Hydroxypropyl methylcellulose based aerogels: Synthesis, characterization and application as adsorbents for wastewater pollutants

• HPMC DS and MS values had no effect on the aerogels density and compressive modulus.
• Aerogels made of high MS HPMC showed high adsorption capacity for ethinyl estradiol.
• Aerogels made of high DS HPMC showed high adsorption capacity for methylene blue.
• Aerogels were recycled after rinsing or light irradiation up to 5 times consecutively.

Hydroxypropyl methylcellulose (HPMC) E4M and J5MS samples with degrees of substitution of methyl groups (DS) 1.9 and 1.5, respectively, and molar substitutions of hydroxypropyl groups (MS) 0.25 and 0.75, respectively, were used to create aerogels in the presence of citric (cit), oxalic (oxa) or terephthalic (ter) acids, as crosslinkers. E4M-cit, J5MS-cit and J5MS-oxa aerogels presented outstanding stability in water, acid media, alcohols, acetone and hydrocarbons, density values of ∼(0.020 ± 0.002) g/cm3, compressive modulus ranging from (111 ± 9) kPa to (133 ± 11) kPa. On the other hand, E4M-oxa, E4M-ter and J5MS-ter aerogels were not adequate adsorbents because they collapsed in water. The adsorption behavior of 17α-ethinyl estradiol (EE) and methylene blue (MB) onto E4M-cit, J5MS-cit and J5MS-oxa aerogels were fitted to Freundlich model, indicating higher affinity of EE for J5MS-cit and J5MS-oxa and higher affinity of MB for E4M-cit aerogels. HPMC aeorogels could be successfully reused.