Enhancement in amoxicillin adsorption and regeneration properties of SBA-15 after surface modification with polyaniline

In this study, the ordered-mesoporous silica SBA-15 was modified into a composite adsorbent (PANI-SBA-15) through in-situ polymerization of aniline inside its mesopores. During polymerization, the residual cationic species from SBA-15 were washed away, which increased the surface negative charge in PANI-SBA-15. It encouraged faster and higher adsorption of amoxicillin (34.2 mg.g(-1)) with PANI-SBA-15, as compared to SBA-15 (24.7 mg.g(-1)). The kinetics study shows that adsorption on PANI-SBA-15 follows pseudo-second-order rate expression and is regulated by the pore-diffusion mechanism. The adsorption mechanism was explained with changes in surface chemistry and kinetics of adsorption. The regeneration of exhausted PANI-SBA-15 with HNO3 is higher (up to 98%) as compared to SBA-15 (86%). The regenerated composite material were reused successfully without significant loss of its adsorption capacity (>80% after 6 cycles). The PANI-SBA-15 removed 64.7 to 70.8% impurities from different simulated hospital wastewater samples.

Automated summary

In this study, ordered-mesoporous silica SBA-15 was modified into a composite adsorbent PANI-SBA-15, with a higher adsorption rate and capacity for amoxicillin due to increased surface negative charge. The adsorption mechanism is regulated by pore-diffusion and regeneration with HNO3 results in high efficiency. PANI-SBA-15 successfully removes impurities from simulated hospital wastewater samples.