Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: KEGG:D01931 (TiO2)
 11,320 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The additives and contaminants which occur in textile fibers vary widely, depending on the type of fiber and the pretreatment which it has received. Synthetic fibers such as nylon and polyester contain trace amounts of contaminants such as catalysts and catalyst deactivators which remain after the synthesis of the basic polymers. In addition, there are frequently a number of materials which are added to perform specific functions in almost all man-made fibers. Examples of these would include traces of metals or metal salts used as tracers for identification of specific lots of fiber, TiO2 or similar materials added as delustrants, and a host of organic species added for such special purposes as antistatic agents or flame retardants. There may also be considerable quantities of residual monomer or small oligomers dissolved in the polymer matrix. The situation becomes even more complex after the fibers are converted into fabric form. Numerous materials are applied at various stages of fabric preparation to act as lubricants, sizing agents, antistats, bleaches, and wetting agents to facilitate the processing, but these are normally removed before the fabric reaches the cutters of the ultimate consumers and therefore usually do not constitute potential hazards. However, there are many other chemical agents which are frequently added during the later stages of fabric preparation and which are not designed to be removed. Aside from dyes and printing pigments, the most common additive for apparel fabrics is a durable press treatment. This generally involves the use of materials capable of crosslinking cellulosics by reacting through such functions as N-methylolated amides or related compounds such as ureas and carbamates. These materials pose some potential hazards due to both the nitrogenous bases and the formaldehyde which they usually release. There is usually also some residual catalyst in fabrics which have received such treatments. Other types of chemical treatments which are often applied to fabrics to achieve special effects include flame retardants, soil release agents, antistatic agents, softeners, water and/or oil repellents, ultraviolet absorbers, bacteriostats, and fungistats.
 ...
PMID:Additives in fibers and fabrics. 124 30

Illumination of aqueous TiO2 suspentions yields hydroxyl radicals, which can be trapped by methanol producing formaldehyde (HCHO). In this work, the photonic efficiency and quantum yield of HCHO formation in colloidal TiO2 solutions and, P25 and UV 100 suspensions have been determined. Differences in photocatalytic activity of the three photocatalysts have been found and are discussed. The photonic efficiency of HCHO formation in the presence of P25 and UV 100 depends on the concentration of TiO2 and the pH. The critical concentration is 2.5 g/L. Below this, the photonic efficiency with P25 is higher than with UV 100, and vice versa. Optimum pH values for P25 and UV 100 giving the maximum photonic efficiency are 7.7 and 10.4, respectively. Compared to P25 and UV 100, the true quantum yield of HCHO formation in colloidal TiO2 solution varies a little with pH and virtually does not change with the amount of loading of TiO2. The true quantum yield varies as the inverse square root of light intensity. The quantum yield increases from 0.02 to 0.08 when the absorbed photon flux decreases from 8.1 x 10(-7) Ein/L s to 4.9 x 10(-8) Ein/L s. A simple model is presented to explain the experimental observation.
 ...
PMID:Determination of photonic efficiency and quantum yield of formaldehyde formation in the presence of various TiO2 photocatalysts. 1169 71

TiO2-mediated photocatalytic degradation process was employed to treat aqueous 2-, 3- and 4-NT (nitrotoluene) pollutants. The NT disappearance and TOC removal rates for three isomers showed no significant differences. Three hydroxylated aromatic intermediates resulting from the photocatalytic degradation of 4-NT were identified; this suggested two (initial) degradation pathways. Formation of acetic acid, formic acid, and formaldehyde was also noted. The mineralization products included NH4+, NO3- and CO2. N2 bubbling or the presence of a positive hole acceptor during 4-NT degradation resulted in a high 4-aminotoluene formation. This indicated an effective reduction of 4-NT's nitro group to amino moiety. Generally, Pt-loaded TiO2 (Pt-TiO2) had no influence on the disappearance rate of 4-NT. However, the use of Pt-TiO2 along with a higher light intensity source resulted in an accelerated TOC removal.
 ...
PMID:Photocatalytic degradation of nitrotoluene in aqueous TiO2 suspension. 1176 18

