An experimental design methodology was applied for response surface modeling and optimization of diethyl phthalate (DEP) removal from synthetic wastewater by continuous-flow ozonation. The five independent variables considered were the initial concentration of DEP, initial solution pH, liquid flow rate, gas flow rate, and ozone concentration in the inlet gas. Using the Box–Behnken design, two quadratic models were developed as a functional relationship between respectively DEP removal efficiency and ozone mass transfer and the independent variables considered. It was found that all the factors considered have a significant effect on the removal efficiency response, except for the gas flow rate which did not influence DEP removal in the ranges considered. The results show that the ozonation efficiency can be predicted and are in very good agreement with the experimental data. Optimal conditions for two different sets of constraints were determined.

Tobacco (Nicotiana tabacum L.) stem ash (TSA) was evaluated as an adsorbent for removal of methylene blue (MB) from aqueous solution by batch adsorption method. MB adsorption increased with increase in contact time, initial solution pH, and adsorbent dose. Contact time for adsorption equilibrium was 180 min. The MB adsorption per unit mass of adsorbent (in milligram per gram) increased with the increasing initial dye concentration. Adsorption of MB onto TSA followed the pseudo-second-order kinetic model with a rate constant (k ₂) of 0.017 g mg⁻¹ min⁻¹. The mechanism of adsorption was described with intra-particle diffusion model. It was found that the intra-particle diffusion was not a sole rate-controlling step. Equilibrium adsorption was investigated by the Freundlich, Langmuir, Temkin, and Jovanoic isotherms. On the basis of coefficient of determination, the order of isotherm fit was Langmuir (R ² = 0.974) > Freundlich (R ² = 0.957) = Temkin (R ² = 0.957) > Jovanoic (R ² = 0.764) isotherm. The maximum monolayer adsorption capacity of TSA was 35.7 mg g⁻¹. The dimensionless separation factor (R L) was low (0.137), indicating favorable adsorption of MB onto TSA. The results clearly demonstrate the potential of TSA as a low-cost and an easily available adsorbent for sequestering MB from wastewater.

This study aimed to evaluate the efficacy of using the byproduct of Moringa oleifera Lam. seeds as an adsorbent for removal of cadmium (Cd) from contaminated water. The material characterization was performed by scanning electron microscopy, infrared spectroscopy, and point of zero charge. The effects of the adsorbent mass, solution pH, contact time, and temperature were evaluated. In the preliminary studies, the mass of adsorbent (200–1200 mg) and pH conditions (5.0, 6.0, and 7.0) were varied. The time studies were performed at 20–180 min and the temperature studies at the range of 25–65 °C. The optimal conditions of adsorption obtained were 400 mg of adsorbent mass, 7.0 pH, and 160 min contact time with the adsorbent. The isotherms of adsorption were linearized according to Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) models. The results showed better fit by the Freundlich and D-R models for Cd adsorption, describing a multilayer adsorption and, according to the value of the sorption energy (E), it has chemical nature. The maximum capacity of adsorption (Q ₘ) obtained was 7.864 mg g⁻¹. For a comparative study, the activated carbon (P.A.) was used applying the same optimal conditions used in the adsorption isotherms and desorption process for the biosorbent, obtaining a Q ₘ as 32.884 mg g⁻¹. The average desorption percentage showed that adsorbents have strong interaction with the metal. Based on these results, it was concluded that the biosorbent was effective in remediation of solutions containing Cd and thus the use of this alternative material is a viable option, since it has low cost and it is a byproduct which has not undergone previous treatment.

The remediation of tributyltin (TBT) by adsorption onto nFeO, activated carbon and nFeO/activated carbon composite material as a function of adsorbent dose, contact time, pH, stirring speed, initial TBT concentration and temperature was studied. The effect of temperature on kinetics and equilibrium of TBT sorption on the precursors and the composite was thoroughly examined. The adsorption kinetics is well fitted using a pseudo-second-order kinetic model, and the adsorption isotherm data of nFeO, activated carbon could be described by the Freundlich isotherm model whereas nFeO/activated carbon composite could be described by the Freundlich and Dubinin-Radushkevich isotherm models. Thermodynamic parameters (i.e. change in the free energy (∆ G°), the enthalpy (∆ H°) and the entropy (∆ S°)) were also evaluated. The overall adsorption process was endothermic and spontaneous in nature. The results obtained also showed that 99.9, 99.7 and 80.1 % TBT were removed from contaminated natural seawater by nFeO/activated carbon composite, activated carbon and nFeO, respectively.

Although aluminum (Al) is considered innocuous to living beings, exposure to high concentrations can elicit damage. Al has been found to cause liver pathologies in various animal models. Its mechanisms of toxicity are unclear; presumably, it interacts with protein sulfhydryl groups and promotes reactive oxygen species formation causing oxidative stress. Lipid peroxidation, protein carbonyl content, and activity of superoxide dismutase, catalase, and caspase-3 were determined in liver of Cyprinus carpio exposed to 0.05, 120, and 239.42 mg Al L⁻¹ for 12, 24, 48, 72, and 96 h. Al induced increased lipid peroxidation and protein carbonyl content as well as changes in enzymatic activity, indicating it elicits oxidative stress and apoptosis in common carp liver.

