“…Some examples of heterogeneous catalyst and pollutants are Fe-SBA-15/H2O2 and Rhodamine B [28], FeOx,SiO2,TiO2/Ti/H2O2 and phenol [22], FeZSM-5 and Reactive Red 120 [29], Fe 3+ /Cu 2+grafted ZnO [37], copper loaded bentonite and Yellow FCF [38], Cu-Zeolites and 2-( m e t hy l m e r c a p t o ) -be n z o t h i a zo l e [ 3 9 ] , Fe/clinoptilolite zeolite and phenol [23], Cum o d i f i e d a l k a l i n i z e d g -C 3 N 4 [ 4 0 ] , CuO/Fe2O3/SBA-15 and N, N-diethyl-p-phenyl diamine degradation [41], Fe2O3/ACF and of acid red B [42], Fe/OMC and 4-chlorophenol [24], GO-Fe2O3 [43], HPW-Fe-Bent and methyl orange [44], Fe/meso-Al2O3 and phenol [45], Fe(III)-SiO2 and polyacrylamide [46], Fe(III)-HY [47], Fe-doped TiO2 and carboxylic acids [48], CsxH3−xPW12O40 [49], CuFeZSM-5 and Rhodamine 6G [50], Bi-doped goethitehematite and actual pesticide [51], Ag2O-ZnO [52], Schwertmannite and phenol [26], Fe- titanate [53], Ferric giniite [54], Fe3O4-GO and phenol [27], BiFeO3-g-C3N4 and lignin [55], MoS2/Fe3O4 [56], Ag loaded CoFe2O4/Fe2O3 and R6G [57]. Figure 1 (a, b, c, and d) shows the number of research papers related to the appli-cation of the hydrothermal method [57][58][59], wet impregnation method [22,28,29], sol-gel method [4,17,60], precipitation and co-precipitation method [61...…”