Adsorption characterization for multi-component organic matters by titanium oxide (TiO<inf>2</inf>) in wastewater

In this study, an experimental and analytical study on adsorption and adsorption kinetics of organic matters in titanium oxide (TiO2, Degussa P25) with synthetic wastewater was investigated. In order to understand the removal of different organic sizes in detail molecular weight (MW) distribution of organics matters was examined in terms of number and weight-average MW. The large MW (33950 dalton) of synthetic organic matters (SOMs) was significantly removed by TiO2 adsorption and the slight decrease of the small MW (970 dalton) occurred with time. A characterization method was applied to evaluate the composition of SOMs in terms of adsorbability by adsorption of TiO2. Several adsorption equilibrium and batch kinetics experiments were conducted with different initial concentrations of SOMs and different amounts of adsorbent. A binomial distribution(s) of SOM fraction with the Freundlich coefficient (k) was obtained. The synthetic wastewater was explained by a finite number of pseudospecies (N) identified with a Freundlich isotherm constant (k) value. These parameters were determined by the characterization procedure, together with ideal adsorbed solution theory (IAST) with the pseudospecies number method. Prediction of adsorption isotherm and kinetics derived from a binomial concentration distribution of the characterization procedure were in good agreement with experimental data conducted

Performance analysis of reverse osmosis, membrane distillation, and pressure-retarded osmosis hybrid processes

© 2015 Elsevier B.V. A performance analysis of a tri-combined process that consists of reverse osmosis (RO), membrane distillation (MD), and pressure-retarded osmosis (PRO) was conducted by using numerical approaches in order to evaluate its feasibility. In the hybrid process, the RO brine is partially used as the MD feed solution, and the concentrated MD brine is then mixed with the rest of the RO brine to be considered as the PRO draw solution. Here, the brine division ratio, incoming flow rate of RO, dimensions of the MD and PRO processes, and the supply cost of the MD heat source were considered as influential parameters. Previously validated process models were employed and the specific energy consumption (SEC) was calculated to examine the performance of the RO-MD-PRO hybrid process. The simulation results confirmed that the RO-MD-PRO hybrid process could outperform stand-alone RO in terms of reducing the SEC and the environmental footprint by dilution of the RO brine in locations where free or low-cost thermal energy can be exploited. Despite the need for further investigations and pilot-tests to determine its commercial practicability, this study provides insights into future directions for water and energy nexus processes for energy efficient desalination

Simultaneous Determination of Seven Constituents in Herbal Prescription Jaeumganghwa-Tang Using HPLC-PDA

A simple and accurate high-performance liquid chromatographic method was applied to the quantitative analysis of seven components of the traditional herbal prescription Jaeumganghwa-tang (JGT), including 5-hydroxymethyl-2-furaldehyde, albiflorin, paeoniflorin, liquiritin, ferulic acid, nodakenin, and glycyrrhizin. All seven compounds were separated in less than 40 min on a Gemini C18 column at 40&#176;C by gradient elution using 1.0% (v/v) aqueous acetic acid and acetonitrile containing 1.0% (v/v) acetic acid as mobile phase. The flow rate was 1.0 mL/min and the detector was a photodiode array (PDA) set at 230 nm, 254 nm, 280 nm, and 330 nm. The calibration curves showed good linearity (r2 &gt; 0.9998) in different concentration ranges. The recovery of each component was in the range of 91.47&#8211;102.62%, with relative standard deviations (RSDs, %) less than 4.5%. The RSDs (%) for intra- and interday precision were 0.06&#8211;2.85% and 0.06&#8211;2.83%, respectively. The concentrations of the seven components in JGT were in the range 0.74&#8211;5.48 mg/g

Recent advances in osmotic energy generation via pressure-retarded osmosis (PRO): A review

© 2015 by the authors. Global energy consumption has been highly dependent on fossil fuels which cause severe climate change and, therefore, the exploration of new technologies to produce effective renewable energy plays an important role in the world. Pressure-retarded osmosis (PRO) is one of the promising candidates to reduce the reliance on fossil fuels by harnessing energy from the salinity gradient between seawater and fresh water. In PRO, water is transported though a semi-permeable membrane from a low-concentrated feed solution to a high-concentrated draw solution. The increased volumetric water flow then runs a hydro-turbine to generate power. PRO technology has rapidly improved in recent years; however, the commercial-scale PRO plant is yet to be developed. In this context, recent developments on the PRO process are reviewed in terms of mathematical models, membrane modules, process designs, numerical works, and fouling and cleaning. In addition, the research requirements to accelerate PRO commercialization are discussed. It is expected that this article can help comprehensively understand the PRO process and thereby provide essential information to activate further research and development

Titania Nanomaterials Produced from Ti-Salt Flocculated Sludge in Water Treatment

