Dong, F.; Wang, Z. Y.; Sun, Y. J.; Ho, W. K.; Zhang, H. D. “Engineering the nanoarchitecture and texture of polymeric carbon nitride semiconductor for enhanced visible light photocatalytic activity”,J. Colloid. Interf. Sci. 2013, 401, 70-79.  Link: http://dx.doi.org/10.1016/j.jcis.2013.03.034 Abstract: In order to develop g-C3N4 for better visible light photocatalysis, g-C3N4 nanoarchitectures was synthesized by direct pyrolysis of cheap urea at 550 °C and engineered through the variation of pyrolysis time. By prolonging the pyrolysis time, the crystallinity of the resulted sample was enhanced, the thickness and size of the layers were reduced, the surface area and pore volume were significantly enlarged, and the band structure was modified. Especially for urea treated for 4 h, the obtained g-C3N4 nanosheets possessed high surface area (288 m2/g) due to the reduced layer thickness and the improved porous structure. A layer exfoliation and splitting mechanism was proposed to explain the gradual reduction of layer thickness and size of g-C3N4 nanoarchitectures with increased pyrolysis time. The as-synthesized g-C3N4 samples were applied for photocatalytic removal of gaseous NO and aqueous RhB under visible light irradiation. It was found that the activity of g-C3N4 was gradually improved as the pyrolysis time was prolonged from 0 min to 240 min. The enhanced crystallinity, reduced layer thickness, high surface area, large pore volume, enlarged band gap, and reduced number of defects were responsible for the activity enhancement of g-C3N4 sample treated for a longer time. As the precursor urea is very cheap and the synthesis method is facile template-free, the as-synthesized g-C3N4 nanoscale sheets could provide an efficient visible light driven photocatalyst for large-scale applications

Dong, F.; Liu H. T.; Ho W. K.; Zhang, H. D.; Fu M.; Wu, Z. B., “(NH4)2CO3 mediated hydrothermal synthesis of N-doped (BiO)2CO3 hollow nanoplates microspheres as high-performance and durable visible light photocatalyst for air cleaning”, Chem. Eng. J , 2013, 214,  198–207. Link: http://dx.doi.org/10.1016/j.cej.2012.10.039 Abstract: This research represents an efficient visible light photocatalytic removal of 450 ppb level of NO in air by employing newly synthesized monodisperse N-doped (BiO)2CO3 hierarchical hollow microspheres (N-BOC). The N-BOC sample was synthesized by template-free hydrothermal treatment of aqueous solution of bismuth citrate and ammonium carbonate mixture. The resulting material was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy, Scanning electron microscopy, Transmission electron microscopy, N2 adsorption–desorption isotherms, and Fourier transform-infrared spectroscopy. The results indicated that the N-BOC sample was hierarchically self-assembled by single-crystalline nanoplates. The regular arrangement of 2D nanoplates at progressively increasing angles to the radial axis resulted in the formation of 3D porous hierarchical hollow architecture, which was favorable for efficient reactants transport and photo-energy utilization. It was found that ammonium carbonate played dual roles in the formation of N-doped (BiO)2CO3 hierarchical hollow microspheres, one as structure directing factor and the other as nitrogen doping source. The doped nitrogen substituted for oxygen in the lattice of (BiO)2CO3, leading to the formation of special two-band-gaps structure (3.25 and 2.0 eV) for N-BOC sample. The band gap of 3.25 eV is intrinsic for (BiO)2CO3 and the small band gap of 2.0 eV can be ascribed to the doped nitrogen forming mid-gap. The N-BOC sample not only exhibited efficient visible light photocatalytic activity but also high stability during long term photocatalytic reaction without deactivation toward purification of NO in air. The characterization of the used N-BOC sample after long term irradiation implied that the nitrogen doping and special hierarchical structure co-contributed to the durable photocatalytic activity. This work demonstrates that the facile hydrothermal synthesis method for N-BOC sample combined with the associated efficient and durable visible light photocatalytic performance could provide an attractive and feasible technology for air cleaning.

