Influence of under pressure dissolved oxygen on trichloroethylene degradation by the H2O2/TiO2 process

Response surface methodology modeling to improve degradation of Chlorpyrifos in agriculture runoff using TiO2 solar photocatalytic in a raceway pond reactor

This paper deals with the use of a raceway pond reactor (RPR) as an alternative photoreactor for solar photocatalytic applications. Raceway pond reactors are common low-cost reactors which can treat large volumes of water. The experiments were carried out with TiO₂ in the agriculture effluent spiked with Chlorpyrifos (CPF) at circumneutral pH. The Response Surface Methodology (RSM) was used to find the optimum process parameters to maximize CPF oxidation from the mathematical model equations developed in this study using R software. By ANOVA, p-value of lack of fit > 0.05 indicated that, the equation was well-fitted. The theoretical efficiency of CPF removal, under the optimum oxidation conditions with UV solar energy of around 697 ± 5.33 lux, was 84.01%, which is in close agreement with the mean experimental value (80 ± 1.42%) confirming that the response model was suitable for the optimization. As far as the authors know, this is the first study of CPF removal using RPR in agriculture runoff at circumneutral pH.

Photocatalytic degradation of atrazine herbicide with Illuminated Fe+3-TiO2 Nanoparticles

BACKGROUND

Atrazine is a herbicide that is widely used to control broadleaf and grassy weeds for growing many crops especially in maize production. It is a frequently detected herbicide in many groundwater resources. This study aimed to assess the feasibility of using ultraviolet radiation UV and fortified nanoparticles of titanium dioxide (TiO₂) doped with trivalent iron to remove atrazine from aqueous phase and determin the removal efficiency under the optimal conditions.

RESULTS

The results of this study demonstrated that the maximum atrazine removal rate was at pH = 11 in the presence of Fe^{+ 3}-TiO₂ catalyst =25 mg/L and the initial concentration of atrazine equal to 10 mg/L. As the reaction time increased, the removal rate of herbicide increased as well. Atrazine removal rate was enhanced by the effect of UV radiation on catalyst activation in Fe⁺³-TiO₂/UV process. It was also revealed that pH has no significant effect on atrazine removal efficiency (p > 0.05).

CONCLUSION

Based on the data obtained in this study, atrazine removal efficiency was increased by increasing pH, initial atrazine concentration, catalyst, and contact time. The results also showed Fe⁺³-TiO₂/UV process was an appropriate method to reduce atrazine in contaminated water resources. In conclusion, Fe⁺³-TiO₂/UV process may enhance the rate of atrazine reduction in highly polluted water resources (more than 99%).