Titania is the most widely used metal oxide for the applications of pigments, paper, solar cells and environmental purification. In order to meet the demand of a large amount of titania, our group has developed a novel process which could significantly lower the cost of waste disposal in water treatment, protect the environment and public health and yield economically valuable titania. Titanium tetrachloride (TiCl4) or titanium sulfate (Ti(SO4)2) as an alternative coagulant in water treatment has been explored for the removal of various pollutants from contaminated water or wastewater. Flocculation efficiencies of the Ti-salts were superior to those of Al- and Fe- salts with additional benefits in that a large amount of titania can be produced by calcinating the flocculated floc. The produced titania showed high photocatalytic activity for the removal of volatile organic compounds. The large amount of titania can be applied to pigments, environment and construction materials which require a lot of titania usages. This review paper presents an historical progress from fundamental to application in terms of the detailed production process, characterization, photoactivity of titania produced from Ti-salt flocculated sludge, and its various applications. © 2011 Springer Science+Business Media, LLC

Preparation of titanium dioxide (TiO<inf>2</inf>) from sludge produced by titanium tetrachloride (TiCl<inf>4</inf>) flocculation of wastewater

Sludge disposal is one of the most costly and environmentally problematic challenges of modern wastewater treatment worldwide. In this study, a new process was developed, which has a significant potential for lower cost of waste disposal, protection of the environment and public health, and yield of economically useful byproducts. Titanium oxide (TiO2), which is the most widely used metal oxide, was produced from the wastewater sludge generated by the flocculation of secondary wastewater with titanium tetrachloride (TiCl4). Detailed analyses were conducted to compare TiCl 4, ferric chloride (FeCl3), and aluminum sulfate (Al 2(SO4)3) flocculation. Removal of organic matter and different molecular sizes by Ti-salt flocculation was similar to that of the most widely used Fe- and Al-salt flocculation. The mean size of Ti-, Fe-, and Al-salt flocs was 47.5, 42.5, and 16.9 μm, respectively. The decantability of the settled flocs by TiCl4 coagulant was similar to that by FeCl3 coagulant and much higher than that of Al 2(SO4)3. The photocatalyst from wastewater (PFW) produced by TiCl4 flocculation was characterized by X-ray diffraction, BET surface area, scanning electron microscopy/energy dispersive X-ray, transmission electron microscopy, photocatalytic activity, and X-ray photoelectron spectroscopy. The resulting PFW was found to be superior to commercial TiO2 (P-25) in terms of photocatalytic activity and surface area. The PFW was also found to be mainly doped with C and P atoms. The atomic percentage of the PFW was TiO1.42C0.44P 0.14. © 2007 American Chemical Society

Constructing near-horizon geometries in supergravities with hidden symmetry

We consider the classification of near-horizon geometries in a general two-derivative theory of gravity coupled to abelian gauge fields and uncharged scalars in four and five dimensions, with one and two commuting rotational symmetries respectively. Assuming that the theory of gravity reduces to a 3d non-linear sigma model (as is typically the case for ungauged supergravities), we show that the functional form of any such near-horizon geometry may be determined. As an example we apply this to five dimensional minimal supergravity. We also construct an example of a five parameter near-horizon geometry solution to this theory with S^1 X S^2 horizon topology. We discuss its relation to the near-horizon geometries of the yet to be constructed extremal black rings with both electric and dipole charges.Comment: Latex, 30 pages. v2: discussion in section 5 modified and improved, other minor changes, references adde

Investigating water transport through the xylem network in vascular plants

A review on experimental methods used to investigate sap flow underlines the necessity to better characterize the relationships between the hydraulic regulation and the structural characteristics of the xylem network.Our understanding of physical and physiological mechanisms depends on the development of advanced technologies and tools to prove or re-evaluate established theories, and test new hypotheses. Water flow in land plants is a fascinating phenomenon, a vital component of the water cycle, and essential for life on Earth. The cohesion-tension theory (CTT), formulated more than a century ago and based on the physical properties of water, laid the foundation for our understanding of water transport in vascular plants. Numerous experimental tools have since been developed to evaluate various aspects of the CTT, such as the existence of negative hydrostatic pressure. This review focuses on the evolution of the experimental methods used to study water transport in plants, and summarizes the different ways to investigate the diversity of the xylem network structure and sap flow dynamics in various species. As water transport is documented at different scales, from the level of single conduits to entire plants, it is critical that new results be subjected to systematic cross-validation and that findings based on different organs be integrated at the whole-plant level. We also discuss the functional trade-offs between optimizing hydraulic efficiency and maintaining the safety of the entire transport system. Furthermore, we evaluate future directions in sap flow research and highlight the importance of integrating the combined effects of various levels of hydraulic regulation.X112418Ysciescopu