A novel immobilized visible light-active photocatalyst (TiO₂/polyvinyl alcohol after thermal treatment (T-PVA)/cordierite honeycomb (CHC)) was successfully prepared by a simple and convenient method combining sol–gel and thermal treatment using tetrabutyl titanate (TBOT) as the titanium source, polyvinyl alcohol (PVA) as the precursor of conjugated polymer, and CHC as the support. The synthesized photocatalyst was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, and field emission scanning electron microscopy. The results showed that PVA was dehydrated to produce conjugated unsaturated T-PVA. The T-PVA not only extended the response spectrum of TiO₂ to visible light region, but also strengthened the adhesion of TiO₂ to CHC. The TiO₂/T-PVA/CHC showed both outstanding adsorption properties and excellent photocatalytic performance under visible light on the decolorization of Rhodamine B. Over eight cycles, the photocatalyst continued to maintain perfect photocatalytic activity, showing good stability.

In the present paper, undoped and Ni-doped TiO2 sol-gel nanopowders have been prepared in order to establish the effect of Ni dopant on both material structure and photocatalytic properties. Two dopant concentrations of the transition metal (0.5 and 2 wt%) have been tested. The influence of both Ni dopant concentration and temperature of thermal treatment on the prepared powders has been followed using X-ray diffraction (XRD) method. A proper program has been used in order to establish the complete XRD structural characterization (lattice parameters, crystrallite sizes, internal strains). X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) coupled with surface area electron diffraction (SAED) techniques have completed the structural and morphological characterization of the prepared materials. Magnetic measurements and photocatalytic activity determinations have also been performed. The correlation between the results of the mentioned methods has been accomplished, and the detailed interpretation of the relation between structure and photocatalytic activity measurements has been done. The concentration of 0.5 wt% of Ni dopant ensures a better photocatalytic activity, compared to that of 2 wt%. © 2013 Springer Science+Business Media Dordrecht.

Quality of the essential commodity, water, is being compromised by contaminants originating from anthropogenic sources, industrial activities, agriculture, etc. Water scarcity and severe droughts in many regions of the world also represent a significant challenge to availability of this resource. Domestic rainwater harvesting, which involves collection and storage of water from rooftops and diverse surfaces, is successfully implemented worldwide as a sustainable water supplement. This review focuses on chemical and microbial qualities of domestic rainwater harvesting, with a particular focus on sources of chemical pollution and major pathogens associated with the water source. Incidences of disease linked to consumption and utilization of harvested rainwater are also discussed. In addition, various procedures and methods used for disinfection and treatment of harvested rainwater, such as implementation of filter systems (activated carbon, slow sand filtration, etc.), heat treatment, and chlorination, among others, are also presented.

Intensive remediation of abandoned former organochlorine pesticides (OCPs) manufacturing areas is necessary because the central and surrounding soils contaminated by OCPs are harmful to crop production and food safety. Organochlorine and its residues are persistent in environments and difficult to remove from contaminated soils due to their low solubility and higher sorption to the soils. We performed a comprehensive study on the remediation of OCPs-contaminated soils using thermal desorption technique and solvent washing approaches. The tested soil was thermally treated at 225, 325, 400, and 500 °C for 10, 20, 30, 45, 60, and 90 min, respectively. In addition, we tested soil washing with several organic solvents including n-alcohols and surfactants. The optimal ratio of soil/solvent was tested, and the recycling of used ethanol was investigated. Finally, activities of polyphenol oxidase (PPO), urease (URE), alkaline phosphatase, acid phosphatase (ACP), and invertase (INV) were assayed in the treated soils. The tested soil was thermally treated at 500 °C for 30 min, and the concentration of contaminants in soil was decreased from 3,115.77 to 0.33 mg kg⁻¹. The thermal desorption in soil was governed by the first-order kinetics model. For the chemical washing experiment, ethanol showed a higher efficiency than any other solvent. Using a 1:20 ratio of soil/solvent, the maximum removal of OCPs was achieved within 15 min. Under this condition, approximately 87 % of OCPs was removed from the soils. More than 90 % of ethanol in the spent wash fluid could be recovered. Activities of some enzymes in soils were increased after ethanol treatment. But ALP, ACP, and INV activities were decreased and PPO and URE showed slightly higher activities following remediation by thermal treatment. Both heating temperature and time were the key factors for thermal desorption of OCPs. The n-alcohol solvent showed higher removal of OCPs from soils than surfactants. The highly efficient removal of OCPs from soil was achieved using ethanol. More than 90 % of ethanol could be recovered and be reused following distillation. This study provides a cost-effective and highly efficient way to remediate the OCPs-contaminated soils.

Samples of gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) were collected at three sampling stations (Xiaomai Island, Laohutan, and Zhangzi Island) in the north Yellow Sea, China during November 2008 and September 2009 to study their atmospheric transport potential and the gas/particle distributions. The composition of PAHs was dominated by gaseous compounds. The percentages of the particle-phase PAHs to the total concentrations were found to be higher during the heating period than the non-heating period. The ratios of naphthalene and acenaphthene to phenanthrene, chrysene and dibenzo(a,h)anthracene showed an increasing trend from Xiaomai Island to Zhangzi Island, which can be called as the local atmospheric distillation of PAHs. Gas/particle partitioning coefficients (K ₚ) and their relationship with the sub-cooled liquid vapor pressures (pºL) of PAHs were investigated. The regressions of logK ₚ versus logpºL gave significant correlations for all samples of the three sites with r ² values in the range 0.56–0.66 (p < 0.01). Both Junge–Pankow adsorption model and octanol–air partition coefficient absorption model tended to underestimate the sorption for most PAHs, but the absorption model appeared to be more suitable for predicting the particle fraction of PAHs than the Junge–Pankow model.