Titanium dioxide(TiO2) was used to catalyze the photolysis of benzene, xylene, n-heptane, methanol, acetone, ethylether, formaldehyde, trichloroethylene and perchloroethlene in air. The photolysis was carried out with a high pressure mercury lamp. The degradation rate of these VOCs was more than 80 percent in five minuts except formaldehyde. The effects of catalyst amount, different types of TiO2 catalyst and density of UV on the degradation rate of the VOCs were also studied.
 ...
PMID:[Photocatalytic oxidation of airborne VOCs on TiO2]. 1257 65

Toluene and formaldehyde are malodorous and cause indoor pollution. These materials have received much attention as hazardous and malodorous substances. It is well known that long-term exposure to even fairly low levels of toluene and formaldehyde brings about the risk of asthma and eczema. In this study, a composite TiO2-zeolite (ZE) sheet prepared using a papermaking technique was applied to remove toluene and formaldehyde under UV irradiation. The optimum composition of the TiO2 (Ti)-ZE sheet was studied in detail with regard to the effective removal of various indoor pollutants. Gaseous toluene and formaldehyde were removed by a composite TiO2-ZE sheet with different efficiencies depending upon the ratio of Ti/ZE in the composite sheet. The composite sheets could decompose formaldehyde and toluene repeatedly after being recharged. It was shown that the sheets are potentially applicable as highly functional materials to be placed on walls and ceilings of houses for the removal of various indoor pollutants.
 ...
PMID:Removal of indoor pollutants under UV irradiation by a composite TiO2-zeolite sheet prepared using a papermaking technique. 1265 32

4.0 X 10(-2) M solutions (pH 5.8) of ribose, arabinose and xylose were irradiated in UV light (1.84 X 10(9) erg cm-2 to 6.12 X 10(9) erg cm-2) in the presence of 5 mg/ml of Al2O3, SiO2, TiO2, V2O5, Cr2O3, Fe2O3, CuO, ZnO, schist and feldspar oxides. The resulting substance had an absorption spectrum with lambda max 245 nm and lambda min 288 nm. In the presence of all the oxides except that of V2O5 lambda max shifted to 265-268 nm. When irradiation was carried out in an alkaline medium (pH 10.0-11.0) containing no oxides the absorption band showed lambda max 265 nm as well. The photolysis was followed by the oxidative breakdown of pentoses resulting in the formation of H2CO, carbonyl substances, organic peroxides and acids. The quantum yield (phi) during photolysis without sensitizers for ribose, arabinose and xylose respectivelywas: phi (H2CO) - 2.32 X 10(-3), 1.99 X 10(-3), 1.69 X 10(-3) and phi (C=O) -1.58 X 10(-3), 1.46 X 10(-3), 1.43 X 10(-3). By the ability to sensitize formation of oxydation products of pentoses, the oxides are arranged as follows: Fe2O3 > or = V2O5 > or = TiO2 > or = SiO2 > Cr2O3 > CuO > pentose > or = ZnO. By their effect on phi (-m) of pentoses the oxides make up the sequence: Fe2O3 > or = TiO2 > or = V2O5 > or = SiO2 > feldspar > schist > Al2O3 > Cr2O3 > pentose > ZnO. By the increase of phi (-m) pentoses are arranged in a row: ribose (6.4 X 10(-3) > arabinose (2.5 X 10(-3)) > xylose (2.1 X 10(-3)). Photolysis in various gases has shown that oxidative destruction of pentoses increases according to: air > N2 > Ar. The results show that in the prebiological period on Earth, and possibly even at present on some other planets, various minerals could produce a photosensitizing effect on the breakdown of pentoses synthesized abiogenically from formaldehyde. Ribose proved to be the least resistant to photolysis. This fact is of interest in relation to studying the chemical evolution of carbohydrates and their interaction with purine and pyrimidine bases.
 ...
PMID:The effect of ultraviolet light (PRK-2) on pentoses in the presence of various minerals. 1266 22

