Photodegradation of Metamifop using Titanium Dioxide- Alumina- Graphene Nanocomposite

The rising demand on staple food, rice, demands the need to protect the crops from weeds by means of using herbicides. Metamifop, a post emergent herbicide belongs to the phenolic hydrocarbon group. It is commonly used in the Asian countries especially in the production of paddy. The persistence of this herbicide in the irrigation water has led to the issue of water pollution. Hence, photodegradation, which is an Advanced Oxidation Process (AOP) is applied by using UV light to trigger production of effective hydroxyl radicals (-OH) to degrade the targeted pollutant. The presence of titanium dioxide-alumina-graphene (TiOz/AlzO3/G) may enhance this process. Therefore, the study on the effect of TiO2/AlzO3/G towards the photodegradation of metamifop was conducted. To study this effect, two conditions which are in the absence and presence of TiOz/A1203/G (10 mg and 20 mg) towards photodegradation of metamifop (5 ppm and 10 ppm) has been conducted. Degradation of5 ppm and 10 ppm metamifop over 3 hours irradiation are 58.65% and 34.04% respectively and act as control variable. lt was identified that, the degradation of 5 ppm metamifop in the absence of UV irradiation over 3 hours increases from 58.65% to 73.88% in the presence of l0 mg TiO;/A1203/G, and further increment to 81.46% when 20 mg TiO;/A120;/G is utilized. Beneficial effect has been obtained when the degradation is repeated under UV irradiation where percentage degradation occurs up to 84.46% and 90.31% in the presence of 10 mg and 20 mg TiO;/Al;O3/G respectively. Next, the addition of2 L/min oxygen also showed an increment of photodegradation percentage to 95.38% and 97.83% respectively. Similar results were obtained for 10 ppm metamifop where the percentage of degradation increases as the amount of TiO; /AlzO3/G use increases. Hence, through this study the presence of TiO;/A1203/G has been proven to enhance the photodegradation of metamifop.