Studies Of Photocatalytic Degradation Of Acetic Acid On TiO₂ Nanoparticles And Nanofilm

Titanium dioxide has wide foreground in photocatalytic degradation of organiccompounds for its strong oxidizing powder, nontoxicity and long-termphotostability. Acetic acid is the main contaminant in the furfural waste water,which counts to 1.0-2.5% . While acetic acid is one of byproducts in thedegradation of some organic compounds. The outflow of the furfural waste waterhardly reaches the discharge standard after depositing it only by the ordinarybiochemistry process presently. But, to the best of our knowledge, the studyregarding photocatalytic degradation of acetic acid is very limited. Hence, it issignificant to research the photocatalytic degradation of acetic acid with Titaniumdioxide photocatalytic method.In this study, TiO2 nanoparticles and TiO2 nanofilms were prepared by sol-gelmethod with cheap inorganic salt TiCl4 as a precursor. While the UV lamp (400W)was lamp-house and acetic acid was an object of research, the photocatalyticdegradation reaction was investigated under the airflow rate with 0.8 l/min andtemperature of 35±2℃.20mg/L of acetic acid was photodegradated with TiO2 nanoparticles asphotocatalyst. According to the results, TiO2 nanoparticles calcined at 460℃for 1hwith 9nm diameter exhibited the best photocatalytic activity, where TiO2 exhibitedcrystallization of anatase structure. The optimal photocatalytic effect was obtainedwhen the amount of TiO2 nanoparticles is 1g/L and the initial pH of reactionsolution was 4.2. At this condition, the disposal rates of acetic acid and TOC in thereaction solution respectively reached 100%, 96.19% within 200min, acetic acidwas completely mineralized in the reaction system. In the range of someconcentration (≦20mg/L), the photodegradation of acetic acid accorded with L-Hfirst-order kinetic pattern. From the effect of inorganic ions on the reaction, it wasconcluded that Fe(Ⅲ)and SO4 inhibited, Cl 和NO3 hardly impacted, Cu(Ⅱ)和Mn(Ⅱ)promoted at lower concentration.The furfural wastewater with COD 550mg./L, where amount of acetic acid was100mg/L, was photodegradated with TiO2 nanoparticles as photocatalyst. It can beseen from the results that the optimal photocatalytic effect on the wastewater wasacquired while the amount of TiO2 nanoparticles is 1g/L and the time of reactionsolution was 9h. At this condition, the disposal rates of acetic acid and COD in thereaction solution respectively reached 60.8%, 69.3%. Other organic compounds inthe wastewater were photodegradated by TiO2 nanoparticles expect acetic acid.Therefore the furfural wastewater could be disposed by potocatalytic oxidationmethod. Although TiO2 particles system in suspension has good photocatalytic functionon the organic contaminants in the aqueous solution, it can not apply to practice asdifficultly reclaimed, easily agglomerating. Immobilized TiO2 photocatalystincreasingly attracts researcher. In this study, ITO (indium-tin oxide) conductive glass plates were chosen as asupport of TiO2 films because its conductive property impeded charge-carrierrecombination. Meanwhile, it was easy to reuse for TiO2/ITO film. After TiO2 filmswere acquired by dip-coating method, Raman spectrascope, SEM and weightingmethod were used to determine TiO2 crystalline structure present and superficialappearance of TiO2/ITO films. we could see that TiO2/ITO film calcined at 500℃for 1h with 4-coating times exhibited crystallization of anatase structure., and theweight and thickness of the films were proportional to the number of dip-coatig, thethin film coated four times with 122nm thickness could strongly absorb ultraviolet. 25mg/L of acetic acid was photodegradated with TiO2 films as photocatalyst.According to the results, TiO2/ITO film calcined at 500℃for 1h with 4-coatingtimes exhibited the best photocatalytic activity. At this time, the disposal rates ofacetic acid and TOC in the reaction solution respectively reached 80.46%, 73.9%within 360min, acetic acid and its byproducts were synchronously degradated in thereaction system. When the initial concentration of acetic acid was smaller than40mg l-1, the photodegradation of acetic acid accorded with first-order kineticpattern. Through the effect of different support on the reaction, it can be found thatcontrasted with respective control experiment, photocatalytic activity of TiO2/ITOfilm about doubled TiO2/glass film's at same film area and close film weight.Furthermore, it was found that TiO2/ITO showed higher photocatalytic activity than...