Trace element concentrations on a dry ash basis in saline-irrigated biomass feedstock from the San Joaquin Valley are investigated using multi-element spectroscopic techniques. The results show high concentrations of both Na and K compared to local baseline soil. The content of Na is higher than observed for nonsaline-irrigated biomass reflecting the salinity of the drainage water. The alkali earth elements as well as other alkali trace elements are, however, not markedly affected by the salinity of the irrigation water. The transition elements Cu and Zn are enriched only in the herbaceous feedstock compared to nonsaline biomass. Sulfur, chlorine, and phosphorus are markedly enriched in the saline feedstock. The ash content of toxic elements invariably exceeds the concentrations in the baseline soil for Cu, As, Se, Cd, Sb, and Pb. Compared to nonsaline biomass ashes, Cu is relatively enriched in the herbaceous feedstock ashes, As only in eucalyptus wood, and Cd, Sb, and Pb in woody feedstock. Selenium is relatively enriched in all saline feedstock. Only the concentrations of Cd in woody saline-irrigated feedstock may potentially exceed environmental guideline concentrations and may, thus, warrant caution for using saline biomass for soil amendment.

This research evaluated the effects of alkyl polyglucoside (APG), an environment-friendly surfactant, on the removal of anthracene (ANT), phenanthrene (PHE), and pyrene (PYR) from the soil cultivated with Scirpus triqueter, an aquatic native pioneer plant in the Yangtze estuarine wetland, China. Soils spiked with about 200 mg kg-1 of ANT, PHE, and PYR were individually irrigated with 0, 10, 20, 30, 40, 50, 100, and 150 mg L -1 of APG. Plant biomass yields, polycyclic aromatic hydrocarbons (PAHs) removal rates, soil microbial, and soil enzyme activities were quantified after 90 days' cultivation of Scirpus triqueter. Experiments demonstrated that APG has an ability to facilitate PAHs degradation at appropriate concentrations. The highest removal rate of the PAHs was observed in 40 mg L-1 APG treatment, and the removal rates increased 23, 54, and 52 %, respectively, compared to the non-amended control pots. However, the PAHs removal rate decreased to a certain extent when high concentrations of APG were added. The effect on PAHs removal in the soil could be explained by the changed levels of plant biomass, soil microbial populations, and soil enzymatic activity affected by the APG. The results suggested that the use of Scirpus triqueter combined with APG was an effective means for the phytoremediation of the PAH-contaminated soil. At the same time, APG's optimal concentration should be determined before the application in the PAH-contaminated wetlands. © 2013 Springer Science+Business Media Dordrecht.

Nanoscaled Bi₂O₃ particles coated on ZnO nanorods (ZNRs) have been fabricated by combining hydrothermal technique with a chemical precipitation method. X-ray diffraction, field emission-scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and UV–vis absorption and photoluminescence studies were adapted to characterize the structure, morphologies, and optical properties of the nanocomposites. The results indicated that small Bi₂O₃ nanoparticles were well distributed on the surfaces of ZNRs. And the Bi₂O₃–ZNR nanocomposites showed high charge separation efficiency and •OH generation ability as evidenced by photoluminescence spectra. Under irradiation of a 55-W compact fluorescent lamp, the Bi₂O₃–ZNR nanocomposites demonstrated photocatalytic activities higher than pure ZNRs in the degradation of two endocrine-disrupting chemicals, phenol and methylparaben, which might be attributed to the high separation efficiency of photogenerated electron–hole pairs based on the cooperative role of Bi₂O₃ loading on ZNRs. Moreover, the Bi₂O₃–ZNR nanocomposite could be easily recovered and reused due to their one-dimensional nanostructural property. All these characteristics brought enormous benefits of Bi₂O₃–ZNR nanocomposites to the practical application in indoor environmental remediation.

The presence of different kinds of leaf packs (native or alien) and environmental gradients can affect the composition and abundance of macroinvertebrate assemblages in freshwater ecosystems, but little is known about the interactive effects. Here, we investigated (1) how environmental gradients could influence leaf packs macroinvertebrates and (2) which was the chief factor (among water quality, mass loss of leaf packs, and flow regime) affecting macroinvertebrate assemblages in impaired streams. We analyzed leaf packs in six sites in impaired streams, characterized by wastewater discharges and dominated by pollution-tolerant macroinvertebrate species. Using principal component analysis, we defined two environmental gradients as follows: a water quality gradient, related to anthropogenic alteration, and a hydromorphological gradient, mostly related to the catchment features. Our results pointed out that, in the tested conditions, biological metrics, such as functional groups and taxa richness, were chiefly influenced by the water quality gradient, while different leaf types in packs influenced the total taxa richness, but did not cause significant variation in the distribution and abundance of macroinvertebrate functional groups. On the contrary, the mass loss differed for different leaf types and was related to the stream and catchment features (mainly flow). This work showed that, in impaired streams, macroinvertebrate assemblages colonizing leaf packs are more influenced by water quality than by leaf types. Thus, the improvement of water quality should be the priority in restoration programs and should be achieved before any effort to restore native riparian vegetation.

Boric acid-treated and sulfur ion-doped multi-modified TiO₂ films with high photocatalytic activities were prepared on soda–lime glass (Na₂O · CaO · 6SiO₂) substrates via the sol–gel method. The as-prepared specimens were characterized using high-resolution field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectra, UV–vis diffuse reflectance spectroscopy, and Brunauer–Emmett–Teller surface area. The photocatalytic activities of the films were evaluated by degradation of organic dyes in aqueous solutions. Compared with boric acid treatment and sulfur surface doping, the integration of both methods gave the best results. It is believed that high photocatalytic activity is correlated with the microstructure of the TiO₂ film.