*3.2. Catalyst Preparation*

By incorporating 10% iron nitrate (3.2 g Fe (NO3)3.9H2O) and 4 g of "*Lantana Camara*" activated carbon, the Fe-C sample was prepared. The sample was then calcined for three h at 350 ◦C in a box resistance furnace [48]. The prepared Fe-C catalyst was mixed with 3 wt% potassium carbonate (0.2675 g K2CO3) by adding 10 mL of deionized water dropwise and letting it sit at room temperature for a day to allow the potassium particles to properly soak into the Fe-C catalyst. In a box resistance furnace, the sample was calcined for three h at 400 ◦C [31]. The sample was maintained in an airtight sample bottle after cooling to room temperature. The procedures for making carbon-supported iron catalysts with and without potassium promoters are shown in Figure 9.

#### *3.3. Catalyst Characterization*

Various techniques were used to characterize the Fe-C and Fe-C-K catalysts. The surface area was examined using the Brunauer–Emmett–Teller method (SBET) (Micromeritics Gemini VII 2390t VI.03, Norcross, GA, USA). Energy dispersive X-ray analysis and a scanning electron microscope were used to assess changes in surface morphology (JEOL JSM 6490 LA, Akishima, Japan). The crystal structure was determined using the X-ray diffraction method (XRD-D8 advanced by Bruker, Bermen, Germany). The thermal deterioration was revealed by the TGA investigation (Model: DTG-60 H, TGA 5500 TA Instrument, New Castle, DE, USA).

**Figure 9.** Synthesis of activated carbon-based catalyst by wet impregnation process.