Zhu, L. L.; Ai, Z. H.; Ho, W. K.; Zhang, L. Z. “Core-shell Fe-Fe2O3 nanostructures as effective persulfate activator for degradation of methyl orange”, Sep. Purif. Technol, 2013, 108, 159-165. Link: http://dx.doi.org/10.1016/j.seppur.2013.02.016 Abstract: In this study, core–shell Fe–Fe2O3 nanostructures (FNs) were used to effectively activate sodium persulfate (Na2S2O8) to induce sulfate radicals (SO4-) oxidation of methyl orange (MO) in aqueous solution (FNs/Na2S2O8). In this FNs/Na2S2O8 system, an enhanced degradation of MO was achieved in comparison with the Fe2+/Na2S2O8Fe2+/Na2S2O8 system using ferrous ions as persulfate activator under neutral pH condition. An acid pH and a high persulfate to FNs molar ratio (Na2S2O8:FNs) were favorable to the MO oxidation in the FNs/Na2S2O8 process. We characterized the prepared FNs and the used FNs during the FNs/Na2S2O8 process via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) systematically. On the basis of the degradation and characterization results, we proposed a mechanism for the degradation of MO in the FNs/Na2S2O8 process, which involved in situ homogenous and heterogeneous activation of persulfate simultaneously

CHEUNG, L. T. O. & FOK, L. (2013). Assessing the Role of Ecotourism Training in Changing Participants' Pro-Environmental Knowledge, Attitude and Behaviour. Asia Pacific Journal of Tourism Research, 1-17 . Abstract Ecotourism training is usually considered to be undertaken only by tourism practitioners for professional development. However, ecotourism training has a more important role to play, as it could be adopted as a long-term strategy for environmental conservation by altering people’s attitudes and behaviours towards greater environmental responsibility. In this study, the role of ecotourism training with respect to pro-environmental knowl- edge enhancement as well as attitude and behavioural changes is investigated. A question- naire survey was conducted on participants of an ecotourism training programme. Participants’ environmental knowledge, attitudes and behaviours were evaluated using a pre- and post-test method. The results indicated that participants demonstrated a signifi- cant increase in environmental knowledge after the training. Moreover, participants’ demographic characteristics such as age group, occupation and salary are significantly associated with the improvement in knowledge, change in pro-environmental attitudes and behaviours. Participants tend to adopt environmentally responsible attitudes and behaviours after completion of ecotourism training.

Fok, L., Peart, M. R. & Chen, J. (2013). The influence of geology and land use on the geochemical baselines of the East River basin, China CATENA, 101, 212-225. Abstract A geochemical baseline refers to the concentration of an element or any chemical property of a naturally occurring substance in the earth's near-surface materials, originating from both natural and non-natural sources. In this study, the Tukey boxplot approach was adopted to develop geochemical baselines for 42 analytes in the East River basin, South China. Data subset analyses, change ratios and factor analyses were used to explore the anthropogenic effects and the influence of land use and geology on the spatial distribution of the geochemical baselines. The sample medium was active, fine-grained (< 63 μm) fluvial bed sediment collected during 2007–2009 at an average spatial density of one sample per 200 km2 (n = 137). Although considerable variation in elemental concentration was exhibited by the dataset, the geochemistry of the study basin was generally consistent with the upper crustal abundance for China and with world average fluvial suspended matter concentrations. Median concentrations of the heavy metals lay within the limits of sediment quality guidelines and the bed sediment of this macro-scale basin was relatively unpolluted. The results revealed that whilst base cations were depleted, background levels of As, Pb, W and some rare earth elements were elevated relative to the crustal values. Subset analysis and factor analysis indicated that As, Pb and W were associated with anthropogenic activities, whereas rare earth elements were affiliated with the igneous geology in the study basin.

