Figure 2. The prepared MoO 3 -based membrane (5 µ m) was used to vacuum-filtrate the dyes at di ff erent Figure 2. The prepared MoO 3 -based membrane (5 µm) was used to vacuum-filtrate the dyes at different concentrations (ppm): ( a ) 10 ppm of methylene blue (MB); ( b ) 10 ppm of rhodamine B (RhB); concentrations (ppm): ( a ) 10 ppm of methylene blue (MB); ( b ) 10 ppm of rhodamine B (RhB); ( c ) 10 ppm ( c ) 10 ppm of methyl orange (MO); ( d ) adsorption percentage in ppm for different dyes; ( e ) FT-IR of methyl orange (MO); ( d ) adsorption percentage in ppm for di ff erent dyes; ( e ) FT-IR spectrum of the spectrum of the membrane: dyes adsorbed; ( f ) FT-IR spectrum of the membrane: dyes desorbed. membrane: dyes adsorbed; ( f ) FT-IR spectrum of the membrane: dyes