References
Figure captions
Figure 1. (a) XRD diffractogram of synthesized goethite. (b) SEM micrograph and EDS spectrum of synthesized goethite.
Figure 2. Goethite XPS characterization. (a) XPS survey spectrum, (b) Fe 2p3/2 high-resolution spectrum.
Figure 3. a) Goethite Mossbauer spectrum, b) Diffuse reflectance spectrum of synthesized goethite.
Figure 4. N2 adsorption-desorption profile of goethite. Insert indicates the pore volume and diameter distribution.
Figure 5. Photocatalytic degradation of 2,4-D (30 mg L-1) under simulated sunlight irradiation (300 W m-2) and dark conditions in Milli-Q water containing goethite (G) (0.3 mg L-1(0.2 mg L-1of total iron)), fluoride (1.2 mg L-1), bicarbonate (86.3 mg L-1) and H2O2(10 mg L-1) at initial pH 6.9. The final pH in all experiments was 7.5. The temperature was not higher than 38 °C. SL: Solar light.
Figure 6. XPS Fe 2p3/2 high-resolution spectrum of goethite in contact with fluoride (1.2 mg L-1) after the photocatalytic experiment.
Figure 7. Mechanisms of goethite fluorination. (a) Formation of free hydroxyl radicals and presence of two kinds of fluoride species adsorbed on the surface. (b) Upward band bending caused by the adsorption of fluorine anions on goethite surfaces.
Figure 8. Factorial experimental design of 2,4-D degradation by goethite (0.3 mg L-1(0.2 mg L-1 of total iron)) and H2O2 (10 mg L-1) at initial pH 6.9 after 90 min of simulated sunlight irradiation (300 W m-2) in the presence of low and high amounts of fluoride and bicarbonate often found in natural well waters. (a) Response surface, (b) Pareto chart, and (c) Factor interactions chart. The final pH in all experiments was 7.5. The temperature was not higher than 38 °C.
Table captions
Table 1. Matrix of factorial experimental design.
Tables
Table 1