Highly ordered mesoporous aluminaosilicate was successfully synthesized for water purification by using fly ash as aluminium and silica sources, which is the major component of suspended particulate matter (PM2.5). The adsorption performance of this adsorbent was investigated by the removal capability of methylene blue and crystal violet. The thermodynamics and kinetics for the dyes adsorption mechanism were also evaluated by pseudo-second-order kinetic model and Langmuir isotherm model. The results show that the obtained adsorbent exhibits high adsorption performances for dyes; in particular, a remarkably high methylene blue adsorption (2003 mg g−1) was recorded. This study highlighted a great potential of using fly-ash based adsorbents for removing dyes from wastewater.