Photocatalytic Degradation Of Simulating Compounds Of Hydroxyl Acid As Lignin In Presence Of Titanium Dioxide

Papermaking black liquid is one of the main resource of papermaking wastewater, lignin has two characters such as uneasy degradated and low transparence. Semiconductor photocatalytic oxidation is a newly developed technique for wastewater treatment. It has been applied for oxidizing and degrading many organic contaminants, which usually are hardly degraded by other methods, into small molecules. TiO2photodegradation technology has some charactors such as high effective, complete, little selective advantages, some contaminations can be degraded completely as CO2, H2O, inorganic salt.In this dissertation, we employed a cylinder photocatalytic reactor, a ultraviolet lamp as light source, and TiO2as catalyst to investigate degradation of simulating organic wastewater with outer refrigerant circulation and aqueous suspension photoreactor.Above all, TiO2was prepared by the sol-gel technique in the lab. The effects of preparation micro scale TiO2on the catalytic activities have been explored. The catalysts were also characterized with SEM, XRD, and hot weight and so on. The results showed the best techinical condition was temperature (25℃), pH2-3, V (butyl titanate):V(ethanol):V(acid glacial):V(pure water)=10mL:60mL:4mL:8mLThe hydroxyl acid, which was used as lignin of simulating compounds that the main contaminant in paper wastewater, has been studied with photocatalytic oxidation method. It was discussed to the factors of photo-degradability ratio included the lamp-house, pH of solution, initial concentration of methyl catechol, dosage of catalyst TiO2, opened tolerance etc..The photo-catalytic degradation kinetic mechanism of hydroxyl acid was investigated using TiO2self-prepared as an activated catalyst. The results showed that the HL photo-catalytic degradation consisted two processes of adsorption and degradation. The adsorption equilibrium constant on TiO2surface Ka=1.597×10-2, max adsorption amount Qmax=20.161mg.g-1, and the kinetic equation were obtained by discussing L-H kinetic equation of HL, which was l/r=6.8823/C+0.1099.In cylindrical photocatalytic reactor, the researches were made on the characters of the hydroxyl acid degradation obtained from organic wastewater, in which the suspended TiO2was used as activated photocatalyst and a11w UV disinfection lamp (λ=253.3nm) as light source. The experimental results showed that the hydroxyl acid could reach adsorption and desorption equilibrium on the surface of TiO2after60min dark reaction, and max adsorption amount was7.1%; removal rate reached68%with20hours illusion, then after12hours HL could be completely degraded.