Xing W., Lu W.J., Zhao Y., Zhang X., Deng W.J., Christensen T.H., 2013.  Environmental impact assessment of leachate recirculation in landfill of municipal solid waste by comparing with evaporation and discharge (EASEWASTE). Waste Management 33(2): 382-389.(SCI Impact Factor: 2.801) Abstract In some arid regions where landfill produces minimal amount of leachate, leachate recirculation is suggested as a cost-effective option. However, its long-term impacts to environment remain disputed. For the purpose of revealing the environmental impacts of leachate recirculation in landfill, four scenarios were modeled using EASEWASTE, comparing the strategies of leachate recirculation (with or without gas management), evaporation and discharge. In the current situation (Scenario A), a total of 280 t of waste was generated and then transported to a conventional landfill for disposal. A number of contaminants derived from waste can be stored in the landfill for long periods, with 11.69 person equivalent (PE) for stored ecotoxicity in water and 29.62 PE for stored ecotoxicity in soil, considered as potential risks of releasing to the environment someday. Meanwhile, impacts to ecotoxicity and human toxicity in surface water, and those to groundwater, present relatively low levels. In Scenario B, leachate evaporation in a collecting pool has minimal impacts on surface water. However, this strategy significantly impacts groundwater (1055.16 PE) because of the potential infiltration of leachate, with major contaminants of As, ammonia, and Cd. A number of ions, such as Cl-, Mg2+, and Ca2+, may also contaminate groundwater. In Scenario C, the direct discharge of leachate to surface water may result in acidification (2.71 PE) and nutrient enrichment (2.88 PE), primarily attributed to soluble ammonia in leachate and the depositional ammonia from biogas. Moreover, the direct discharge of leachate may also result in ecotoxicity and human toxicity via water contaminated by heavy metals in leachate, with 3.96 PE and 11.64 PE respectively. The results also show that landfill gas is the main contributor to global warming and photochemical ozone formation due to methane emission. In Scenario D, landfill gas flaring was thus be modeled and proven to be efficient for reducing impacts by approximately 90% in most categories, like global warming, photochemical ozone formation, acidification, nutrient enrichment, ecotoxicity, and human toxicity. Therefore, leachate recirculation is considered a cost-effective and environmentally viable solution for the current situation, and landfill gas treatment is urgently required. These results can provide important evidence for leachate and gas management of landfill in arid regions.

Wang, W.J.; Ho, W.K.*; Ng, T.W., Huang, J.H.; Liang, S.J; An; T.C; Li, G.Y., Yu, J.C.; Wong, P.K. *, “CdIn2S4 Microsphere as an Efficient Visible-Light-DrivenPhotocatalyst for Bacterial Inactivation: Synthesis, Characterizations and Photocatalytic Inactivation Mechanisms”, Applied Catalysis B: Environmental. 2013, 129, 482-490.http://www.sciencedirect.com/science/article/pii/S0926337312004559 Abstract New types of visible-light-driven photocatalysts with high activity for bacterial inactivation are needed to address the problems caused by outbreak of harmful microorganisms. In this study, cadmium indium sulfide (CdIn2S4) microsphere, which can be synthesized continuously by a facile ultrasonic spray pyrolysis method, was used as an efficient photocatalyst in inactivation ofEscherichia coli K-12 under visible light (VL) irradiation for the first time. The as-prepared CdIn2S4 showed a micro-spherical morphology with diameter of 0.5–1.0 μm. It had an energy band gap of 2.02 eV and BET surface area of 34.8 m2/g. It was found that bacterial cells could also be effectively inactivated inside a partition system without the direct contact with the photocatalyst, which was attributed to the diffusible photon-generated hydrogen peroxide (H2O2) rather than hydroxyl radicals (OH). Large amounts of H2O2 were produced from both conduction and valance bands with the involvement of superoxide (O2−). The used CdIn2S4 could be easily recycled by the partition system without loss of activity. The destruction process of bacterial cells was from the cell wall to the intracellular components as confirmed by TEM study. In addition, the O2− and OH radicals were also detected in the CdIn2S4-VL system by ESR spin-trap with DMPO trapping technology.