Electrolysis - Photocatalytic Degradation Of Organic Dyes And Collaborative Research

Degradation of basic violet by solo electrolysis and solo photocatalysis, and degradation of eosin and basic violet by electrolysis-photocatalysis were investigated.(l)Both anodic oxidation on PbO₂ anode and direct oxidation of H₂O₂ are responsible for degradation of basic violet. At pH 4.0 and current density of 10.0mA/cm²,the degradation ratio of basic violet was only 16.8% after 240.0min of treatment, indicating insufficient degradation of basic violet by sole electrolysis.(2)In photocatalysis system, pH value has some influence on degradation of basic violet. The removal efficiency was founded to be the best at pH 9.0. The presence of NO₃^- , Cl^- , SO₄^2- retards photocatalytic degradation with NO₃^- exhibiting the weakest inhibitive effect among the three anions. The inhibitive effect of the three anions on photocatalytic degradation of basic violet was greater in acidic solutions than that in neutral or alkaline solutions. The photocatalytic degradation was identified to occur on the surface of the photocatalysts.(3)The degradation rate of eosin in electrolysis-photocatalysis system was the fastest in acidic solution and the slowest in alkaline solution, while the fastest and the slowest rate for basic violet degradation was observed in alkaline solutions and neutral solutions, respectively. Increasing current from 5.0 mA/cm2 to 10.0mA/cm2 resulted in a pronounced increase in degradation of dyes, but a further increase in current had little influence on dyes removal. With the increase of initial concentration of dyes, the degradation ratio dropped but the concentration of degraded dyes increased. Both PO₄^3- and SO₄^2- impede photocatalytic degradation of dyes, but Cl^- improves the treatmentefficiency. The degradation and COD removal of the two dyes in electrolysis-photocatalysis system was founded to be much more efficient than the sum of those by sole electrolysis and photocatalysis alone, indicating a significant synergetic effect between electrolysis and photocatalysis. Decomposition and COD removal of the two dyes in electrolysis-photocatalysis system were well fitted by the first order kinetics. The first order rate constant was 0.08335 min"1 and 0.01651 min"1 for eosin degradation and COD removal, respectively, and 0.03109 min"1 and 0.01033 min"1 for basic violet degradation and COD removal, respectively.