping areas of α-HCH, γ-HCH, p,p′-DDE, p,p′-DDD, and p,p′-DDT were found to be 9.3 × 10−5, 4.6 × 10−3, 4.3 × 10−2, 2.2 × 10−2, and 4.2 × 10−2, respectively. The risks from DDTs were higher than those from HCHs, the risk from α-HCH being the smallest. The MOS10 values of α-HCH, γ-HCH, p,p′-DDE, p,p′-DDD, and p,p′-DDT were 2.6 × 103, 97, 5.9, 15, and 8.6, respectively, i.e. greater than 1.0, indicating limited overlaps between the distributions of exposure concentrations and of toxicity data, and thus minimal ecological risk. Health risk calculations based on incremental lifetime risks for HCHs and DDTs were conducted to evaluate human cancer risk and non-carcinogenic hazard. The total cancer risks from organochlorine pesticides (OCPs) in the studied area were in the range of 10−8–10−7, lower than the baseline value of acceptable risk (10−6). Non-carcinogenic hazard indices of OCPs ranging from 10−6 to 10−5 were much lower than the threshold values (1.0). These results suggest that the water from the upper reaches of the Huaihe River does not pose any health risk for local residents using river water as a source for drinking water.

PAH contamination in road dust from a moderate city in North China: The significant role of traffic emission

ABSTRACT To investigate the contamination level, distribution, possible source, and human exposure risk of polycyclic aromatic hydrocarbons (PAHs) in the urban traffic environment, 15 PAHs were measured in 34 road dust samples (particle size < 25 μm) collected from three grades of roads and park paths in Xinxiang, China. ΣPAHs concentrations ranged from 311 to 21200 ng g−1, with a mean of 5890 ng g−1 and decreased in the following order: main roads (7650 ng g−1) > collector streets (7410 ng g−1) > bypasses (2970 ng g−1) > park paths (1570 ng g−1), indicating that significant positive correlation existed between PAH contamination and traffic density. PAHs in all samples were dominantly composed of 4-ring PAHs, accounting for 44.8% of the total. Pyrene, fluoranthene, and chrysene were the predominant individual components and accounted for 14.7% (1.2–19.2%), 12.9% (3.3–20.3%), and 11.0% (2.5–18.6%) of ΣPAHs, respectively. The specific isomer ratios indicated that traffic emission was the dominant source of PAHs in road dust. The incremental lifetime cancer risk values showed that cancer risk from exposure to road dust–borne PAHs was acceptable for local residents in Xinxiang.

Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Sediments from the Upper Reach of Huaihe River

Based on the available toxicity data and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in 16 surface sediments from upper reach of Huaihe River, overlapping areas of probability density curves and margin of safety (MOS10) were used to estimate the ecological risk of eight PAHs to aquatic organisms. The results indicated that the overlapping areas of Pyr, Nap, Fla, Ant, Phe, Ace, BaP, and Flu were 0.38, 0.29, 0.16, 0.11, 0.07, 0.03, 0.03, and 0.01, respectively. The risk of Pyr was the highest while that of Flu was the lowest. The overlapping area of ΣPAH8 was 0.72, higher than that of any individual PAHs due to their joint effect. The calculated MOS10 for Nap, Ace, Flu, Phe, Ant, Fla, Pyr, and BaP were 6.86, 5.42, 19.0, 2.72, 0.93, 0.75, 0.03, and 63.0, respectively. The probabilities of Nap, Ace, Flu, Phe, and BaP surpassing the 10th percentile value of the toxicity data were 0.07%, 0.30%, 0.05%, 1.97%, and 0.01%, respectively, suggesting minimal risk to aquatic organisms. However, the probabilities of Ant, Fla, and Pyr exceeding this value were 11.3%, 12.9%, and 64.8%, indicating potential risks. Among the individual PAHs, the ecological risk from Pyr was the highest, followed by Fla, Ant, Phe, Ace, Nap, Flu, and BaP. Additionally, the combined ecological risk of ΣPAH8 in the upper reach of Huaihe River was significantly higher than that of any individual PAH alone, which the probabilities of ∑PAH8 in excess of the 10th percentile of the toxicity data were 99.4%.

Source Apportionment and Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from Upper Reach of Huaihe River, China

Fifteen priority PAHs in 16 sediments from upper reach of Huaihe River collected in 2007 were measured. Source apportionment derived from PCA/MLR indicated that the highest contribution to ΣPAHs was from biomass burning (34.1%), followed by coal combustion (29.7%), vehicular emission (25.8%), and coke oven origin (10.4%). Risk assessment for each identified source was quantitatively calculated by combining the benzo[a]pyrene equivalent (BaPE) with estimated source contribution. The results showed that coal combustion posed the highest toxic risk, with BaPE value of 13.1 ng g−1 dw, and the BaPE values for biomass burning, vehicular emission and coke oven were 5.6 ng g−1 dw, 7.8 ng g−1 dw, and 4.1 ng g−1 dw, respectively. The distributions of contribution for total PAHs burden and BaPE of each identified source showed similar pattern among different sampling sites.