119 research outputs found
Recommended from our members
Combined photooxidation/photoreduction using TiO{sub 2} photocatalysts to treat organic/inorganic metal-laden wastewaters
Titanium dioxide (TiO{sub 2}) colloids prepared from titanium chloride (TiCl{sub 4}) were used as photocatalysts in the experiments. Cysteine was selected as the model derivative for the surface modification of the TiO{sub 2} nanoparticles. Testing of TiO{sub 2} photocatalysts conducted in the absence of organic compounds demonstrated that adsorption of lead ions occurred in the system with either untreated (virgin) or treated (modified using cysteine) TiO{sub 2} photocatalysts. Adsorption rates of the metal ions in the systems that used treated TiO{sub 2} photocatalysts were about three times faster than those where untreated TiO{sub 2} photocatalysts were used. Lead ion concentrations in the irradiated solutions decreased as the UV irradiation time increased; greater metal removals were achieved at longer irradiation times. The rate of decreasing lead ion concentrations in the system that used treated TiO{sub 2} photocatalysts was about two to three times faster than that in the system using untreated TiO{sub 2} photocatalysts. Experiments were also performed in which organic compounds (naphthalene or phenol) and heavy metals (Pb{sup 2+}) were simultaneously treated with TiO{sub 2} photocatalysts. The presence of lead ions did not interfere with the photo-degradation of the selected organic compounds from solution. The presence of phenol compound appeared not to affect the photoreduction of lead ions, while addition of naphthalene compound resulted in a lag-time effect on the photoreduction of lead ions from solution. All of the experimental results showed that the cysteine-modified TiO{sub 2} resulted in faster and more effective removal than that for the untreated TiO{sub 2} system. This technique has resulted in the simultaneous photocatalytic removal/recovery of organic and inorganic compounds in the system
Strangeness nuclear physics: a critical review on selected topics
Selected topics in strangeness nuclear physics are critically reviewed. This
includes production, structure and weak decay of --Hypernuclei, the
nuclear interaction and the possible existence of bound
states in nuclei. Perspectives for future studies on these issues are also
outlined.Comment: 63 pages, 51 figures, accepted for publication on European Physical
Journal
Recommended from our members
Basic Research Needs for Countering Terrorism
To identify connections between technology needs for countering terrorism and underlying science issues and to recommend investment strategies to increase the impact of basic research on efforts to counter terroris
The triplet state in bacterial photosynthesis: Possible mechanisms of the primary photo-act
Recommended from our members
Use of cysteine-modified TiO{sub 2} photocatalyst for treatment of combined organic/inorganic wastewaters
The utilization of semiconductor-based photocatalysts, such as titanium dioxide (TiO{sub 2}), for carrying out photochemical reactions to treat water contaminated with organic and inorganic compounds has received considerable attention in recent years. The authors strategy for optimizing the process of photocatalytic reduction of heavy metals on TiO{sub 2} colloids involves modifying the colloid surface. Specific project objectives included: (1) identification and development of potential biomimetic photocatalysts for simultaneous heavy metal recovery and organic destruction; (2) identification of treatment conditions that minimize the residual metal concentration(s) contained in the effluent, even in the presence of complexants and interferences, and development of appropriate scale-up criteria; and (3) determination of system performance, including an economic analysis for comparison with conventional technologies (such as pump-and-treat using metal hydroxide precipitation of ion exchange). The experimental results indicate that simultaneous removal of organic compounds (such as naphthalene) and inorganic compounds (such as lead ions) in aqueous solution can be achieved using a TiO{sub 2} photocatalyst system with UV light. The removal rates of organic and inorganic compounds can be enhanced through surface modification of the TiO{sub 2} photocatalyst using an organic substance such as cysteine. The cysteine-modified TiO{sub 2} photocatalyst enhanced the oxidation rates of organics as well as the reduction rates of heavy metals in the irradiated solution, resulting in improved treatment efficiencies for combined organic/inorganic wastestreams
A New Metal-Binding Site in Photosynthetic Bacterial Reaction Centers That Modulates Q A
Transient W-Band EPR Study of Sequential Electron Transfer in Photosynthetic Bacterial Reaction Centers
- …