The photocatalytic production of hydrogen using aqueous Pt/TiO2 suspension has been investigated in single component and mixture systems of electron donors (pollutants). The reaction systems consisted of oxalic acid, formic acid and formaldehyde, respectively. The adsorption of these donors on TiO2 was also monitored by in situ attenuated total reflection infrared spectroscopy (ATRIR). In the single component systems, the efficiency order of electron donors is as follows: H2C2O4 > HCOOH > HCHO. The order is consistent with the order of adsorption affinity of the electron donors on TiO2 determined by ATRIR, which suggests a link between the strength of surface interaction and the efficiency of photocatalytic hydrogen evolution. In the binary mixture systems, competitive inhibition kinetics is observed. When a donor adsorbed strongly on TiO2 in a state of saturated adsorption in a binary system, the overall rate of the hydrogen evolution is consistent with that of decomposition of the donor, and the system can be treated as a single component system.
 ...
PMID:Photocatalytic production of hydrogen in single component and mixture systems of electron donors and monitoring adsorption of donors by in situ infrared spectroscopy. 1275 85

The photocatalytic destruction of methanol, formaline (mixture of formaldehyde, methanol and water) and formaline wastes from the preservation of vertinarian physiologic samples has been attempted by two different processes, at high concentrations of reagents and by dossification of reagents, varying pH in both. Experiment evolution has been monitored by measuring the organic matter such as TOC and formaldehyde concentrations [H2CO]. Also, methanol and methanol-formaldehyde interactions with the TiO2 surface have been analysed by FTIR spectroscopy. Results indicate that at high concentrations the catalyst surfacial alterations given by methoxy, formates or carbonates, according to the pH of the sample can profoundly affect catalyst behaviour. It has been established that reagent dossification is advantageous for enhancing photonic efficiency as it minimizes the adsorbate presence that hampers the photocatalytic process.
 ...
PMID:Photocatalytic degradation of formaldehyde containing wastewater from veterinarian laboratories. 1504 Dec 94

The use of advanced oxidation processes (AOPs) to remove pollutants in various water treatment applications has been the subject of study for around 30 years. Most of the available processes (Fenton reagent, O3 under basic conditions, O3/H2O2, O3/UV, O3/solid catalyst, H2O2/M(n+), H2O2/UV, photo-assisted Fenton, H2O2/solid catalyst, H2O2/NaClO, TiO2/UV etc.) have been investigated in depth and a considerable body of knowledge has been built up about the reactivity of many pollutants. Various industrial applications have been developed, including ones for ground remediation (TCE, PCE), the removal of pesticides from drinking water, the removal of formaldehyde and phenol from industrial waste water and a reduction in COD from industrial waste water. The development of such AOP applications has been stimulated by increasingly stringent regulations, the pollution of water resources through agricultural and industrial activities and the requirement that industry meet effluent discharge standards. Nevertheless, it is difficult to obtain an accurate picture of the use of AOPs and its exact position in the range of water treatment processes has not been determined to date. The purpose of this overview is to discuss those processes and provide an indication of future trends.
 ...
PMID:Applications of advanced oxidation processes: present and future. 1507 76

This paper presents the results of the treatment of phenolic compounds containing wastewater generated from phenol-formaldehyde resin manufacturing, oil refinery and bulk drug manufacturing industries by electrochemical method. Experiments were conducted at a fixed current density of 5.4 A/dm2 using Ti/TiO2-RuO2-IrO2 electrode and an undivided reactor. During the various stages of electrolysis, parameters such as COD and TOC concentrations were determined in order to know the feasibility of electrochemical treatment. Adsorbable organic halogens (AOX) were detected at high concentrations during the electrolytic treatment of the effluents. However, it was observed that increasing the electrolysis time bring down the AOX concentration to lower levels. Energy consumption and current efficiency during the electrolysis were calculated and presented. The present study proves the effectiveness of electrochemical treatment for highly concentrated bio-refractory organic pollutants present in the industrial wastewater.
 ...
PMID:Electrochemical treatment of industrial wastewater. 1536 21


1 2 3 4 5 6 7 8 Next >>